Effect of Perioperative Vitamin C Supplementation on Postoperative Pain and the Incidence of Chronic Regional Pain Syndrome: A Systematic Review and Meta-analysis.

OBJECTIVES:

: Postoperative pain can contribute to increased risk for complications and lengthened hospital stays. The objective was to analyze the effects of perioperative vitamin C supplementation on postoperative pain and the development of complex regional pain syndrome I (CRPS I) in patients undergoing surgical procedures.

METHODS:

: A systematic review of published literature was performed through April 2014. References from relevant studies were scanned for additional studies. Results were screened for relevance independently, and full-text studies were assessed for eligibility. Reporting quality was assessed using a modified Newcastle-Ottawa Scale.

RESULTS:

: The search strategy yielded 710 studies, of which 13 were included: seven on postoperative pain and six on CRPS I. In the final analysis, one relevant study found a reduction in postoperative morphine utilization after preoperative vitamin C consumption, while another showed no difference in postoperative pain outcomes between the vitamin C and control groups. A meta-analysis of three applicable CRPS I studies showed a decrease in postoperative CRPS I after perioperative vitamin C supplementation (relative risk (RR)=2.25; tau=0).

DISCUSSION:

: There is moderate level evidence supporting the use of a 2 g preoperative dose of vitamin C as an adjunct for reducing postoperative morphine consumption, and high level evidence supporting perioperative vitamin C supplementation of 1 g per day for 50 days for CRPS I prevention after extremity surgery. Additional studies are necessary to increase the level of evidence to determine the overall effectiveness and optimum dosage of vitamin C.