This lack of consistent standards has persisted, despite earlier efforts to call attention to it, according to Arthur L. Burnett, II, MD, professor of urology at the James Buchanan Brady Urological Institute, Johns Hopkins Medical Institutions, Baltimore.
"This was shown 11 years ago, and we're still no further ahead," he said. "It's just shameful."
AUA initiated the study by enlisting Dr. Burnett and 15 other researchers in a prostate cancer clinical guideline panel to update treatment options for clinically localized prostate cancer from the 1995 guidelines. As a side analysis, the panel sought to evaluate how erectile dysfunction and erectile function after prostate cancer treatment are reported in the urological literature.
Researchers conducted National Library of Medicine PubMed searches for the years 1991 through 2004 using the search terms "prostate neoplasm," "prostate cancer," and "therapy." They screened 13,888 citations and abstracts for articles that reported outcomes of prostate cancer treatments in at least 50 patients with stage T1 or T2 disease. Using these criteria, they selected 592 articles for further analysis.
The results were disturbing, Dr. Burnett said. No consistent definitions for erectile dysfunction or erectile function emerged, and authors used a wide variety of qualitative descriptions, generic terminology, and rating systems.
"We found that a whole host of terminology was used," he said.
Only 100 articles included actual descriptions of erectile dysfunction or erectile function, and only 30 of those included frequency rates for these outcomes.
Wide variance in rates
Even in those papers in which the authors clearly attempted to state a frequency rate for erectile dysfunction or erectile function, the rates reported varied so widely that they offered little guidance in counseling patients. For example, in radical prostatectomy, erectile dysfunction measurements ranged from 10% to 100% and erectile function measurements ranged from 6% to 86%. In external beam radiotherapy, erectile dysfunction measurements ranged from 4% to 87%, and erectile function measurements ranged from 18% to 85%. In interstitial seed therapy, erectile dysfunction measurements ranged from 14% to 61%, and only one paper stated an erectile function rate: 18%.
The wild variations in terminology, definitions, and results have badly muddied the literature on erectile function following prostate cancer treatments, Dr. Burnett said. Comparing one study to another or drawing any definitive conclusions is difficult. He called for a set of standard outcomes measures to be used by researchers in this area.
"Perhaps some sort of consensus body should be impaneled to work on standards," he suggested.
But even agreeing upon standard measurements may not clear the confusion if the measurements aren't meaningful, commented John J. Mulcahy, MD, PhD, a consultant in urology at the Southern Arizona Veterans Administration Health Care System in Phoenix.
Most researchers have used questionnaires, either the International Index of Erectile Function or the Sexual Health Inventory for Men, he said.
"And when it comes to erection, men lie," Dr. Mulcahy said. "They don't want to admit they are not the men they were."
Instead of asking men if they can get erections, researchers should rely on more objective data; for example, by using the RigiScan (Timm Medical Technologies, Inc.; Eden Prairie, MN), a device that measures a man's erections while he is sleeping, Dr. Mulcahy suggested. The patient's wife can also be questioned, he said.