Bayesian assessment of publication bias in meta-analyses of cervical cancer and oral contraceptives

Meta-analysis is well known to be susceptible to publication bias (PB), caused by lack of publication of all works on the area in question. This paper applies a recently developed Bayesian method for assessing PB to a collection of studies of the possible effects of oral contraceptive use on incidence of cervical cancer. We build on a meta-analysis developed in Delgado-Rodriguez et al. [2]. We apply a more formal approach to evaluating and adjusting for PB than the ad hoc funnel plot procedure used in that paper. We conclude that there is support for the existence of publication bias in the main data set analyzed in [2], and we show it is probably caused by the explicit disregard of 'low quality' studies in [2]. Overall we conclude that there is rather weak support for a positive association between oral contraceptive use and incidence of cervical cancer.