This study aimed to assess the quality and characteristics of RCTs in the ASEAN Member States (AMS) during a decade of harmonization efforts.

This study is a systematic review to assess the quality of RCTs conducted in AMS. Studies were included if they were (1) reports of RCTs involving AMS from 2010 to 2021; (2) published in English; and (3) available in full text. Literature searches were conducted in MEDLINE and EMBASE. Study quality was assessed using the Cochrane’s risk-of-bias tool and were classified as high- or low-quality. Multiple logistic regression analysis was used to identify characteristics associated with RCT quality.

A total of 51,177 articles were identified, among which 437 studies were eligible for quality assessment. Of the 437 studies, 41.6% were of high-quality. The use of blinding and a higher number of participants (100–1000 and > 1000) contributed positively to study quality (odds ratio (OR): 1.60 [95% confidence interval (CI): 1.05–2.41]; OR: 1.91 [95%CI: 1.24–2.94]; OR: 3.14 [95%CI: 1.22–8.10], respectively). Whereas the use of non-parallel assignment in the type of randomization contributed negatively to study quality (OR: 0.51 [95% CI: 0.26–1.03], P = 0.060). Among the six AMS with a high number of RCTs, two had high-quality studies > 50%, three had slightly more than 40% and one had less than 20%.

In the decade of regulatory harmonization, less than half of RCTs in AMS were of high-quality. Large numbers of participants and the use of blinding were associated with high-quality RCTs, while the opposite was true for studies with non-parallel assignment. To improve the quality of RCTs, more training and capacity building of local researchers is needed, with particular attention to study design.