Increasing prescription of drugs for secondary prevention after myocardial infarction

Subjects, methods, and results

About 75% of patients with suspected myocardial infarction are admitted to the coronary care unit3 and managed by the admitting medical firm according to guidelines provided by the cardiologist. On a daily ward round the consultant cardiologist supervises management, but on discharge patients return to the care of the admitting physician. The last time the cardiologist has direct contact with the patient may be less than 48 hours after admission.

We audited 170 consecutive admissions (128 men; average age 63 years, range 31-90) to the coronary care unit from 1 February 1992 to 31 July 1992 with a confirmed diagnosis of acute myocardial infarction.3 Readmitted patients were excluded. In 120 (71%) a thrombolytic drug was given, and 146 (86%) patients were discharged alive. Drugs prescribed for secondary prevention at discharge and at the first outpatient appointment, four to six weeks later, were noted. Notes were assessed for contraindications to the prescription of β blockers.

In December 1992 a stamp was introduced into the notes of patients with myocardial infarction on day 2 in the coronary care unit, which stated the cardiologist's recommended drug treatment for secondary prevention. Criteria for the choice of drug were derived from published trials.1 The recommendation was for two drugs (aspirin plus another), since there are few published data on the efficacy of multiple drug combinations for secondary prevention. Following this a repeat audit of 185 consecutive patients (126 men; average age 66 years, range 25-90) admitted between 1 February 1993 and 31 July 1993 was performed. One hundred and twenty five (68%) were given thrombolysis, and 153 (83%) were discharged alive.

More patients were discharged taking β blockers and angiotensin converting enzyme inhibitors after the intervention (table). The number of patients not discharged on a β blocker in the absence of a documented contraindication fell from 20/66 (30%) to 7/72 (10%) (P<0.01, Fisher's exact test). In 1992 only 29% (29/99) of case notes stated reasons why β blockers were not given and contraindications were not always clear; the reason for not prescribing an alternative was stated in only 3/55 (5%). In 1993 the stamp was identified in the notes of 117/153 (76%) patients and the recommendation was not followed in 25 (21%) patients. The reasons for this were numerous and detailed in 18/25 case notes, ranging from adverse drug reactions (8), development of contraindications after discharge from the coronary care unit (4), and choice of other drugs (6). In 1992, of 118 patients followed up at one month, 40 (34%) were prescribed ß blockers, of whom 36 had been discharged taking the drug. This compared with 53/116 (46%) in 1993 and 51.

Comment

This study shows that widely accepted and proved treatments for preventing reinfarction and death after recovery from myocardial infarction are still underused despite evidence from clinical trials1 and expert advice.4 The use of a simple method of marking the case notes resulted in an increase in prescriptions for β blockers, so that only 10% of eligible patients were discharged without this treatment. β blocker usage was continued beyond the first outpatient appointment following hospital discharge, suggesting that side effects and complications were not the cause of the initial low prescribing. Trials of angiotensin converting enzyme inhibitors after infarction were published only in 1992-3 and their use in clinical practice was facilitated by the intervention. The lag time from trial publication to implementation would be expected to be much longer.5 Recommendations made on day 2 of admission were followed in almost 80% of cases. Despite the fact that the recommendation appeared in the notes of only 76% of patients there was improvement in the second group as a whole.

In conclusion, a simple method of flagging the medical records to highlight a therapeutic decision appears to be beneficial. The study also shows that a specialist can influence the practice of a wide range of general physicians after only a short period of patient contact.