Seemingly Unrelated Regression Analysis of the Cost and Health-Related Quality of Life Outcomes of the REVAMP Randomized Clinical Trial.

This study aimed to evaluate the 9-month cost and health-related quality of life (HRQOL) outcomes of resistance versus viral load testing strategies to manage virological failure in low-middle income countries. We analyzed secondary outcomes from the REVAMP clinical trial: a pragmatic, open label, parallel-arm randomized trial investigating resistance versus viral load testing for individuals failing first-line treatment in South Africa and Uganda. We collected resource data, valued according to local cost data and used the 3-level version of EQ-5D to measure HRQOL at baseline and 9 months. We applied seemingly unrelated regression equations to account for the correlation between cost and HRQOL. We conducted intention-to-treat analyses with multiple imputation using chained equations for missing data and performed sensitivity analyses using complete cases. For South Africa, resistance testing and opportunistic infections were associated with statistically significantly higher total costs, and virological suppression was associated with lower total cost. Higher baseline utility, higher cluster of differentiation 4 (CD4) count, and virological suppression were associated with better HRQOL. For Uganda, resistance testing and switching to second-line treatment were associated with higher total cost, and higher CD4 was associated with lower total cost. Higher baseline utility, higher CD4 count, and virological suppression were associated with better HRQOL. Sensitivity analyses of the complete-case analysis confirmed the overall results. Resistance testing showed no cost or HRQOL advantage in South Africa or Uganda over the 9-month REVAMP clinical trial. • We analyzed cost and health-related quality of life (HRQOL) data using seemingly unrelated regression equations to account for joint correlation: this method is not widely published. • We undertook analysis in the context of a marginal, nonsignificant benefit in clinical primary outcome, proceeding based on strong economic hypotheses suggesting cost and HRQOL benefits for resistance testing. • Our study benefits from rich, primary, individual patient-level data to compare baseline and 9-month cost and HRQOL. • Notably, in contrast to high-income countries, resistance testing showed no 9-month cost or HRQOL advantage compared with viral load testing in low-middle income countries. • Results are key to informing multinational partners, nongovernment organizations, and public health policy makers about the use of resistance testing in clinical practice. • They are also important for informing the lifetime cost-effectiveness analysis of resistance testing in the era of new resistance testing methods and treatment regimens. [ABSTRACT FROM AUTHOR]