Osteoarthritis of the thumb carpometacarpal joint in women and occupational risk factors: a case-control study.

PURPOSE Among other etiologic factors involved in first carpometacarpal (CMC) osteoarthritis (OA), occupational factors have been postulated as influencing the occurrence of this condition. Very few epidemiologic studies, however, have evaluated this topic. Determining the occupational risk factors is important in proposing preventive measures at the workplace. This case-control study was undertaken to explore whether there was a history of greater exposure to some occupational factors (eg, occupations, hand postures, tasks involving the CMC joint) in women requiring surgery for CMC OA compared with women with no CMC OA noted by history and physical examination. METHODS The case subjects were 61 women surgically treated for primary CMC OA and the control subjects were 120 aged matched women without history or features of CMC OA. A detailed structured interview was developed to elicit information about age, smoking habits, medical history, lifestyle history, and occupational factors. Occupational factors were based on a detailed history of jobs, coded according to the International Standard Classification of Occupations. For the main occupation/job held for the longest duration and during an average working day, subjects were asked about hand posture or tasks involving requirements presumed to cause a strain or a high load to the CMC joint and about certain work conditions. RESULTS Of the 61 case and 120 control subjects, 5 and 14, respectively, had never worked. There was no difference between the average number of jobs through the working lifetime of the group of case subjects compared with the group of control subjects. Logistic regression analysis showed that after adjustment for age, smoking status, obesity, CMC OA family history, hysterectomy history, parity, and occasional job, the following occupational factors were risk factors for CMC OA: occupations presumed to be associated with increased risk for CMC OA, occupations involving repetitive thumb use, and jobs perceived by the subject having not enough rest breaks during a day. The group of case subjects had a higher prevalence of hysterectomy history and family CMC OA history compared with the group of control subjects. CONCLUSIONS Although previous studies have reported that work and exposure history may lack precision as risk factors, our results give further evidence to support the role of certain occupational factors in the occurrence of CMC OA in women. TYPE OF STUDY/LEVEL OF EVIDENCE Therapeutic II.