Skip to main content
Advertisement
Browse Subject Areas
?

Click through the PLOS taxonomy to find articles in your field.

For more information about PLOS Subject Areas, click here.

  • Loading metrics

Evaluation of the psychometric properties of the HIV Disability Questionnaire among adults living with HIV in the United Kingdom: A cross-sectional self-report measurement study

  • Darren A. Brown ,

    Contributed equally to this work with: Darren A. Brown, Bryony Simmons, Rachel Aubry, Richard Harding, Kelly K. O’Brien

    Roles Conceptualization, Data curation, Formal analysis, Methodology, Project administration, Writing – original draft, Writing – review & editing

    Darren.Brown@chelwest.nhs.uk

    Affiliation Chelsea and Westminster Hospital NHS Foundation Trust, Therapies Department, London United Kingdom

  • Bryony Simmons ,

    Contributed equally to this work with: Darren A. Brown, Bryony Simmons, Rachel Aubry, Richard Harding, Kelly K. O’Brien

    Roles Data curation

    Affiliation Imperial College London, Faculty of Medicine, Department of Medicine, London, United Kingdom

  • Marta Boffito ,

    Roles Conceptualization, Project administration, Resources

    ‡ These authors also contributed equally to this work.

    Affiliation Chelsea and Westminster Hospital NHS Foundation Trust, Department of HIV Medicine, London, United Kingdom

  • Rachel Aubry ,

    Contributed equally to this work with: Darren A. Brown, Bryony Simmons, Rachel Aubry, Richard Harding, Kelly K. O’Brien

    Roles Data curation, Writing – original draft

    Affiliation Department of Physical Therapy, University of Toronto, Toronto, Canada

  • Nneka Nwokolo ,

    Roles Conceptualization, Project administration

    ‡ These authors also contributed equally to this work.

    Affiliation Chelsea and Westminster Hospital NHS Foundation Trust, London, United Kingdom

  • Richard Harding ,

    Contributed equally to this work with: Darren A. Brown, Bryony Simmons, Rachel Aubry, Richard Harding, Kelly K. O’Brien

    Roles Funding acquisition, Methodology, Writing – review & editing

    Affiliation Florence Nightingale Faculty of Nursing, Midwifery & Palliative Care, King’s College London, Department of Palliative Care, Policy & Rehabilitation, London, United Kingdom

  • Kelly K. O’Brien

    Contributed equally to this work with: Darren A. Brown, Bryony Simmons, Rachel Aubry, Richard Harding, Kelly K. O’Brien

    Roles Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Supervision, Writing – original draft, Writing – review & editing

    Affiliations Department of Physical Therapy, University of Toronto, Toronto, Canada, Institute of Health Policy, Management and Evaluation (IHPME), University of Toronto, Toronto, Canada, Rehabilitation Sciences Institute (RSI), University of Toronto, Toronto, Canada

Abstract

Objective

To evaluate the psychometric properties of the HIV Disability Questionnaire (HDQ) among people living with HIV (PLHIV) in London, United Kingdom (UK).

Methods

This is a cross-sectional measurement study. We recruited and administered the self-reported HDQ, seven criterion measures, and a demographic questionnaire with adults living with HIV accessing HIV care. We determined median and interquartile ranges (IQR) for disability presence, severity and episodic scores (range 0–100). We calculated Cronbach’s alpha (α) Kuder-Richardson-20 (KR-20) statistics for disability and episodic scores respectively (internal consistency reliability), smallest detectable change (SDC) for each HDQ severity item and domain (precision), and tested 36 a priori hypotheses assessing correlations between HDQ and criterion scores (construct validity).

Results

Of N = 243 participants, all were male, median age 40 years, 94% currently taking antiretroviral therapy, and 22% living with ≥2 concurrent health conditions. Median HDQ domain scores ranged from 0 (IQR: 0,7) (difficulties with day-to-day activities domain) to 27 (IQR: 14, 41) (uncertainty domain). Cronbach’s alpha for the HDQ severity scale ranged from 0.85 (95% Confidence Interval (CI): 0.80–0.90) in the cognitive domain to 0.93 (95%CI: 0.91–0.94) in the mental-emotional domain. The KR-20 statistic for the HDQ episodic scale ranged from 0.74 (95%CI: 0.66–0.83) in the cognitive domain to 0.91 (95%CI: 0.89–0.94) in the uncertainty domain. SDC ranged from 7.3–15.0 points on the HDQ severity scale for difficulties with day-to-day activities and cognitive symptoms domains, respectively. The majority of the construct validity hypotheses (n = 30/36, 83%) were confirmed.

Conclusions

The HDQ possesses internal consistency reliability and construct validity with varied precision when administered to males living with HIV in London, UK. Clinicians and researchers may use the HDQ to measure the nature and extent of disability experienced by PLHIV in the UK, and to inform HIV service provision to address the health-related challenges among PLHIV.

Background

For the 36.9 million people living with HIV (PLHIV) globally [1], effective treatment offers normal life expectancy [2]. Consequently, PLHIV surviving past 50 years of age are increasing at exponential and unprecedented rates [3]. In 2017, more than a third (39%) of PLHIV receiving HIV care in the UK were aged 50 years or older [4]. Moreover by 2028 it is estimated over half of people in UK HIV care will be aged ≥50 years [5] with repeated patterns forecast in Europe and North America [6]. As people live longer with chronic HIV infection, they are susceptible to health conditions arising from the underlying infection, potential side effects of treatments, and ageing [7], resulting in increasingly more prevalent multi-morbidity [8]. Common conditions include bone and joint disorders [9,10], mental health conditions [11], cardiovascular disease [1214], cancer [15,16], and neurocognitive decline [17,18]. The presence of these conditions can create physical, mental, cognitive and social health-related challenges that are conceptualised as disability [19].

Disability is multi-dimensional [20] and episodic in nature [19]. The Episodic Disability Framework in HIV defines disability as: physical, cognitive, mental and emotional symptoms and impairments, difficulties carrying out day-to-day activities, challenges to social inclusion, and uncertainty or worrying about the future [19]. These can fluctuate on a daily basis and over the life course. Furthermore, these dimensions of disability can be exacerbated or alleviated by extrinsic contextual factors (e.g. social support and stigma) and intrinsic contextual factors (e.g. living strategies and personal attributes) [21].

As people live longer, disability assessment and treatment will be a critical component to HIV care. Measuring disability in the context of HIV is important for determining the prevalence and impact of disability, identifying interventions that may reduce disability, and to inform disability-inclusive programming [22]. A valid and reliable patient-reported outcome measure (PROM) for PLHIV that can be used by PLHIV, community-based service organisations, and health providers, is critical to identify the nature and extent of disability experienced by PLHIV, assess the burden of disability living with HIV, and determine the effect of medical and rehabilitation interventions in mitigating disability. This knowledge could be used by clinicians, social service providers, health service commissioners, and policy makers, to help guide policy and program development and inform the allocation of health care resources to improve care, treatment and support, designed to reflect the long-term nature of HIV care [23].

Existing HIV-specific health status instruments tend to focus on impairments and do not fully capture the breadth of disability, specifically lacking items related to social inclusion and uncertainty [21]. Impairment data alone is not an adequate proxy for disability, as people with the same impairment can experience different types and degrees of limitations, depending on personal and environmental factors [24]. The majority of studies assessing disability among PLHIV focused on measurements of single impairments [25], providing a relatively narrow understanding of disability [26] that is insufficient in capturing the multi-dimensional nature of HIV [19,25]. To our knowledge, there is no known self-reported data on disability, beyond impairments alone, experienced by PLHIV in the UK.

The HIV Disability Questionnaire (HDQ) is a new self-administered HIV-specific PROM developed to measure the presence, severity and episodic nature of disability among PLHIV [27]. The HDQ is comprised of six dimensions of disability that were derived from the Episodic Disability Framework, a conceptual framework developed from the perspective of PLHIV to characterise the health-related challenges living with HIV [28]. The HDQ is novel in that it is the sole HIV-specific PROM of disability [29]. However, disability may vary depending on the context and region of the world in which PLHIV live [30]. Therefore, it is critical to assess psychometric properties with a population and setting that is representative of the context in which questionnaires will be used [31]. The HDQ possessed sensibility (including face and content validity) with a sample of adults living with HIV in Canada [32]. The HDQ demonstrated construct validity and test-retest reliability when used with PLHIV in Canada [33], and construct validity and internal consistency reliability when used with PLWH in Ireland [34] and the United States [35]. Compared to these contexts, the UK has a different healthcare system [36] with more PLHIV accessing antiretroviral therapy and achieving viral suppression [4,37], rendering the relevance and applicability of the HDQ to PLHIV in other developed countries, such as the UK unknown.

Our aim was to assess the measurement properties, specifically internal consistency reliability, precision of measurement, and construct validity, of the HDQ for its ability to measure disability experienced by adults living with HIV in London, UK.

Methods

We conducted a cross-sectional measurement study, to assess construct validity and reliability of the HDQ. We used quality criteria for assessing measurement properties of health status questionnaires to guide our methodological approach [31]. We recruited adults, 18 years of age or older, living with HIV who attended an outpatient HIV clinic in central London, UK between March 2016 and May 2017. Potential participants were approached during regular clinic visits for their participation in the study. All participants provided written informed consent. Ethical approval was obtained from the London Dulwich Research Ethics Committee and Health Research Authority (IRAS 165402) and the HIV/AIDS Research Ethics Board at the University of Toronto, Canada (Protocol #34126). A data sharing agreement was approved between St Stephen’s Clinical Research, Cicely Saunders Institute King’s College London, and the University of Toronto.

We administered the HDQ, a demographic questionnaire, and seven health status criterion measures (Patient Health Questionnaire (PHQ-9) [38], General Anxiety Disorder (GAD) Questionnaire [39], Fatigue Severity Scale [40], Wellness Thermometer [41], Epworth Sleepiness Scale (ESS) [42], Everyday Memory Questionnaire (EMQ) [43], and International HIV Dementia Scale (IHDS) [44]. Participants had the option to either complete the questionnaires at their clinic visit, or take them home and return later via the post. Clinical characteristics were obtained from participants’ electronic medical records including number of years since HIV diagnosis, antiretroviral therapy use, most recent CD4 count (cells/mm3), viral load (cells/ml), and diagnosed concurrent health conditions.

HIV disability questionnaire (HDQ)

The HDQ, English Version 10.5, 2017, is a 69 item self-administered questionnaire developed from the Episodic Disability Framework, through a community-academic partnership, to describe the presence, severity and episodic nature of disability experienced by PLHIV [19,27]. The HDQ includes six disability domains: i) physical, ii) cognitive and, iii) mental and emotional health symptoms and impairments, iv) uncertainty, v) difficulty with day-to-day activities, and vi) challenges to social inclusion, and one ‘good day/bad day’ health classification item. Participants are asked to rate the level of presence and severity of each health challenge on a given day ranging from 0 (not at all) to 4 (extreme). HDQ scores range from 0 to 100 with higher scores indicating a greater presence, severity and episodic nature of disability. The HDQ has demonstrated sensibility, validity, internal consistency reliability and test-retest reliability in samples of adults living with HIV in Canada, Ireland and the United States [3335]. Median administration time is 8–15 minutes.

We calculated disability presence, severity and episodic scores on the HDQ [45]. Disability presence scores were calculated by summing the number of health challenges experienced for each domain and total HDQ and transforming them to a score out of 100. Disability severity scores were calculated by summing individual item scores from each domain and then linearly transforming them into domain disability severity scores out of 100. Episodic disability scores were calculated by summing the number of challenges identified as episodic in each domain and then transforming to a score out of 100. We summed the number of participants and proportion who completed the HDQ on a ‘good day’ or ‘bad day’ living with HIV (health classification). We computed missing response rates for the disability, episodic, and health classification sections of the HDQ accordingly. To maximise HDQ data, we performed mean (severity) or median (episodic) imputation on items with less than ≤10% missing responses. List wise deletion was performed for criterion measures with missing responses. We examined the distribution of HDQ item scores for a floor effect (defined as >15% of responses at the bottom (0) of the HDQ scale) and ceiling effect (defined as >15% of responses at the high end (4) of the HDQ scale).

Demographic questionnaire

Participants completed a self-reported questionnaire to capture demographic characteristics including; age (years), gender, ethnicity, nationality, sexuality, smoking status, household description, employment status, educational attainment, and whether registered with GP physician.

Reliability—internal consistency

We calculated the Cronbach’s alpha (α) (severity scales) and Kuder-Richardson-20 statistics (episodic scales) for the HDQ domain scores to assess internal consistency reliability (degree to which the items within the instrument are correlated with each other) [α and KR-20 >0.8 defined as acceptable for individual patients] [46].

Precision of measurement

Standardised Error of Measurement (SEM) is a measure of precision of an instruments ability to estimate the true state of a concept. We used Wyrich criteria [47] to calculate the SEM for each item and domain score to determine the precision of measurement, meaning how accurate the observed HDQ score is with the participants’ true HDQ scores. [SEM = standard deviation*sqrt (1-Cronbach alpha)]. We then calculated the smallest detectable change (SDC) to determine the range in which we can be 95% confident that the true HDQ is within this range. [Observed score +/- 1.96*SEM].

Construct validity

Measuring disability poses several challenges, with a wide range of disability definitions, and varying approaches to disability measurement [24,48]. In the absence of a ‘gold standard’ approach to measuring disability [49], we assessed the accuracy of the HDQ by testing a priori hypotheses about predicted relationships between scores of measures that relate to disability [3844] with scores of the HDQ.

We determined the extent to which the HDQ relates or does not relate to the seven criterion measures [3844]. The appropriate subscale scores of the HDQ were compared to criterion measures using correlation analysis. We tested 8 primary and 29 exploratory hypotheses theorising relationships between data collected in the HDQ and criterion measures using correlation coefficients (Pearson if scores normally distributed, Spearman if not normally distributed). Hypotheses included convergent and divergent construct validity testing based on previous construct validity assessment of the HDQ [3335], and aimed to maximise data related to dimensions of the HDQ and subscale scores data collected from criterion measures. Correlation coefficients of |≥0.30|, |≥0.50| and |≥0.70|, were defined as ‘weak’, ‘moderate,’ and ‘strong,’ respectively [31]. We considered the HDQ to possess construct validity if results confirm at least 75% of the predetermined hypotheses [31]. All data analyses were performed using SAS software version 9.4 [50].

Sample size

Our required sample size was estimated based on our construct validity analysis. To detect a weak correlation from our construct validity hypothesis, r = 0.30, with a power of 0.80, and alpha of 0.05, we required a sample of n = 85, inflated to at least 102 for an estimated 20% missing response rate at item level.

Results

Participant characteristics

Of the 244 participants recruited, all but one identified as male (Table 1). We excluded the one participant who identified as female resulting in a total of 243 participants in this study. The median age of participants was 40 years (20% were ≥50 years), with a median year of diagnosis of 2012 (96% diagnosed 1996 or after). The majority were employed (87%), 94% were currently taking antiretroviral therapy, and 82% had an undetectable viral load (Table 1). Fifty-four percent (54%) of participants were living with a concurrent health condition in addition to HIV, and 22% reported living with at least two or more concurrent health conditions. The most common concurrent health condition was mental health (e.g. anxiety, depression, personality disorder, or schizophrenia).

thumbnail
Table 1. Characteristics of participants in analysis (n = 243).

https://doi.org/10.1371/journal.pone.0213222.t001

Data completeness

The median number of missing responses for HDQ items was 7 (2.9%) for the presence and severity scale and 13 (5.3%) for the episodic scale. Proportion of missingness was <3% for the severity scale and <10% for the episodic scale. Rates for missing responses for each item were higher on the episodic scale, with 11.7% (n = 109/929) of missing episodic scale responses also missing severity scale responses. However 77.7% (n = 637/820) of missing episodic scale responses were present in conjunction with a severity scale score of zero, which might be attributed to some participants skipping this item if they did not feel as if they had that specific health challenge. There were 10 missing responses (4.1%) for the ‘good day / bad day’ item on the HDQ.

HDQ scores

HDQ item scores were not normally distributed. A floor effect was evident in all 69 HDQ items (100%) with >20% of the sample responding 0 (no challenge), and 52 of the items (75.4%) had a floor effect >40%. Floor effect was most prominent in the physical (95%), cognitive (100%), and day-to-day activities (100%) domains. A ceiling effect was not present in any of the HDQ items.

Highest disability presence score was in the uncertainty domain, followed by domains mental-emotional health symptoms, challenges to social inclusion, physical symptoms, and cognitive symptoms. Highest disability severity score also was in the uncertainty domain, followed by challenges to social inclusion, mental-emotional symptoms, physical symptoms, and cognitive symptoms. Physical symptoms had the highest episodic score (Table 2). The number of participants who identified as completing the HDQ on a ‘good day’ living with HIV was 193 (79%).

thumbnail
Table 2. HDQ Summary scores for participants in the UK sample (n = 243).

https://doi.org/10.1371/journal.pone.0213222.t002

Criterion measures

Similar to the HDQ, criterion measure summary scores were skewed to the healthier range of the scales (Shapiro Wilk Test for all criterion items and summary scores p<0.0001; data not shown). Median PHQ-9 scores were 4 out of possible range 0–27 (IQR: 2, 8) indicating ‘minimal’ depression severity. Median GAD scores were 10 out of possible range 0–21 (IQR: 8, 14) indicating low to moderate anxiety. Median scores of the international HIV dementia scale was 12 out of possible range 0–12 (IQR: 7,12), and 8 out of possible range 0–52 (IQR: 4, 15) on the EMQ, indicating high cognitive health. Median scores on the Wellness Thermometer was 7 out of possible range 0–10 (IQR: 5, 8) indicating participants reported to tend to feel well. Median scores of the Fatigue Scale were 29 out of possible range 9–63 (IQR: 21, 38) indicating participants may be approaching fatigue. Median scores on the ESS was 6 out of possible range 0–64 (IQR: 3, 9) indicating no evidence of abnormal daytime sleepiness in this sample.

Reliability—Internal consistency

HDQ severity scores.

All individual items correlated with the HDQ Total Severity Score >0.2 except for Item #8 –‘I have trouble swallowing food’ (r = 0.14; p = 0.03), and Item #15 –‘I am unintentionally losing weight’ (r = 0.19; p = 0.03), and each item correlated with its corresponding domain score >0.20.

HDQ episodic scores.

All individual items correlated with the HDQ Total Episodic Score >0.20 except for Item #8 (r = 0.11; p = 0.08) and Item #15 (r = 0.15; p = 0.02), and each item correlated with its corresponding domain score >0.20.

Cronbach’s alpha for the entire HDQ was 0.96 (95% Confidence Interval (CI): 0.96–0.97) and ranged from 0.85 (95%CI: 0.80–0.90) in the cognitive domain to 0.93 (95% CI: 0.91–0.94) in the mental-emotional domain. The KR-20 statistic for the entire episodic scale of the HDQ was 0.95 (95% CI: 0.94–0.96) and ranged from 0.74 (95% CI: 0.66–0.83) in the cognitive domain to 0.91 (95% CI: 0.89–0.94) in the uncertainty domain (Table 3).

thumbnail
Table 3. Internal consistency reliability for HDQ items (n = 243).

https://doi.org/10.1371/journal.pone.0213222.t003

Precision of measurement

The standardised error of measurement (SEM) for HDQ items ranged from 0.05 (Item #8 –I have trouble swallowing food) to 0.28 (Item #64 –I find it hard to talk to others about my illness). Level of precision for the HDQ domain scores ranged from most precise in the difficulties with day-to-day activities domain (SEM: 3.71; SDC: 7.29) to the least precise in the cognitive symptoms domain (SEM: 7.68; SDC: 15.05) (Table 4).

thumbnail
Table 4. Level of precision of HDQ scores for participants (n = 243).

https://doi.org/10.1371/journal.pone.0213222.t004

Construct validity

Of the 36 construct validity hypotheses (8 primary, 28 exploratory), seven (88%) primary, 23 (28%) exploratory, and 30 (83%) of the total hypotheses were confirmed (Table 5).

Discussion

The HDQ demonstrated internal consistency reliability and construct validity among a community dwelling sample of males living with HIV in an urban UK setting. Internal consistency reliability was achieved with Cronbach’s alpha and KR-20 statistics (scores >0.8) for all domain and total scores for episodic and severity scores, except for the cognitive domain for the episodic scale. This suggests that collectively items in the HDQ are homogenous within the six HDQ domains to collectively measure the broader construct of disability at one time point [34]. Precision of measurement varied with subscales scores demonstrating highest levels of precision in the difficulties with day-to-day activities domain (SDC: 7.68), to lowest levels of precision in the cognitive symptoms domain (SDC: 15.05), suggesting among PLHIV, the HDQ possesses levels of measurement error and day-to-day variability. Construct validity was achieved as demonstrated by 88% primary (n = 7/8) and 83% total (n = 30/36) hypothesised relationships confirmed between the HDQ and criterion measures, which surpassed our 75% construct validity threshold [31]. Our results build on previous evidence establishing internal consistency reliability and construct validity of the HDQ in Canada [33], Ireland [34], and the United States [35], as well as test-retest reliability in Canada [34].

Our study provides the first known assessment of HDQ psychometric properties including internal consistency reliability, construct validity, and level of precision of HDQ domain scores in the UK. Internal consistency reliability findings in this UK sample were similar to those among PLHIV for HDQ severity and episodic scores in Canada (α range: 0.87–0.97; KR-20 range: 0.81–0.98) (33), Ireland (α range: 0.84–0.96; KR-20 range: 0.85–0.96) (34), and the United States (α range: 0.89–0.93; KR-20 range: 0.87–0.96) (35), demonstrating the HDQ is reliable in measuring disability across high-income settings for PLHIV. Across all settings, Cronbach’s α or KR-20 were >0.8 for all domains and total scores for both episodic and severity disability scores, except for the UK cognitive symptoms and impairments domain for the episodic summary score (KR-20; 0.74). The cognitive domain possesses the fewest number of items (n = 3), which might account for the lower alpha and KR-20 coefficients in this domain. Nevertheless, internal consistency reliability coefficients in this study exceeded the Special Advisory Committee of the Medical Outcomes Trust recommendations, that considers a Cronbach’s alpha of ≥0.70 to be acceptable [51].

Precision of the HDQ scores varied across HDQ domains ranging from a SDC of 7.68 (difficulties with day-to-day activities) to 15.50 (cognitive domain). The smaller the SDC, the more precise the domain. These values suggest the minimum difference in HDQ domain scores that would need to occur in order to be confident that an individual had a true change in disability beyond day-to-day variability or measurement error. Our study is the first to report on levels of precision of the HDQ. SEM dually reflects precision of an instrument, as well as the measure's variation within a patient sample [52]. Nevertheless, results are cross-sectional distribution based scores, and there is no universal consensus on how many SEMs an individual must change in order for a change in scores to be considered significant, nor clinically important [52]. Future research should assess the interpretability of HDQ scores to determine the meaning of HDQ scores (cross-sectionally) as well as the minimally clinically importance difference (MCID) (longitudinally) that represent the important ‘amount’ and ‘importance’ of change in disability over time.

The HDQ possesses construct validity in this UK sample, for its ability to measure disability as demonstrated by confirmation of total hypothesised relationships between HDQ and criterion measures (83%), which was above our a priori defined threshold of 75% [31]. Construct validity was similarly demonstrated in Canada (80%) [34] and the United States (87%) [35], and also was demonstrated in Canada using confirmatory factor analysis [33]. However it is not possible to compare the UK construct validity results to these previous studies, because the UK analysis used different criterion measures.

While the HDQ overall demonstrated internal consistency reliability and construct validity for use among males with HIV in the UK and PLHIV in other high-income countries, reasons may exist for variations in HDQ scores and properties across different cultural contexts. Diversity in sample populations, recruitment procedures, and mechanisms in which the HDQ and reference measures were administered, may account for differences in HDQ scores and measurement property coefficients. For instance, UK participants were all male, mostly economically active and university educated, and living with well controlled HIV, recruited from an HIV clinic setting, compared with HDQ assessment with PLHIV in Ireland [34]; where fewer participants were working for pay, and had been living longer with their HIV diagnosis. Moreover participants in Canada [33] were older, living with more comorbidities, and fewer working for pay, when recruited from community-based organisations. Furthermore, UK participants completed measurements either during their clinic visit or independently at home following their routine outpatient HIV care appointments, while Irish participants completed measures intermittently while seeing various health providers in a busy HIV outpatient setting, and Canadian participants completed measures consecutively in one single sitting in a quiet location at an HIV service organisation [34]. This may have introduced inconsistencies in the way participants responded to items across the questionnaires, creating variations in correlations between measures [34]. Similarly the different criterion measures used in the UK analysis may have resulted in different estimations of the extent to which we hypothesised items in the HDQ would correlate with items included in these criterion measures. Notably, our UK analysis did not include universal measures of disability, therefore to compare to other conditions a generic disability measurement tool might be recommended (e.g. World Health Organization Disability Assessment Schedule 2.0) [53]. Hence, measurement properties should be interpreted cautiously and specific to the context and sample population.

Our results indicate that the HDQ domain of uncertainty or worrying about the future, was the most present and severe domain of disability in this UK sample of PLHIV. Uncertainty is a unique domain of disability within the Episodic Disability Framework [54]. It is also a core dimension of disability experienced by adults ageing with HIV [55]. Older PLHIV may worry about HIV specific age-related uncertainties [56] and the trajectory of episodic disability [57]. The role of uncertainty has also been incorporated into rehabilitation recommendations for adults ageing with HIV [58], whereby interventions can promote stability, mitigate increasing disability, and increase time between episodes [57]. Our results indicate that uncertainty can be experienced across the life-course among a younger sample of PLHIV in the UK, building on existing literature that uncertainty is the most present and severe domain of disability experienced by PLHIV in Canada [33], Ireland [34], and the United States [35]. In this UK sample, the most episodic domain of disability was in the physical domain, which was similarly observed in Ireland [34] and the United States [35]. This is likely attributed to health challenges in this domain more likely to fluctuate on a daily basis (e.g. aches and pains, fatigue) opposed to items in the social inclusion domain (e.g. employment, relationships), which may fluctuate over a longer duration of time. Further exploration is warranted into the experiences of uncertainty and episodic health challenges across the life-course among PLHIV in the UK, and the impact of rehabilitation, such as group-based interventions [59] to address disability including uncertainty.

Our study has limitations. Firstly participants were all male, mostly aged younger than 50 years, with half the sample living with at least one concurrent health condition, and living in an urban setting. Therefore this sample is not representative of the UK population of PLHIV, of which 36% are living in London, 31% are female, with more than one third aged ≥50 years, and 73% who are living with at least one concurrent health condition [4,60]. This may demonstrate recruitment bias, with the sample representing people living ‘well’ with HIV in an urban setting accessing HIV care. However, the HDQ was developed primarily with men living with HIV in a large metropolitan city, which may explain the high construct validity in this study, as this study sample might resemble the sample from which the HDQ was originally derived, validated, and refined in Ontario, Canada [34]. Nevertheless, evaluation of the psychometric properties of the HDQ among females living with HIV, and in other low to middle income contexts is warranted. Secondly, given this study was part of a larger cohort study (IRAS 165402), the criterion measures to assess construct validity were not consistent with previous HDQ psychometric evaluations [3335]. Therefore caution should be applied when comparing the validity and reliability of the HDQ. Next, because our goal was to assess the measurement properties of the HDQ in the UK, rather than to measure disability experienced by PLHIV in the UK, HDQ scores should be interpreted cautiously. Lastly, given the one-time administration of the HDQ, our analysis was limited to assessing internal consistency reliability and construct validity of the HDQ in the UK. Further analysis of the reproducibility, responsiveness and interpretability of the HDQ among PLHIV in the UK is needed.

Identification of the HDQ as a valid and reliable self-reported disability assessment tool has important implications for clinical practice, research and policy. Clinicians, HIV community organisations, and researchers, may use the HDQ to assess disability experienced by PLHIV in the UK. The aim of the HDQ is to describe the health-challenges experienced among PLHIV, whether these challenges are related to HIV or other concurrent health conditions [34]. The HDQ should be administered in combination with other health status instruments that capture extrinsic contextual factors (e.g social support, stigma) and intrinsic contextual factors (e.g. concurrent health conditions) that can influence disability in order to provide a better understanding of the context in which disability is experienced by PLHIV [27]. To our knowledge, there is no known evidence exploring disability experienced by PLHIV in the UK. Data on disability experienced by PLHIV, capturing multiple domains of functional limitations, is therefore required in the UK. Measuring disability can provide information on the nature and extent of disability, and the health care needs of PLHIV in the UK. This knowledge can help to inform ways in which HIV services can adopt approaches to better respond to the changing needs of PLHIV [23], while ensuring function is incorporated into the provision of person-centered care [61]. Results provide a foundation for future research to utilise the HDQ to examine the extent and nature of disability among PLHIV in the UK and international cross-cultural comparisons of disability for PLHIV.

Conclusions

The HDQ possesses internal consistency reliability and construct validity with varied levels of precision across domain scores, when administered to adults living with HIV in the UK. Results are specific to a mainly community dwelling sample of males, who are mostly economically active and university educated, living with well-controlled HIV. Future research should examine HDQ properties among women living with HIV in the UK, PLHIV in low-to middle income countries, responsiveness to change, and interpretability of HDQ scores. Future research should consider cross-cultural, international comparisons of disability, and the ability of the HDQ to detect clinically important changes in disability for examining effectiveness of interventions.

Acknowledgments

We gratefully acknowledge the support of St Stephen’s Clinical Research in managing the Dean Street Cohort Study. We also gratefully acknowledge the Dean Street Cohort Study participants, involved in this study.

References

  1. 1. UNAIDS. Fact Sheet; 2017 Global HIV Statictics—July 2018. 2018; Available at: http://www.unaids.org/sites/default/files/media_asset/UNAIDS_FactSheet_en.pdf. Accessed 22nd October, 2018.
  2. 2. Antiretroviral Therapy Cohort Collaboration. Survival of HIV-positive patients starting antiretroviral therapy between 1996 and 2013: a collaborative analysis of cohort studies. The Lancet HIV 2017.
  3. 3. Thurn M, Gustafson DR. Faces of Frailty in Aging with HIV Infection. Curr HIV/AIDS Rep 2017 02;14(1):31–37. pmid:28210943
  4. 4. Nash S, Desai S, Croxford S, Guerra L, Lowndes C, Connor N, et al. Progress towards ending the HIV epidemic in the United Kingdom: 2018 report. November 2018, Public Health England, London. 2018.
  5. 5. Yin Z, Kall M, Skingsley A, Dalpech V. Over half of people in HIV care in the United Kingdom by 2028 will be aged 50 years or above. 2015; Available at: http://www.ucl.ac.uk/voices/pdfs/HIV_care. Accessed January, 2019.
  6. 6. Smit M, Brinkman K, Geerlings S, Smit C, Thyagarajan K, van Sighem A, et al. Future challenges for clinical care of an ageing population infected with HIV: a modelling study. The Lancet Infectious Diseases 2015;15(7):810–818. pmid:26070969
  7. 7. Nixon SA, Hanass-Hancock J, Whiteside A, Barnett T. The increasing chronicity of HIV in sub-Saharan Africa: Re-thinking" HIV as a long-wave event" in the era of widespread access to ART. Globalization and health 2011;7(1):41.
  8. 8. Deeks SG, Lewin SR, Havlir DV. The end of AIDS: HIV infection as a chronic disease. The Lancet 2013;382(9903):1525–1533.
  9. 9. Mallon PW. Aging with HIV: osteoporosis and fractures. Curr Opin HIV AIDS 2014 Jul;9(4):428–435. pmid:24871090
  10. 10. Compston J. HIV infection and bone disease. J Intern Med 2016;280(4):350–358. pmid:27272530
  11. 11. Chuah FLH, Haldane VE, Cervero-Liceras F, Ong SE, Sigfrid LA, Murphy G, et al. Interventions and approaches to integrating HIV and mental health services: a systematic review. Health Policy Plan 2017.
  12. 12. Cerrato E, Calcagno A, D'Ascenzo F, Biondi-Zoccai G, Mancone M, Marra WG, et al. Cardiovascular disease in HIV patients: from bench to bedside and backwards. Open heart 2015;2(1):e000174. pmid:25815207
  13. 13. Freiberg MS, So-Armah K. HIV and Cardiovascular Disease: We Need a Mechanism, and We Need a Plan. J Am Heart Assoc 2016 Mar 24;4(3):e003411. pmid:27013540
  14. 14. Shah ASV, Stelzle D, Lee KK, Beck EJ, Alam S, Clifford S, et al. Global Burden of Atherosclerotic Cardiovascular Disease in People Living with the Human Immunodeficiency Virus: A Systematic Review and Meta-Analysis. Circulation 2018 Jul 2.
  15. 15. Silverberg MJ, Lau B, Achenbach CJ, Jing Y, Althoff KN, D'souza G, et al. Cumulative Incidence of Cancer Among Persons With HIV in North AmericaA Cohort StudyCumulative Incidence of Cancer Among Persons With HIV in North America. Ann Intern Med 2015;163(7):507–518. pmid:26436616
  16. 16. Yarchoan R, Uldrick TS. HIV-Associated Cancers and Related Diseases. N Engl J Med 2018 03/15; 2018/03;378(11):1029–1041. pmid:29539283
  17. 17. Nightingale S, Winston A, Letendre S, Michael BD, McArthur JC, Khoo S, et al. Controversies in HIV-associated neurocognitive disorders. The Lancet Neurology 2014;13(11):1139–1151. pmid:25316020
  18. 18. Saylor D, Dickens AM, Sacktor N, Haughey N, Slusher B, Pletnikov M, et al. HIV-associated neurocognitive disorder [mdash] pathogenesis and prospects for treatment. Nature Reviews Neurology 2016;12(4):234–248. pmid:26965674
  19. 19. O'brien KK, Bayoumi AM, Strike C, Young NL, Davis AM. Exploring disability from the perspective of adults living with HIV/AIDS: development of a conceptual framework. Health and Quality of Life Outcomes 2008;6(1):76.
  20. 20. World Health Organization. How to use the ICF: a practical manual for using the International Classification of Functioning, Disability and Health (ICF). Exposure draft for comment. October 2013. Geneva: WHO. 2013; Available at: http://www.who.int/classifications/drafticfpracticalmanual.pdf.
  21. 21. O'Brien KK, Davis AM, Strike C, Young NL, Bayoumi AM. Putting episodic disability into context: a qualitative study exploring factors that influence disability experienced by adults living with HIV/AIDS. J Int AIDS Soc 2009 Nov 9;12:5-2652-2-5.
  22. 22. UNAIDS. Disability and HIV. 2017; Available at: http://www.unaids.org/en/resources/documents/2017/jc2905_disability-and-hiv.
  23. 23. Baylis A, Buck D. The future of HIV services in England: shaping the response to changing needs. King's Fund; 2017.
  24. 24. World Health Organization. The World Bank. World report on disability. 2011. WHO Library Cataloguing-in-Publication Data 2011.
  25. 25. Banks LM, Zuurmond M, Ferrand R, Kuper H. The relationship between HIV and prevalence of disabilities in sub‐Saharan Africa: systematic review (FA). Tropical medicine & international health 2015;20(4):411–429.
  26. 26. Mactaggart I, Kuper H, Murthy G, Oye J, Polack S. Measuring disability in population based surveys: the interrelationship between clinical impairments and reported functional limitations in Cameroon and India. PloS one 2016;11(10):e0164470. pmid:27741320
  27. 27. O'Brien KK, Bayoumi AM, King K, Alexander R, Solomon P. Community engagement in health status instrument development: experience with the HIV disability questionnaire. Progress in community health partnerships: research, education, and action 2014;8(4):549–559.
  28. 28. O'Brien KK AR, King K, Tebeje M, Murray J, Bayoumi AM, Bereket T, Swinton M, Norman GR, Solomon P. Developing a new HIV disability questionnaire: A community integrated approach. The Ontario HIV Treatment Network Research Conference; 2009; Toronto, Ontario, Canada. 2009.
  29. 29. Engler K, Lessard D, Lebouché B. A review of HIV-specific patient-reported outcome measures. The Patient-Patient-Centered Outcomes Research 2017;10(2):187–202. pmid:27637488
  30. 30. Hanass-Hancock J, Regondi I, Naidoo K. Disability and HIV: What drives this relationship in Eastern and Southern Africa? African journal of disability 2013;2(1).
  31. 31. Terwee CB, Bot SD, de Boer MR, van der Windt, Daniëlle AWM, Knol DL, Dekker J, et al. Quality criteria were proposed for measurement properties of health status questionnaires. J Clin Epidemiol 2007;60(1):34–42. pmid:17161752
  32. 32. O'Brien K,K., Bayoumi AM, Bereket T, Swinton M, Alexander R, King K, et al. Sensibility assessment of the HIV Disability Questionnaire. Disabil Rehabil 2013 04;35(7):566–577. pmid:22816434
  33. 33. O'Brien K,K., Solomon P, Bayoumi AM. Measuring disability experienced by adults living with HIV: assessing construct validity of the HIV Disability Questionnaire using confirmatory factor analysis. BMJ Open 2014 09/01;4(8):e005456–e005456. pmid:25180054
  34. 34. O'Brien K,K., Solomon P, Bergin C, O'Dea S, Stratford P, Iku N, et al. Reliability and validity of a new HIV-specific questionnaire with adults living with HIV in Canada and Ireland: the HIV Disability Questionnaire (HDQ). Health Qual Life Outcomes 2015 08/12;13:124–124. pmid:26263898
  35. 35. O’Brien KK, Kietrys D, Galantino ML, Parrott JS, Davis T, Levin T, Tran Q, Solomon P. Reliability and Validity of the HIV Disability Questionnaire (HDQ) with Adults Living with HIV in the United States. 26th Annual Canadian Conference on HIV/AIDS (CAHR Conference). Montreal, Quebec. April 6–9, 2017. 2017.
  36. 36. Mossialos E, Djordjevic A, Osborn R, Sarnak D. International Profiles of Health Care Systems. The Commonwealth Fund 2017.
  37. 37. UNAIDS. UNAIDS data 2018. 2018; Available at: http://www.unaids.org/sites/default/files/media_asset/unaids-data-2018_en.pdf. Accessed February/3rd, 2019.
  38. 38. Kroenke K, Spitzer RL, Williams JB. The PHQ‐9: validity of a brief depression severity measure. Journal of general internal medicine 2001;16(9):606–613. pmid:11556941
  39. 39. Spitzer RL, Kroenke K, Williams JB, Löwe B. A brief measure for assessing generalized anxiety disorder: the GAD-7. Arch Intern Med 2006;166(10):1092–1097. pmid:16717171
  40. 40. Valko PO, Bassetti CL, Bloch KE, Held U, Baumann CR. Validation of the fatigue severity scale in a Swiss cohort. Sleep 2008;31(11):1601–1607. pmid:19014080
  41. 41. Croston M, Petrak J, Ustianowski A. Use of the wellness thermometer to improve consultations for patients with human immunodeficiency virus. Nursing Standard (2014) 2017;31(41):46.
  42. 42. Johns MW. A new method for measuring daytime sleepiness: the Epworth sleepiness scale. Sleep 1991;14(6):540–545. pmid:1798888
  43. 43. Royle J, Lincoln NB. The Everyday Memory Questionnaire–revised: Development of a 13-item scale. Disabil Rehabil 2008;30(2):114–121. pmid:17852284
  44. 44. Sacktor NC, Wong M, Nakasujja N, Skolasky RL, Selnes OA, Musisi S, et al. The International HIV Dementia Scale: a new rapid screening test for HIV dementia. AIDS 2005;19(13):1367–1374. pmid:16103767
  45. 45. MILO. McMaster Industry Liaison Office (MILO); HIV Disability Questionnaire (HDQ). 2017; Available at: https://milo.mcmaster.ca/questionnaires/HDQ.
  46. 46. Nunnally J, Bernstein I. Psychometric Theory. 3rd ed. New York: McGraw-Hill; 1978.
  47. 47. Wyrwich KW, Nienaber NA, Tierney WM, Wolinsky FD. Linking clinical relevance and statistical significance in evaluating intra-individual changes in health-related quality of life. Med Care 1999:469–478. pmid:10335749
  48. 48. Palmer M, Harley D. Models and measurement in disability: an international review. Health Policy Plan 2011;27(5):357–364. pmid:21729911
  49. 49. Mont D. Measuring disability prevalence (English). SP discussion paper; no. 706. Washington, DC: World Bank. 2007; Available at: http://documents.worldbank.org/curated/en/578731468323969519/Measuring-disability-prevalence.
  50. 50. SAS Institute Inc. SAS 9.4 computer software. Copyright (c) 2016 by SAS Institute Inc., Cary, NC, USA. 2016;9.4.
  51. 51. Lohr KN. Assessing health status and quality-of-life instruments: attributes and review criteria. Quality of Life Research 2002;11(3):193–205. pmid:12074258
  52. 52. Wyrwich KW. Minimal important difference thresholds and the standard error of measurement: is there a connection? J Biopharm Stat 2004;14(1):97–110. pmid:15027502
  53. 53. Üstün TB. Measuring health and disability: Manual for WHO disability assessment schedule WHODAS 2.0.: World Health Organization; 2010.
  54. 54. O’Brien K, Hanna S, Solomon P, Worthington C, Ibáñez-Carrasco F, Chan-Carusone S, et al. Characterizing the Disability Experience among Adults Living with HIV: A Structural Equation Model Using the HIV Disability Questionnaire (HDQ). Revisions Submitted: January 2019. BMC Infect Dis 2019.
  55. 55. Solomon P, O’Brien K, Wilkins S, Gervais N. Aging with HIV: A model of disability. Journal of the International Association of Providers of AIDS Care (JIAPAC) 2014;13(6):519–525.
  56. 56. Solomon P, O'Brien K, Wilkins S, Gervais N. Aging with HIV and disability: the role of uncertainty. AIDS Care 2014;26(2):240–245. pmid:23799874
  57. 57. Solomon P, O’Brien KK, Nixon S, Letts L, Baxter L, Gervais N. Trajectories of Episodic Disability in People Aging with HIV: A Longitudinal Qualitative Study. Journal of the International Association of Providers of AIDS Care (JIAPAC) 2018;17:2325958218759210.
  58. 58. O’Brien KK, Ibáñez-Carrasco F, Solomon P, Harding R, Cattaneo J, Chegwidden W, et al. Advancing research and practice in HIV and rehabilitation: a framework of research priorities in HIV, disability and rehabilitation. BMC infectious diseases 2014;14(1):724.
  59. 59. Brown D, Claffey A, Harding R. Evaluation of a physiotherapy-led group rehabilitation intervention for adults living with HIV: referrals, adherence and outcomes. AIDS Care 2016;28(12):1495–1505. pmid:27264319
  60. 60. Auzenbergs M, Delpech V, Gold D, Kall M, Petretti S, Smithson K, et al. Positive Voices, the national survey of people living with HIV; Changing Perceptions: "Talking about HIV and our needs". 2018; Available at: https://img1.wsimg.com/blobby/go/db9f6878-0f44-42a6-b528-581039772168/downloads/1csbtcptn_723688.pdf. Accessed March/30, 2019.
  61. 61. Kogan AC, Wilber K, Mosqueda L. Person‐centered care for older adults with chronic conditions and functional impairment: A systematic literature review. J Am Geriatr Soc 2016;64(1):e1–e7. pmid:26626408