We identified 279 studies totally. After the initial screening through the titles and abstracts, we assessed the full-test articles eligibly for detailed assessment. Finally, 11 studies met the inclusion criteria and were included in the research. The flowchart of the procedure is shown in Fig.1.
Characteristics of the included studies
Of the total 11 studies that are included in our studies, the details of the studies are presented in Table 1.
Results of each study
Results of studies which dedicated to investigate the changes in self-reported sexual function on obese patients who underwent bariatric surgery, have been controversial and were illustrated in Table 2.
Sarwer et al. conducted a prospective cohort study, containing 32 man who underwent a Roux-en-Y gastric bypass, and investigated the sexual function of individuals by using the International Index of Erectile Functioning (IIEF) and sex hormones. The results showed that there was no significant change of the sexual function from the baseline except of overall satisfaction at prospective year 3 (P = 0.008), though the men reported improvements in sexual functioning.
On the contrary, the prospective cohort study performed by Reis et al. studied 10 morbidly obese men to measure the degree to sexual function change after life style modifications (exercise and diet) for 4 months and subsequently gastric bypass. Weight loss associated with bariatric surgery was found to improve erectile function quality in the research.
Ranasinghe et al. investigated the effects of weight loss and laparoscopic gastric banding surgery on sexual function among 20 obese men. The results suggested that the IIEF score achieve an improvement significantly after surgery while there existed worsening of erectile index (P = 0.005) and orgasmic function (P=0.002).
In a prospective study, Mora et al. found the IIEF score increased significantly after 1 year by investigating 39 men undergoing bariatric surgery. Meanwhile, Li et al., conducting a retrospective cohort study, found a significant improvement in IIEF score of 39 obese men after RYGB. Groutz et al. enrolled 39 consecutive obese man, undergoing a laparoscopic sleeve gastrectomy, to investigate the effect of bariatric surgery on male’s sexual function in a prospective study. The IIEF were completed preoperatively and postoperatively. The results demonstrated that male’s sexual function, including erectile function, overall intercourse satisfaction and overall satisfaction, was significantly improved. Meanwhile, the main finding of the prospective study, performed by Efthymious et al., was that the bariatric surgery could lead to a significant improvement in sexual functioning and especially could be find in the first 6 months postoperatively. In a prospective study of bariatric surgery, which used the IIEF score respectively, Aleid et al. similarly find significant improvements in male erectile function.
Araujo et al. examined the changes following Fobi-Capella gastroplasty in the quality of male’s sexual life on 21 men with morbid obesity and favorable changes occurred in sexual function postoperatively.
Dallal et al. compared the Brief Male Sexual Function Inventory (BSFI) before and after gastric bypass surgery to measure its effect to the sexual function in morbidly obese man. On average, the patients reported a significant increase in all domains of BSFI scores post-operatively, compared with preoperative score.
Goitein et al. found the BSFI scores in males increased but did not reach statistical significance (P = 0.08). However, general satisfaction, erection and desire were significantly improved within BSFI.
279 articles were yielded by our initial search, of which 268 remained after 11 duplicates were removed. Two interviewers independently check these articles and found 11 articles met our inclusion criteria and finally 9 contain the necessary data for quantitative analysis.
The analysis was based on 370 patients from 11 studies with 3 to 24 months follow-up that measured male`s sexual function preoperatively and postoperatively. In these studies[11, 14, 24, 26-30], the erectile function was found a 5.33-point increase significantly (Fig 2A 95% CI 4.12-6.54, p < 0.001) while there was a 2.57-point increase in the intercourse satisfaction (Fig 2B 95% CI 1.19-3.94, p = 0.0002), a 0.50-point increase in orgasmic function (Fig 2C 95%CI 0.60-0.94, p = 0.03), a 1.67-point increase in overall satisfaction (Fig 3A 95% CI 0.78-2.56, p = 0.0002), a 1.27-point increase in sexual desire (Fig 3B 95% CI 0.61- 1.93, p = 0.0001) in those studies[11, 14, 24, 26-30]. Meanwhile, total erectile function showed a 7.21-point increase in these studies (Fig 3C 95% CI 4.33-10.10, p < 0.001). The above articles all used the IIEF as the index to measure the sexual function. However, the articles[33, 34] which used BSFI as the index suggested a 2.53-point increase in erection (95% CI 2.39-2.67, p < 0.001), a 1.40-point increase in ejaculation (95% CI 1.28-1.51, p < 0.001), a 1.40-point increase in desire(95% CI 1.32-1.49, p < 0.001) a 2.20-point increase in problem assessment (95% CI 2.06-2.34, p < 0.001) and a 0.70-point increase in sexual satisfaction (95% CI 0.60-0.76, p < 0.001).