ObjectiveThrough the analysis on outcome measurements in domestic and overseas randomized controlled trials (RCTs) of smoking cessation, this study aimed to provide references for clinical trial design in the future. MethodsWe searched CNKI, WanFang Data, VIP, PubMed, EMbase, ScienceDirect and SpringLink databases to collect RCTs regarding smoking cessation from January 1998 to December 2013. Two reviewers screened literature according to the inclusive and exclusive criteria, extracted the data, and analyzed the outcome measurements of included RCTs. ResultsA total of 68 RCTs regarding smoking cessation were included. As for the baseline measurements, the frequency from high to low were age, sex, daily cigarette, smoking duration, Fagerstrom Test For Nicotine Dependence (FTND), race and education, etc.; there were significant differences of race, education level, smoking duration, smoking, starting age of smoking, attempts of trying to stop smoking, the presence of other basic disease, FTND and quit date between English and Chinese RCTs (all P<0.05). As for efficacy measurements, the continuous abstinence rate (77.8%) was mainly adopted in Chinese RCTs, while point abstinence rate (95.1%) and continuous abstinence rate (82.9%) was selected in English RCTs. As for the follow-up measurements, 22.1% of the included RCTs did not report it, 70.6% of the RCTs reported abstinence rate, and the follow-up time in Chinese RCTs was shorter than that in the English RCTs (P<0.05). ConclusionThe selection of outcome measurements is significantly different among RCTs regarding smoking cessation, the Chinese RCTs are inferior to English RCTs, and these are needed to be improved in the future clinical trials.
Inconsistency, impracticability and non-standardization of the selection, measurement and reporting of outcomes are three primary existing issues in clinical trials. These problems pose a threat to huge research waste when the results of similar studies are not able to be combined or compared. The key for resolution will be to standardize outcomes in traditional Chinese medicine (TCM) clinical trials and to establish a core outcome set (COS), which is a set of outcomes to be reported as a minimum in all TCM clinical trials of similar healthcare system and syndromes. The first step in the development of COS is to collect all existing outcomes, that is, to build a pool of outcomes for clinical trials of TCM. A pool of outcome is the basis of developing COS, which is important to follow strict and scientific methodology. This paper aims to construct an outcome pool from published literature, clinical trial registration protocols, and clinicians, and patients questionnaires were used to form a list of outcomes. In addition, the influencing factors of constructing an outcome pool and considerations for each problem are summarized in order to provide guidance and reference for the development of COS in clinical trials for TCM.