A three-year retrospective cohort study of predictors of medication adherence in first-episode psychosis in Hong Kong

Abstract

Objectives Medication adherence is one of the most important aspects of the treatment plan for successful recovery of patients with psychosis. Medication non-adherence leads to increased relapse rate, risk of violence, symptom severity, hospitalization, and suicide risk; reduced mental function and life satisfaction; as well as increased economic burden to society. The aim of this study was to examine the predictors of medication adherence for first-episode psychosis patients in a three-year retrospective cohort study.

Methods The retrospective cohort study evaluated the potential predictors of medication adherence over 3 years in first-episode psychosis patients. Patients having a good adherence rating (1 or 2 on a 4-point scale) for 8 months or more were categorized into the good adherence group for that year. Patients having a poor adherence rating (3 or 4 on a 4-point scale) for 5 months or more were categorized into the poor adherence group for that year. Potential predictors for medication adherence were gender, age, years of education, migration, occupation impairment, premorbid functioning, duration of untreated psychosis, mode of onset, diagnosis, hospitalization at first presentation, positive, negative and depressive symptoms at 1 month, stressful life experiences, and early intervention. The dependent variable was medication adherence by the patient. Binary logistic regression analyses were performed to explore predictors for non-adherence at 1, 2 and 3 years.

Results Among the 1400 patients recruited into the study, non-adherence rates were 15.7% (190/1208) at year 1, 15.3% (171/1115) at year 2, and 12.1% (125/1029) at year 3. From the logistic regression analyses, suicide attempt at baseline (p=0.027, OR=2.233) and mode of onset (p=0.035, OR=1.583) were found to be predictors of poor medication adherence at 3 years following the first episode. Common significant predictors were identified at year 1 and year 2. Standard care (p=0.000, OR=2.332), hospitalization at baseline (p=0.001, OR=2.095), stressful life event (p=0.015, OR=1.567), migration status (p=0.048, OR=1.472), more years of education (p=0.024, OR=1.084), lower positive symptom severity (p=0.001, OR=1.372) and paranoid schizophrenia (p=0.043, OR=1.444) were found to be predictors of poor medication adherence in the two years following the first episode.

Conclusions It is clear from our study that early intervention comprising an individualized care plan enhanced medication adherence, but these benefits lasted only until the treatment ended. It is recommended that the early intervention service should be extended to 5 years and include patient-centred interventions for high-risk patients: an adjustment and adaptation programme for immigrants (specifically new immigrants to Hong Kong); a stigma reduction programme for teenagers; psychotherapy, group therapy and individual counseling for patients who have experienced stressful life events or attempted suicide; and sustained education on medication adherence for acute and sub-acute onset patients. These strategies of intervention tailored to the individual could be introduced to improve medication adherence in psychosis patients. Further studies on medication predictors including insight level, side effects of medication, social support level, level of premorbid intelligence and therapeutic relationships, could identify potential predictors of medication adherence, which can be targeted to reduce relapse, decrease hospitalization and reduce the cost to society.