The results from our survey of internal medicine physicians at 1 academic institution in the United States suggest that physicians have very poor knowledge of the charges for diagnostic tests, as less than a quarter of total charge estimations were within 25% of the true charge. Of the 15 diagnostic tests included in our survey, only 4 (blood culture, lipid panel, chest radiography, and brain magnetic resonance imaging) had correct response rates of greater than 33%. Our results are similar to those from a prior systematic review, which included mostly studies done in countries with national health care systems, in which only a third of diagnostic cost estimates were between 20% and 25% of the true cost.12
These results highlight the need for better education of both resident and faculty physicians on the charges of diagnostic tests. It is notable that faculty felt as uncomfortable as residents at charge estimation, suggesting that little has been done to train physicians in this area to date. A recent study showed low levels of feedback to residents on their resource utilization,16
which may in part be due to the uncertainty faculty members feel regarding their knowledge on this topic. Therefore, it would seem that any intervention would need to target both trainees and their supervising physicians. Our results suggest that both groups are quite open to educational interventions that target this area of need.
Our respondents also felt that improving knowledge of charges would affect their ordering behavior. Given the societal interest in controlling health care costs, it would seem that a fairly straightforward intervention would be to simply improve the transparency of charges. Would such an intervention really change ordering behavior? Several studies, involving both written scenarios,17,18
and real-world settings,,19–24
have shown a decrease in test ordering after physicians were provided charge information. In those studies done in real-world settings, providing physicians the charges for select diagnostic tests at the time of ordering (either on an order sheet or in a computer order entry system) produced a 10% to 30% decrease in test ordering and total charges without any significant increase in adverse events. Use of additional educational methods (such as didactic sessions on health care economics or computerized feedback on utilization of services) would most likely provide additional benefit. A recent review on cost-effectiveness and cost-containment curricula in graduate medical education found that interventions that used multiple simultaneous educational strategies were most successful in achieving positive outcomes.25
Our study does have several limitations. As it was performed at a single academic institution and included a specific group of physicians, generalizability is limited. Research in a variety of settings, ranging from community family medicine physicians and residents in British Columbia, Canada, to anesthesiologists at university-affiliated hospitals in Denmark, has found similar results.,15,26–28
Performing a similar study in the United States involving multiple institutions would be useful but difficult owing to the significant variation in charges across health care systems. Another limitation of our study is that a relatively high percentage of physicians did not return their surveys, leading to possible response bias. While it seems unlikely that these physicians had significantly different knowledge of charges, it is possible that their beliefs regarding charges might have been different (eg, not completing the survey might be indicative of having less interest in knowing the charges for diagnostic tests). There is also the question of how best to determine the range for “correct” estimations. We chose to use a percentage range, rather than an absolute dollar figure or other measurement, which is in line with the methods used in prior studies.13
This means, of course, that the correct range of estimations for expensive tests is larger than that for inexpensive tests. This did not seem to have that significant of an impact, however, as the more expensive laboratory tests actually had more incorrect responses than the less expensive ones.