Reliability and validity of a questionnaire on vulnerability to sexually transmitted infections among adults with chronic mental illness: PESSOAS Project.

Objective: To describe reliability/validity of a semi-structured questionnaire designed to assess risk behavior to sexually transmitted diseases among adults with chronic mental illness.

Method: A cross-sectional pilot study was conducted in one psychiatric hospital and one mental health outpatient clinic. Clinical, behavioral and demographic data were collected from semi-structured interviews and medical charts. One-hundred and twenty patients were randomly selected from pre-defined lists in both centers while 89 (74%) were interviewed, indicating 26% nonparticipation rate. Protocol, participation rates, consent form and feasibility issues were assessed. The semi-structured interview was evaluated with regard to reliability (intra- and inter-rater) and construct validity by randomly repeating the interviews in a 1:1 ratio up to one-week interval. Reliability was estimated by percent agreement and Kappa statistics (95% confidence interval). Construct validity was assessed by Grade of Membership model.

Results: Kappa statistics ranged from 0.40 to 1.00 for most variables. Grade of Membership analysis generated three profiles. Profile one was represented by mostly women with no condom use in stable relationships; profile two revealed mostly men in stable relationship but with multiple risk behaviors; while profile three indicated a higher proportion of licit or illicit substance use.

Conclusions: Reliability and construct validity assessment using Grade of Membership analysis indicated that the semi-structured interview was suitable for capturing risk behavior among patients with chronic mental illness.