Table 4. Incidence of acute respiratory failure for the study cohort stratified by comorbidities and estimation of the risk of respiratory failure for different levels of comorbidities using multivariate Cox proportional hazards regression analysis.
| Variable | Non-PM/DM cohort | PM/DM cohort | Adjusted HR (95% CI) | P value* | |||||
|---|---|---|---|---|---|---|---|---|---|
| Event | PYs | Rate | Event | PYs | Rate | ||||
| Asthma | 0.0934 | ||||||||
| No | 281 | 85,319 | 32.9 | 141 | 6,679 | 211.1 | 5.62 (4.43–7.12) | ||
| Yes | 54 | 5,017 | 107.6 | 30 | 774 | 387.6 | 3.58 (2.13–6.01) | ||
| Hypertension | 0.0008 | ||||||||
| No | 107 | 67,873 | 15.8 | 97 | 5,723 | 169.5 | 7.90 (5.56–11.20) | ||
| Yes | 228 | 22,463 | 101.5 | 74 | 1,730 | 427.7 | 4.01 (2.99–5.36) | ||
| Diabetes | 0.06 | ||||||||
| No | 237 | 82,453 | 28.7 | 140 | 6,786 | 206.3 | 5.83 (4.56–7.45) | ||
| Yes | 98 | 7,883 | 124.3 | 31 | 667 | 464.8 | 3.69 (2.34–5.83) | ||
| COPD | 0.005 | ||||||||
| No | 242 | 84,163 | 28.8 | 129 | 6,508 | 198.2 | 6.21 (4.82–8.01) | ||
| Yes | 93 | 6,173 | 150.7 | 42 | 945 | 444.4 | 3.04 (2.04–4.54) | ||
| Pneumonia | 0.4808 | ||||||||
| No | 254 | 78,790 | 32.2 | 102 | 5,690 | 179.3 | 4.60 (3.53–6.00) | ||
| Yes | 81 | 11,546 | 70.2 | 69 | 1,763 | 391.4 | 6.08 (4.22–8.78) | ||
| Cancer | 0.5946 | ||||||||
| No | 311 | 88,625 | 35.1 | 162 | 7,211 | 224.7 | 5.75 (4.64–7.13) | ||
| Yes | 24 | 1,711 | 140.3 | 9 | 241.5 | 372.7 | 3.46 (1.44–8.34) | ||
| CAD | 0.2117 | ||||||||
| No | 211 | 79,628 | 26.5 | 123 | 6,471 | 190.1 | 5.09 (3.89–6.65) | ||
| Yes | 124 | 10,708 | 115.8 | 48 | 982 | 488.8 | 4.94 (3.40–7.16) | ||
| Heart failure | 0.06 | ||||||||
| No | 305 | 89,092 | 34.2 | 160 | 7,236 | 221.1 | 5.95 (4.79–7.39) | ||
| Yes | 30 | 1,244 | 241.2 | 11 | 217 | 506.9 | 2.64 (1.19–5.85) | ||
| PVD | 0.0388 | ||||||||
| No | 326 | 90,114 | 36.2 | 165 | 7,361 | 224.2 | 5.38 (4.33–6.68) | ||
| Yes | 9 | 221 | 407.2 | 6 | 91 | 659.3 | 18.4 (2.21–153.80) | ||
Adjusted for age, sex, CCI score, and medicine of oral steroid. *, P for interaction. PM/DM, polymyositis/dermatomyositis; rate, per 10,000 person-years; PYs, person-years; CI, confidence interval; HR, hazard ratio; COPD, chronic obstructive pulmonary disease; CAD, coronary artery disease; PVD, pulmonary vascular disease; CCI score, Charlson comorbidity index score.