Table 8 Multivariable Cox proportional hazards regression on suspected acute exacerbation in the subsequent period

 White vs. non-white

0.63 (0.45–0.88)

0.007*

 Marginal decline vs. stable

2.02 (1.13–3.59)

0.011*

 Significant decline vs. stable

2.86 (1.69–4.85)

<0.001*

 25–30 vs. <25

0.82 (0.53–1.26)

0.362

 ≥30 vs. <25

0.75 (0.45–1.23)

0.245

 Cardiac disorder vs. no cardiac disorder

1.57 (1.04–2.37)

0.031*

 Pulmonary hypertension vs. no pulmonary hypertension

1.65 (1.03–2.63)

0.036*

 Emphysema vs. no emphysema

1.89 (1.02–3.50)

0.043*

 Gastroesophageal reflux disease vs. no gastroesophageal reflux disease

1.07 (0.74–1.54)

0.736

 History of smoking vs. no history of smoking

0.91 (0.64–1.31)

0.608

 Yes vs. no

2.98 (1.92–4.62)

<0.001*

 Both vs. neither

1.40 (0.76–2.55)

0.276

 Prednisone only vs. neither

1.23 (0.81–1.87)

0.335

 Azathioprine only vs. neither

0.99 (0.32–3.05)

0.980

 Dyspnea vs. no dyspnea

1.39 (0.68–2.83)

0.368

 Weight loss vs. no weight loss

1.16 (0.66–2.05)

0.595

 Academic vs. non-academic

1.02 (0.69–1.51)

0.910

GAP index (per unit increase)^b

1.07 (0.94–1.22)

0.301