Selected risk factors for motor fluctuations in Parkinson's disease: a meta-analysis

Motor fluctuations are a common and disabling complication of Parkinson's disease (PD), impairing patients' quality of life and imposing a healthcare burden. Our study aimed to comprehensively assess the risk factors for motor fluctuations in patients with PD.

We conducted a systematic search up to September 2023, utilizing PubMed, Embase, Web of Science, SCOPUS and Google Scholar. Cohort and case-control studies that clearly defined motor fluctuations and presented relevant data were included. The data were analyzed to generate a pooled effect size and 95 % confidence interval (CI).

Our meta-analysis included 13 studies involving a total of 3346 patients with PD, of whom 1194 (35.7 %) had motor fluctuations. The development of motor fluctuations was positively associated with female sex (HR 1.44, 95 % CI 1.12-1.86), levodopa dose (HR 1.20, 95 % CI 1.14-1.27), years of education (OR 1.34, 95 % CI 1.06-1.69), and higher Unified Parkinson's Disease Rating Scale (UPDRS) motor score (HR 1.02, 95 % CI 1.00-1.04). Conversely, age at diagnosis (HR 0.95, 95 % CI 0.94-0.97) and age at PD onset (HR 0.92, 95 % CI 0.86-0.99) were inversely associated with motor fluctuations. No significant associations were found between motor fluctuations and Hoehn & Yahr stage III, disease duration, tremor-dominant subtype, smoking (ever vs. never), caffeine intake or longer levodopa treatment duration.

Several factors were identified as associated with motor fluctuations in PD. These findings may aid in discerning patients who are at risk of developing motor fluctuations and optimizing their treatment strategies.