Objective: Adherence to antipsychotic treatment is an important aspect of the long-term management of schizophrenia. The evaluation of adherence is often difficult in the clinical setting. This study compared patient self-reporting and clinician judgment of adherence behaviour in patients with early and chronic schizophrenia.
Method: Clinician-rated questionnaires and parallel patient self-rated questionnaires were administered to 229 patients with early schizophrenia (illness duration < 5 years) and 255 patients with chronic schizophrenia. Items in the questionnaires addressed two forms of adherence behaviour (forgetting to take medication and deciding to stop medication) as well as attitudes toward medication.
Results: Significant non-adherent behaviour was reported by patients, particularly in the early schizophrenia group. Non-adherent behaviour was related to feelings of embarrassment about taking medication. Both non-adherence and embarrassment were under-recognized by clinicians. Starting from a prior probability of 0.24, knowledge of the patients' attitudes increased the posterior probability to 0.33, whereas clinicians' detection of non-adherence (deciding to stop medication) improved the posterior probability to 0.65. When both clinicians' evaluations and patients' attitudes were known, the posterior probability improved to 0.68.
Conclusion: Non-adherence is a widespread phenomenon in early schizophrenia. Increasing clinicians' sensitivity to patients' feelings of embarrassment may be an important factor in the detection of non-adherence. When taking a base rate of non-adherence into consideration, clinicians' evaluations appeared to be more effective in detecting non-adherence than simple information obtained from patients on their attitudes toward medication. Pragmatic real-life estimation of non-adherence has important implications for the possibility of intervention.