Table 2. SIRs and 95% CIs of intra- and extrahepatic cholangiocarcinomas in the gallstone cohort, (consisting of 192 960 patients with gallstone disease who did not undergo cholecystectomy) and in the cholecystectomy cohort, (consisting of 345 251 cholecystectomised patients) in Sweden between 1965 and 2008.

	Gallstone cohort				Cholecystectomy cohort
	Intrahepatic cholangiocarcinoma		Extrahepatic cholangiocarcinoma		Intrahepatic cholangiocarcinoma		Extrahepatic cholangiocarcinoma
	Cases (no.)	SIR* (95% CI†)	Cases (no.)	SIR* (95% CI†)	Cases (no.)	SIR* (95% CI†)	Cases (no.)	SIR* (95% CI†)
All	72	2.77 (2.17–3.49)	169	2.58 (2.21–3.00)	98	1.38 (1.12–1.69)	227	1.25 (1.09–1.42)
Male	32	3.13 (2.14–4.42)	75	2.88 (2.27–3.61)	50	1.92 (1.42–2.53)	94	1.44 (1.17–1.77)
Female	40	2.54 (1.81–3.46)	94	2.38 (1.92–2.91)	48	1.07 (0.79–1.42)	133	1.14 (0.95–1.35)
Age at cohort entry
<60 years	29	4.48 (3.00–6.43)	43	2.78 (2.02–3.75)	49	1.38 (1.02–1.82)	100	1.10 (0.89–1.33)
60–69 years	15	2.41 (1.35–3.98)	45	2.74 (2.00–3.67)	27	1.30 (0.86–1.89)	63	1.17 (0.90–1.49)
⩾70 years	28	2.11 (1.40–3.05)	81	2.41 (1.91–2.99)	22	1.52 (0.95–2.30)	64	1.74 (1.34–2.22)
Years of follow-up
1–4	37	3.59 (2.52–4.94)	96	3.71 (3.00–4.53)	27	1.80 (1.19–2.62)	86	2.29 (1.83–2.82)
5–9	16	2.09 (1.19–3.39)	30	1.55 (1.05–2.22)	28	1.68 (1.12–2.43)	52	1.22 (0.91–1.61)
⩾10	19	2.38 (1.43–3.71)	43	2.12 (1.53–2.85)	43	1.10 (0.79–1.48)	89	0.87 (0.70–1.07)

Abbreviations: CI=confidence interval; SIR=standardised incidence ratio.