“…Most studies were single centre 22,29,31–33,39–42,44,45,48–52,54,57,59–66 and conducted in Europe. 13,19,28,30–33,39,41,43–51,53,56–63,65,67 The sample size ranged from 2 to 1292 participants, and the population was majority male. Twenty-eight studies were cross-sectional, 19,27,28,30–33,39–41,44,45,47–51,53,55,56,61–67 3 were prospective cohort studies, 43,46,57 3 were prospective intervention studies with no control group, 22,59,60 2 nonrandomized controlled studies, 42,52 and 1 randomized controlled study, 58 1 case–control study, 29 and 1 case-report.…”