Men who undergo minimally invasive radical prostatectomy (MIRP) for prostate cancer have significantly shorter hospital stays and fewer surgical complications than those who undergo retropubic radical prostatectomy (RRP), but they experience significantly more genitourinary complications and erectile dysfunction (ED), according to a study.

Researchers found that MIRP patients had a median hospital stay of two days compared with three for RRP patients. Compared with RRP patients, MIRP patients had an 89% decreased risk of requiring blood transfusions, a 37% decreased risk of postoperative respiratory complications, and a 25% decreased risk of miscellaneous surgical complications. MIRP patients, however, had a twofold increase risk of genitourinary complications and a 30% and 40% increased risk of incontinence and ED, respectively.

Additionally, the researchers, led by Jim C. Hu, MD, MPH, of Brigham and Women’s Hospital in Boston, found that fewer black and Hispanic patients opted for MIRP rather than RRP, whereas Asian men were more likely to choose MIRP over RRP. White men opted for MIRP and RRP in similar proportions. Compared with RRP patients, men who underwent MIRP tended to have higher socioeconomic status: They were more likely to live in areas with at least 90% high school graduation rates and to have a median household income of $60,000.

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“This socio-demographic variation may result from the highly successful robotic-assisted MIRP marketing campaign disseminated via the Internet, radio, and print media channels likely to be frequented by men of higher socioeconomic status,” the authors stated in the Journal of the American Medical Association (2009;302:1557-1564). “Additionally, black men and Hispanic men with lower economic status may not have access to networks or surgeons that offer MIRP.”

The researchers based their findings on a study of 8,837 men who underwent radical prostatectomy from January 1, 2003 through December 31, 2007, including 1,938 men who underwent MIRP and 6,899 who underwent RRP. The team used Medicare data and data from the Surveillance, Epidemiology, and End Results (SEER) database.

The researchers used CPT codes to identify men who underwent MIRP and RRP and the complications that resulted. They could not distinguish whether MIRP was robotic assisted or not.

“In light of our mixed outcomes associated with MIRP,” the authors concluded, “our finding that men of higher socioeconomic status opted for a high-technology alternative despite insufficient data demonstrating superiority over an established gold standard may be a reflection of a society and health care system enamored with new technology that increased direct and indirect health care costs but had yet to uniformly realize marketed or potential benefits during early adoption.”

The authors acknowledged a number of study limitations. Their finding that men undergoing MIRP were more likely to be diagnosed as having urinary incontinence and ED than those undergoing RRP is subject to observer bias. “For instance, erectile dysfunction that impairs quality of life but does not necessitate seeking medical attention may not be captured from Medicare claims, and patient self-assessment with validated quality-of-life instruments provides a more precise measure of these outcomes.” In addition, the team was unable to adjust for nerve-sparing surgical technique, which improves postoperative sexual function.

Commenting on the study findings, Ashutosh K. Tewari, MD, Director of Robotic Prostatectomy and Prostate Cancer-Urologic Oncology Outcomes at Brady Urology Foundation, Weill Cornell Medical College in New York, noted that the study looked only at Medicare patients, who generally are aged 65 years and older, so the findings may not be generalized to the non-Medicare prostate cancer population. Moreover, the study did not differentiate robotic and non-robotic laparoscopies, which may be associated with different outcomes, said Dr. Tewari, who has received research funding from Intuitive Surgical, which makes the da Vinci Surgical System for robotic-assisted minimally invasive surgery.

In addition, Dr. Tewari observed that MIRP patients tended to live in more affluent areas. These patients usually participate in postoperative urinary and sexual rehabilitation programs. Participation in these programs requires them to have prescriptions for various treatments for incontinence (such as biofeedback and anti-cholinergic drugs) and ED (such as oral medications, injections, and pumps).

“Thus, they are more likely to have doctors office visits with ICD coding for urinary and sexual issues. If that is captured in electronic claims data, it will appear that these patients have more problems.” This could explain why MIRP had a greater unadjusted incidence of these adverse effects at baseline compared with RRP, he said. Dr. Tewari point out, however, that the need for incontinence and ED treatments, as reported by Dr. Hu’s team, was similar for the two cohorts.

The propensity score method adjusts for observed differences between the treatment groups at baseline, Dr. Hu explained. Therefore, differences in adjusted outcomes, such as more ED and incontinence diagnoses in the minimally invasive  versus open group, persisted even after adjusting for confounders that Dr. Tewari mentions (education and income).

Dr. Tewari also noted that the surgeon is the most important predictor of prostate surgery outcomes, and surgeons have different techniques and outcomes with either MIRP or RRP.

With respect to the observer bias acknowledged by Dr. Hu’s team, David Shin, MD, Chief of the Center for Sexual Health and Fertility at Hackensack University Medical Center in Hackensack, N.J., noted: “Their data analysis was based on surgeons coding for ED and incontinence during follow-up visits,” he said. “This is a subjective evaluation by the surgeon and may not accurately reflect a patient’s condition or the severity of their condition.”

Dr. Hu pointed out that the Prostate Cancer Outcomes Study demonstrated a high degree of correlation between the diagnosis of incontinence and patient-reported outcomes of worse urinary function, “so it is not entirely subjective.”

Noting that the Detroit and California tumor registries contributed nearly two-thirds of the MIRP data, Dr. Shin observed: “Since the data is weighted towards two regions of the country, the author’s findings may not be reflective of other institutions’ current experiences.”

He also noted that the outcomes data for men undergoing MIRP and RRP in the latter half of 2006 and 2007 were excluded from postoperative functional outcomes assessment, so the researchers based their assessment on data from 2003 through the first half of 2006.

“During this time period, MIRP was in its infancy and still being refined as a surgical technique,” Dr. Shin said. “Therefore, it would be plausible for higher rates of incontinence and ED to be seen during the initial development of the technique. A better indication of the rates of ED and incontinence after MIRP would be to analyze data reflective of 2007-2009 since the technique has matured and is being performed at multiple institutions.”

Like Dr. Tewari, Dr. Shin noted that the study’s conclusions are based on data captured only from the Medicare population and thus limit the ability to generalize the study findings.

However, Dr. Hu observed that, in contrast to the many published single-surgeon series, the study “gives us a sense of what is going on in a population-based fashion, which includes a lot of hospitals that do not publish their outcomes.”