Risk factors for shoulder pain and stiffness in adults aged 44 and older: an 11-year longitudinal population-based study.

We conducted a longitudinal observational study over 11 years to identify the risk factors for developing shoulder pain, stiffness, or both. The study population (n = 1645) was identified from Health 2000 Survey, a nationally representative sample of Finns aged ≥ 44 years, without shoulder pain and stiffness at the start of the study based on a questionnaire. The independent variables included age, sex, body mass index (BMI), education level, diabetes, physical work exposures, and Beck's depression score. We used multinomial logistic regression models to estimate relative risk ratios and 95% confidence intervals for three outcomes: shoulder pain, shoulder stiffness, and both combined. We found that excess body mass and depressive symptoms were shared statistically significant risk factors for all three outcomes. However, we also observed distinct risk factor profiles: older age was associated with lower risk of shoulder pain but higher risk for shoulder stiffness with or without pain, while females had a lower risk of shoulder stiffness with or without pain. Participants with diabetes had higher risk of shoulder stiffness only. Physical workload factors predicted an increased risk of the combination of shoulder pain and stiffness. Our study identified increased BMI and depressive symptoms as consistent risk factors for shoulder pain, stiffness, or both. Older age increased the risk of shoulder stiffness but lowered the risk of pain alone, while females had a lower risk of stiffness. Diabetes was specifically linked to shoulder stiffness, and physical workload increased the risk of combined pain and stiffness.