Management of myocardial infarction in Scotland: have clinical trials changed practice?

Predictors of physician compliance with a published guideline on management of febrile infants

BACKGROUND

Previous studies have demonstrated clinicians' poor compliance with published management strategies and protocols, but the reasons why physicians often choose to vary their management of the febrile infant from published guidelines are poorly understood.

OBJECTIVE

We conducted a study of physicians to learn more about the issues that influence their decisions in the management of febrile infants.

METHODS

A survey study of pediatricians, emergency physicians and family physicians randomly selected from a list of licensed physicians in the United States. Chi square and Kruskal-Wallis tests were used to measure differences in responses by specialty. Odds ratios from logistic regression were used to measure differences in compliance with a recently published guideline.

RESULTS

We received 193 completed surveys from pediatricians, 177 from emergency physicians and 104 from family physicians. After controlling for other variables, odds for compliance with a recently published guideline were higher for pediatricians [odds ratio (OR) = 9.13] and emergency physicians (OR = 2.5) than for family physicians (P < 0.001). Factors associated with decreased odds of compliance included more years since graduation from medical school (OR = 0.93), a higher proportion of office visits by children < 1 year of age (OR = 0.97) and increased comfort diagnosing serious bacterial illness (OR = 0.35). Factors associated with increased odds of compliance included a higher perceived likelihood of serious bacterial illness in febrile infants (OR = 1.01) and better reported knowledge of the recently published guideline (OR = 2.01).

CONCLUSIONS

We found that specialty as well as other factors were associated with physician compliance with a recently published guideline. This information may facilitate guideline development and implementation by providing a better understanding of what motivates physicians in their clinical decision making.

Knowledge and practices of generalist and specialist physicians regarding drug therapy for acute myocardial infarction

BACKGROUND

The respective roles of generalist and specialist physicians in the care of patients is currently a matter of debate. Information is limited about the knowledge and practices of generalist and specialist physicians regarding conditions that both groups treat, such as myocardial infarction.

METHODS

We therefore surveyed 1211 cardiologists, internists, and family practitioners in the states of New York and Texas about four treatments demonstrated by randomized clinical trials to be associated with improved survival after myocardial infarction (thrombolytic therapy, immediate and long-term use of aspirin, and long-term use of beta-blockers) and two treatments for which such evidence is lacking (diltiazem for patients with pulmonary congestion and prophylactic lidocaine). We asked physicians about the effect of each treatment on survival and the likelihood that they would prescribe each class of drugs.

RESULTS

For the four beneficial treatments, the cardiologists believed more strongly than the internists and family physicians that survival was improved by the treatment, and they were more likely to prescribe these drugs (P < 0.001). For example, 94.1 percent of cardiologists said they were very likely to prescribe thrombolytic agents to treat an acute myocardial infarction, as compared with 82.0 percent of internists and 77.3 percent of family practitioners. Conversely, for the two treatments for which trials showed no evidence of a survival benefit, cardiologists were less likely than internists and family practitioners to think there was such a benefit and less likely to prescribe the drugs (P < 0.001). For example, 4.7 percent of cardiologists reported that they were very likely to use prophylactic lidocaine, as compared with 13.1 percent of internists, and 16.5 percent of family practitioners. When we used logistic regression to adjust for potential confounders, all the differences between the cardiologists and the internists and family practitioners remained significant (P < 0.02).

CONCLUSIONS

Internists and family practitioners are less aware of or less certain about key advances in the treatment of myocardial infarction than are cardiologists. This finding underscores the need to improve the dissemination of information from clinical trials to generalist physicians, particularly if they are to have an enlarged role in the evolving health care system.

Clinical trials versus clinical practice in the secondary prevention of myocardial infarction

To examine whether the results of trials on the secondary prevention of myocardial infarction have led to a change of prescription practice, the discharge forms of a random sample of 737 patients admitted to a university hospital with a diagnosis of acute myocardial infarction (MI) with Q wave from 1982 to 1988 were examined. Information about cardiovascular and other risk factors, contraindications, and prescription of beta-adrenoceptor antagonists (beta AA), acetylsalicylic acid (ASA) and calcium channel blockers (CCB) was collected. The prescription of these drugs was analysed in relation to clinical variables and the date of patients' discharge from hospital. During the 7 years of follow-up, the prescription of beta AA increased gradually from 20% to 30-35%; the prescription of CCB was above 30% during the same period and did not change significantly with time. The prescription of ASA increased from 0% to 30-35% in the last 3 years of follow-up. Contraindications to beta AA were present in 23.2% of cases and contraindications to ASA in 14.4%. In a multivariate analysis, hypertension (odds ratio 2.29, 95% confidence interval 1.55-3.38) and the period 1986-1988 (OR 2.27, 95% CI 1.57-3.30) were associated with the prescription of beta AA, although the prescription of beta AA decreased significantly with advancing age. Other variables inversely associated with the prescription of beta AA were contraindications (OR 0.41, 95% CI 0.24-0.66) and the presence of heart failure during admission (OR 0.08, 95% CI 0.03-0.20).(ABSTRACT TRUNCATED AT 250 WORDS)

British Heart Foundation surveys (1987 and 1989) of United Kingdom treatment policies for acute myocardial infarction

Consultant physicians and cardiologists were surveyed early in 1987 and 1989 to document the management policies for the treatment of acute myocardial infarction in United Kingdom hospitals and to assess the influence of major clinical trials on these policies. The response rate to both these surveys was high (84% (1178 physicians) in 1987 and 76% (982 physicians) in 1989). The percentage of physicians that reported using antiplatelet therapy "routinely" in acute myocardial infarction rose from 9% in 1987 to 84% in 1989 while those who reported using it "rarely or never" fell from 42% to 3%. Similarly, "routine" use of fibrinolytic therapy rose from 2% to 68%, and use "rarely or never" fell from 53% to 3%. This increase in the reported use of fibrinolytic therapy was accompanied by greater certainty about its efficacy and relative safety and by a general widening of the indications for its use. The use of other treatments in acute myocardial infarction (for example, the general use of anticoagulants, beta blockers, nitrates, calcium antagonists, or prophylactic antiarrhythmic agents) seemed to change little during this period, although the routine use of coronary angiography and oral anticoagulants after fibrinolytic therapy fell substantially between 1987 and 1989 (from 23% to 4%, and from 24% to 7% respectively). Fibrinolytic and antiplatelet therapy were accepted into the routine management of myocardial infarction during a relatively short period that coincided with the reporting of several positive controlled trial results. Clinical trials have rarely been seen to have had such a great impact on practice. In this case the rapid acceptance of the trial results may have been due to the consistency and reliability of the estimates of the size of the benefits (and risks) of therapy seen in these unusually large studies.

The applicability of the results of streamlined trials to clinical practice

During recent decades we have seen an encouraging development of trial methodology. Less effort, however, has been devoted to the application of findings of trials to the practice of medicine. We cannot expect results of controlled trials alone to determine standard therapy, for clinical judgements are also required. Both beneficial and adverse effects are often only detectable on the group level. There are generally very few indications that drug effects differ qualitatively in subgroups of patients. It is important not only to prove or disprove effects, but also to find out how to implement a proper therapy for a majority of eligible patients. Four examples from treatment after myocardial infraction show that drug usage may not always be based upon results of clinical trials. The adoption of Swedish guidelines for thrombolytic therapy in acute myocardial infarction is taken as an example of an apparently optimal application of trial results in practice.