Creating a Crosswalk to Estimate AIDS Clinical Trials Group Quality of Life Scores in a Nationally Representative Sample of Persons in Care for HIV in the United States
Published in: HIV Clinical Trials, v. 6, no. 3, May-June 2005, p. 147-157
Posted on RAND.org on December 31, 2004
BACKGROUND: Optimizing health-related quality of life (HRQOL) is an increasingly important goal in the treatment of HIV/AIDS. Interpretation of HRQOL scores in clinical trials is enhanced by comparative data. PURPOSE: To estimate AIDS Clinical Trials Group (ACTG) QOL 601-602 questionnaire scale scores for a nationally representative sample of persons in care for HIV. METHOD: The study cohort was from the HIV Cost and Services Utilization Study (HCSUS), a multistage national probability sample. The authors derived HCSUS HRQOL scale scores from the items shared between the ACTG QOL 601-602 and HCSUS HRQOL questionnaires using regression equations. Cronbach's alpha coefficient was used to estimate the reliability of the multi-item scales in the ACTG QOL 601-602 and HCSUS HRQOL instruments. Correlation coefficients and R2s of regression models were calculated to determine the concordance of the models. Multiple regression was used to determine if patient characteristics accounted for differences (residuals) between scores observed from the full HCSUS HRQOL instruments and scores predicted using the subset of shared items in ACTG QOL 601-2. RESULTS: Internal consistency reliability estimates were acceptable (>0.70) for all scales in the ACTG QOL 601-602 and HCSUS HRQOL instruments. Correlations between corresponding ACTG QOL 601-602 and HCSUS HRQOL scale scores were high (>0.9). The R2s for predicting HCSUS HRQOL scores from the ACTG QOL 601-602 scales were also high (>0.8). For physical functioning, emotional well-being, and general health perceptions, the predictors of differences (residuals) in observed and predicted HCSUS HRQOL scores were gender and CDC stage of HIV infection (p < .05). CONCLUSION: This study provides normative data from the US HIV/AIDS population for comparison to the ACTG QOL 601-602 questionnaire. Accuracy of estimation is enhanced if done separately by gender and HIV disease stage.