Update of a meta-analysis on lung cancer and welding.
OBJECTIVE
This study is an update, over the period 1954-2004, of a previous meta-analysis completed in 1994. It was aimed at assessing lung cancer risk among welders, while addressing heterogeneity, publication bias, and confounding issues.


METHODS
Combined relative risks (CRR) and their variances were calculated using fixed and random effects models. Heterogeneity was tested using the Q statistic. The publication bias was estimated using funnel plots, and Egger's regression and partially controlled by excluding studies with positive reporting bias.


RESULTS
The literature provided 60 studies eligible for the meta-analysis. No heterogeneity was observed. The fixed effect CRR for all of the welders and all of the studies was 1.26 (95% CI 1.20-1.32) after partial control of publication bias. No difference was observed according to welding activities. Smoking did not appear to be a marked confounder in the relationship between lung cancer and welding, but the effect of asbestos could not be assessed.


CONCLUSIONS
The meta-analysis showed a 26% excess of lung cancer for welders without any difference according to welding activities.
Ambroise
Denis
D
Department of Industry-based Epidemilogy, French National Institute for Research and Safety, Vandoeuvre Les Nancy, France.
Wild
Pascal
P
Moulin
Jean-Jacques
JJ
D000569:Americas / Q000453:epidemiology; D016022:Case-Control Studies; D005060:Europe / Q000453:epidemiology; D006801:Humans; D008175:Lung Neoplasms / Q000453:epidemiology* / Q000209:etiology / Q000401:mortality; D014896:Welding / Q000706:statistics & numerical data*