Health outcomes cannot be accurately assessed if they are measured predominantly by resource utilization indicators and efficacy of interventions.

The economic evaluation of nonadherence requires the identification of the associated costs and outcomes. It is logical that nonadherence entails a cost due to the occurrence of the undesired effects that the recommended regimen tries to minimize. In terms of outcomes, nonadherence results in increased clinical risk and therefore in increased morbidity and mortality.

For health professionals, policy-makers and donors, measuring the performance of their health programmes and systems using resource utilization end-points and the efficacy of interventions is easier than measuring the desired health outcomes. While such indicators are important, over-reliance on them can bias evaluation towards the process of health care provision, missing indicators of health care uptake which would make accurate estimates of health outcomes possible (64).

The population-health outcomes predicted by treatment efficacy data will not be achieved unless adherence rates are used to inform planning and project evaluation.