• patient compliance
• medication effectiveness

The typical assessment of mediation compliance by physicians is similar to the assessment of an iceberg from the ship captain's window. The difference is that when a captain sees ice in the water, he assumes that what he sees might be only the “tip of the iceberg” requiring attention. In contrast, patients who inadvertently omit many doses and doctors who attribute poor control to lack of drug efficacy may have no concept that the underlying problem is poor compliance with the prescribed regimen. If the captain fails to recognise an iceberg in advance, he knows that he must turn his immense vessel rapidly to avoid disaster. Failing to recognise inadequate compliance as the source of the patient's problem, the physician is unaware of the appropriate action to be taken. Instead, the physician typically prescribes even more medication as a higher dose, or an alternative or second drug. Unfortunately, the patient often remains on a potentially fatal collision course. Why is this scenario so common in medical practice?

Inherent in the answers to these questions is a message for every clinician who prescribes medications: Look under the surface. Don't assume that you know which patients take their medication regularly. Don't assume that failure to control hypertension, hyperlipidaemia or other measures of cardiovascular disease is caused by lack of efficacy of the prescribed medications.

In daily practice, after the physician determines the diagnosis and selects an appropriate treatment, the burden of achieving a good outcome is shifted to the patient. Depending on the setting, patients might be left to accomplish this important task of self management with little guidance. Both physicians and patients need to understand that key factors affecting outcome are “compliance” (that is, attempting to take the medication each day as prescribed) and “persistence” (that is, continuing to take the …