Search strategy and selection criteriaFour electronic databases were searched for articles published up to April 1, 2016 without language restriction, containing Pub Med, EMBASE, Cochrane Central and Web of Science. The search terms used are presented as follows: ['heart-lung bypass' OR 'bypass, heart-lung' OR 'bypasses, heart-lung' OR 'heart lung bypass' OR 'heart-lung bypasses' OR 'bypass, cardiopulmonary' OR 'bypasses, cardiopulmonary' OR 'cardiopulmonary bypasses'] AND ['metipred' OR '6-methylprednisolone' OR '6 methylprednisolone' OR 'urbason' OR 'medrol'] AND ['random' OR 'randomized controlled trial']. The reference lists of relevant reviews were also hand searched to identify additional studies. We included studies according to the following inclusion criteria:A. Participants undergoing cardiopulmonary bypass; B. Patients were randomized grouped into the methylprednisolone group (without other drug) and the placebo group (with or without placebo ); C. Not less than one outcome ((tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10)); D. Randomized controlled trials. The articles which were retrospective studies, observational studies, case series, reviews, comments, duplicate published articles, and studies without original data were also eliminated.
Data extractionTwo authors independently collected on the following data: the first author, publication year, sample size, study design, patient characteristics, the methylprednisolone group (dosage, duration), the placebo group (dosage, duration), and measured outcome (tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10)).We made a detailed discussion when disagreements of this process occurred.