Significantly impaired shoulder function in the first years of rheumatoid arthritis: a controlled study

INTRODUCTION: Patients with rheumatoid arthritis (RA) risk impaired shoulder function due to the inflammatory process. The knowledge of shoulder function in the early years of the disease is limited. The aim was to compare shoulder function and activity limitation related to the shoulder-arm-hand in women with RA in early disease course compared to age-matched healthy women. METHOD: This controlled cross-sectional study included 103 women with rheumatoid arthritis and a reference group of 103 age-matched healthy women. The mean age was 47.1 (SD 10.0) years, the mean disease duration was 20.3 (SD 8.5) months and the mean DAS28 score was 3.8 (SD 1.4) among the patients. Participants were provided with self-reported questionnaires quantifying activity limitations. Shoulder function was assessed by isometric strength of the shoulder, shoulder-arm movement and shoulder pain. Hand-grip force was assessed and examination was made of tender and swollen joints among the patients. RESULTS: Patients showed significantly (p < 0.0001) impaired shoulder muscle strength, shoulder-arm movement, and shoulder pain compared to the reference group. Patients shoulder muscle strength was approximately 65 % of the results observed in the reference group. Activity limitations related to the shoulder-arm-hand (DASH) were significantly (p < 0.0001) higher in the patient group compared to the reference group and indicates limitations in daily activities for the patients. CONCLUSION: Patients with RA were found to have significantly impaired shoulder function already 1.5 years after disease onset compared to age-matched subjects. Reduced shoulder muscle strength was found to be associated with activity limitations (DASH) implying that screening of the shoulder function, emphasising the shoulder muscle strength, should be initiated from disease onset. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13075-015-0777-0) contains supplementary material, which is available to authorized users.