Protocol for systematic review and meta-analysis: hop (Humulus lupulus L.) for menopausal vasomotor symptoms

INTRODUCTION Menopause is a critical stage in every woman's life. It can cause a distressing time for women by creating various vasomotor symptoms (VMS). Phytoestrogens can potentially exert various favourable effects and alleviate VMS in postmenopausal women. The hop (Humulus lupulus L.) contains 8-prenylnaringenin (8-PN), the most potent phytoestrogen known to date. The hop is eight times stronger than any other herbal oestrogens. This study aims to conduct a comprehensive systematic review and a meta-analysis survey of the effects of hop in the management of VMS in postmenopausal women. METHODS Only randomised controlled clinical trials, with cluster randomisation and crossover, blinded and non-blinded designs, conducted between 2000 and 2015, will be included in this review. Quasi-experimental and observational studies as well as case reports will be excluded. The studies will be selected if their participants were aged 40-60 years, had elevated follicle-stimulating hormone (FSH) levels and/or menstrual irregularities, and experienced discomforting VMS (at least hot flashes or night sweats). The primary outcome will be the rate of response to treatment, such as changes in frequency and intensity of symptoms in the intervention and placebo groups. 'Hop', 'Humulus', 'menopause', 'vasomotor', 'hot flashes', 'phytoestrogen' and 'night sweats' will be used as search key words. Prior to their inclusion in the review, the selected papers will be assessed by two independent reviewers for methodological validity. Any disagreements will be resolved through a third reviewer. The risk of bias will be independently determined using the Cochrane Risk of Bias Tool. The quality of the papers will be assessed based on the CONSORT checklist. ETHICS AND DISSEMINATION Results will be disseminated through traditional academic literature. Dissemination of results will occur by peer-reviewed publications. The results of our project can help reproductive health researchers when evaluating the discomforts of research procedures described in study protocols or when designing a study. Information on experiences of menopausal women involved in previous studies may also help in future research. The expected dissemination actions are effective treatment in designing strategies that aim to develop women's health and healthcare providers when offering treatment for women with vasomotor symptoms.