title: Estrogens and the risk of complex regional pain syndrome (CRPS).
abstract: OBJECTIVE
  Since complex regional pain syndrome (CRPS) shows a clear female predominance, we investigated the association between the cumulative as well as current exposure to estrogens, and CRPS.
  
  
  METHODS
  A population-based case-control study was conducted in the Integrated Primary Care Information (IPCI) project in the Netherlands. Cases were identified from electronic records (1996-2005) and included if they were confirmed during a visit (using International Association for the Study of Pain Criteria), or had been diagnosed by a specialist. Controls were matched to cases on gender, age, calendar time, and injury. Measures of cumulative endogenous estrogen exposure were obtained by questionnaire and included age of menarche and menopause, menstrual life, and cumulative months of pregnancy and breast-feeding. Current estrogen exposure at CRPS onset was retrieved from the electronic medical records and determined by current pregnancy or by the use of oral contraceptive (OC) drugs or hormonal replacement therapy (HRT).
  
  
  RESULTS
  Hundred and forty-three female cases (1493 controls) were included in analyses on drug use and pregnancies, while cumulative endogenous estrogen exposure was studied in 53 cases (58 controls) for whom questionnaire data were available. There was no association between CRPS and either cumulative endogenous estrogen exposure, OC, or HRT use. CRPS onset was increased during the first 6 months after pregnancy (OR: 5.6, 95%CI: 1.0-32.4), although based on small numbers.
  
  
  CONCLUSIONS
  We did not find an association between CRPS onset and cumulative endogenous estrogen exposure or current OC or HRT use, but more powered studies are needed to exclude potential minor associations.
authors.affiliation: Pharmaco-Epidemiology Unit, Department of Medical Informatics and Epidemiology & Biostatistics, Erasmus University Medical Center, Rotterdam, The Netherlands. m.vrolijk-demos@erasmusmc.nl
authors.forename: M
authors.initials: M
authors.lastname: de Mos
authors.forename: F J P M
authors.initials: FJ
authors.lastname: Huygen
authors.forename: B H Ch
authors.initials: BH
authors.lastname: Stricker
authors.forename: J P
authors.initials: JP
authors.lastname: Dieleman
authors.forename: M C J M
authors.initials: MC
authors.lastname: Sturkenboom
mesh_terms: D000328:Adult; D017668:Age of Onset; D000368:Aged; D016022:Case-Control Studies; D020918:Complex Regional Pain Syndromes / Q000453:epidemiology / Q000209:etiology*; D003276:Contraceptives, Oral / Q000009:adverse effects; D015914:Estrogen Replacement Therapy / Q000009:adverse effects; D004967:Estrogens / Q000008:administration & dosage / Q000009:adverse effects* / Q000378:metabolism; D005260:Female; D006801:Humans; D007774:Lactation / Q000378:metabolism; D008572:Menarche / Q000378:metabolism; D008593:Menopause / Q000378:metabolism; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D011247:Pregnancy; D012307:Risk Factors; D012737:Sex Factors; D011795:Surveys and Questionnaires; D013997:Time Factors
chemical_list: D003276:Contraceptives, Oral; D004967:Estrogens