In this large, prospective, multi-center study, we demonstrated that when primary care providers identified increased subclinical atherosclerosis on an office-based CUS, they lowered their SBP and LDL-C targets and were more likely to prescribe preventive therapies such as aspirin and lipid-lowering medications. The vast majority of these subjects would not have qualified for LDL-C reduction or aspirin based on their CVD risk. Although the estimated CVD risk of the subjects in our study was low to moderate, the majority of our subjects had AbnlCUS, as previously described in populations with risk factors but low short-term CVD risk.
3, 25, 26 Despite identical training, differences in physicians’ prescription of cholesterol medication were observed between the sites, most likely due to variations in baseline practices and disease severity. Similar practice variation in prescription of preventive therapies has been described in other studies.
27,28The most interesting and unique findings from this study are those related to patients’ intentions and self-reported behaviors after 30 days. One of the most salient findings is that regardless of the results of the ultrasound, our patients reported an increased perceived ability to change HRBs after screening. Discovering AbnlCUS did not influence the patients’ perceptions of their ability to change HRBs.
Therefore, it is likely that the very act of screening itself, not the results of the test, increased patients’ perceived self-efficacy to make behavioral changes to decrease their CVD risk. This finding is consistent with previous studies by our research group that were performed in academic medical centers and research centers, showing that increased patient motivation for behavioral change is not related to having an abnormal CUS, but instead is related to the screening process.
11,18 It is possible that the observed increases in patients’ perceived self-efficacy were related to having a more intensive clinical encounter with their primary provider and not the screening; however, previous research suggests that single CVD risk discussions are not very effective.
29Immediately after CUS, subjects with AbnlCUS perceived themselves to be at increased CVD risk. Previous studies have demonstrated that immediately after CUS, there is an increase in CVD risk perception.
11,18 Although risk perception is a key motivator for change, there have been conflicting results about risk perception as a predictor of behavioral change.
28,30–32 Patients with AbnlCUS were more likely to intend to reach exercise goals, make dietary changes and quit smoking, so finding AbnlCUS did affect some patients’ intentions. Several models of behavioral change suggest that individuals’ intentions are among the most important predictors of behavior.
30,31 Self-efficacy and outcome expectations are critical predictors of intentions; however, the relationship between these processes is unclear.
32–34 Unfortunately, increased intention to make HRB changes does not consistently predict that an individual actually will make changes (the “intention-behavior gap”).
22 Some behavioral models suggest that there is a major distinction between pre-intentional motivation processes that lead to behavioral intention and post-intentional processes that lead to documented behavioral change.
35 Thus, to help bridge the intention-behavior gap, pre-intentional factors such as threat perception and self-efficacy and post-intentional factors such as strategic planning on how to initiate and maintain behavioral changes should be addressed before assuming that intentions will translate into action
35 Planning should also include anticipation of barriers and alternatives to overcome them.
22, 35A strength of this study was the evaluation of 30-day outcomes. Behavioral changes reported after 30 days included increased exercise frequency, certain dietary changes, and weight loss. However, the presence of AbnlCUS only predicted specific dietary changes after 30 days, not changes in exercise frequency or reported weight loss. In spite of their intentions and the high percentage of subjects with AbnlCUS, a substantial portion of subjects did not report any HRB changes after 30 days. A separate survey to measure self-efficacy was not used and it is possible that differences in self-reported behavioral change in our study reflected differences in individuals’ baseline levels of self-efficacy, since individuals with lower self-efficacy are less likely to transition from intention to action.
14 Previous smoking cessation studies demonstrated that individuals with higher self-efficacy were more likely to engage in cessation therapy.
14,36 In a small randomized study, the effect of the carotid ultrasound imaging on smoking cessation behaviors was mediated by self-efficacy.
14 In behavior prediction models, intention and perceived behavior control only account for 14–25% of population variance in documented behavior change, so large effects on intention can result in only small behavioral changes.
22,30,33 This supports the need for recurring CVD risk education and counseling and emphasizes the limitations of effectiveness of one-time interventions.
34 Because human behavior is so complex, additional research is needed to thoroughly evaluate the role of carotid ultrasound screening, or any atherosclerosis imaging technique, and the optimal frequency of feedback necessary to initiate and maintain behavioral change.
34Limitations
Although this study performed a prospective intervention and each physician and patient served as their own control, it was not a randomized clinical trial, so a strategy of CUS was not compared to standard care or to CVD risk counseling alone. This study design is susceptible to the Hawthorne Effect, whereby subjects - in this study, both doctors and patients - alter their behavior simply because they are being observed, and not due to an effect from the experimental intervention.
37 Although patients may have overestimated their intentions and reported 30-day outcomes differently because they were being studied, the presence of AbnlCUS had very little effect on self-reported behavioral changes after 30 days. Therefore, if significant behavioral changes were not noted in this type of study, it is unlikely that a randomized clinical trial would have a
greater effect on patient behaviors. The Hawthorne Effect most likely biased the changes observed in physician behaviors. Because of the training the physicians received and their awareness of being observed, it is not surprising that finding AbnlCUS influenced their prescribing practices. A randomized clinical trial would be necessary to determine if the more aggressive treatment strategies adopted by physicians after finding AbnlCUS translate into CVD event reduction. Prescription of statins in patients with increased CIMT reduces CIMT progression,
38 but its effects on CVD events have not been studied. Although prescribing aspirin was considered a reasonable intervention for patients with subclinical atherosclerosis when this study was designed, recent studies suggest it might not be beneficial.
39We used surveys rather than direct measurements to describe some of the 30-day outcomes; however, direct measurement would have further reduced the modest effects at 30 days. The surveys have not been independently validated, but have been revised based on previous experience from our research group.
11,18 Although the 30-day follow-up period is relatively short, it is unlikely that we would have seen larger effects if the study was longer. Indeed, health behavior decay - a gradual migration away from newly adopted healthy behavior - is more likely.
40 Although imaging for CVD risk assessment is recommended for intermediate risk individuals, low to intermediate risk individuals, such as those recruited into this study, frequently are referred to such screening programs.
9,18,41 Finally, the lack of racial/ethnic diversity and limited geographical area of the clinical sites may limit the generalization of the findings.
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