Purpose: This study examined functional status abnormalities in pulmonary rehabilitation patients, its responsiveness to pulmonary rehabilitation intervention, and its relationship to patient characteristics and traditional measures of disease severity.
Methods: One hundred sixty-four men and women age 69 years (SD +/- 8), who participated in 1 of 10 pulmonary rehabilitation programs in Connecticut, were studied pre- and postrehabilitation with the following outcome measures: (1) the 6-minute walk distance, (2) the Pulmonary Functional Status Scale (PFSS), and (3) in a subset of 60 subjects, health-related quality of life was measured using the Chronic Respiratory Disease Questionnaire (CRDQ). Patient characteristics were compared to baseline values of these measures using Spearman correlations and Wilcoxon Rank Sum tests, whereas pre- to post-changes in outcome measures were evaluated using Wilcoxon signed-ranks tests. Effect size, representing a standardized measure of change, was calculated for the PFSS.
Results: The mean FEV1 was 0.95 +/- 0.50 liters (38 +/- 18% predicted). Rehabilitation resulted in significant increases in the 6-minute walk distance (24%, P < 0.001, the total PFSS scores [13%, P < 0.001, effect size 1.0]) and the total CRDQ (18% P < 0.001). The prerehabilitation function subscore and total PFSS score correlated strongly with the 6-minute walk distance (r = 0.76, 0.73; P < 0.001) and to a lesser degree with the FEV1 (r = 0.31, 0.33; P < 0.001). Males scored higher baseline scores in several PFSS subscales, the total PFSS score, and the 6-minute walk distance; females showed more improvement in some of the PFSS scores.
Conclusion: The 6-minute walk distance, the PFSS, and CRDQ all improved significantly with rehabilitation. Functional status, as measured by the PFSS is very strongly correlated with the 6-minute walk. Gender differences in the timed walk distance and functional status highlight the need to study this variable more thoroughly.