Adjusted hazard ratios for death and COPD-related admissions to hospitals and other outcomes associated with peridiagnostic pulmonary function testing in all patients with physician-diagnosed COPD and those diagnosed with COPD in ambulatory care and hospital settings
| Outcome | With peridiagnostic testing n = 28 386 | Without peridiagnostic testing n = 40 512 | Unadjusted risk difference in outcome at 3 yr, % (95% CI)† | Adjusted regression | |||
|---|---|---|---|---|---|---|---|
| Had outcome, % | Time to outcome, d, median (IQR)* | Had outcome, % | Time to outcome, d, median (IQR)* | Adjusted HR (95% CI)‡ | p value§ | ||
| All patients | |||||||
| Hospital admission for COPD or death from any cause | 30.9 | 1001 (562–1504) | 43.5 | 936 (398–1468) | 10.4 (9.7–11.2) | 0.91 (0.89–0.94) | < 0.001 |
| Hospital admission for COPD or a related respiratory disease¶ or death from any cause | 33.1 | 974 (527–1483) | 45.9 | 895 (354–1440) | 10.5 (9.8–11.3) | 0.92 (0.89–0.94) | < 0.001 |
| Hospital admission for any reason or death from any cause | 53.3 | 705 (224–1223) | 65.9 | 524 (104–1091) | 11.7 (10.9–12.5) | 0.91 (0.89–0.93) | < 0.001 |
| Death from any cause | 22.6 | 1098 (684–1576) | 35.9 | 1043 (560–1553) | 11.0 (10.3–11.7) | 0.87 (0.84–0.90) | < 0.001 |
| COPD diagnosed in the ambulatory care setting | |||||||
| Hospital admission for COPD or death from any cause | 23.0 | 1061 (651–1546) | 30.7 | 994 (547–1498) | 7.01 (7.01–7.02) | 0.80 (0.76–0.84) | < 0.001 |
| Hospital admission for COPD or a related respiratory disease or death from any cause¶ | 24.9 | 1037 (629–1533) | 32.8 | 969 (511–1476) | 7.08 (7.07–7.09) | 0.80 (0.76–0.83) | < 0.001 |
| Hospital admission for any reason or death from any cause | 44.6 | 810 (361–1320) | 51.4 | 717 (244–1218) | 7.11 (7.10–7.12) | 0.82 (0.79–0.85) | < 0.001 |
| Death from any cause | 16.1 | 1131 (715–1595) | 25.1 | 1058 (638–1544) | 8.16 (8.16–8.17) | 0.72 (0.69–0.76) | < 0.001 |
| COPD diagnosed in the hospital setting | |||||||
| Admission to hospital for COPD or death from any cause | 49.8 | 839 (304–1402) | 53.5 | 882 (283–1442) | 1.06 (1.04–1.07) | 1.05 (1.01–1.09) | 0.02 |
| Admission to hospital for COPD or a related respiratory disease or death from any cause¶ | 52.7 | 804 (268–1366) | 56.1 | 841 (242–1413) | 0.79 (0.78–0.80) | 1.06 (1.02–1.10) | 0.005 |
| Admission to hospital for any reason or death from any cause | 74.3 | 365 (69–936) | 77.3 | 344 (61–967) | 1.22 (1.21–1.23) | 1.02 (0.99–1.05) | 0.3 |
| Death from any cause | 38.3 | 1016 (534–1520) | 44.3 | 1031 (472–1564) | 3.73 (3.71–3.74) | 1.03 (0.99–1.08) | 0.1 |
Note: CI = confidence interval, COPD = chronic obstructive pulmonary disease, HR = hazard ratio, IQR = interquartile range.
↵* Time until 50% of patients experienced the event derived from Kaplan–Meier survival curves.
↵† For each group (testing and nontesting), the unadjusted estimated survival at 3 years, along with the standard error of the estimate, was obtained using a Kaplan–Meier analysis. The risk difference for the outcome is the difference between the unadjusted estimated survivals at 3 years. The variance of this difference is the sum of the variances of the individual measures.
↵‡ Reflects the risk in the group with pulmonary function testing compared with the group without pulmonary function testing. Hazard ratios are adjusted for propensity score, pulmonary function testing before and after the peridiagnostic period, age, sex, whether patients were ambulatory or in hospital for COPD in the peridiagnostic period, asthma and hospital admission within the previous 6 months for a COPD-related disease.
↵§ Testing the hypothesis that the hazard ratio is equal to 1.00.
↵¶ Pneumonia, influenza or acute bronchitis.