Using PRECIS-2 in Chinese herbal medicine randomized controlled trials for irritable bowel syndrome: A methodological exploration based on literature

Background

The pragmatism levels of randomized controlled trials (RCTs) mean how similar the interventions delivered in the trial setting match those in the setting where the results will be applied. We aimed to investigate the association between the consistency of pragmatism among the characteristics of RCT design and its effect size of results in Chinese herbal medicine (CHM) for irritable bowel syndrome (IBS).

Methods

Eight English and Chinese language databases were searched for RCTs on CHM for IBS. Six reviewers independently assessed the pragmatism of trials using the pragmatic-explanatory continuum indicator summary 2 (PRECIS-2) tool. The consistency of pragmatism levels among the characteristics of RCT design was calculated using the coefficient of variation. Linear regression models were adopted to explore influence factors of the pragmatism of RCTs.

Results

78 RCTs were included. The level of consistency in the pragmatism for RCT's design was significantly correlated with the effect size of the results (binary outcome, r = -0.413; P = 0.005; continuous outcome, r = -0.779, P < 0.001). PRECIS-2 score was higher in trials with individualized interventions than fixed interventions (3.29 [0.32] vs 2.90 [0.32]; Cohen's d relative effect size, 0.52; P < 0.001) and in standard or usual-treatment-controlled trials than placebo-controlled (3.05 [0.37] vs 2.83 [0.28]; Cohen's d relative effect size, 0.32; P = 0.048).

Conclusion

The consistency of pragmatism level across the 9 domains of the PRECIS-2 tool in CHM IBS RCTs was positively correlated with the effect size of the results.