Table 1 Associations between serum bilirubin and clinically relevant outcomes
From: Serum bilirubin and chronic obstructive pulmonary disease (COPD): a systematic review
First author, year | Measure | Outcome | Model covariates |
|---|---|---|---|
Apperly 2015 [13] | Logistic regression of relationship between bilirubin quintile and mortality | OR of mortality in quintile 1 vs 5 (reference) 1.15 (95% CI 0.80–1.65; p = 0.32) OR of respiratory mortality in quintile 1 vs 5 (reference) 1.59 (95% CI 0.50–5.11; p = 0.58) | Age, sex, BMI, race, and pack-years smoked |
Brown 2017 [19] | Time dependent multivariable Cox proportional hazards analysis for time to first AECOPD | STATCOPE (development and calibration): aHR per log(10) increase in bilirubin = 0.89 (95% CI 0.74–1.09; p = 0.26) MACRO (validation): aHR per log(10) increase in bilirubin = 0.80 (95% CI 0.67–0.94; p = 0.008) | Treatment assignment, sex, race, BMI, chronic bronchitis, supplemental O2 use, SGRQ score, inhaler use, steroid or antibiotic use in last year Treatment assignment, sex, race, BMI, bronchitis, supplemental O2 use, SGRQ score, inhaler use, steroid or antibiotic use in last year |
Horsfall 2011 [17] | Poisson regression between overall mortality and bilirubin levels Poisson regression between diagnosis of COPD and bilirubin levels | Men: aIRR per 0.1 mg/dL increase in bilirubin 0.97 (95% CI 0.97–0.98; p < 0.001) Women: aIRR per 0.1 mg/dL increase in bilirubin 0.97 (95% CI 0.96–0.98; p < 0.001) Men: aIRR per 0.1 mg/dL increase in bilirubin 0.94 (95% CI 0.93–0.95; p < 0.001) Women: aIRR per 0.1 mg/dL increase in bilirubin 0.94 (95% CI 0.92–0.95; p < 0.001) | Age, BMI, systolic blood pressure, smoking status, alcohol intake, social deprivation score Treatment assignment, sex, race, BMI, bronchitis, supplemental O2 use, SGRQ score, inhaler use, steroid or antibiotic use in last year |
Lee 2018 [22] | Modified Poisson regression for risk of COPD in high vs low bilirubin | aRR 1.17 (95% CI 0.80–1.71; p = 0.431) | Age, sex, BMI |
Leem 2019 [27] | Cox regression model for mortality Linear mixed model and generalized estimating equations for number of exacerbations per year, 6 MW, CAT, and SGRQ | HR = 1.60 (95% CI 0.65–3.97; p = 0.311) # Exacerbations/year: β = 0.62 (SE 0.18; p = 0.001) 6 MW: β = 20.5 (SE 12.2; p = 0.094) CAT: β = 0.4 (SE 1.2; p = 0.746) SGRQ: β = 2.9 (SE 2.5; p = 0.261) | age, sex, BMI, Smoking, baseline FEV1 |
Milevoj Kopcinovic 2016 [29] | Bilirubin in COPD vs controls by Mann–Whitney or t-test | 6.4 (IQR 5.2–8.3) vs 7.1 (IQR 5.5 to 10.9); p = 0.102 | No difference so not included in additional analysis |
Wei 2015 [28] | Bilirubin in COPD vs controls by one-way ANOVA | No significant difference, values not reported | None |