High-sensitivity C-reactive protein (hs-CRP), a marker of inflammation, is known to be elevated in patients with erectile dysfunction (ED). However, its role in predicting therapeutic response to phosphodiesterase-5 inhibitors is incompletely understood.

The aim of this study was to understand the relationship among hs-CRP, mechanism of ED, and therapeutic response of ED to tadalafil, a phosphodiesterase-5 inhibitor.

A total of 282 men (mean age 36.6 ± 12.0 years) with ED were included. All subjects underwent detailed evaluation, including estimation of a 6-item abbreviated version of the International Index of Erectile Function (IIEF-6) score, penile Doppler studies, and measurement of hs-CRP. IIEF-6 scoring and hs-CRP measurement were repeated after 6 weeks of tadalafil therapy (10 mg/day). The patients were categorized into vasculogenic and nonvasculogenic ED groups based on penile Doppler findings.

The main outcome measure was the therapeutic response to tadalafil, in relation to the mechanism of ED and hs-CRP levels.

Vasculogenic ED was much less common (23.8% of the subjects) than non-vasculogenic ED. Subjects with vasculogenic ED were older, had higher prevalence of cardiovascular risk factors, had more severe (mean IIEF-6 score 9.2 ± 4.6 vs 14.8 ± 4.7; P < .001) and longer duration ED, and responded less favorably to therapy (response rate 10.4% vs 75.0%; P < .001). Those showing improvement with tadalafil had lower hs-CRP at baseline (median 1.5 mg/L [interquartile range 0.9-2.3] vs 2.0 mg/L [interquartile range 1.1-3.1; P = .034]) and had proportionately greater reduction in its level. However, on multivariate analysis, only shorter duration of ED (P = .008), non-vasculogenic origin (P = .025), and higher IIEF-6 score at baseline (P = .013) were independent predictors of response to treatment.

Serum hs-CRP is elevated in patients who are less likely to respond to vasodilator therapy but does not have an independent predictive value for this purpose.

This is the largest study to evaluate the relationship among the mechanism of ED, serum hs-CRP level, and therapeutic response of ED to tadalafil. All patients underwent a penile Doppler study to characterize the type of ED. The limitations were nonrandomized nature of the study and nearly 22% dropout rate.

Serum hs-CRP level is higher in vasculogenic ED compared with non-vasculogenic ED, and is associated with poorer response to tadalafil therapy. However, this association is not independent of underlying risk factors and mechanism of ED. Jamaluddin, Bansal M, Srivastava GK, et al. Role of Serum High-Sensitivity C-Reactive Protein as a Predictor of Therapeutic Response to Tadalafil in Patients With Erectile Dysfunction: A Prospective Observational Study. J Sex Med 2019;XX:XXX-XXX.

The journal of sexual medicine. 2019 Oct 24 [Epub ahead of print]

Manish Bansal, Gauraw Kumar Srivastava, Narmada Prasad Gupta

Associate Director Cardiology, Medanta The Medicity, Gurgaon, India. Electronic address: ., Senior Consultant, Department of Radiology and Imaging, Medanta The Medicity, Gurgaon, India., Chairman, Academic and Research Division, Kidney and Urology Institute, Medanta The Medicity, Gurgaon, India.