Measuring disability experienced by adults living with HIV: assessing construct validity of the HIV Disability Questionnaire using confirmatory factor analysis

Abstract

ObjectivesTo assess the construct validity of the HIV Disability Questionnaire (HDQ), a self-administered questionnaire that describes the presence, severity and episodic nature of disability experienced by people living with HIV.DesignWe conducted a confirmatory factor analysis. We hypothesised that domains in the HDQ characterised six dimensions of disability, each represented by HDQ items: physical symptoms and impairments (20 items); cognitive symptoms and impairments (3 items); mental and emotional health symptoms and impairments (11 items); uncertainty (14 items); difficulties with day-to-day activities (9 items) and challenges to social inclusion (12 items). We developed a measurement model to test these hypotheses. We used maximum likelihood methods of estimation to determine model fit. We considered a threshold for the Root Mean Square Error of Approximation (RMSEA) of <0.05 as an indication of overall goodness of model fit. We considered variables with factor loadings of >0.30 as representing a given domain of disability.SettingWe recruited adults with HIV from hospital clinics, AIDS service organisations and a specialty hospital in Ontario.ParticipantsOf the 361 adults with HIV who completed the HDQ, 80% were men, 36% were 50 or older and 77% reported living with at least two concurrent health conditions in addition to HIV.Outcome MeasuresWe administered the HDQ followed by a demographic questionnaire.ResultsThe model achieved good overall fit as indicated by a RMSEA of 0.030 (90% CI 0.028 to 0.033). All HDQ items represented our hypothesised dimensions of disability (factor loadings >0.30). Factor loadings ranged from 0.34 to 0.90. Domains of disability correlated with each other ranging from r=0.47 (between difficulties with day-to-day activities and uncertainty) to r=0.88 (between mental-emotional health challenges and challenges to social inclusion).ConclusionsThe six domain structure of the HDQ demonstrated construct validity when administered to adults living with HIV.

Evaluation of the psychometric properties of the HIV Disability Questionnaire among adults living with HIV in the United Kingdom

“…Older PLHIV may worry about HIV specific age-related uncertainties(55) and the trajectory of episodic disability(56).The role of uncertainty has also been incorporated into rehabilitation recommendations for adults ageing with HIV (57), whereby interventions can promote stability, mitigate increasing disability, and increase time between episodes(56). 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(32) , Ireland(33), and the United States(34). In this UK sample, the most episodic domain of disability was in the physical domain, which was similarly observed in Ireland(33) and the United States(34).…”

“…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%) (33) and the United States (87%) (34), and also was demonstrated in Canada using confirmatory factor analysis (32 Our study has limitations. Firstly participants were all male, living in an urban setting, therefore this sample is not representative of the UK population of PLHIV who are 69% male and 36% living in London (4) .…”

“…Nevertheless, evaluation of the psychometric properties of the HDQ 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 (32)(33)(34). Therefore caution should be applied when comparing the validity and reliability of the HDQ.…”

“…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 (32)(33)(34) . Median administration time is 8-15 minutes.…”

“…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(33), where fewer participants were working for pay, and had been living longer with their HIV diagnosis. Moreover participants in Canada(32) 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(33).…”