Low Annual Caseloads of United States Surgeons Conducting Radical Prostatectomy

Results 

We identified 6,621 patients treated with radical prostatectomy in 2005 by 1 of 933 surgeons from the NIS. The distribution of the surgeon annual radical prostatectomy caseload is summarized in the table. Nationally the most common number of radical prostatectomies performed in 2005 was 1 (for more than 25% of surgeons). More than 80% of surgeons had an annual volume of 10 or fewer procedures. Assuming a typical surgeon operates for 25 to 30 years, and that volumes do not fluctuate greatly from year to year, it is unlikely that many of these surgeons would reach a level of experience associated with adequate cancer control during their career.

Percentage of surgeons with various annual radical prostatectomy caseloads and the percentage of patients seen by those surgeons

	Annual Caseload	NIS		SPARCS
		% Surgeons (933)	% Pts Seen	% Surgeons (393)	% Pts Seen
	1	26.9	3.8	27.0	2.6
	2	16.2	4.6	16.5	3.2
	3	9.4	4.0	8.4	2.4
	4	6.3	3.6	6.6	2.5
	5	7.1	5.0	4.8	2.3
	6–10	16.9	18.4	15.3	11.3
	10 or Fewer	82.9	39.3	78.6	24.4
	11–24	13.3	28.2	13.0	18.7
	25 or More	3.9	32.4	8.4	56.9
	50 or More	1.8	22.8	4.1	42.9

Less than 4% of surgeons had an annual caseload that would allow them to reach the learning curve plateau within approximately 10 years (at least 25 surgeries). Because some of these surgeons are likely to be on the early part of the learning curve, it seems reasonable to suppose that a majority of patients with prostate cancer pursuing a surgical cure receive treatment from a surgeon with inadequate experience.

It is plausible that some surgeons perform radical prostatectomies at more than 1 institution. Because the NIS sampling unit is the hospital this practice could lead to an underestimate of the annual caseload of some surgeons. This is not true of the SPARCS database, which lists every hospital discharge in New York State. The table shows that the results from New York State are similar to those obtained nationally. There are slightly more high volume surgeons (approximately 4% vs 2%), likely because New York City includes several high volume hospitals. Although we cannot exclude the possibility that surgeons in New York State work at institutions outside of New York, we believe that such practices would have only a minimal impact on our results. If we consider surgeons operating at different hospitals within New York as independent surgeons, thereby underestimating caseload, our results were not importantly changed. We would have concluded that 84% of surgeons performed 10 or fewer cases and that 3.4% performed 50 or more. Far fewer surgeons would operate across state borders than at different hospitals within New York and, thus, it is unlikely cross-border practice would substantively alter our results.

As a sensitivity analysis we analyzed 2 ICD-9 codes that might in some cases have been used for radical prostatectomy, namely retropubic prostatectomy (ICD-9 code 60.4, defined as excluding radical prostatectomy) or other prostatectomy (ICD-9 code 60.69). Only a small number of cases were coded as undergoing either procedure. In the SPARCS data set there were only 286 and 1 cases, respectively, compared to 4,081 for ICD-9 code 60.5. Accordingly the inclusion of these codes had little influence on our results with a slight increase in the proportion of surgeons with low case volumes.

Discussion 

The majority of surgeons performing radical prostatectomy in the United States have extremely low annual caseloads. Given that caseload and overall experience are associated with improved outcomes, this scenario is likely to lead to suboptimal outcomes. By definition, high volume surgeons treat many patients each year so a small shift in the distribution of these surgeons can have a large effect on patient care. The slightly greater proportion of high volume surgeons (50 or more cases per year) in New York (approximately 4%) compared to nationally (approximately 2%) has resulted in a large difference in the number of patients receiving care from the highest volume surgeons (approximately 20% to 40%).

Our estimate of experience is based on the annual caseload for only 1 year. We cannot link multiple years of NIS data because the sampling frame changes each year. However, it seems unlikely that surgeon volume would fluctuate dramatically year to year. To check this assumption we compared the average volume during a 3-year period (2003 to 2005) with that from 2005 using SPARCS data. There were 204 surgeons who performed 10 or fewer surgeries in 2005, and whose cases were also included in the SPARCS data set in 2004 and 2003. Of these surgeons only 11 had an average annual caseload greater than 10 (and all but 1 of these had a volume of 7 or higher in 2005). Furthermore, we only found 1 surgeon whose average caseload differed qualitatively from that in 2005 (average volume of 28 cases vs 2005 volume of 9). Thus, we are confident that our estimate of volume is a good reflection of typical annual caseloads of most surgeons. We are also confident in our conclusion that most surgeons will not reach 250 radical prostatectomy cases in their surgical careers.

We acknowledge that using 250 prior surgeries as a criterion for reaching the plateau of the learning curve is a somewhat arbitrary cut point that is open to discussion. However, the majority of surgeons have such low annual volumes that our conclusions would not change even if we halved the minimum number of surgeries considered to be adequate. Moreover we see 250 as somewhat of a minimum. For organ confined disease the learning curve continues to lead to improving results until well more than 1,000 surgeries.

We also acknowledge that annual volume is not deterministic of patient outcome. Even among high volume surgeons there is significant variation in patient outcomes and it seems highly plausible that a talented, low volume surgeon could have results superior to those of a higher volume counterpart.8 However, something similar may be true when comparing 2 drugs. Even if drug A has a higher response rate than drug B, it is plausible that some patients may fare better on drug B than drug A. However, on average in the absence of further information we would advise patients to take drug A. Analogously higher volume surgeons have on average lower complication rates and improved cancer control and, in the absence of other information, annual caseload must be seen as a useful surrogate of surgical proficiency.

Conclusions 

Almost all surgeons conducting radical prostatectomy in the United States have low annual caseloads. These low surgical volumes are known to be associated with increased complication rates and decreased cancer control.