Measurement of health-related quality of life in the national emphysema treatment trial

Abstract

Purposes: To evaluate two generic and two disease-specific measures of health-related quality of life (QOL) using prerandomization data from the National Emphysema Treatment Trial (NETT).

Method: The analyses used data collected from the 1,218 subjects who were randomized in the NETT. Patients completed evaluations before and after completion of the prerandomization phase of the NETT pulmonary rehabilitation program. Using data obtained prior to participation in the rehabilitation program, QOL measures were evaluated against physiologic and functional criteria using correlational analysis. The physiologic criteria included estimates of emphysema severity based on FEV(1) and measures of Pao(2) obtained with the subject at rest and breathing room air. Functional measures included the 6-min walk distance (6MWD), maximum work, and hospitalizations in the prior 3 months.

Results: Correlation coefficients between QOL measures ranged from -0.31 to 0.70. In comparison to normative samples, scores on general QOL measures were low, suggesting that the NETT participants were quite ill. All QOL measures were modestly but significantly correlated with FEV(1), maximum work, and 6MWD. Patients who had stayed overnight in a hospital in the prior 3 months reported lower QOL on average than those who had not been hospitalized. There were significant improvements for all QOL measures following the rehabilitation program, and improvements in QOL were correlated with improvements in 6MWD.

Comment: The disease-specific and general QOL measures used in the NETT were correlated. Analyses suggested that these measures improved significantly following the rehabilitation phase of the NETT.