Patients with CHD must look at their repeat prescription list with some trepidation, such is the number of evidence-based drugs that they are prescribed. This must be all the more disconcerting if the patient was on no medication prior to their coronary event. However, these drugs are only effective if they are taken as prescribed and a study has looked at a simple method of addressing patient compliance to determine the effect on cardiovascular events.

More than 1,000 patients with established CHD were asked a single question: 'In the past month, how often did you take your medications as the doctor prescribed?' Patients were defined as non-compliant if they were taking their medication as prescribed 75% of the time or less. Cardiovascular events (CHD death, MI or stroke) were recorded prospectively from medical records for a mean follow-up of four years.

The results showed that 8.2% of patients were non-compliant and 14.4% developed cardiovascular events. Those that were non-compliant were more likely to develop cardiovascular events during follow-up (22.9% vs 13.8%, P=0.03). Furthermore, non-compliance was independently predictive of cardiovascular events after adjusting for baseline cardiac disease severity, traditional risk factors and depression.

This study has quantified what common sense would predict by showing that not taking medication as prescribed can double the rate of subsequent cardiovascular events.

The method used in this study is simple and would appear to be an effective way of identifying patients at increased risk of cardiovascular events. These patients could then be targeted, perhaps by involving relatives, explaining carefully what the drugs are for at more frequent follow-up visits or by using pill boxes.