Table 4.
Subgroup analysis of the RV/TLC ratio and the risk of COPD exacerbation.
| Moderate to severe exacerbation | Severe exacerbation | ||||
|---|---|---|---|---|---|
| Subgroup | No. of patients | Adjusted OR (95% CI, p) | P interaction | Adjusted OR (95% CI, p) | P interaction |
| Age (years) | <70 (n = 206) | 1.50 (1.09–2.12, 0.015) | 0.508 | 1.40 (0.99–1.99, 0.056) | 0.958 |
| ≥70 (n = 204) | 1.08 (0.71–1.64, 0.718) | 1.39 (0.95–2.07, 0.097) | |||
| BMI (kg/m2) | <23 (n = 212) | 1.54 (1.05–2.32, 0.032) | 0.339 | 1.49 (1.07–2.12, 0.021) | 0.608 |
| ≥23 (n = 198) | 1.20 (0.86–1.70, 0.280) | 1.16 (0.76–1.76, 0.492) | |||
| Smoking amount (pack-years) | <40 (n = 167) | 1.21 (0.85–1.75, 0.283) | 0.355 | 1.36 (0.88–2.10, 0.161) | 0.867 |
| ≥40 (n = 243) | 1.47 (1.04–2.12, 0.032) | 1.35 (0.97–1.88, 0.075) | |||
| Occupational exposure | No (n = 233) | 1.47 (1.06–2.05, 0.022) | 0.201 | 1.43 (1.01–2.03, 0.042) | 0.291 |
| Yes (n = 177) | 1.15 (0.77–1.72, 0.508) | 1.23 (0.82–1.88, 0.320) | |||
| mMRC | <2 (n = 238) | 1.29 (0.95–1.76, 0.105) | 0.377 | 1.52 (1.02–2.29, 0.041) | 0.145 |
| ≥2 (n = 172) | 1.51 (0.93–2.56, 0.104) | 1.22 (0.86–1.76, 0.264) | |||
| FEV1 (%-predicted) | <60 (n = 142) | 1.34 (0.91–2.02, 0.143) | 0.696 | 2.17 (1.04–4.63, 0.039) | 0.423 |
| ≥60 (n = 268) | 1.39 (1.00–1.95, 0.052) | 1.27 (0.96–1.69, 0.096) | |||
| Triple inhaled therapy | No (n = 272) | 1.43 (1.08–1.93, 0.015) | 0.534 | 1.79 (1.26–2.56, 0.001) | 0.002 |
| Yes (n = 138) | 1.11 (0.63–1.98, 0.716) | 0.95 (0.64–1.39, 0.781) | |||
| Hypertension | No (n = 238) | 1.20 (0.86–1.67, 0.276) | 0.852 | 1.13 (0.80–1.59, 0.481) | 0.157 |
| Yes (n = 172) | 1.75 (1.17–2.69, 0009) | 1.70 (1.13–2.65, 0.014) | |||
| Diabetes | No (n = 322) | 1.43 (1.06–1.94, 0.019) | 0.569 | 1.31 (0.98–1.76, 0.070) | 0.935 |
| Yes (n = 88) | 1.21 (0.77–1.94, 0.419) | 1.42 (0.82–2.46, 0.197) | |||
Age, college graduate, occupational exposure, BMI, mMRC, smoking amount, categorized FEV1, triple inhaler, cardiovascular disease, hypertension, and diabetes mellitus were used in the adjustment. The bold values indicate statistically significance at the p <0.05 level.
RV, residual volume; TLC, total lung capacity; COPD, chronic obstructive pulmonary disease; BMI, body mass index; OR, odds ratio; CI, confidence interval; mMRC, modified medical research council; FEV1, forced expiratory volume in 1 second.