Reliability of prisoners’ survey responses: comparison of self-reported health and biomedical data from an australian prisoner cohort

OBJECTIVE: Prisoner health surveys primarily rely on self-report data. However, it is unclear whether prisoners are reliable health survey respondents. This paper aimed to determine the level of agreement between self-report and biomedical tests for a number of chronic health conditions. METHOD: This study was a secondary analysis of existing data from three waves (1996, 2001, 2009) of the New South Wales (NSW) Inmate Health Survey. The health surveys were cross-sectional in nature and included a stratified random sample of men (n=2,114) from all NSW prisons. Self-reported histories of hepatitis, sexually transmissible infections, and diabetes were compared to objective biomedical measures of these conditions. RESULTS: Overall, the sensitivity (i.e., the respondents who self-reported having the condition also had markers indicative of the condition using biomedical tests) was high for hepatitis C (96%) and hepatitis B (83%), but low for all other assessed conditions (ranging from 9.1% for syphilis using RPR to 64% for diabetes). However, Kappa scores indicated substantial agreement only for hepatitis C. That is, there were false positives and false negatives which occurred outside of chance leading to poor agreement for all other assessed conditions. CONCLUSIONS: Prisoners may have been exposed to serious health conditions while failing to report a history of infection. It may be possible that prisoners do not get tested given the asymptomatic presentation of some conditions, were unaware of their health status, have limited health-service usage preventing the opportunity for detection, or are subject to forgetting or misunderstanding prior test results. These findings demonstrate the importance of the custodial environment in screening for health conditions and referral for treatment should this be needed. Testing on entry, periodically during incarceration, and prior to release is recommended.