Background: Factors influencing patient and clinician perspectives in the assessment of medication adherence have never been compared.
Method: This study used baseline and 12-month follow-up data from the QUATRO study, an international multicentre study. At baseline, information on patient sociodemographic characteristics, treatment factors, psychopathology, functioning and experience of antipsychotic side effects was gathered. After 12 months of follow-up, psychopathology, functioning and patient experience of antipsychotic side effects were measured once more, and a patient and clinician rating of adherence was obtained by means of the Medication Adherence Rating Scale (MARS) and the Compliance Rating Scale (CRS).
Results: During the recruitment period, 409 subjects with a diagnosis of schizophrenia were recruited. Patients were more often men and single. Mean age was 41.5 years. At the time of the assessment, more than 40% were unemployed and on average had been on antipsychotic treatment for more than 10 years. Nearly 70% were receiving second-generation antipsychotics, and 50% received adherence therapy during the 12 months after enrollment. The relationship between the MARS and the CRS scores showed only a small overlap (correlation coefficient = 0.26). In the multivariate model, the only factor significantly associated with both patient and clinician ratings of adherence was psychopathology. Unemployment and poor subjective tolerability of antipsychotics were significantly associated with low levels of patient ratings of adherence. Conversely, length of treatments and use of newer antipsychotics were significantly associated with better clinician ratings of adherence.
Conclusion: Patient and clinician ratings of adherence do not measure the same dimension. Factors that may positively affect adherence in terms of compliance with prescribed medication regimens may not affect patients' views on adherence, and this should be taken into consideration when planning and negotiating treatment modalities with each individual patient suffering from schizophrenia.