title: Smoking and socio-economic status in the etiology and severity of Legg-Calvé-Perthes' disease.
abstract: BACKGROUND
  The etiology of Legg-Calvé-Perthes disease is poorly understood. An association has been found in the past between Legg-Calvé-Perthes disease and smoking as well as low socio-economic status.
  
  
  METHODS
  A prospective study was carried out in which families with a child diagnosed with Legg-Calvé-Perthes' disease were interviewed about the presence and duration of household second-hand smoke exposure to children. A control group of randomly selected families seen at our institution were interviewed with identical questions. The radiographs of children with Legg-Calvé-Perthes disease were reviewed and classified according to the Herring lateral pillar classification system.
  
  
  RESULTS
  Thirty-eight of the 60 patients (63.3%) with Legg-Calvé-Perthes disease were noted to have at least one smoker living in the child's household with a mean of 1.03 smoker-years per year of life exposure to smoke. The median income of the patients with Legg-Calvé-Perthes disease was USD 20,300. The median income of the patients in the control group was USD 17,000. Thirty-eight of the 96 control patients (39.6%) were noted to have at least one smoker living in the child's household with a mean of 0.48 smoker-years per year of life. A significant association was noted between living with a smoker and Legg-Calvé-Perthes disease as well as between increasing smoke exposure and increased risk of developing Legg-Calvé-Perthes disease. No significant association was noted between lower income and Legg-Calvé-Perthes disease. There was no association between increased smoke exposure and increased severity of Legg-Calvé-Perthes disease as measured by the lateral pillar classification.
  
  
  CONCLUSIONS
  The presence of second-hand smoke seems to be a significant risk factor in the development of Legg-Calvé-Perthes disease. The presence of second-hand smoke may represent the 'unknown industrial factor' that has been discussed.
authors.affiliation: Department of Orthopaedic Surgery, Washington University School of Medicine, St Louis, Missouri, USA. gordone@msnotes.wustl.edu
authors.forename: J Eric
authors.initials: JE
authors.lastname: Gordon
authors.forename: Perry L
authors.initials: PL
authors.lastname: Schoenecker
authors.forename: John D
authors.initials: JD
authors.lastname: Osland
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Dobbs
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Szymanski
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Luhmann
mesh_terms: D016022:Case-Control Studies; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007873:Legg-Calve-Perthes Disease / Q000145:classification / Q000209:etiology*; D008297:Male; D011446:Prospective Studies; D012111:Residence Characteristics; D012307:Risk Factors; D012720:Severity of Illness Index; D012959:Socioeconomic Factors; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
chemical_list: D014028:Tobacco Smoke Pollution