To evaluate the efficacy of continuous positive airway pressure (CPAP) on serum testosterone in men with obstructive sleep apnea (OSA).
Two reviewers independently searched PubMed, Cochrane library, Embase and Web of Science before June 2014. Information on characteristics of subjects, study design, pre- and post-CPAP treatment of serum total testosterone, free testosterone and sexual hormone blinding protein (SHBG) was extracted for analysis.
A total of 7 studies with 9 cohorts that included 232 men were pooled into meta-analysis. There was no change of total testosterone levels before and after CPAP treatment in OSA men (standardized mean difference (SMD) = −0.14, 95%CI: −0.63 to 0.34, z = 0.59, p = 0.558), even subdivided by CPAP therapeutic duration (>3 months). Meanwhile, no significant differences in free testosterone and SHBG were detected after CPAP treatment (SMD = 0.16, 95%CI: −0.09 to 0.40, z = 1.25, p = 0.211 and SMD = −0.58, 95%CI: −1.30 to 0.14, z = 1.59, p = 0.112, respectively).
Citation: Zhang X-B, Jiang X-T, Du Y-P, Yuan Y-T, Chen B (2014) Efficacy of Continuous Positive Airway Pressure on Testosterone in Men with Obstructive Sleep Apnea: A Meta-Analysis. PLoS ONE 9(12): e115033. https://doi.org/10.1371/journal.pone.0115033
Editor: Stephen L. Atkin, Weill Cornell Medical College Qatar, Qatar
Received: July 23, 2014; Accepted: November 17, 2014; Published: December 11, 2014
Copyright: © 2014 Zhang et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: The authors confirm that all data underlying the findings are fully available without restriction. All relevant data are within the paper.
Funding: This work was supported by grant 2013-2-88 for Youth Research Fund from Fujian Provincial Health Bureau. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
Obstructive sleep apnea (OSA) is a common disorder, affecting approximately 4% of the male and 2% of the female middle-aged adults . The characteristics of OSA are intermittent hypoxia and sleep fragmentation. The pathogenesis of OSA is the interaction of the following factors: anatomical abnormality of upper airway and ventilator control instability .
Accumulating evidence showed that OSA is correlated with endocrinal dysfunction, disorder of hypothalamic-pituitary-gonadal axis –, Sexual dysfunction, particularly erectile dysfunction (ED), is common in OSA men , and ED can been ameliorated via continuous positive airway pressure (CPAP), the standard treatment modality of OSA , . Testosterone is one of sexual hormones and terminal part of hypothalamic-pituitary-gonadal axis. Robust evidence confirmed that low testosterone is tightly associated with sexual dysfunction , and testosterone administration can improve sexual dysfunction in men , . Several studies found that low serum testosterone levels were observed in patients with OSA –. Some investigations indicated that testosterone administration, however, aggravates the severity of OSA , . Previous data recommended that CPAP can improve sexual dysfunction and endocrinal disorder , , , , however, whether serum testosterone levels may be ameliorated or not by CPAP is unclear.
The aim of the present meta-analysis was to quantitatively evaluate the impact of CPAP on testosterone in men with OSA.
The electronic databases PubMed, Cochrane Library, Embase and Web of Science were searched by two reviewers (XB Zhang and B Chen). The combination of the following terms was used: ‘sleep apnea’, ‘continuous positive airway pressure’, ‘testosterone’. We searched articles published from their inception to June, 15th, 2014. The reference lists of the included studies were also hand-searched.
Studies were included if they met the following criteria: 1) participants enrolled in the studies were male, if study reported the data of both gender, only the male data was extracted. 2)OSA was diagnosed with overnight polysomnography; 3) the studies must report serum testosterone levels as primary outcome or secondary outcome before and after application of CPAP; 4) studies must provide sufficient data for meta-analysis. Excluded criteria were as following: 1)studies which did not satisfy the criteria would be excluded; 2)non-English article; 3)studies presented as correspondence, review, case report; 4)studies whose essential data were presented as median and interquartile range; 5)unpublished data from conference. If the required data of studies was ambiguous, the corresponding author was contacted, after two no response attempt, the studies were also ruled out. Any disagreement between the two reviewers(XB Zhang and B Chen) were resolved by discussing with a third reviewer(XT Jiang).
Two reviewers (XB Zhang and YT Yuan) independently evaluated the included studies. The following variables were retrieved: first author, publication year, country of the study, participant characteristics, study design, CPAP using duration, serum testosterone levels before and after CPAP treatment. If study population included both men and women, only male data were extracted for analysis. Jadad score  was used to assess the quality of randomized controlled trial (RCT).
Statistical analysis was performed using Stata Version 12.0 (Stata Corporation, College Station, Texas, USA) and Review manager 5.2. Standardized mean difference (SMD) and 95%confidence interval (CI) were calculated for presenting continuous outcomes. I-square (I2) was used to present statistical heterogeneity. Random effects model was performed to combine effect size if I2>50%, otherwise, fixed effects model was conducted. Sensitivity analysis was conducted to investigate the influence of a single study on overall efficacy of CPAP. Publication bias was presented using funnel plot and tested by ‘Begg test’ and ‘Egger test’. A p value less than 0.05 was adopted as statistical significance.
A total of 59 studies were retrieved to screen after searching duplication. Forty-six studies were exclude after browsing the titles and abstracts. The remaining 13 studies were selected for full-text review. Of the 13 studies, 6 were further exclude for following reasons: 3 were conference articles –, 1 lacked essential data , the data of one study present as bar graph  and one study had no measure unit of essential data . A total of 7 studies , , , , – (9 cohorts) pooled for final meta-analysis. Two of them were RCT , , 5 were observational study. The study flow diagram is outlined in Fig. 1.
Characteristics of the included studies
The 7 studies (9 cohorts) with 232 men were entered into the meta-analysis. One study reported the data from men and women, only the data of men was extracted . One study reported results separately for 1 month group and 6 months group , another study reported results separately for 1 month and 3 months . All 7 studies with 9 cohorts presented total testosterone levels before and after CPAP treatment, 4 studies with 5 cohorts reported free testosterone levels , , , , and sex hormone binding protein (SHBG) was reported in 4 studies with 5 cohorts , , , . The characteristics of the included studies and the relevant data are outlined in Table 1. Two RCT studies are summarized separately in Table 2.
Meta-analysis on total testosterone, free testosterone and SHBG
No significant difference in total testosterone was observed before and after CPAP treatment (SMD = −0.14, 95%CI: −0.63 to 0.34, z = 0.59, p = 0.558), even after subgroup analysis by CPAP therapy duration (Fig. 2). Two RCTs were separately analyzed, when compared with control groups (sham CPAP or oral appliance), testosterone levels was no changed in CPAP group (SMD = −0.05, 95%CI: −0.38 to 0.27, z = 0.31, p = 0.757) (Fig. 3). The changes in free testosterone and SHBG had also not got statistical significances between pre- and post-CPAP treatment (SMD = 0.16, 95%CI: −0.09 to 0.40, z = 1.25, p = 0.211 and SMD = −0.58, 95%CI: −1.30 to 0.14, z = 1.59, p = 0.112, respectively) (Figs. 4 and 5). Even after omitting the study of Grunstein's , the SMD changed to 0.082, sensitivity analysis had not yet reached statistical significance (95%CI:−0.083 to 0.247) (Table 3).
Fig. 6 shows that publication bias seem to exist, however, both Begg and Egger tests proved that there is no strong statistical evidence for publication bias in the present meta-analysis (p = 0.917 and 0.823, respectively).
The present study with 7 articles and 9 cohorts quantitatively evaluated the efficacy of CPAP on testosterone in men with OSA. Subsequently, subgroup and sensitivity analysis were conducted to further analysis. The result of present study indicated that CPAP has not impact on testosterone, irrespective of CPAP duration and study design.
To our best knowledge, present study was the first meta-analysis addressing the effect of CPAP on testosterone in OSA men. Our meta-analysis has several strengths. Firstly, pooling of the interesting data from all eligible studies yielded more precise and reliable conclusions than the data from individual study. Secondly, Two RCTs with relatively high Jadad scores were enrolled in our meta-analysis, it strengthened our conclusion. Thirdly, there was no strong statistical evidence for publication bias in our meta-analysis. Fourthly, we performed sensitivity analysis and subgroup analysis subdivided by CPAP therapeutic duration, both the results did not show a statistical significance.
Several limitations of our study have to be mentioned. Firstly, Most of the included studies were before and after treatment study, only two RCTs, pre-and post-treatment data rather than treatment and control groups data were drawn. It may, to some extent, weaken the reliability of our conclusions. Secondly, the small sample size restrict the extrapolation of our conclusion, additional large-scale, well-designed and long-term RCT investigation is required. Thirdly, since data was extracted from men in each individual study, the conclusion may be unreasonable to extrapolate to women. Fourthly, only papers published in English were enrolled, it may cause potential publication bias.
OSA can impair hypothalamic-pituitary-adrenal/gonadal axis, causing endocrinal and sexual dysfunction, and these dysfunction can be ameliorated by CPAP therapy , , . However, the exact role of intermittent hypoxia and sleep fragmentation in the correlation between OSA, endocrinal dysfunction and sexual dysfunction still needs further study to elucidate. Testosterone, considered as one of sexual hormones, is negatively correlated with the severity of OSA and sexual dysfunction in men , , . Although men with OSA have low testosterone levels, some investigations have found that testosterone administration aggravates OSA , , the causality between testosterone and OSA is still unclear. CPAP is the first choice for OSA treatment. As mentioned above, previous studies have confirmed the efficacy of CPAP on endocrinal disordering and sexual dysfunction in OSA patients , , , however, whether serum testosterone can be normalized or not by CPAP in OSA patients is controversial. In the present meta-analysis, excepting Grunstein and colleague  early in 1989 suggested that CPAP can improve testosterone in 43 OSA men, the remaining 6 studies (including 2 RCTs) with 8 cohorts elucidated that there is no influence of CPAP on serum total testosterone, free testosterone and SHBG in men with OSA. Additional further subgroup analysis showed that the results did not change when subdivided by CPAP duration (< = 3 months and>3 months). Meanwhile, sensitivity analysis was conducted to omit each including study, the pooled SMD was not yet changed in the meta-influence analysis.
In conclusion, the present meta-analysis demonstrated that CPAP treatment does not improve testosterone levels in OSA men, irrespective of CPAP therapeutic duration and study design.
Conceived and designed the experiments: XBZ XTJ. Performed the experiments: XBZ YTY BC. Analyzed the data: XBZ YPD BC. Contributed reagents/materials/analysis tools: YPD YTY. Wrote the paper: XBZ XTJ YTY.
- 1. Young T, Palta M, Dempsey J, Skatrud J, Weber S, et al. (1993) The occurrence of sleep-disordered breathing among middle-aged adults. N Engl J Med 328:1230–1235.
- 2. White DP (2005) Pathogenesis of obstructive and central sleep apnea. Am J Respir Crit Care Med 172:1363–1370.
- 3. Bahammam SA, Sharif MM, Jammah AA, Bahammam AS (2011) Prevalence of thyroid disease in patients with obstructive sleep apnea. Respir Med 105:1755–1760.
- 4. Luboshitzky R, Lavie L, Shen-Orr Z, Herer P (2005) Altered luteinizing hormone and testosterone secretion in middle-aged obese men with obstructive sleep apnea. Obes Res 13:780–786.
- 5. Bercea RM, Mihaescu T, Cojocaru C, Bjorvatn B (2014) Fatigue and serum testosterone in obstructive sleep apnea patients. Clin Respir J doi:https://doi.org/10.1111/crj.12150.
- 6. Takeuchi S, Kitamura T, Ohbuchi T, Koizumi H, Takahashi R, et al.. (2014) Relationship between sleep apnea and thyroid function. Sleep Breath doi:https://doi.org/10.1007/s11325-014-0966-0.
- 7. Bratel T, Wennlund A, Carlstrom K (1999) Pituitary reactivity, androgens and catecholamines in obstructive sleep apnoea. Effects of continuous positive airway pressure treatment (CPAP). Respir Med 93:1–7.
- 8. Luboshitzky R, Aviv A, Hefetz A, Herer P, Shen-Orr Z, et al. (2002) Decreased pituitary-gonadal secretion in men with obstructive sleep apnea. J Clin Endocrinol Metab 87:3394–3398.
- 9. Hoekema A, Stel AL, Stegenga B, van der Hoeven JH, Wijkstra PJ, et al. (2007) Sexual function and obstructive sleep apnea-hypopnea: a randomized clinical trial evaluating the effects of oral-appliance and continuous positive airway pressure therapy. J Sex Med 4:1153–1162.
- 10. Goncalves MA, Guilleminault C, Ramos E, Palha A, Paiva T (2005) Erectile dysfunction, obstructive sleep apnea syndrome and nasal CPAP treatment. Sleep Med 6:333–339.
- 11. Karacan I, Karatas M (1995) Erectile dysfunction in sleep apnea and response to CPAP. J Sex Marital Ther 21:239–247.
- 12. Liao M, Huang X, Gao Y, Tan A, Lu Z, et al. (2012) Testosterone is associated with erectile dysfunction: a cross-sectional study in Chinese men. PLoS One 7:e39234.
- 13. Giltay EJ, Tishova YA, Mskhalaya GJ, Gooren LJ, Saad F, et al. (2010) Effects of testosterone supplementation on depressive symptoms and sexual dysfunction in hypogonadal men with the metabolic syndrome. J Sex Med 7:2572–2582.
- 14. Yassin DJ, Doros G, Hammerer PG, Yassin AA (2014) Long-term testosterone treatment in elderly men with hypogonadism and erectile dysfunction reduces obesity parameters and improves metabolic syndrome and health-related quality of life. J Sex Med 11:1567–1576.
- 15. Camargo CA (1983) Obstructive sleep apnea and testosterone. N Engl J Med 309:314–315.
- 16. Canguven O, Salepci B, Albayrak S, Selimoglu A, Balaban M, et al. (2010) Is there a correlation between testosterone levels and the severity of the disease in male patients with obstructive sleep apnea? Arch Ital Urol Androl 82:143–147.
- 17. Gambineri A, Pelusi C, Pasquali R (2003) Testosterone levels in obese male patients with obstructive sleep apnea syndrome: relation to oxygen desaturation, body weight, fat distribution and the metabolic parameters. J Endocrinol Invest 26:493–498.
- 18. Sandblom RE, Matsumoto AM, Schoene RB, Lee KA, Giblin EC, et al. (1983) Obstructive sleep apnea syndrome induced by testosterone administration. N Engl J Med 308:508–510.
- 19. Cistulli PA, Grunstein RR, Sullivan CE (1994) Effect of testosterone administration on upper airway collapsibility during sleep. Am J Respir Crit Care Med 149:530–532.
- 20. Luboshitzky R, Lavie L, Shen-Orr Z, Lavie P (2003) Pituitary-gonadal function in men with obstructive sleep apnea. The effect of continuous positive airways pressure treatment. Neuro Endocrinol Lett 24:463–467.
- 21. Meston N, Davies RJ, Mullins R, Jenkinson C, Wass JA, et al. (2003) Endocrine effects of nasal continuous positive airway pressure in male patients with obstructive sleep apnoea. J Intern Med 254:447–454.
- 22. Jadad AR, Moore RA, Carroll D, Jenkinson C, Reynolds DJ, et al. (1996) Assessing the quality of reports of randomized clinical trials: is blinding necessary? Control Clin Trials 17:1–12.
- 23. Liu P (2011) Hormonal, metabolic and reproductive consequences of obstructive sleep apnoea (OSA). J Sleep Res 20:5.
- 24. Wittert G, Martin S, Adams R, Reynolds A, Shi Z, et al.. (2012) Obstructive sleep apnea is not an independent determinant of plasma testosterone. Endocrine Reviews 33..
- 25. Suehiro M, Juszczyk MA (2014) Obstructive sleep apnea (OSA) and sleep-disordered breathing (SDB) are the peripheral manifestations of systemic inflammation. Endocrine Practice 20:37A–38A.
- 26. Zhuravlev VN, Frank MA, Gomzhin AI (2009) Sexual functions of men with obstructive sleep apnoea syndrome and hypogonadism may improve upon testosterone administration: a pilot study. Andrologia 41:193–195.
- 27. Vlkova B, Mucska I, Hodosy J, Celec P (2014) Short-term effects of continuous positive airway pressure on sex hormones in men and women with sleep apnoea syndrome. Andrologia 46:386–390.
- 28. Macrea MM, Martin TJ, Zagrean L (2010) Infertility and obstructive sleep apnea: the effect of continuous positive airway pressure therapy on serum prolactin levels. Sleep Breath 14:253–257.
- 29. Grunstein RR, Handelsman DJ, Lawrence SJ, Blackwell C, Caterson ID, et al. (1989) Neuroendocrine dysfunction in sleep apnea: Reversal by continuous positive airways pressure therapy. J Clin Endocrinol Metab 68:352–358.
- 30. Celec P, Mucska I, Ostatnikova D, Hodosy J (2014) Testosterone and estradiol are not affected in male and female patients with obstructive sleep apnea treated with continuous positive airway pressure. J Endocrinol Invest 37:9–12.
- 31. Knapp A, Myhill PC, Davis WA, Peters KE, Hillman D, et al.. (2014) Effect of continuous positive airway pressure therapy on sexual function and serum testosterone in males with type 2 diabetes and obstructive sleep apnoea. Clin Endocrinol doi:https://doi.org/10.1111/cen.12401.
- 32. Vgontzas AN, Pejovic S, Zoumakis E, Lin HM, Bentley CM, et al. (2007) Hypothalamic-pituitary-adrenal axis activity in obese men with and without sleep apnea: effects of continuous positive airway pressure therapy. J Clin Endocrinol Metab 92:4199–4207.
- 33. Liu PY, Yee B, Wishart SM, Jimenez M, Jung DG, et al. (2003) The short-term effects of high-dose testosterone on sleep, breathing, and function in older men. J Clin Endocrinol Metab 88:3605–3613.