title: Graft for prevention of Frey syndrome after parotidectomy: a systematic review and meta-analysis of randomized controlled trials.
abstract: OBJECTIVE
  To detect the effect and safety of different types of grafts for the prevention of Frey syndrome after parotidectomy.
  
  
  METHODS
  The following data bases were searched electronically: MEDLINE (using OVID, from 1948 to July 2011), Cochrane Central Register of Controlled Trials (CENTRAL, issue 2, 2011), EMBASE (available from: http://embase.com, 1984 to July 2011), World Health Organization International Clinical Trials Registry Platform (July 2011), Chinese BioMedical Literature Database (1978 to July 2011), and the China National Knowledge Infrastructure (1994 to July 2011). The relevant journals and reference lists of the included studies were manually searched for randomized controlled trials studying the effect and safety of different types of grafts for preventing Frey syndrome after parotidectomy. The risk of bias assessment using Cochrane Collaboration's tool and data extraction was independently performed by 2 reviewers. The meta-analysis was performed using Review Manager, version 5.1.
  
  
  RESULTS
  A total of 14 randomized clinical trials and 1,098 participants were included. All had an unclear risk of bias. The meta-analysis results showed that the use of an acellular dermis matrix can reduce by 82% the risk of Frey syndrome compared with the no-graft group using an objective assessment (relative risk [RR] 0.18, 95% confidence interval [CI] 0.12 to 0.26; P < .00001; Grading of Recommendations, Assessment, Development, and Evaluation [GRADE] quality of evidence: high). The acellular dermis matrix can also reduce by 90% the risk of Frey syndrome compared with the no-graft group using a subjective assessment (RR 0.10, 95% CI 0.05 to 0.22; P < .00001; GRADE quality of evidence: high). The muscle flaps can reduce by 81% the risk of Frey syndrome compared with the no-graft group (RR 0.19, 95% CI 0.13 to 0.27; P < .00001; GRADE quality of evidence: high). No statistically significant difference was found between the acellular dermal matrix and muscle flap groups (RR 0.73, 95% CI 0.15 to 3.53, P = .70; GRADE quality of evidence: low). No serious adverse events were reported.
  
  
  CONCLUSIONS
  The present clinical evidence suggests that grafts are effective in preventing Frey syndrome after parotidectomy. More randomized clinical trials are needed to confirm our conclusions and prove the safety of the grafts.
authors.affiliation: Department of Oral and Maxillofacial Surgery, State Key Laboratory of Oral Diseases, West China School of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Chunjie
authors.initials: C
authors.lastname: Li
authors.forename: Xianrui
authors.initials: X
authors.lastname: Yang
authors.forename: Jian
authors.initials: J
authors.lastname: Pan
authors.forename: Zongdao
authors.initials: Z
authors.lastname: Shi
authors.forename: Longjiang
authors.initials: L
authors.lastname: Li
mesh_terms: D062088:Acellular Dermis; D015982:Bias; D006801:Humans; D018482:Muscle, Skeletal / Q000637:transplantation; D010306:Parotid Gland / Q000601:surgery*; D011183:Postoperative Complications / Q000517:prevention & control*; D016032:Randomized Controlled Trials as Topic; D012307:Risk Factors; D016038:Skin Transplantation / Q000379:methods*; D013524:Surgical Flaps; D013547:Sweating, Gustatory / Q000517:prevention & control*