Table 2. Exposure to human insulin and incidences of bladder cancer and hazard ratios comparing exposed to unexposed.

Exposure to human insulin	Case number	Incident bladder cancer	%	Person-years	Incidence rate (per 100,000 person-years)	Age-sex-adjusted model			Full model*
						HR	95% CI	P	HR	95% CI	P
Never-users	697294	3330	0.48	3514835.83	94.74	1.000			1.000
Ever-users	87940	454	0.52	376802.58	120.49	1.238	(1.122, 1.366)	<0.0001	1.063	(0.951, 1.187)	0.2821
Tertile cutoffs
Time since starting insulin (months)
Never-users						1.000			1.000
<34	28954	140	0.48	124969.58	112.03	1.188	(1.003, 1.407)	0.0464	1.058	(0.887, 1.262)	0.5322
34–67	28996	145	0.50	124194.42	116.75	1.210	(1.025, 1.429)	0.0247	1.060	(0.890, 1.263)	0.5111
≥67	29990	169	0.56	127638.58	132.41	1.310	(1.122, 1.529)	<0.0001	1.069	(0.906, 1.261)	0.4284
P-trend								<0.0001			0.3116
Cumulative dosage of insulin exposure (units)
Never-users						1.000			1.000
<5,000	28591	146	0.51	123848.83	117.89	1.201	(1.017, 1.418)	0.0305	1.112	(0.936, 1.321)	0.2277
5,000–41,070	29448	132	0.45	123113.42	107.22	1.126	(0.946, 1.341)	0.1802	0.954	(0.795, 1.146)	0.6161
≥41,070	29901	176	0.59	129840.33	135.55	1.375	(1.182, 1.601)	<0.0001	1.114	(0.947, 1.310)	0.1944
P-trend								<0.0001			0.3133
Cumulative duration of insulin exposure (months)
Never-users						1.000			1.000
<3.0	29075	140	0.48	124956.92	112.04	1.142	(0.964, 1.352)	0.1253	1.049	(0.880, 1.250)	0.5928
3.0–23.9	28969	132	0.46	121588.25	108.56	1.164	(0.978, 1.385)	0.0875	1.005	(0.836, 1.207)	0.9608
≥23.9	29896	182	0.61	130257.42	139.72	1.393	(1.200, 1.617)	<0.0001	1.121	(0.955, 1.316)	0.1614
P-trend								<0.0001			0.2126

^*Adjusted for all variables in Table 1.

HR: hazard ratio; CI: confidence interval.