Background
Methods
Data source
Sample selection
Study period
Independent variables and outcome measures
Statistical analysis
Results
Physician characteristics
Patient characteristics
By lung-function change category (based on relative change in FVC%)a
| ||||||
---|---|---|---|---|---|---|
Stable [A] | Marginal [B] | Significant [C] |
P-value* | |||
(N = 250) | (N = 98) | (N = 142) | [C] vs. [A] | [C] vs. [B] | [B] vs. [A] | |
Male, N (%) | 167 (66.8 %) | 70 (71.4 %) | 98 (69.0 %) | 0.999 | 0.999 | 0.999 |
Age (years), mean (SD) | 60.8 (10.8) | 62.1 (9.6) | 60.9 (11.5) | 0.999 | 0.999 | 0.930 |
BMI, mean (SD) | 26.7 (4.9) | 26.5 (4.4) | 26.3 (4.6) | 0.999 | 0.999 | 0.999 |
Race, N (%)b
| ||||||
White | 183 (73.2 %) | 82 (83.7 %) | 104 (73.2 %) | 0.999 | 0.193 | 0.098 |
Black or African American | 34 (13.6 %) | 11 (11.2 %) | 24 (16.9 %) | 0.999 | 0.650 | 0.999 |
Hispanic, Latino, or Spanish Origin | 26 (10.4 %) | 5 (5.1 %) | 13 (9.2 %) | 0.999 | 0.646 | 0.295 |
Asian | 7 (2.8 %) | 1 (1.0 %) | 1 (0.7 %) | 0.479 | 0.999 | 0.952 |
Other | 2 (0.8 %) | 0 (0.0 %) | 0 (0.0 %) | |||
Insurance type, N (%)b
| ||||||
Commercial/private insurance | 113 (45.2 %) | 45 (45.9 %) | 80 (56.3 %) | 0.193 | 0.502 | 0.999 |
Medicare | 109 (43.6 %) | 44 (44.9 %) | 61 (43.0 %) | 0.999 | 0.999 | 0.999 |
Medicaid | 26 (10.4 %) | 12 (12.2 %) | 17 (12.0 %) | 0.999 | 0.999 | 0.999 |
Military insurance (VA or active military) | 9 (3.6 %) | 2 (2.0 %) | 3 (2.1 %) | 0.999 | 0.999 | 0.999 |
Other | 0 (0.0 %) | 1 (1.0 %) | 0 (0.0 %) | - | - | - |
No insurance | 8 (3.2 %) | 1 (1.0 %) | 1 (0.7 %) | 0.228 | 0.999 | 0.584 |
Smoking status at diagnosis, N (%) | 0.789 | 0.999 | 0.999 | |||
Never smoked | 98 (39.2 %) | 44 (44.9 %) | 48 (33.8 %) | |||
Former smoker | 124 (49.6 %) | 42 (42.9 %) | 77 (54.2 %) | |||
Current smoker | 21 (8.4 %) | 11 (11.2 %) | 16 (11.3 %) | |||
Unknown/not sure | 7 (2.8 %) | 1 (1.0 %) | 1 (0.7 %) | |||
Exposure to activities/ environmental agents, N (%)b
| ||||||
Asbestos | 10 (4.0 %) | 3 (3.1 %) | 11 (7.7 %) | 0.336 | 0.650 | 0.999 |
Farming/agriculture | 27 (10.8 %) | 9 (9.2 %) | 25 (17.6 %) | 0.213 | 0.131 | 0.999 |
Hairdressing | 12 (4.8 %) | 4 (4.1 %) | 4 (2.8 %) | 0.999 | 0.999 | 0.999 |
Metal dust | 18 (7.2 %) | 2 (2.0 %) | 10 (7.0 %) | 0.999 | 0.172 | 0.154 |
Stone cutting/polishing | 7 (2.8 %) | 0 (0.0 %) | 6 (4.2 %) | 0.999 | <0.001* | <0.001* |
Coal mining | 5 (2.0 %) | 1 (1.0 %) | 2 (1.4 %) | 0.999 | 0.999 | 0.999 |
Other | 3 (1.2 %) | 3 (3.1 %) | 2 (1.4 %) | 0.999 | 0.999 | 0.669 |
None | 182 (72.8 %) | 78 (79.6 %) | 92 (64.8 %) | 0.340 | 0.037* | 0.598 |
Family history of pulmonary fibrosis, N (%) | 16 (6.4 %) | 6 (6.1 %) | 5 (3.5 %) | 0.564 | 0.923 | 0.999 |
Measurement period (days) | ||||||
Concurrent, mean (SD) | 172.8 (55.5) | 174.9 (53.7) | 181.6 (56.8) | 0.575 | 0.999 | 0.999 |
Subsequent, mean (SD) | 438.3 (283.1) | 423.0 (280.0) | 340.1 (275.9) | 0.013* | 0.118 | 0.999 |
Total follow-up, mean (SD) | 611.1 (282.7) | 597.9 (285.8) | 521.7 (286.6) | 0.036* | 0.225 | 0.999 |
By lung-function change category (based on relative change in FVC%)a
| ||||||
---|---|---|---|---|---|---|
Stable [A] | Marginal [B] | Significant [C] |
P-value* | |||
(N = 250) | (N = 98) | (N = 142) | [C] vs. [A] | [C] vs. [A] | [C] vs. [A] | |
Comorbidities, N (%)b
| ||||||
Gastroesophageal reflux disease | 82 (32.8 %) | 26 (26.5 %) | 45 (31.7 %) | 0.999 | 0.999 | 0.999 |
Cardiac disorder | 43 (17.2 %) | 28 (28.6 %) | 34 (23.9 %) | 0.260 | 0.999 | 0.053 |
Metabolic disorder | 38 (15.2 %) | 20 (20.4 %) | 29 (20.4 %) | 0.500 | 0.999 | 0.642 |
Other vascular disorder | 32 (12.8 %) | 23 (23.5 %) | 27 (19.0 %) | 0.300 | 0.999 | 0.069 |
Pulmonary hypertension | 31 (12.4 %) | 20 (20.4 %) | 16 (11.3 %) | 0.999 | 0.095 | 0.198 |
Emphysema | 18 (7.2 %) | 8 (8.2 %) | 15 (10.6 %) | 0.783 | 0.999 | 0.999 |
Other pulmonary disorder | 14 (5.6 %) | 7 (7.1 %) | 13 (9.2 %) | 0.435 | 0.999 | 0.999 |
Symptoms at IPF diagnosis, N (%)b
| ||||||
Dyspnea/shortness of breath | 209 (83.6 %) | 88 (89.8 %) | 132 (93.0 %) | 0.030* | 0.999 | 0.668 |
Cough | 175 (70.0 %) | 71 (72.4 %) | 110 (77.5 %) | 0.428 | 0.999 | 0.999 |
Fatigue or malaise | 107 (42.8 %) | 47 (48.0 %) | 78 (54.9 %) | 0.145 | 0.999 | 0.999 |
Rapid, shallow breathing | 25 (10.0 %) | 11 (11.2 %) | 14 (9.9 %) | 0.999 | 0.999 | 0.999 |
Gradual, unintended weight loss | 17 (6.8 %) | 9 (9.2 %) | 24 (16.9 %) | 0.035* | 0.317 | 0.999 |
Clubbing | 14 (5.6 %) | 11 (11.2 %) | 17 (12.0 %) | 0.309 | 0.999 | 0.321 |
Other | 1 (0.4 %) | 0 (0.0 %) | 2 (1.4 %) | - | - | - |
GAP index, mean (SD)c
| 3.3 (1.5) | 3.5 (1.5) | 3.7 (1.4) | 0.149 | 0.999 | 0.774 |
Lung-function measures at IPF diagnosis, mean [median] (SD) | ||||||
FVC (liters) | 2.6 (1.1) | 2.4 (0.9) | 2.4 (1.0) | 0.821 | 0.999 | 0.796 |
FVC% | 61.7 %(26.1 %) | 58.5 % (24.0 %) | 59.5 % (27.6 %) | 0.999 | 0.999 | 0.999 |
FEV1 (liters) | 2.0 (0.9) | 1.8 (0.7) | 1.7 (0.6) | 0.021* | 0.901 | 0.395 |
FEV1/FVC | 79.6 % (12.6 %) | 79.9 % (11.8 %) | 80.7 % (12.5 %) | 0.999 | 0.999 | 0.999 |
DLCO percent predicted | 53.4 % (14.4 %) | 51.2 % (16.1 %) | 47.7 % (16.5 %) | 0.033* | 0.583 | 0.962 |
Unadjusted analysis of clinical characteristics and HRU in the concurrent period
By lung-function change category (based on relative change in FVC%)a
| ||||||
---|---|---|---|---|---|---|
Stable [A] | Marginal [B] | Significant [C] | Relative effect measure (95 % CI) | |||
(N = 250) | (N = 98) | (N = 142) | [C] vs. [A] | [C] vs. [B] | [B] vs. [A] | |
6-Month IR per Patient | IRR | |||||
Rate of suspected AEx | 0.21 | 0.25 | 0.25 | 1.20 (0.69–2.09) | 1.00 (0.55–1.82) | 1.20 (0.63–2.28) |
6-Month Risk | OR | |||||
Risk of suspected AEx | 14.1 % | 16.7 % | 20.4 % | 1.56 (0.78–3.15) | 1.27 (0.56–2.91) | 1.23 (0.56–2.70) |
Risk of progression | 23.4 % | 38.7 % | 48.6 % | 3.09 (1.67–5.72) | 1.50 (0.75–3.00) | 2.07 (1.07–3.97) |
6-Month IR per Patient | IRR | |||||
Rate of IPF-related outpatient visits | 1.85 | 1.95 | 1.78 | 0.96 (0.82–1.12) | 0.91 (0.75–1.12) | 1.05 (0.87–1.27) |
Unscheduled and/or urgent care | 0.16 | 0.23 | 0.22 | 1.42 (0.64–3.15) | 0.97 (0.48–1.96) | 1.46 (0.76–2.80) |
For a suspected AEx | 0.17 | 0.19 | 0.19 | 1.16 (0.58–2.31) | 1.04 (0.52–2.09) | 1.11 (0.54–2.29) |
Rate of IPF-related ER visits | 0.18 | 0.16 | 0.14 | 0.81 (0.31–2.11) | 0.87 (0.37–2.01) | 0.94 (0.40–2.17) |
For a suspected AEx | 0.04 | 0.02 | 0.05 | 1.15 (0.34–3.86) | 2.46 (0.41–14.72) | 0.47 (0.07–3.17) |
Rate of IPF-related hospitalizations | 0.06 | 0.08 | 0.05 | 0.80 (0.20–3.12) | 0.59 (0.17–1.98) | 1.36 (0.35–5.20) |
For a suspected AEx | 0.04 | 0.06 | 0.04 | 0.96 (0.19–4.82) | 0.63 (0.17–2.32) | 1.52 (0.27–8.60) |
Rate of hospital days | 0.39 | 0.48 | 0.25 | 0.63 (0.10–3.82) | 0.52 (0.10–2.62) | 1.22 (0.28–5.26) |
Rate of ICU stays | 0.03 | 0.03 | 0.02 | 0.59 (0.07–4.97) | 0.47 (0.07–2.95) | 1.25 (0.21–7.58) |
Rate of ICU days | 0.08 | 0.18 | 0.07 | 0.79 (0.05–12.62) | 0.36 (0.03–4.05) | 2.16 (0.23–20.59) |
Unadjusted analysis of clinical outcomes in the subsequent period
By lung-function change category (based on relative change in FVC%)a
| ||||||
---|---|---|---|---|---|---|
Stable [A] | Marginal [B] | Significant [C] | Relative effect measure (95 % CI) | |||
(N = 250) | (N = 98) | (N = 142) | [C] vs. [A] | [C] vs. [B] | [B] vs. [A] | |
12-Month IR per Patient | IRR | |||||
Rate of suspected AEx | 0.26 | 0.47 | 0.74 | 2.87 (1.71–4.82) | 1.58 (0.95–2.64) | 1.82 (1.02–3.23) |
12-Month Risk | OR | |||||
Risk of suspected AEx | 19.2 % | 37.1 % | 50.9 % | 4.37 (2.09–9.16) | 1.76 (0.81–3.80) | 2.49 (1.28–4.82) |
Risk of progression | 62.6 % | 76.2 % | 85.6 % | 3.56 (1.66–7.64) | 1.86 (0.81–4.26) | 1.92 (0.91–4.04) |
Mortalityb
| Risk by 12 Months | HR | ||||
Death due to any cause | 6.4 % | 13.1 % | 28.0 % | 5.05 (2.75–9.27) | 1.85 (1.05–3.26) | 2.73 (1.51–4.94) |
Death due to IPF | 5.5 % | 10.3 % | 24.3 % | 6.23 (2.96–13.14) | 1.94 (1.01–3.70) | 3.22 (1.59–6.53) |
Death due to AEx | 5.0 % | 9.3 % | 13.1 % | 3.91 (1.56–9.84) | 1.22 (0.54–2.77) | 3.21 (1.41–7.30) |
Unadjusted analysis of HRU outcomes in the subsequent period
By lung-function decline category (based on relative change in FVC%)a
| ||||||
---|---|---|---|---|---|---|
Stable [A] | Marginal [B] | Significant [C] | Relative effect measure (95 % CI) | |||
(N = 250) | (N = 98) | (N = 142) | [C] vs. [A] | [C] vs. [B] | [B] vs. [A] | |
12-Month IR per Patient | IRR | |||||
Rate of IPF-related outpatient visits | 2.24 | 2.57 | 2.55 | 1.14 (0.89–1.46) | 0.99 (0.76–1.30) | 1.15 (0.91–1.45) |
Unscheduled and/or urgent care | 0.18 | 0.38 | 0.54 | 3.01 (1.51–5.97) | 1.41 (0.78–2.55) | 2.13 (1.05–4.34) |
For a suspected AEx | 0.19 | 0.33 | 0.54 | 2.81 (1.47–5.40) | 1.64 (0.86–3.11) | 1.72 (0.80–3.69) |
Rate of outpatient visits indicating that the following medications/treatments were prescribed for IPF | ||||||
Prednisone | 1.06 | 1.16 | 1.60 | 1.51 (1.08–2.10) | 1.38 (1.02–1.86) | 1.10 (0.79–1.52) |
Azathioprine | 0.36 | 0.31 | 0.54 | 1.51 (0.78–2.93) | 1.72 (0.84–3.53) | 0.88 (0.44–1.76) |
N-acetylcysteine | 0.65 | 0.70 | 0.79 | 1.22 (0.79–1.89) | 1.13 (0.67–1.90) | 1.08 (0.69–1.70) |
Rate of outpatient visits that included the following tests/procedures | ||||||
Arterial blood gas test | 0.17 | 0.23 | 0.34 | 2.04 (0.77–5.38) | 1.46 (0.53–4.03) | 1.40 (0.55–3.56) |
HRCT | 0.23 | 0.35 | 0.35 | 1.55 (0.74–3.21) | 1.02 (0.45–2.31) | 1.51 (0.76–2.99) |
Chest X-ray | 0.48 | 0.66 | 0.60 | 1.23 (0.75–2.02) | 0.90 (0.55–1.48) | 1.36 (0.84–2.20) |
Lung biopsy | 0.03 | 0.04 | 0.01 | 0.44 (0.02–8.70) | 0.31 (0.02–4.91) | 1.42 (0.13–15.70) |
Pulmonary rehabilitation | 0.18 | 0.19 | 0.26 | 1.44 (0.79–2.63) | 1.35 (0.58–3.11) | 1.07 (0.52–2.23) |
Rate of IFP-related ER visits | 0.35 | 0.54 | 0.53 | 1.53 (0.71–3.28) | 0.98 (0.51–1.87) | 1.56 (0.66–3.71) |
For a suspected AEx | 0.13 | 0.22 | 0.29 | 2.22 (0.95–5.21) | 1.32 (0.60–2.87) | 1.69 (0.67–4.27) |
Rate of ER visits that included the following tests/procedures | ||||||
Arterial blood gas test | 0.15 | 0.35 | 0.33 | 2.24 (1.01–4.99) | 0.95 (0.45–2.00) | 2.36 (1.01–5.49) |
HRCT | 0.09 | 0.18 | 0.20 | 2.17 (0.85–5.58) | 1.09 (0.37–3.22) | 1.99 (0.60–6.67) |
Chest X-ray | 0.20 | 0.28 | 0.30 | 1.51 (0.69–3.32) | 1.10 (0.55–2.21) | 1.37 (0.61–3.09) |
Supplemental oxygen therapy | 0.17 | 0.23 | 0.29 | 1.74 (0.73–4.14) | 1.26 (0.52–3.04) | 1.39 (0.46–4.20) |
Rate of IPF-related hospitalizations | 0.24 | 0.32 | 0.61 | 2.53 (0.70–9.10) | 1.89 (0.94–3.78) | 1.34 (0.34–5.29) |
For a suspected AEx | 0.09 | 0.21 | 0.43 | 4.69 (1.84–11.99) | 2.05 (1.03–4.08) | 2.29 (0.82–6.35) |
Rate of hospital days | 1.13 | 2.32 | 5.25 | 4.63 (1.31–16.42) | 2.27 (0.86–5.97) | 2.05 (0.66–6.33) |
Rate of ICU stays | 0.05 | 0.17 | 0.26 | 4.95 (1.20–20.41) | 1.53 (0.59–3.99) | 3.23 (0.72–14.53) |
Rate of ICU days | 0.30 | 0.69 | 1.22 | 4.05 (0.79–20.91) | 1.75 (0.58–5.35) | 2.31 (0.54–9.83) |
Rate of hospitalizations that included the following tests/procedures | ||||||
Arterial blood gas test | 0.10 | 0.19 | 0.35 | 3.58 (1.33–9.64) | 1.87 (0.73–4.80) | 1.92 (0.61–6.00) |
Mechanical ventilation | 0.04 | 0.11 | 0.14 | 3.29 (0.63–17.23) | 1.33 (0.38–4.70) | 2.47 (0.57–10.73) |
Non-invasive ventilation | 0.02 | 0.08 | 0.22 | 10.17 (3.25–31.86) | 2.80 (1.05–7.51) | 3.63 (0.90–14.70) |
Supplemental oxygen therapy | 0.07 | 0.13 | 0.28 | 3.95 (1.38–11.29) | 2.11 (0.93–4.82) | 1.87 (0.62–5.66) |
12-Month Risk | OR | |||||
Risk of having ≥1 outpatient visit | 97.5 % | 97.3 % | 95.0 % | 0.48 (0.14–1.62) | 0.52 (0.12–2.20) | 0.93 (0.23–3.76) |
Unscheduled or urgent care | 11.4 % | 26.9 % | 34.5 % | 4.10 (1.95–8.63) | 1.43 (0.69–2.98) | 2.87 (1.39–5.92) |
For a suspected AEx | 12.7 % | 21.9 % | 33.8 % | 3.52 (1.62–7.67) | 1.82 (0.82–4.05) | 1.93 (0.90–4.15) |
Risk of having ≥1 ER visit | 14.4 % | 29.4 % | 32.4 % | 2.85 (1.36–5.98) | 1.15 (0.53–2.52) | 2.47 (1.22–5.03) |
For a suspected AEx | 7.8 % | 16.7 % | 22.1 % | 3.33 (1.40–7.94) | 1.42 (0.57–3.54) | 2.35 (0.98–5.65) |
Risk of having ≥1 hospitalizations | 7.8 % | 19.1 % | 30.0 % | 5.04 (2.13–11.93) | 1.82 (0.71–4.66) | 2.76 (1.14–6.70) |
Intensive care unit (ICU) stay | 2.4 % | 8.4 % | 12.4 % | 5.86 (1.43–24.01) | 1.56 (0.41–5.90) | 3.77 (0.88–16.03) |
For a suspected AEx | 5.9 % | 15.1 % | 27.8 % | 6.08 (2.45–15.07) | 2.16 (0.84–5.54) | 2.81 (1.10–7.20) |
Multivariable analysis
Mortalitya
| ||
---|---|---|
Hazard ratio (95 % CI) |
P-value* | |
Race | ||
White vs. non-white | 0.70 (0.39–1.26) | 0.231 |
Lung-function decline group | ||
Marginal decline vs. stable | 2.38 (1.04–5.45) | 0.036* |
Significant decline vs. stable | 4.42 (2.01–9.71) | <0.001* |
BMI | ||
25–30 vs. < 25 | 0.53 (0.29–0.97) | 0.038* |
≥30 vs. < 25 | 0.38 (0.18–0.80) | 0.012* |
Comorbidities | ||
Cardiac disorder vs. no cardiac disorder | 1.63 (0.94–2.82) | 0.080 |
Pulmonary hypertension vs. no pulmonary hypertension | 2.53 (1.33–4.80) | 0.005* |
Emphysema vs. no emphysema | 1.49 (0.67–3.35) | 0.328 |
Gastroesophageal reflux disease vs. no gastroesophageal reflux disease | 1.10 (0.64–1.92) | 0.725 |
Smoking status | ||
History of smoking vs. no history of smoking | 1.08 (0.64–1.83) | 0.773 |
Suspected AEx in the concurrent period | ||
Yes vs. no | 2.59 (1.49–4.53) | <0.001* |
Use of prednisone and azathioprine in the concurrent period | ||
Both vs. neither | 2.48 (1.19–5.19) | 0.016* |
Prednisone only vs. neither | 1.41 (0.66–3.01) | 0.376 |
Azathioprine only vs. neither | 1.11 (0.18–7.01) | 0.909 |
Symptoms at initial IPF diagnosis | ||
Dyspnea vs. no dyspnea | 1.29 (0.48–3.48) | 0.609 |
Weight loss vs. no weight loss | 1.95 (1.02–3.73) | 0.044* |
Physician's main practice setting | ||
Academic vs. non-academic | 0.95 (0.51–1.77) | 0.876 |
GAP index (per unit increase)b
| 1.19 (0.98–1.44) | 0.080 |
Hospitalizationa
| ||
---|---|---|
Hazard Ratio (95 % CI) |
P-value* | |
Race | ||
White vs. non-white | 0.50 (0.32–0.79) | 0.003* |
Lung-function decline group | ||
Marginal decline vs. stable | 2.50 (1.06–5.91) | 0.033* |
Significant decline vs. stable | 3.37 (1.62–7.00) | <0.001* |
BMI | ||
25–30 vs. <25 | 0.59 (0.34–1.03) | 0.061 |
≥30 vs. <25 | 0.95 (0.51–1.74) | 0.861 |
Comorbidities | ||
Cardiac disorder vs. no cardiac disorder | 1.87 (1.06–3.32) | 0.032* |
Pulmonary hypertension vs. no pulmonary hypertension | 2.09 (1.15–3.83) | 0.017* |
Emphysema vs. no emphysema | 1.44 (0.62–3.36) | 0.399 |
Gastroesophageal reflux disease vs. no gastroesophageal reflux disease | 1.08 (0.67–1.73) | 0.746 |
Smoking status | ||
History of smoking vs. no history of smoking | 1.02 (0.61–1.70) | 0.935 |
Suspected AEx in the concurrent period | ||
Yes vs. no | 1.86 (1.06–3.26) | 0.030* |
Use of prednisone and azathioprine in the concurrent period | ||
Both vs. neither | 1.24 (0.59–2.62) | 0.575 |
Prednisone only vs. neither | 1.25 (0.72–2.16) | 0.428 |
Azathioprine only vs. neither | 0.74 (0.09–6.38) | 0.780 |
Symptoms at initial IPF diagnosis | ||
Dyspnea vs. no dyspnea | 1.43 (0.43–4.80) | 0.562 |
Weight loss vs. no weight loss | 1.45 (0.77–2.76) | 0.250 |
Physician's main practice setting | ||
Academic vs. non-academic | 0.89 (0.51–1.55) | 0.680 |
GAP index (per unit increase)b
| 1.23 (1.04–1.46) | 0.018* |
Suspected Acute Exacerbationa
| ||
---|---|---|
Hazard Ratio (95 % CI) |
P-value* | |
Race | ||
White vs. non-white | 0.63 (0.45–0.88) | 0.007* |
Lung-function decline group | ||
Marginal decline vs. stable | 2.02 (1.13–3.59) | 0.011* |
Significant decline vs. stable | 2.86 (1.69–4.85) | <0.001* |
BMI | ||
25–30 vs. <25 | 0.82 (0.53–1.26) | 0.362 |
≥30 vs. <25 | 0.75 (0.45–1.23) | 0.245 |
Comorbidities | ||
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 |
Smoking status | ||
History of smoking vs. no history of smoking | 0.91 (0.64–1.31) | 0.608 |
Suspected AEx in the concurrent period | ||
Yes vs. no | 2.98 (1.92–4.62) | <0.001* |
Use of prednisone and azathioprine in the concurrent period | ||
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 |
Symptoms at initial IPF diagnosis | ||
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 |
Physician's main practice setting | ||
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 |