3.2. Mortality
During a median 8.9-year follow-up duration, the overall mortality rate was 1,312/100,000 PY in the asthma cohort and 1,174/100,000 PY in the control cohort (p < 0.001), which is consistent with survival analysis (p < 0.01 for a log-rank test; Figure 1 ). Patients in the asthma cohort had a significantly higher all-cause mortality rate than subjects in the control cohort (HR = 1.13, 95% CI = 1.07–1.19). As shown in Figure 2A , a positive association between asthma and all-cause mortality was observed in both age groups. However, the association was only significant in males, patients who received medical aid, patients with COPD, patients without bronchiectasis, and patients without pneumonia. The association was stronger in males than females (p for interaction = 0.004), in patients who received medical aid than in patients who received other medical insurance, and in patients with COPD than in patients without COPD (p for interaction = 0.003)
The HR for respiratory mortality was 2.63 (95% CI = 2.28–3.03). As shown in Figure 2B , the positive association between asthma and respiratory mortality was consistent in all subgroups. The association was stronger in males than females (p for interaction = 0.043) and in younger patients (age < 60 years) than older patients (age\(\geq\ \)60 years; p for interaction = 0.005).