From compliance to adherence: Changing views, changing concepts.

Sir,

Rao et al.[1] studied persistence with medication use in patients with psychosis. We were struck by their use of “compliance” as a descriptor of patient behavior. Compliance denotes the conformity of patient behavior to treatment recommendations. It places the onus of noncompliance entirely on the patient and implies that noncompliant patients are uncooperative and untrustworthy. Adherence, on the other hand, is a value-neutral term that considers patient participation in treatment as a shared decision-making process.[2]

Adherence is a complex and dynamic construct. The taxonomy of adherence comprises three components: initiation as taking the first dose of medication, implementation as conformity to the advised regime, and discontinuation as no longer taking the medication.[3]

Implementation nonadherence includes missing doses, not taking the prescribed dose, and not following the frequency and specified time of drug intake.[3] By considering only missing doses, Rao et al.[1] measured a subcomponent of adherence.[1] Of note, in their study even the “noncompliant” patients were adherent to outpatient follow-up for one year; they were thus actually partially adherent. The completely nonadherent patients who did not follow-up for treatment were not assessed in this study. Contacting this group with letters and phone calls might have helped capture the entire spectrum of nonadherence.

Although the 80% figure is a commonly used cutoff to define nonadherence, its appropriateness has been questioned.[4] The impact of nonadherence is not only dependent on the percentage of missing doses but also on the disease, the timing of nonadherence, and the medication.[5] Furthermore, the complexity of assessing adherence increases when patients are prescribed more than one drug. It is not clear how Rao et al.[1] assessed such patients. In this context, being nonadherent to antipsychotics in their study would have had different implications for schizophrenia and mood disorder patients.

Persistence describes the continuation of treatment for the prescribed period. It is the duration between initiation and discontinuation of therapy.[4] Rao et al. used the concepts of adherence and persistence interchangeably.[1]

Last but not least, in Rao et al.'s study,[1] if a compliant patient was one who took medication for at least 80% of the time in the past year (i.e., for at least 292 days), he could have been noncompliant for up to 72 days; he could have relapsed because of noncompliance; and he might then have taken his medications regularly for the rest of the year. Nevertheless, despite having relapsed due to noncompliance, he would have been classified as being compliant. The 80% cutoff is, therefore, more suited to short-term studies.

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