Table 2

Observational relationships between mean serum total bilirubin and lung cancer incidence by smoking status in white British unrelated participants in UK Biobank

	Lung cancer events	PYs (10 000)	Lung cancer incidence rate per 10 000 PYs (95% CI)	Adjusted IRR per 5 μmol/L increase (95% CI)*	P value	Predicted incidence change in 10 000 PYs per 5 μmol/L increase (95% CI) *
Overall	1901	251	7.6 (7.2 to 7.9)	0.85 (0.80 to 0.92)	<0.0001	−1.2 (−1.8 to −0.7)
Never smokers	261	137	1.9 (1.7 to 2.1)	1.00 (0.87 to 1.15)	0.97	0.01 (−0.3 to 0.3)
Former smokers	888	88	10.1 (9.5 to 10.8)	0.87 (0.79 to 0.96)	0.0037	−1.2 (−2.1 to −0.4)
Current smokers	743	25	29.7 (27.6 to 31.9)	0.74 (0.63 to 0.86)	<0.0001	−10.2 (−15.0 to −5.5)
Prefer not to report	9	1	10.8 (5.6 to 20.7)
Regular smokers (cigarettes per day) †
Overall	1422	75	18.9 (17.9 to 19.9)	0.77 (0.70 to 0.84)	<0.0001	−5.0 (−6.8 to −3.2)
Former 1–19	187	24	7.7 (6.7 to 8.9)	0.95 (0.80 to 1.12)	0.52	−0.4 (−1.7 to 0.8)
Former ≥20	554	32	17.5 (16.1 to 19.0)	0.79 (0.69 to 0.90)	0.0006	−3.7 (−5.9 to −1.6)
Current 1–19	285	11	27.0 (24.0 to 30.3)	0.88 (0.70 to 1.13)	0.32	−4.2 (−12.3 to 3.9)
Current ≥20	341	7	51.7 (46.5 to 57.5)	0.76 (0.60 to 0.95)	0.021	−18.4 (−33.3 to −3.4)

*Adjusted for age, gender, calendar year, ethnicity (first 40 principal components), height, weight, recruitment centre and smoking status. Adjusted and unadjusted incidence rate ratios are reported in online supplementary table 1.
†Adjusted for pack-years, age, gender, calendar year, ethnicity (first 40 principal components), height, weight, recruitment centre. Participants currently smoking less than one cigarette per day at recruitment are excluded from the smoking subcategories but included in the overall analysis of regular smokers if they had formerly smoked one or more per day and it was possible to calculate pack-years.
IRR, incidence rate ratio; PYs, person-years.