Primary care physicians surveyed in this study reported high and increasing rates of PSA testing for asymptomatic men over age fifty. Physicians also demonstrated increasing agreement from 1993 to1998 with attitudes favoring PSA testing as a community standard and as a reason for malpractice liability if omitted. However, less than half of physicians agreed that radical prostatectomy reduces prostate cancer–specific mortality or disagreed that treatment harms might outweigh treatment benefits, two statements directly addressing patient outcomes from screening.
These results suggest that beliefs unrelated to direct clinical patient outcomes were significant determinants of primary care physician PSA screening practices in 1993 and 1998. This statement is supported by findings that only approximately half of even high testing physicians felt that prostate cancer treatment benefits outweighed treatment harms or that aggressive early treatment in the form of surgery reduced disease-specific mortality. If belief in improved patient outcomes were driving PSA testing practices, more physicians reporting high levels of testing should have supported the efficacy of prostate cancer treatment. Standard of care belief, malpractice concerns, interpretation of PSA test operating characteristics, and markers of community versus academic practice appear to be more highly associated and may be more influential drivers of PSA screening use.
These conclusions are substantiated by our subgroup analysis of physicians who did not endorse the efficacy of early prostate cancer aggressive treatment. This analysis indicated that high testing physicians were much more likely than low to moderate testers to believe that PSA tests represent standard practice and have acceptable test characteristics for disease screening. The strong inverse relationship between overall PSA testing and patient demand–driven testing negates the possibility that patient demand explains the high PSA testing practices of the majority of physicians, indicating instead that patient demand plays an important role for low PSA testing physicians.
The high PSA testing rates observed in this study are consistent with evidence from other studies demonstrating self-reported PSA testing rates from 55% to 87%.12–18
These data corroborate earlier reports that PSA testing is associated with the belief that it represents a standard of practice or common practice,16,17
that PSA tests are ordered based on fear of lawsuits,17
and that PSA tests are acceptable to physicians.17
Our results contrast with other studies that have shown that a primary16
or important reason12,17
for PSA testing was belief that aggressive treatment would reduce mortality or that screening would reduce mortality. The 1998 survey showed a trend favoring an association between physician gender and testing, as have 4 of 5 recent U.S. surveys.12,13,15,16,18
Other studies have shown that physician age12,17
and number of years since graduation from medical school18
were both associated with greater PSA testing, associations also noted in our study. Community versus academic practice location, a major determinant of test ordering in our study, has also been noted by studies in Ohio17
To illuminate the observed differences in PSA testing, several potential explanations merit consideration. In our study population, high testing physicians were generally located in the community-based practices and low testing physicians were located in the academic practices. The community physicians were older, more likely to be male, and had practiced a greater number of years than had academic physicians. Given the multi-collinearity of these explanatory variables and the small sample size, it was not possible to determine their independent effect on testing by multivariable analysis. However, other surveys have demonstrated similar age and gender relationships with PSA testing, so these may represent unique associations, particularly since gender-associated variation in primary care physician screening practices has been well described.19,20
A potential explanation for the strong association between academic versus community physician practice and PSA testing is that the academic-based physicians may be more likely to incorporate the principles of disease screening and evidence-based medicine into their calculus of medical decision making. This tendency might result in a higher threshold among academic physicians to adopt new technology or a delay before embracing new screening methods such as PSA testing. This idea is consistent with the concept of “‘evangelists’ (advocates of screening)” and “‘snails’ (advocates of the scientific method)” described by Sackett and Holland21
and applied to prostate cancer by Collins and Barry.22
In our 1993 survey, the “evangelists” are the high testing, almost exclusively community physicians and the “snails” are a mix of low testing, mostly academic physicians. Our 1998 data suggest no reduction in enthusiasm for screening on the part of the “evangelists.” Consistent with a lag phase, half the initial “snails” reported a change to a moderate or high testing frequency and acknowledged patterns of attitudes more favorably disposed to PSA testing in 1998. However, the pattern of belief changes we observed, along with the lack of interval-published data in support of PSA screening, suggest that the “converted snail” behavior was not a result of evidence-based review but more likely due to a growing influence of standard of care beliefs and other non–patient outcome–related factors.
The apparent paradox of low belief in treatment efficacy yet high screening practice on the part of some physicians may be due to grouping physician uncertainty and disagreement about early treatment efficacy together for analysis purposes. Disaggregating these response categories revealed that in the presence of uncertainty about efficacy, community and academic physicians adopted opposite testing strategies: 84% of uncertain community physicians adopted high testing strategies, whereas 88% of uncertain academic physicians adopted low or moderate strategies. The findings were similar in both surveys. These relatively high testing rates among community physicians in the face of uncertainty about treatment efficacy support our conclusion that other factors are more influential drivers of PSA test ordering, particularly among community physicians. It also confirms a higher threshold among academic physicians for adoption of a new screening modality.
The fundamental requirements of an effective screening program are well established.23,24
Prostate cancer is an important health problem that can be diagnosed in a presymptomatic stage, two key requirements for effective screening. However, another key principle is that screening programs are only effective when treatment at the presymptomatic stage improves patient mortality or other important outcomes, a point still unsettled in the case of prostate cancer. Given the other potential influences on physician behavior we have described, our findings could be explained if some physicians elect to screen patients widely before these fundamental principles of screening are satisfied. Primary care physicians might choose to limit their role to identification of presymptomatic disease, deferring decisions about treatment appropriateness to specialists. If so, these physicians, who are essentially delinking the utilities of disease identification and treatment, are adopting a more circumscribed posture that diminishes their role in disease screening. This approach might be expected to produce less–well-informed but more frequently tested patients, a hypothesis that may warrant future investigation.
Alternately, physicians may choose to test a high proportion of patients because suggestions to incorporate principles of informed consent and shared decision making may be too difficult to implement in the hectic pace of primary care. Studies of informed decision making show that patients are substantially less likely to elect PSA testing if provided with detailed information about the pros and cons of testing.25–28
Unfortunately, all the methods used in these studies are cumbersome to apply in busy primary care practices. To the extent that these time pressures may weigh most heavily on high testing community physicians, academic physicians may have a greater opportunity to use shared decision making techniques that would be expected to produce lower PSA testing rates. This explanation is also consistent with our finding that low testing physicians are more likely to test as the result of patient demand.
There are several potential limitations to this study. The physician sample was fairly small and was drawn from a large metropolitan area serving an insured, nonindigent patient base with a high managed care penetration. Thus, generalizability to other settings may be limited. Furthermore, community physicians in this study generally received reimbursement on a mixed discounted fee-for-service and capitated basis while academic physicians received salaried compensation from the medical center. While physician estimates of managed care penetration were not associated with PSA testing, confounding may be introduced by failure to account for more subtle differences in payment mechanism. Finally, physicians were asked to self-report their estimated PSA testing rate. The extent to which this reflects their actual PSA ordering behavior is not known.
Our results suggest that beliefs unrelated to direct clinical patient outcomes are important determinants of physician PSA testing practices and that such testing has continued to proliferate and diffuse in recent years. To foster informed patient decision making about prostate cancer screening, physicians need clear and credible data with respect to disease and quality-of-life outcomes in this area. Clinicians need objective guidelines based on such data instead of the current contradictory guidelines based on differing perspectives. Physicians and patients would also benefit from financial and organizational mechanisms that foster a collaborative decision-making process. Without such evidence, tools, and support, physicians will continue to make screening decisions on the basis of perceived imperatives rather than actual patient preferences and objective data.