Prevalence of Supine Hypertension in Alpha‐Synucleinopathies: A Systematic Review and Meta‐Analysis

Background Alpha‐synucleinopathies, including Parkinson's Disease (PD), Dementia with Lewy Bodies (DLB), Multiple System Atrophy (MSA), and Pure Autonomic Failure (PAF), are associated with autonomic dysfunctions such as orthostatic hypotension (OH) and supine hypertension (SH). SH, characterized by elevated supine blood pressure, carries significant cardiovascular and cognitive risks, yet its prevalence in α‐synucleinopathies remains inadequately defined. Objectives We aimed to conduct a systematic review and meta‐analysis to assess the prevalence of SH in α‐synucleinopathies. Methods We systematically searched PubMed, Embase, and Web of Science databases for studies reporting SH prevalence in patients with α‐synucleinopathies. A random‐effects model estimated prevalence, stratified by disease type, study design, SH definition, OH presence, and disease duration. Sensitivity analyses were applied to explore sources of variability. Results Nineteen studies involving 4973 patients were included. The overall SH prevalence was 30.4% (95% CI: 26.4–34.7; I 2 = 87.6%). In PD, SH prevalence was 28.3% (95% CI: 24.0–32.9; I 2 = 86.4%), with OH significantly increasing prevalence (33.9% vs. 21.3%, P = 0.0341). In MSA, SH prevalence was 31.1% (95% CI: 25.9–36.9; I 2 = 30.5%), with OH similarly associated with higher SH prevalence (46.5% vs. 19.8%, P = 0.0023). In DLB, the pooled SH prevalence was 48.7% (95% CI: 39.5–58.1; I 2 = 11.9%). For PAF, a single study reported a prevalence of 48.4% (95% CI: 35.7–61.2). Conclusion SH is highly prevalent across α‐synucleinopathies, with variability by disease type and OH presence. Standardizing diagnostic criteria and investigating its clinical implications are essential to enhance management strategies.