CHICAGO — Adherence to continuous positive airway pressure (CPAP) therapy in men with obstructive sleep apnea (OSA) and erectile dysfunction (ED) significantly improves erections and sexual desire, a randomized sham-controlled study has found.

This finding should motivate men with both ED and OSA — a common co-occurrence — to use their prescribed CPAP machine nightly, principal investigator Kerri Melehan, MAppSci, a doctoral student in Sydney, Australia, told Medscape Medical News.

"If sex sells it at the end of the day and gets more men to use their CPAP, that's great," said Ms. Melehan, a sleep researcher at Sydney's Royal Prince Alfred Hospital, where the study took place. She presented the results last week in a poster at ICE/ENDO 2014.

Their study, Ms Melehan said, is the first sham-controlled trial in men with ED and OSA to test the efficacy of CPAP — the gold-standard treatment of OSA — in improving sexual function.

Asked by Medscape Medical News to comment on the study, Vin Tangpricha, MD, PhD, an endocrinologist at Emory University in Atlanta, Georgia, said, "I haven't heard of this connection between treatment of sleep disorders and improved erectile dysfunction. It is a novel approach."

Dr. Tangpricha, who was a poster judge but did not participate in this study, said hypogonadism is the cause in only a small percentage of his patients with ED.

"I would consider looking into obstructive sleep apnea as a cause of erectile dysfunction in my patients," he said. "Instead of trying to treat men with erectile dysfunction and sleep disorders using hormones [initially], it may be worth treating the sleep disorder first."

Study Also Examined Effects of PDE-5 Inhibitor Vardenafil

Ms. Melehan's study also looked at the effects on sleep-disordered breathing of vardenafil (Levitra, GlaxoSmithKline; Staxyn, Bayer Healthcare, GlaxoSmithKline), a phosphodiesterase type 5 (PDE-5) inhibitor — to her knowledge, the first such trial to do so, she noted. These medications are the first-line therapy for ED.

Contrary to prior studies showing that another PDE-5 inhibitor, sildenafil (Viagra, Pfizer), had a detrimental effect on respiratory parameters of men with OSA, low-dose vardenafil treatment did not worsen sleep apnea, the new study found.

Why CPAP Improves Sexual Function and Desire

Ms. Melehan and colleagues recruited 61 men with moderate or severe OSA (apnea-hypopnea index >20/h) and a 6-month or longer history of erectile dysfunction (International Index of Erectile Function-ED domain score <26).

They randomly assigned them to 12 weeks of treatment with either CPAP or sham CPAP. In addition, the men received either 10 mg/day orally of vardenafil or placebo in a 2 × 2 factorial design. Both the subjects and Ms. Melehan were blinded to the treatment received.

I can say with complete certainty that CPAP improves erectile dysfunction.

Subjects underwent polysomnography before and after treatment. The investigators measured the men's number of sleep-related erections by recording and monitoring penile tumescence and rigidity (RigiScan, Timm Medical Technologies). Participants also reported subjective measures of their sexual function, relationship satisfaction, self-esteem, quality of life, sleepiness level, and satisfaction with ED treatment.

The 55 men who completed the trial had a mean age of 54 years, an average body mass index of 32.8 kg/m2, and a mean serum testosterone level at baseline of 10.1 nmol/L. They had an apnea-hypopnea index of 43.9/h on average.

Twenty men reported CPAP adherence, as defined by use 4 or more hours per night, and their data were analyzed separately.

In the CPAP vs sham-CPAP part of the study, there were 2 statistically significant findings for the entire group — those receiving actual CPAP had more erections during sleep (average of 4.1 vs 2.4; P = .0006) and better overall sexual satisfaction (P = .04), according to the poster:

But the quality of erectile function did not significantly improve (P = .68), the findings showed.

For the subgroup of CPAP recipients who adhered to at least 4 hours of treatment nightly, however, there were additional significant improvements in erectile function/quality (P = .04) and sexual desire (P = .03), as well as self-esteem, sleepiness, social function, and mental health, with reductions in depression and stress (all P < 0.05).

"I can say with complete certainty that CPAP improves erectile dysfunction," Ms Melehan said. "I think mental factors play a role because they feel more alive and awake." In addition, she speculated that better oxygenation with CPAP may improve arterial stiffness.

Apnea No Worse With Vardenafil

In the second part of the study, vardenafil (n = 30), compared with placebo (n = 31), improved the quality of sleep-related erections (P < .05) but not their frequency.

Although the study was not designed to compare CPAP and vardenafil treatment of ED, Ms. Melehan agreed with a conference attendee who commented that vardenafil did not improve sexual function as much as correction of the apnea by CPAP.

"The 10-mg daily dose of vardenafil may have been too low," she said. "There was a…difference in improved erectile dysfunction [between vardenafil and placebo], but it was not statistically significant."

Vardenafil treatment was associated with improved self-esteem and reduced distress due to sexual dysfunction. But sleepiness and other quality of life measures did not improve in the vardenafil group.

However, the investigators saw no worsening of OSA on polysomnograms in the 31 participants who received vardenafil and sham CPAP.

That is good news for men with OSA who also have ED, and vice versa. On-demand PDE-5 inhibitor treatment of ED has worsened OSA, according to a 2007 report (Expert Opin Drug Saf. 2007;6: 423-430), and Ms. Melehan said past studies of vardenafil have shown increased nasal obstruction (Am J Rhinol. 2008;22: 276-279).

This study was funded by the National Health and Medical Research Council, Canberra, Australia; Bayer Australia, Pymble, Australia; and Philips Respironics, North Ryde, Australia. Ms. Melehan has disclosed no relevant financial relationships; disclosures for the coauthors are listed in the abstract. Dr. Tangpricha has disclosed no relevant financial relationships.

Joint Meeting of the International Society of Endocrinology and the Endocrine Society: ICE/ENDO 2014; June 22, 2014. Abstract SUN-0058.


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