Reliability and validity of an HIV-specific health-related quality-of-life measure for use with injecting drug users

Objective: To assess the reliability and validity of an HIV-specific quality of life (QoL) questionnaire for use with injecting drug users (IDU). Method: One hundred IDU with HIV infection (27 asymptomatic, 48 symptomatic, 25 with AIDS) completed the HIV adaptation of the Medical Outcomes Study questionnaire (MOS-HIV). Validity of the scale was assessed by comparing the scores on the MOS-HIV with measures of health and psychological status. Measures of health status used included Centers for Disease Control and Prevention (CDC) stage, CD4 cell count and number of HIV-related illnesses. Psychological status was assessed using the Hospital Anxiety and Depression Scale. Sociodemographic data and information on illegal drug consumption were also collected. Results: The MOS-HIV showed a good internal reliability on all scales and the factor structure was comparable with that reported from previous studies. The psychological scales from the MOS-HIV showed good concurrent validity. For the physical aspects of QoL, however, some scales were poor at discriminating between different HIV disease stages. One reason for this may have been that factors associated with a history of injecting drug use had a significant negative impact on QoL, particularly for asymptomatic patients. It was notable that QoL in asymptomatic infection was found to be substantially lower than has been reported for gay/bisexual men using the same instruments and was more strongly associated with factors related to drug use rather than to HIV disease status. Conclusion: The MOS-HIV is a reliable and valid measure, but in patients with a history of injecting drug use some of the scales measuring the physical aspects of QoL may be relatively insensitive to changes in health.