Radical prostatectomy (RP) is the most common treatment for localized prostate cancer. However, rates of erectile dysfunction (ED) after surgery range from 26% to 100%.

Some men use pharmacologic treatments [including phosphodiesterase type 5 (PDE5) inhibitors and intracavernosal injections] to improve their erections after RP, but these approaches are not successful for all patients. As a result, some men opt for penile prosthesis implantation.

Past research suggests that about 2.3% of patients undergo penile implantation after RP. However, less is known about predictors for this approach.

The current study aimed to:

• Describe non-oncologic predictors of penile prosthesis implantation after RP in a diverse cohort of men.
• Identify patient characteristics that predict a longer time frame between RP and prosthesis implantation.

Methods

This study was a retrospective review of data from patients in Florida, USA between 2006 and 2015. Data came from the Health Care Utilization Project (HCUP), State Inpatient Database (SID), and State Ambulatory Surgery Database (SASD).

Inclusion was based on International Classification of Diseases, Ninth Revision, Clinical Modification (ICD9-CM) procedure and diagnosis codes. All patients underwent RP for prostate cancer between 2006 and 2012. They were tracked for ambulatory or inpatient penile prosthesis surgery between 2006 and 2015.

The study’s primary outcome was penile prosthesis surgery after RP. The secondary outcome was predictors of time between RP and prosthesis.

Results 

Overall, 29,288 men underwent RP during the study period. Their average age was 61.6 years. Of these, 1,449 men (4.9%) underwent penile prosthesis implantation an average of 2.6 years following RP.

Men who received penile implants were more likely to:

• be African American
• be Hispanic
• have Medicare insurance
• have had an open RP

Risk factors for increased likelihood of prosthesis implantation included:

• African American race
• Hispanic ethnicity
• Medicare insurance
• Diabetes mellitus
• Open RP

Factors associated with a lower likelihood of prosthesis implantation included:

• Age over 70 years
• Belonging to highest zip code-based income quartile

Patients in the lowest quartile of time received their implants between 0 and 1.2 years after RP. The highest quartile of time ranged from 3.5 to 9.3 years.

Predictors for the highest quartile of time (relative to the lowest) included:

• Medicaid insurance
• Private insurance
• Self-pay
• Highest income quartile
• Laparoscopic RP

Discussion 

Among 29,288 men who underwent RP, less than 5% went on to have penile prosthesis implantation within the next 3 years.

It was noted that men who lived in wealthier areas were less likely to undergo implantation compared to men who lived in lower-income areas. However, this finding should be interpreted carefully. It is possible that wealthier patients could more easily afford expensive pharmacologic ED treatments. Another possibility is that wealthier patients “may rely less on sexual activity for recreation.”

In addition, better-educated patients might have been more likely to seek second and third opinions before implantation surgery, which might have extended the time between RP and implantation.

Further investigation is recommended on the duration of time between RP and prosthesis implantation. The current study suggests that men with the longest time frame came from higher-income areas, had non-Medicare insurance, and underwent open or laparoscopic RP compared to men with the shortest time frames. The findings “suggest further ED treatment disparities in timing of prosthesis implantation related to income, insurance status, and possibly even RP surgical technique.”

Several limitations were acknowledged:

• ICD-9 coding may have inaccuracies.
• Some men might have undergone prosthesis implantation outside of Florida.
• It is unknown how many men received penile implants after 2015.
• Information about oncologic outcomes, functional outcomes, patients’ goals, and patients’ costs is unknown.
• Arbitrary cutoffs were used for quartile-based analysis, which limits “early” and “late” penile prosthesis implantation comparisons.

Conclusions 

“These findings may suggest ED treatment disparities, which merit further investigation. Counseling patients on all ED treatment options and redirecting those who fail or have contraindications to conservative treatments may minimize lost quality of life years.”