Adhesive capsulitis of the shoulder is associated with an increased risk for Parkinson's disease: a population-based longitudinal follow-up study.

IntroductionPrevious studies have suggested a positive association between adhesive capsulitis of the shoulder (ACS) and Parkinson's disease (PD), but longitudinal data were lacking. The present population-based longitudinal follow-up study therefore investigated the risk of developing PD in patients with ACS.MethodsThis study utilized data from Taiwan's Longitudinal Health Insurance Database 2005 (LHID 2005). We defined our ACS group as the 19,920 patients aged between 40 and 79 who had been diagnosed with ACS between 2002 and 2006. The non-ACS group consisted of an age- and sex-matched but otherwise random selection of 19,920 patients without a diagnosis of ACS. The Kaplan-Meier method was then used to examine inter-group differences in PD-free survival rates, and Cox proportional-hazard regression modeling was used to evaluate the impact of ACS on PD risk.ResultsDuring a median follow-up period of 105 months, 242 subjects in the ACS group and 208 subjects in the non-ACS group developed PD. The adjusted hazard ratio (HR) of 1.53 (1.26-1.86) indicated that ACS patients had a significantly higher risk of developing PD than their non-ACS counterparts, regardless of sex and age. Landmark analysis that excluded PD cases detected within the first 2 years after an ACS diagnosis showed that the HR was almost unchanged, at 1.56 (1.26-1.95).ConclusionsPatients with ACS are at a high risk of developing PD.Key points• This population-based study showed that adhesive capsulitis of the shoulder (ACS) is associated with a higher risk of Parkinson's disease (PD). • This study broke new ground by using a longitudinal follow-up design and a nationally representative sample. • Our findings suggest that clinicians who care for ACS patients need to be aware of this increased risk of developing PD.