title: Serum Insulin-Like Growth Factor-1 in Patients with De Novo, Drug Naïve Parkinson's Disease: A Meta-Analysis.
abstract: OBJECTIVE
  Insulin-like growth factor-1 (IGF-1) is reported to be neuroprotective in the setting of Parkinson's disease (PD), and there is increasing interest in the possible association of serum IGF-1 levels with PD patients, but with conflicting results. Therefore, we conducted a meta-analysis to evaluate the association of serum IGF-1 levels in de novo, drug naïve PD patients compared with healthy controls.
  
  
  METHODS
  Pubmed, ISI Web of Science, OVID, EMBASE, and Cochrane library databases from 1966 to October 2014 were utilized to identify candidate studies using Medical Subjective Headings without language restriction. A random-effects model was chosen, with subgroup analysis and sensitivity analysis conducted to reveal underlying heterogeneity among the included studies.
  
  
  RESULTS
  In this meta-analysis, we found that PD patients had higher serum IGF-1 levels compared with healthy controls (summary mean difference [MD] = 17.75, 95%CI = 6.01, 29.48). Subgroup analysis demonstrated that the source of heterogeneity was population differences within the total group. Sensitivity analysis showed that the combined MD was consistent at any time omitting any one study.
  
  
  CONCLUSIONS
  The results of this meta-analysis demonstrate that serum IGF-1 levels were significantly higher in de novo, drug-naïve PD patients compared with healthy controls. Nevertheless, additional endeavors are required to further explore the association between serum IGF-1 levels and diagnosis, prognosis and early therapy for PD.
authors.affiliation: Department of Neurology & Institute of Neurology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
authors.forename: Dun-Hui
authors.initials: DH
authors.lastname: Li
authors.affiliation: Department of Neurology & Institute of Neurology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
authors.forename: Ya-Chao
authors.initials: YC
authors.lastname: He
authors.affiliation: Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, Michigan, 48073, United States of America.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Quinn
authors.affiliation: Department of Neurology & Institute of Neurology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
mesh_terms: D016022:Case-Control Studies; D016001:Confidence Intervals; D005260:Female; D015870:Gene Expression; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism*; D008297:Male; D010300:Parkinson Disease / Q000097:blood* / Q000175:diagnosis* / Q000235:genetics
chemical_list: D007334:Insulin-Like Growth Factor I