Frozen shoulder could be early indicator of Parkinson's disease: Study

A recent study published in the Clinical Epidemiology journal suggests that frozen shoulder characterized by stiffness and pain in the shoulder joint, may be an early preclinical symptom of Parkinson’s disease (PD). This study examined the risk of developing PD after a frozen shoulder diagnosis and assessed whether this condition could be a manifestation of parkinsonism that precedes the clinical recognition of PD.

The study utilized data from the Danish population-based medical registries by focusing on individuals over 40 years, who were diagnosed with frozen shoulder for the first time between 1995 and 2016. The study selected a cohort from the general population matched by age and sex for comparison. To address the potential detection bias and verify the specificity of the frozen shoulder diagnosis, a sensitivity analysis was performed using a similar patients group diagnosed with back pain.

The study included a total of 37,041 individuals with frozen shoulder with 3,70,410 general population comparators and 1,11,101 individuals to compare for back pain. The primary outcome measured was the incidence of PD. Over a follow-up period of up to 22 years, the cumulative incidence of PD was 1.51% in the frozen shoulder cohort when compared to 1.03% in the general population cohort and 1.32% in the back pain cohort.

When comparing the group with frozen shoulder to the general population, the adjusted hazard ratios (HRs) revealed a significantly increased risk of PD. Within the first year of follow-up, the HR was 1.94 which indicated nearly double the risk of PD development for the individuals with frozen shoulder. Over the entire follow-up period of 22 years, the HR remained elevated close to 1.45. This indicates that individuals with frozen shoulder have a 45% higher risk of PD development when compared to the general population.

The frozen shoulder cohort was compared to the back pain cohort and found the adjusted HRs were 0.89 at 0 to1 years and 1.01 over the entire follow-up period. These findings suggest no significant difference in risk of PD between the frozen shoulder and back pain cohorts which highlighted the importance of the general population as a more suitable group for comparison.

The study found that patients with frozen shoulder have an elevated risk of developing PD when compared to the general population, although the absolute risks remained relatively low. The findings suggest that frozen shoulder could sometimes represent an early manifestation of PD. These findings unveil the potential of using frozen shoulder as a screening tool for early PD detection. Clinicians could implement earlier monitoring and intervention strategies by identifying individuals at higher risk, this could potentially improve the patient outcomes and quality of life.

Source:

Gadgaard, N., Veres, K., Henderson, V., & Pedersen, A. (2024). Frozen Shoulder and the Risk of Parkinson’s Disease: A Danish Registry-Based Cohort Study. In Clinical Epidemiology: Vol. Volume 16 (pp. 447–459). Informa UK Limited. https://doi.org/10.2147/clep.s463571