title: Roles of interleukin (IL)-6 gene polymorphisms, serum IL-6 levels, and treatment in obstructive sleep apnea: a meta-analysis.
abstract: BACKGROUND
  Inconsistent results regarding the relationship between interleukin (IL)-6 gene polymorphisms, serum IL-6 levels, and the treatment in obstructive sleep apnea (OSA) have been reported. This meta-analysis assessed the associations between IL-6 gene polymorphisms and OSA susceptibility, IL-6 levels in OSA, and CPAP (continuous positive airway pressure) and T&A (tonsillectomy and adenoidectomy) therapy for IL-6 in OSA.
  
  
  METHODS
  Studies regarding IL-6 polymorphisms, serum IL-6 levels, and OSA treatment were identified using PubMed and Embase. The associations between IL-6 gene polymorphisms and OSA risk (estimated by pooling odds ratios (ORs) with 95 % confidence intervals (CIs)) were assessed using an allele model. The pooled standardized mean differences (SMDs) with 95 % CI of IL-6 were estimated using a random-effects model. Meta-regression, sensitivity analysis, and publication bias were also evaluated.
  
  
  RESULTS
  In total, 53 studies were included. In adults, a significant association between -174 G/C and OSA susceptibility was observed (OR = 1.46, 95 % CI = 1.14-1.87) and IL-6 levels were higher in OSA compared to controls (SMD = 1.56, 95 % CI = 1.18-1.95); however, no association was observed for the -572 G/C allele (OR = 1.13, 95 % CI = 0.87-1.47) and OSA susceptibility and there was no significant change in IL-6 in pre- and post-CPAP therapy (SMD = -0.24, 95 % CI = -0.73 to 0.26). In children, IL-6 levels were also higher in OSA (SMD = 1.27, 95 % CI = 0.29-2.26) and T&A treatment significantly decreased them (SMD = -0.97, 95 % CI = -1.72 to -0.22).
  
  
  CONCLUSIONS
  This meta-analysis indicates that the IL-6 gene polymorphism -174 G/C, and not -572 G/C, is associated with adult OSA risk. Although IL-6 levels increased in OSA, CPAP did not significantly suppress them in adults with OSA. In children with OSA, IL-6 levels also increased and T&A therapy significantly decreased them.
authors.affiliation: Department of Respiratory Diseases, The Second Affiliated Hospital of Soochow University, 1055 Sanxiang Road, Suzhou, 215004, China.
authors.forename: Anyuan
authors.initials: A
authors.lastname: Zhong
authors.affiliation: Department of Endocrinology, The Affiliated Drum Tower Hospital, Nanjing Medical University, Zhongshan Road 321, Nanjing, 210008, China.
authors.forename: Xiaolu
authors.initials: X
authors.lastname: Xiong
authors.affiliation: Department of Respiratory Diseases, The Second Affiliated Hospital of Soochow University, 1055 Sanxiang Road, Suzhou, 215004, China. shiminhua@163.com.
authors.forename: Minhua
authors.initials: M
authors.lastname: Shi
authors.affiliation: Department of Otolaryngology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Otolaryngology Institute of Shanghai Jiao Tong University, 600 Yishan Road, Shanghai, 200233, China. sunnydayxu2010@sjtu.edu.cn.
authors.forename: Huajun
authors.initials: H
authors.lastname: Xu
mesh_terms: D000233:Adenoidectomy; D000328:Adult; D000483:Alleles; D002648:Child; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D015850:Interleukin-6 / Q000097:blood* / Q000235:genetics*; D011110:Polymorphism, Genetic / Q000235:genetics*; D020181:Sleep Apnea, Obstructive / Q000097:blood / Q000235:genetics* / Q000628:therapy*; D014068:Tonsillectomy
chemical_list: C508600:IL6 protein, human; D015850:Interleukin-6
keywords: Interleukin (IL)-6; Meta-analysis; Obstructive sleep apnea