Table 4.

Cohort studies for association of chronic HCV infection with thyroid cancer (TC).

Author	Country	Study period	Total number of subjects	TC (n)/HCV (+) cases (n)	TC (n)/HCV (−) cases (n)	OE	EC	Person-years	Risk (95% CI)
Duberg et al. [37]	Sweden	1990–2000	27,150	NA/27,150	NA	5	NA	122,272	SIR 1.5 (0.5–3.6)
Giordano et al. [4]	USA	1997–2004	718,687	NA/146,394	NA/572,293	NA	NA	HCV (+) 280,676 HCV (−) 1,095,911	HR∗ 0.7 (0.5–0.9)
Allison et al. [34]	USA	2006–2010	2,143,369	6/12,126	NA/2,131,243	NA	NA	39.984	SRR 1.1 (0.6–1.6)
Omland et al. [35]	Denmark	1994–2003	4204	1/4204	NA	1	0.5	15,980	SIR 2.1 (0.1–12.0)
Amin et al. [28]	Australia	1990–2002	117,547	9/75,834	NA	9	NA	356,775	SIR 0.3 (0.2–0.7)
Swart et al. [36]	Australia	1993–2007	29,613	5/14,892	NA	5	6.8	213,008	SIR 0.7 (0.2–1.7)

OC: observed cases; EC: expected cases; CI: confidence interval; SIR: standardized incidence ratio; HR: hazard ratio; ^∗HR adjusted for age, sex, race, baseline visit date, type of visit (inpatient or outpatient) for the baseline visit and a preceding visit, previous VA use, and era of military service; NA: not available.