***TASK***
the task is to simplify the input abstract of a biomedical literature

***INPUT***
the input is the abstract of a biomedical literature

***OUTPUT***
the output is the simplified abstract for the input abstract of a biomedical literature

***DOCUMENTATION***

***EXAMPLES***

Input: We identified 11 completed trials (1369 participants) and one ongoing trial. Trials were heterogeneous in participants recruited, qigong duration and length of follow-up periods. We were unable to ascertain the risk of bias in nine trials published in Chinese, as insufficient methodological details were reported and we were unable to contact the study authors to clarify this. We performed no meta-analyses, as trials were small and were at significant risk of bias. Clinical events were detailed in subsequent reports of two trials when statistically significant effects of qigong were seen for all-cause mortality, stroke mortality and stroke incidence at 20 to 30 years after completion of the trials. However, these trials were designed to examine outcomes in the short term, and it is not clear whether qigong was practised during extended periods of follow-up; therefore effects cannot be attributed to the intervention. None of the included studies reported other non-fatal CVD events. Six trials provided data that could be used to examine the effects of qigong on blood pressure. Reductions in systolic blood pressure (SBP) and diastolic blood pressure (DBP) were seen in three and two trials, respectively. Three trials examined the effects of qigong on blood lipids when favourable effects were seen in one trial for total cholesterol, low-density lipoprotein (LDL) cholesterol and triglycerides, and two trials showed favourable effects on high-density lipoprotein (HDL) cholesterol. The only trial considered at low risk of selection and detection bias did not demonstrate statistically significant effects on CVD risk factors with qigong, but this study was small and was underpowered. None of the included studies reported incidence of type 2 diabetes (T2D), adverse events, quality of life or costs. Currently, very limited evidence is available on the effectiveness of qigong for the primary prevention of CVD. Most of the trials included in this review are likely to be at high risk of bias, so we have very low confidence in the validity of the results. Publication of the ongoing trial will add to the limited evidence base, but further trials of high methodological quality with sufficient sample size and follow-up are needed to be incorporated in an update of this review before the effectiveness of qigong for CVD prevention can be established.
Output:

The evidence is current to November 2014. We included trials with interventions lasting at least three months. We found 11 completed trials (1369 participants). These trials showed variation in participants recruited, duration of qigong and follow-up of the interventions. For two trials that were followed up for many years after trial completion, results showed that qigong had a beneficial effect on all-cause mortality, stroke mortality and stroke incidence, but it is not clear whether this effect can be attributed to qigong, as it is uncertain whether qigong was practised during the years after the trials ended. Some beneficial effects of qigong on blood pressure and blood lipid levels were observed, but these results were based on only a small number of studies with small sample size that were at significant risk of bias. Therefore, additional large, high-quality, long-term trials are needed before we will be able to determine whether qigong is beneficial for the prevention of cardiovascular disease.