Outcomes reported in clinical studies of stable angina pectoris on traditional Chinese medicine: a systematic review towards a core outcome set

Abstract Background Traditional Chinese medicine (TCM) plays an important role in contributing to the public health in China. However, non-standardized outcomes in TCM related studies posed great difficulty in data synthesis for healthcare decisions. An agreed set of standardized outcomes, or termed as a core outcome set (COS), can solve this existing problem of outcome heterogeneity. This review aimed to analyze outcome heterogeneity, assess the quality of outcome reporting and providing a list of potential outcomes for COS development of SAP using TCM. Methods 8 literature databases were searched to identify clinical studies about TCM for SAP (SAP-TCM) of yearly samples of 2005, 2010, 2015, 2016, 2018 and 2019. 2 clinical registry databases were searched from inception to October 2020. Outcomes definition, measurement methods and time-point were extracted and categorized into 7 themes which include clinical symptoms and signs, physical and chemical examination, TCM-related outcomes, adverse events, quality of life, long-term prognosis and economic evaluation. Timing and quality assessment of the outcomes reported were analyzed and evaluated. Results A total of 1166 studies were included from 12962 potential studies, involving 111426 patients. 231 outcomes were identified and a total of 89 outcomes reported at least twice in the studies. The most commonly reported theme was clinical symptoms and signs. The most frequently reported outcomes were total rate of ECG efficiency and angina attack in clinical studies of published literature and clinical registries databases respectively. Outcomes reported in a single study ranged from 1 to 15, and 5 outcomes on average per study. 80% of the studies lack reporting of primary outcomes. A wide variation of measurement instruments or methods was used. A range of 1–17 measurement time-points were recorded. Quality assessment of outcome reporting was generally low, with 65.6% of the studies scoring 3 to 4 points. Conclusion Outcomes reported in studies on SAP-TCM are heterogeneous. A lack of standardization complicates comparisons of outcomes across studies. Developing a COS for SAP-TCM could contribute to the standardization of outcome reporting and offer a stronger evidence for health decision-making.