The majority of surgeons performing radical prostatectomies in the US have extremely low annual caseloads. Given that caseload and overall experience are associated with improved outcomes, this is likely to lead to suboptimal outcomes.
As high volume surgeons, by definition, treat many patients each year, a small shift in the distribution of high volume surgeons can have a large effect on patient care. The slightly greater proportion of very high volume surgeons (50 or more cases per year) in New York (~4%) compared to nationally (~2%), led to a large difference in the number of patients receiving care from the highest volume surgeons (~20% to ~40%).
Our estimate of experience is based on only one year’s annual caseload. We cannot link multiple years of the NIS data because the sampling frame changes each year; however, it seems unlikely that a surgeon’s volume would fluctuate dramatically between years. To check this assumption, we compared the average volume over a 3 year period (2003-2005) with that from 2005 using the SPARCS data. There were 204 surgeons who performed 10 or fewer surgeries in 2005 and whose cases were also included in the SPARCS dataset in 2004 and 2003. Of these surgeons, only 11 had an average annual caseload above 10 (and all but one of these had a volume of 7 or higher in 2005). Furthermore, we only found one surgeon whose average caseload differed qualitatively from that in 2005 (‘average volume’ of 28 versus ‘2005 volume’ of 9 cases). Thus we feel confident that our estimate of volume is a good reflection of most surgeons’ typical annual caseloads. 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 open to discussion. However, the majority of surgeons have such low annual volumes that our conclusions would not change even if we, say, halved the minimum number of surgeries considered to be adequate. Moreover, we see 250 as somewhat as a minimum: for organ-confined disease, the learning curve continues to lead to improving results until well above 1000 surgeries.
We also acknowledge that annual volume is not deterministic of patient outcome. Even among high volume surgeons, there is significant variation in patient outcomes8
, and it seems highly plausible that a talented, low volume surgeon could have results superior to that of higher volume counterpart. Yet something similar may be true when comparing two drugs: even if drug A has a higher response rate than drug B, it is plausible that some patients may do better on drug B than drug A. On average though, 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.