Table 2.

Observational studies included in the meta-analysis

Study	Study location	Study design	All subjects	HM cases	RR (95% CI)	Control for potential confounders*	Type of HM studied
Fortuny et al. 2006 [30]†	Czech Rep., France, Germany, Ireland, Italy and Spain	C-C	4568	2362	0.61 (0.45, 0.84)	1–3	Incident lymphoma
Iwata et al. 2006 [31]	Japan	C-C	1100	221	2.24 (1.37, 3.66)	1, 2, 4–6	Incident lymphoma and myeloma
Landgren et al. 2006 [32]	USA	C-C	870	179	0.4 (0.2, 0.8)	1, 7–9	Incident myeloma
Friis et al. 2005 [33]	Denmark	Cohort	334 754	1626	0.88 (0.60, 1.29)	1, 2, 10–13	Incident haematological malignancies
Graaf et al. 2004 [34]	The Netherlands	C-C	20105	93	0.28 (0.06, 1.30)	1, 2, 12–22	Incident lymphoma
Zhang et al. 2004 [35]	USA	C-C	1318	601	0.5 (0.4, 0.8)	1, 9, 23, 24	Incident non-Hodgkin lymphoma
Blais et al. 2000 [36]	Canada	C-C	264	24	2.17 (0.38, 12.36)	1, 2, 4, 18, 25, 26	Incident lymphoma
Traversa et al. 1998 [37]	Italy	C-C	2222	202	1.5 (0.8, 2.6)	1, 2	Incident leukaemia

HM, Haematological malignancy; RR, relative risk; CI, confidence interval.

^*1, age; 2, gender; 3, country; 4, year of visit; 5, serological status for antihepatitis B surface antigens; 6, serological status for antihepatitis C virus antibodies; 7, race; 8, education; 9, body mass index; 10, calendar period; 11, use of cardiovascular drugs; 12, use of nonsteroidal anti-inflammatory drugs; 13, use of hormone replacement therapy; 14, geographical region; 15, duration of follow-up; 16, diabetes mellitus; 17, prior hospitalizations; 18, chronic disease score; 19, chronic use of diuretics; 20, chronic use of angiotensin-converting enzyme inhibitors; 21, chronic use of calcium channel blockers; 22, use of other lipid-lowering therapy; 23, menopausal status; 24, family history of non-Hodgkin lymphoma in first-degree relatives; 25, previous neoplasm; 26, use of fibric acids.

^†Numbers in parentheses, reference citation.