This review concluded that preoperative statin therapy reduced postoperative all-cause mortality in patients undergoing cardiac surgery, but that further research, using randomised controlled trials, is needed. The methods of the review were not reported, search was limited, and data came mainly from observational studies, so the authors' conclusion should be treated with caution.

To assess the effects on postoperative mortality of preoperative statin therapy in cardiac surgery.

PubMed was searched from 1966 to December 2007. Search terms were reported. References of identified papers, reviews and commentaries were checked. Only studies published as full text articles, in English, were eligible for inclusion.

Controlled studies that assessed the effects of preoperative statin therapy in patients undergoing cardiac surgery were eligible for inclusion. Included studies had to report on postoperative all-cause mortality. Comparator groups were either placebo or no statins.

In the included studies the majority of participants underwent elective coronary artery bypass graft surgery.

The authors did not state how studies were selected for the review.

The authors did not state that they assessed validity.

Odds ratio (OR) with 95% confidence intervals (CI) were calculated for each study. For cohort studies, where available, adjusted odds ratios for mortality were also extracted.

The authors did not state how the data were extracted for the review.

Pooled odds ratios and 95% confidence intervals were calculated using a random-effects model. In addition, where available, adjusted odds ratios from cohort studies were pooled with results from RCTs.

Heterogeneity was assessed using the Χ² test. Subgroup analysis was performed on data from those studies that only recruited patients undergoing coronary artery bypass graft surgery.

Publication bias was assessed using the adjusted rank correlation test.

Thirteen studies (19,542 participants) were included. Of these, three were randomised controlled trials (RCTs; 317 participants) and 10 were cohort (observational) studies (19,225 participants). Study size ranged from 36 to 5,469 participants.

Preoperative statin reduced all cause mortality, unadjusted odds ratio 0.55 (95% CI 0.46 to 0.66; three RCTs and 10 cohort studies) and adjusted odds ratio 0.76 (95% CI 0.64 to 0.90; three RCTs and six cohort studies). The results were similar for coronary artery bypass graft surgery only studies (OR 0.59, 95% CI 0.36 to 0.97; two RCTs and three cohort studies).

There was no evidence of heterogeneity or of publication bias.

Preoperative statin therapy reduced postoperative all-cause mortality in patients undergoing cardiac surgery.

This review was published as a brief communication and much of the detail of the methods was not reported. The inclusion criteria were clearly stated in terms of participants, treatment and outcome, but were less clear for study design. The search was limited to full text articles published in English and listed in one database or references. Therefore, it was possible that other relevant studies may have been missed and that language bias or publication bias could have affected the results of the review. The methods of study selection and data extraction were not described, so it was not possible to comment on their suitability for limiting the effects of possible error or reviewer bias.

There was no mention of any assessment of study quality, and there was little information about the included studies or their participants. This meant it was not possible to comment on either the validity of the data or the generalisability of results. The majority of the included studies were observational studies and, as the authors acknowledged, they are not considered to be as high quality as RCTs. It was possible that selection of participants for these studies may have been influenced by factors which may have had an influence on the results.

In view of this, along with the limited search and the lack of reporting of methods, the authors' conclusion should be treated with caution. However, they appear to partially acknowledge this by also stating that further research, using RCTs, is needed.

Practice: The authors stated that there was insufficient evidence to advocate routine preoperative statin therapy in cardiac surgery.

Research: The authors stated that larger RCTs are needed to provide a definite answer of the effects of preoperative statins in cardiac surgery.

Not stated.

Kapoor AS, Kanji H, Buckingham J, Devereaux PJ, McAlister FA. Strength of evidence for perioperative use of statins to reduce cardiovascular risk: systematic review of controlled studies. BMJ 2006;333:1149

Hindler K, Shaw AD, Samuels J, Fulton S, Collard CD, Riedel B. Improved postoperative outcomes associated with preoperative statin therapy. Anesthesiology 2006;105(6):1260-1272

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.