title: Osteoarthritis in the carpometacarpal joint of the thumb. Prevalence and associations with disability and mortality.
abstract: BACKGROUND
  This study was designed to investigate the prevalence of osteoarthritis in the carpometacarpal joint of the thumb in adults thirty years of age or older in Finland.
  
  
  METHODS
  Between 1978 and 1980, a representative population sample of 8000 Finns thirty years of age or older were invited to have a comprehensive health examination; 90% accepted. Hand radiographs were made of 3595 subjects. Since the examination, the subjects have been followed systematically to assess work disability and mortality by reviewing registers covering the whole population.
  
  
  RESULTS
  The age-adjusted prevalence of thumb carpometacarpal osteoarthritis of Kellgren grade 2, 3, or 4 was 7% for men and 15% for women. After adjustment for age, sex, and other alleged risk factors, body mass index was found to be directly proportional to the prevalence of thumb carpometacarpal osteoarthritis in both sexes. The adjusted odds ratio was 1.29 (95% confidence interval, 1.15 to 1.43) per 5-kg/m(2) increment in body mass index. No significant association was found between the physical workload history and thumb carpometacarpal osteoarthritis. Restricted mobility of the thumb and local tenderness and swelling were frequently found in conjunction with radiographic evidence of thumb carpometacarpal osteoarthritis. Advanced (grade-3 or 4) thumb carpometacarpal osteoarthritis predicted the total mortality rate in men (adjusted relative risk, 1.32; 95% confidence interval, 1.03 to 1.69). Radiographic signs of thumb carpometacarpal osteoarthritis did not predict work disability.
  
  
  CONCLUSIONS
  and
  
  
  CONCLUSIONS
  Obesity is a strong determinant of thumb carpometacarpal osteoarthritis in both sexes. The effect of thumb carpometacarpal osteoarthritis on disability and mortality in the general population is modest. Because of the rarity of ensuing disability, carpometacarpal osteoarthritis of the thumb is likely to be underdiagnosed in clinical practice.
authors.affiliation: Department of Orthopaedic Surgery, Kuopio University Hospital, P.O. Box 1627, FIN-70211 Kuopio, Finland. mhaara@hytti.uku.fi
authors.forename: Mikko M
authors.initials: MM
authors.lastname: Haara
authors.forename: Markku
authors.initials: M
authors.lastname: Heliövaara
authors.forename: Heikki
authors.initials: H
authors.lastname: Kröger
authors.forename: Jari P A
authors.initials: JP
authors.lastname: Arokoski
authors.forename: Pirjo
authors.initials: P
authors.lastname: Manninen
authors.forename: Alpo
authors.initials: A
authors.lastname: Kärkkäinen
authors.forename: Paul
authors.initials: P
authors.lastname: Knekt
authors.forename: Olli
authors.initials: O
authors.lastname: Impivaara
authors.forename: Arpo
authors.initials: A
authors.lastname: Aromaa
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008662:Metacarpophalangeal Joint; D008875:Middle Aged; D010003:Osteoarthritis / Q000150:complications / Q000453:epidemiology / Q000401:mortality; D015995:Prevalence; D013933:Thumb