To adhere or not, and what we can do to help.

Two factors predict treatment outcome, how effective the treatment is and whether the patient takes or follows the treatment plan. As clinicians or scientists, we strive to develop newer and more effective treatments, both pharmacological and non-pharmacological to improve treatment outcome in our patient population. Adherence is the single most modifiable factor associated with treatment outcome, yet how often is the issue of adherence addressed in clinical consultations? The best treatment is rendered useless if not adhered to. Initial adherence rates are low and get worse with time, but methodological difficulties in studies make it difficult to determine both the clinical implication of suboptimal adherence and successful strategies. Further research should apply more rigour to the area of definition and measurement, be sufficiently powered and long term, and measure possible confounders, to allow for an understanding on the link and impact between adherence and clinical outcome. This article reviews some of the main issues with regard to adherence and cost implications of suboptimal adherence and suggests future directions.