Review of the methods to measure non-adherence with a focus on chemical adherence testing

A substantial number of patients with cardiovascular disease do not take their medications as prescribed. This can lead to an increased risk of disease complications, hospitalisations and death. Therefore, it is necessary to determine methods to detect non-adherence in patients accurately to ensure that patients can be identified and engaged with. This will allow adequate support to be provided to these patients to improve adherence rates and thus lead to better disease outcomes. This review looks at a wide range of methods to establish medication non-adherence. There is a particular focus on chemical adherence testing as this method has gained acceptance in use in many hypertension clinics and has been recommended by European guidelines for use in patients with suspected resistant hypertension. This review goes onto discuss the use of chemical adherence testing in hypertension clinics currently and also discusses some of the reasons behind non-adherence and provides solutions that can be discussed with the patients to overcome these challenges. The discussion between the clinician and the patient regarding the chemical adherence test result needs to be held in a no-blame environment to ensure that the patient can engage in an open and honest discussion with the clinician. More training is required for clinicians and healthcare professionals to ensure they feel confident to discuss adherence with their patients. Even though chemical adherence testing is being used increasingly as the first-choice method to determine non-adherence, more research is required to increase uptake of chemical adherence testing in a wider range of settings.