TABLE 2.
IMPROVEMENT IN EXERCISE CAPACITY AND HEALTH-RELATED QUALITY OF LIFE AT 24 MONTHS
| Improvement in Exercise Capacity |
Improvement in Health-related Quality of Life |
|||||||
| Surgery Group | Medical-Therapy Group | Surgery Group | Medical-Therapy Group | |||||
| Patients | No./Total No. (%) | No./Total No. (%) | Odds Ratio | P Value | No./Total No. (%) | No./Total No. (%) | Odds Ratio | P Value |
| All patients | 54/371 (15) | 10/378 (3) | 6.27 | <0.001 | 121/371 (33) | 34/378 (9) | 4.90 | <0.001 |
| High-risk* | 4/58 (7) | 1/48 (2) | 3.48 | 0.37 | 6/58 (10) | 0/48 | — | 0.03 |
| Other | 50/313 (16) | 9/330 (3) | 6.78 | <0.001 | 115/313 (37) | 34/330 (10) | 5.06 | <0.000 |
| Subgroups† | ||||||||
| Predominantly upper lobe emphysema | ||||||||
| Low exercise capacity | 25/84 (30) | 0/92 | — | <0.001 | 40/84 (48) | 9/92 (10) | 8.38 | <0.001 |
| High exercise capacity | 17/115 (15) | 4/138 (3) | 5.81 | 0.001 | 47/115 (41) | 15/138 (11) | 5.67 | <0.001 |
| Predominantly non−upper lobe emphysema | ||||||||
| Low exercise capacity | 6/49 (12) | 3/41 (7) | 1.77 | 0.50 | 18/49 (37) | 3/41 (7) | 7.35 | 0.001 |
| High exercise capacity | 2/65 (3) | 2/59 (3) | 0.90 | 1.00 | 10/65 (15) | 7/59 (12) | 1.35 | 0.61 |
Reprinted by permission from Reference 17.
Improvement in exercise capacity in patients, monitored for 24 months after randomization, was defined as an increase in the maximal workload of more than 10 W from the patient's postrehabilitation baseline value. Improvement in the health-related quality of life in patients, monitored for 24 months after randomization, was defined as a decrease in the score on the St. George's Respiratory Questionnaire of more than 8 points (on a 100-point scale) from the patient's postrehabilitation baseline score. For both analyses, patients who died or who missed the 24-month assessment were considered not to have improvement. Odds ratios are for improvement in the surgery group as compared with the medical therapy group. P values were calculated by Fisher's exact test. A low baseline exercise capacity was defined as a postrehabilitation on baseline maximal workload at or below the sex-specific 40th percentile (25 W for women and 40 W for men); a high exercise capacity was defined as a workload above this threshold.
High-risk patients were defined as those with an FEV1 that was 20% or less of the predicted value and either homogeneous emphysema on computed tomography or a carbon monoxide diffusing capacity that was 20% or less than the predicted value.
High-risk patients were excluded from the subgroup analyses. For improvement in exercise capacity, P for interaction = 0.005; for improvement in health-related quality of life, P for interaction = 0.03. These P values were derived from binary logistic-regression models with terms for treatment, subgroup, and the interaction between the two, with the use of an exact-score test with 3 degrees of freedom. Other factors that were considered as potential variables for the definition of subgroups included the baseline FEV1, carbon monoxide diffusing capacity, partial pressure of arterial carbon dioxide, residual volume, ratio of residual volume to total lung capacity, ratio of expired ventilation in 1 minute to carbon dioxide excretion in 1 minute, distribution of emphysema (heterogeneous vs. homogeneous), perfusion ratio, Health-related Quality of Life score, Quality of Well-Being score, age, race or ethnic group, and sex.