title: Which dimensions of disability does the HIV Disability Questionnaire (HDQ) measure? A factor analysis.
abstract: OBJECTIVE
  To assess the dimensions of disability measured by the HIV Disability Questionnaire (HDQ), a newly developed 72-item self-administered questionnaire that describes the presence, severity and episodic nature of disability experienced by people living with HIV.
  
  
  METHODS
  We recruited adults living with HIV from hospital clinics, AIDS service organizations and a specialty hospital and administered the HDQ followed by a demographic questionnaire. We conducted an exploratory factor analysis using disability severity scores to determine the domains of disability in the HDQ. We used the following steps: (a) ensured correlations between items were >0.30 and <0.80; (b) conducted a principal components analysis to extract factors; (c) used the Scree Test and eigenvalue threshold >1.5 to determine the number of factors to retain; and d) used oblique rotation to simplify the factor loading matrix. We assigned items to factors based on factor loadings of >0.30.
  
  
  RESULTS
  Of the 361 participants, 80% were men and 77% reported living with at least two concurrent health conditions in addition to HIV. The exploratory factor analysis suggested retaining six factors. Items related to symptoms and impairments loaded on three factors (physical [20 items], cognitive [3 items], and mental and emotional health [11 items]) and items related to worrying about the future, daily activities, and personal relationships loaded on three additional factors (uncertainty [14 items], difficulties with day-to-day activities [9 items], social inclusion [12 items]).
  
  
  CONCLUSIONS
  The HDQ has six domains: physical symptoms and impairments; cognitive symptoms and impairments; mental and emotional health symptoms and impairments; uncertainty; difficulties with day-to-day activities and challenges to social inclusion. These domains establish the scoring structure for the dimensions of disability measured by the HDQ. Implications for Rehabilitation As individuals live longer and age with HIV, they may be living with the health-related consequences of HIV and concurrent health conditions, a concept that may be termed disability. Measuring disability is important to understand the impact of HIV and its comorbidities. The HIV Disability Questionnaire (HDQ) is a self-administered questionnaire developed to describe the presence, severity and episodic nature of disability experienced by people living with HIV. The HDQ is comprised of six domains of disability including: 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). These domains represent the dimensions of disability measured by the HDQ. The HDQ is the first known HIV-specific disability measure for adults living with HIV. The HDQ may be used by clinicians and researchers to assess disability experienced by adults living with HIV.
authors.affiliation: Department of Physical Therapy, University of Toronto , Toronto, Ontario , Canada .
authors.forename: Kelly K
authors.initials: KK
authors.lastname: O'Brien
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: Bayoumi
authors.forename: Paul
authors.initials: P
authors.lastname: Stratford
authors.forename: Patricia
authors.initials: P
authors.lastname: Solomon
mesh_terms: D000328:Adult; D004185:Disability Evaluation; D006233:Persons with Disabilities / Q000534:rehabilitation*; D005163:Factor Analysis, Statistical; D005260:Female; D015658:HIV Infections / Q000534:rehabilitation*; D006801:Humans; D008297:Male; D008603:Mental Health; D008875:Middle Aged; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires / Q000592:standards*; D035501:Uncertainty
keywords: Factor analysis; HIV Disability Questionnaire; HIV/AIDS