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Although the definition of usual care has not been standardized, it can include the routine care received by patients for prevention or treatment of diseases.
In cardiology, the type of routine care can vary by disease type and severity, the practice in which the patient is seen, health care system, and individual physician. Major task forces such from the American College of Cardiology and American Heart Association have published guidelines on the diagnosis, prevention, and treatment of several cardiovascular diseases. These guidelines are based on expert opinion as well as on the strength of the evidence. The purpose of these guidelines is to ensure that these recommendations are disseminated to the practicing cardiology community, as the type and quality of diagnostic, preventive, and treatment strategies widely varies.
In randomized trials, there has been some debate about the advantages and disadvantages of including a usual care arm as a control group. The Declaration of Helsinki states that the “benefits, risks, burdens, and effectiveness of a new method should be tested against those of the best current prophylactic, diagnostic, and therapeutic methods.” In theory, it makes sense that in a randomized controlled trial, the usual care arm should be defined by the “best current” method available. The main advantage, of course, is to test the intervention against what is currently available in evidence-based clinical practice. However, there has been disagreement on what should constitute “usual” care in a randomized controlled trial. First, in the community, usual care can sometimes include suboptimal or older practices. Thus, whether “usual care” should really be changed to “optimal care” or “evidence-based care” remains unclear. Second, the outcome in the usual care arm may be affected by the Hawthorne effect. It is difficult to blind the physicians and the patients to being in the usual care arm. The physicians or the patients may improve or modify their behavior after finding out that they are not in the active intervention arm. Third, because physician treatment patterns vary, the components of the usual care arm and their effects on the outcome are difficult to quantify. Some investigators have advocated for proposing a standardized treatment plan for patients randomized to the usual care arm. Further, differences between the active intervention arm and the usual care arm could be minimized if the usual care arm contains the proposed intervention. Finally, the types and nature of treatment typically given by physicians in the usual care arm could change during the study period.
For example, in the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT-LLT), 10,355 persons, aged 55 years or older with hypertension and moderately elevated low-density lipoprotein cholesterol levels, were randomized in an unblinded fashion to pravastatin (a statin) or to usual care. During a mean follow-up of 5 years, there was no significant difference in all-cause mortality or coronary heart disease events. ALLHAT-LLT was unique as it was one of the few trials that did not show the beneficial effects of statin therapy on cardiovascular events in patients who were at risk for future events. The reasons for the lack of difference in outcomes between the two arms are unknown, but the inclusion of a usual care arm as a control group may have played a role. For example, ALLHAT-LLT was conducted during a period that several other randomized trials of statin therapy were published. Thus, over time, physicians could have treated patients in the control arm with statin therapy. In fact, there was a steady increase in the use of statins in the usual care arm: 8.2% at year 2, 17.1% at year 4, and 26.1% at year 6. In addition to statins, other treatments in the usual care arm could have played a role. For example, physicians could have disproportionately recommended non-pharmacologic strategies (i.e., exercise, diet, and weight reduction) to their patients in the usual care arm as well. Given that the types of and intensity of the treatments in the usual care arm were likely variable, ultimately, these reasons remain speculative. Overall, ALLHAT-LLT is one example of the potential limitations, described above that may be associated with a usual care arm.
References and Further Reading
- ALLHAT Officers and Coordinators for the ALLHAT Collaborative Research Group. (2002). Major outcomes in moderately hypercholesterolemic, hypertensive patients randomized to pravastatin vs usual care: The antihypertensive and lipid-lowering treatment to prevent heart attack trial (ALLHAT-LLT). Journal of the American Medical Association, 288, 2998–3007.CrossRefGoogle Scholar