Exploring the association between erectile rigidity and treatment adherence with sildenafil

J Sex Med. 2013 Jul;10(7):1861-6. doi: 10.1111/jsm.12014. Epub 2012 Dec 17.


Introduction: Erection hardness has been shown to correlate with increased self-confidence, sexual satisfaction, and improvement in psychosocial factors such as sexual and overall relationship. It is estimated that one-third of men using phosphodiesterase type 5 inhibitors (PDE5) cease use of medication after one prescription and one-half cease use by 6 months.

Aim: This study was undertaken to explore the link between erection hardness and treatment adherence.

Methods: Men presenting with erectile dysfunction (ED) who were candidates for PDE5 therapy constituted the study population. They were assessed at the baseline regarding their erectile function (EF) and rigidity using autoquestionnaires. Patients then received regular follow-up using the same assessment tools and were also asked about continued use of PDE5. The final patient assessment was conducted at a time point no sooner than 12 months after commencing PDE5. Multivariable analysis was conducted to define predictors of continued PDE5 use.

Main outcome measures: Patients were assessed using the International Index of Erectile Function (IIEF) questionnaire and the Erection Hardness Score (EHS). Adherence was defined as continued use of PDE5 at least once per month.

Results: One hundred eighty-six men were analyzed. The mean age and the duration of ED were 61 ± 22 and 2.2 ± 2.9 years, respectively. Sixty-three percent were married or partnered. The mean partner age was 52 ± 8 years. Of the 186 patients, 32% had one vascular comorbidity, 34% had two vascular comorbidities, 26% had three vascular comorbidities, and 6% had ≥ 4 vascular comorbidities. All patients were treated with sildenafil and were sexually active. The mean time to end-of-treatment (EOT) interview and repeat completion of questionnaires was 17 ± 4 months. At the baseline, 26% were EHS 3 (mild ED), 42% were EHS 2 (moderate ED), and 32% were EHS 1 (severe ED). The mean baseline EF domain score was 14 ± 10, and at the EOT, it was 22 ± 5 (P < 0.01). At the follow-up interview, 4% were EHS 1, 12% were EHS 2, 28% were EHS 3, and 56% were EHS 4. Overall, 67% of the men continued to use PDE5 at follow-up. The distribution of patients continuing to use PDE5 after commencement was 15% of those achieving EHS 1, 30% for EHS 2, 66% for EHS 3, and 82% for EHS 4. Based on logistic regression analysis, the factors predictive of continued PDE5 use were being partnered, partner age, frequency of sexual activity, a shift of ≥ 2 points on the EHS, and reaching level 4 on the EHS scale.

Conclusion: There is an excellent relationship between erection hardness and adherence to PDE5 treatment. Driving men to greater erectile rigidity appears to translate into lower dropout rates.

Keywords: Adherence; Compliance; Erectile Dysfunction; Erection Hardness; PDE5; Persistence.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Erectile Dysfunction / drug therapy*
  • Erectile Dysfunction / psychology
  • Humans
  • Male
  • Medication Adherence*
  • Middle Aged
  • Penile Erection / drug effects*
  • Penile Erection / psychology
  • Personal Satisfaction
  • Phosphodiesterase 5 Inhibitors / therapeutic use*
  • Piperazines / therapeutic use*
  • Purines / therapeutic use
  • Self Concept
  • Sexual Behavior
  • Sexual Partners
  • Sildenafil Citrate
  • Sulfones / therapeutic use*
  • Surveys and Questionnaires


  • Phosphodiesterase 5 Inhibitors
  • Piperazines
  • Purines
  • Sulfones
  • Sildenafil Citrate