Methodological quality of systematic reviews on treatments for Parkinson's disease: A cross-sectional study

Systematic reviews (SR) of high methodological quality can provide the best evidence for clinical practice. However, the methodological quality of SRs on Parkinson's disease treatments has not been evaluated comprehensively. The study aims to assess the methodological quality of a representative sample of SRs on Parkinson's disease treatments.

Four databases were searched to obtain potentially eligible SRs published between January 2016 and December 2021. A pre-designed questionnaire was used to extract the bibliographical characteristics of the included SRs. The AMSTAR-2 (Assessing the Methodological Quality of Systematic Reviews) tool was used to assess the methodological quality of SRs. Factors associated with methodological quality were assessed using multivariate regression analyses.

A total of 119 eligible SRs were included and appraised. Only one SR (0.8%) was of high overall methodological quality. Four (3.4%) and 7 (5.9%) SRs were of moderate and low overall methodological quality, respectively. Among the appraised SRs, only 3 (2.5%) applied a comprehensive literature search strategy, 11 (9.2%) provided a list of excluded studies with justifications for exclusion, and 4 (3.4%) reported the sources of funding among the original studies included in the SR. Cochrane SRs and SRs published in journals with higher impact factors had relatively higher overall methodological quality.

This study demonstrated that SRs on Parkinson's disease treatments are of low methodological quality. To enhance the quality and hence the trustworthiness of SRs, the protocols of future reviews should be designed and registered a priori, and researchers should conduct a comprehensive literature search, provide a list of excluded studies with justifications for exclusion, and report sources of funding for the included original studies.