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Original research
Possible predictors of phenoconversion in isolated REM sleep behaviour disorder: a systematic review and meta-analysis
  1. Chunyi Wang1,
  2. Fangzheng Chen1,
  3. Yuanyuan Li1,
  4. Jun Liu1,2,3
  1. 1 Department of Neurology & Institute of Neurology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
  2. 2 CAS Center for Excellence in Brain Science & Intelligence Technology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
  3. 3 Co-innovation Center of Neuroregneration, Nantong University, Nantong, China
  1. Correspondence to Dr Jun Liu, Department of Neurology & Institute of Neurology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China; jly0520{at}hotmail.com; Dr Yuanyuan Li, Department of Neurology & Institute of Neurology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China; liyuanyuan258{at}126.com

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.

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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.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.