Clusters of non-adherence to medication in neurological patients

Background: Non-adherence to medication is a common and serious problem in health care. To develop more effective interventions to improve adherence, there is a need for a better understanding of the individual types of non-adherence. Objective: To determine clusters of non-adherence in neurological patients using a complex adherence questionnaire. Methods: In this observational, monocentric study 500 neurological patients (consecutive sampling) were recruited in the Department of Neurology at the Jena University Hospital, Germany (outpatient clinic, wards) over a period of 5 months. Patients with severe dementia or delirium who were unable to complete the questionnaire were excluded. Due to missing adherence data, in total, 429 patients with common neurological disorders were analyzed. Different types and clusters of non-adherence using the German Stendal Adherence to Medication Score (SAMS) were determined. Results: For the 429 patients, the mean age was 63 years (SD = 16), 189 were female. According to the SAMS total score 74 (17.2%) were fully adherent, 252 (58.7%) showed moderate non-adherence and 103 (24%) showed clinically significant non-adherence. Principal component analysis with Varimax rotation revealed three independent factors explaining 60.5% of the SAMS variance. The bulk of non-adherence was attributed to modifications of medication (41.7%) and forgetting to take the medication (33.2%) followed by lack of knowledge 25.1% about reasons, dosages and time of administration for the medication. Conclusions: Intentional non-adherence was the primary self-reported behavior identified among non-adherent neurological participants. Many patients modified their prescribed medication due to various reasons, such as side effects or lacking effect. Different clusters require different interventions. While for the cluster ´forgetfulness' the reduction of poly-medication and a behavioral approach with reminders seems reasonable, patients in cluster ´missing knowledge' and cluster ´modifications' may need an educational approach.