Objective It is postulated that increased load from pinch and grasp in occupational tasks increases the risk of thumb carpometacarpal (CMC1) osteoarthritis (OA). We sought to characterise the relationship between doctor-diagnosed CMC1 OA and occupation in a large working population.
Methods We performed a matched case–control study using a Swedish healthcare register. We identified residents aged 30–65 years in 2013 with physician-diagnosed CMC1 OA from 1998 to 2013. We matched four controls per person with CMC1 OA by age, sex, education and postcode. Swedish Standard Classification of Occupations was used to assign occupation. Occupation was categorised as light, light–moderate, moderate and heavy labour. We used conditional logistic regression to estimate ORs with 95% CIs.
Results We identified 3462 patients with CMC1 OA and matched 13 211 controls. The mean age of the CMC1 OA group was 63 (SD 7) years, with 81% women. The ORs for CMC1 OA in men were 1.31 (95% CI 0.96 to 1.79) for light–moderate, 1.76 (95% CI 1.29 to 2.40) for moderate and 2.00 (95% CI 1.59 to 2.51) for heavy compared with light work. Women had ORs for CMC1 OA of 1.46 (95% CI 1.32 to 1.61) for light–moderate, 1.27 (95% CI 1.10 to 1.46) for moderate and 1.31 (95% CI 1.07 to 1.59) for heavy compared with light work.
Conclusions The association between increased manual load in occupation and risk of CMC1 OA is more pronounced in men than in women, likely due to higher workload in the heavy labour category.
- thumb carpometacarpal joint
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Contributors JMW and IA planned the study. AT abstracted the data and performed the initial data analysis. JMW, IA, ME and AT performed substantive data evaluation and results review. JMW wrote the manuscript, which was edited extensively by IA, ME and AT.
Funding This study was funded by the Swedish Research Council, Greta and Johan Kock Foundation, Österlund Foundation, The Swedish Rheumatism Association and Governmental Funding of Clinical Research within National Health Service.
Competing interests JW receives salary for work as a deputy editor for the Journal of Hand Surgery.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information. These healthcare and occupational registers are maintained by state authorities in Sweden and are protected data per the ethics agreement. Thus the data are not made available for public or research review.