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Abstract
Background A number of promising biomarkers for predicting imminent α-synucleinopathies have been suggested in isolated rapid eye movement sleep behaviour disorder (iRBD). However, existing evidence is conflicting without quantitative evaluation.
Methods PubMed, Web of Science and ClinicalTrials.gov were searched through June 2021 to identify possible predictors of phenoconversion from iRBD to Parkinson’s disease (PD). The pooled HRs and standardised mean differences (SMDs) with 95% CIs were calculated using fixed-effects or random-effects model.
Results A total of 123 studies were included in the meta-analysis. Significant motor dysfunction (HR 1.83, 95% CI 1.33 to 2.51, I2=86.8%, p<0.001), constipation (HR 1.52, 95% CI 1.26 to 1.84, I2=8.3%, p=0.365), orthostatic hypotension (HR 1.93, 95% CI 1.05 to 3.53, I2=54.9%, p=0.084), hyposmia (HR 2.78, 95% CI 1.83 to 4.23, I2=23.9%, p=0.255), mild cognitive impairment (HR 2.27, 95% CI 1.58 to 3.27, I2=0%, p=0.681) and abnormal colour vision (SMD −0.34, 95% CI −0.63 to −0.05, I2=45.6%, p=0.087) correlated with susceptibility to PD. The process can also be traced by putaminal dopamine transporter imaging (HR 2.60, 95% CI 1.94 to 3.48, I2=0%, p=0.781) and tonic electromyographic activity (HR 1.50, 95% CI 1.04 to 2.15, I2=70%, p=0.018).
Conclusions The predictive value of each biomarker was initially highlighted with comprehensive evaluation. Combining specific predictors with high sensitivity is promising for detecting phenoconversion in the prodromal stage. Large-scale and multicentre studies are pivotal to extend our findings.
- sleep disorders
- parkinson's disease
- meta-analysis
Data availability statement
Data are available on reasonable request. All data relevant to the study are included in the article or uploaded as online supplemental information. All data relevant to the study are available from published articles referenced in the text and online supplemental information. Extracted data used for analysis are uploaded as online supplemental information or available at reasonable request.
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Data availability statement
Data are available on reasonable request. All data relevant to the study are included in the article or uploaded as online supplemental information. All data relevant to the study are available from published articles referenced in the text and online supplemental information. Extracted data used for analysis are uploaded as online supplemental information or available at reasonable request.
Footnotes
CW and FC are joint first authors.
Contributors CW and JL conceived the project. CW and FC independently performed the literature search, extracted the data, critically reviewed references, analyzed the data and wrote the first draft of the manuscript. YL and JL critically reviewed references and revised the manuscript for intellectual content. All authors critically revised successive drafts of the paper and approved the final version. YL and JL are responsible for the overall content as guarantors.
Funding This work was supported by grants from the National Natural Science Foundation of China (81873778, 82071415 and 82001341).
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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