Evaluating complex interventions: one size does not fit all.

The article analyzes the Keep Well cardiovascular anticipatory care program in Scotland in an effort to demonstrate the problems associated with the proposal of the British Medical Research Council (MRC) to implement a sequential approach to testing complex interventions in medical care. Keep Well was launched to address the inequalities in cardiovascular morbidity and mortality. The authors argue that Keep Well could have been standardized and better developed to make evaluation easy. They add that no clinical evaluation approach or randomized controlled trial is suited for all patients.