Adherence and Continuation of Treatment with First- and Second-generation Antipsychotics in Schizophrenia

Despite a large body of evidence, the issue of differences in adherence and continuation of treatment with first-generation antipsychotics (FGAs) and second-generation antipsychotics (SGAs) in schizophrenia remains unresolved. This study compared adherence and continuation of treatment between patients on SGAs and FGAs and examined the influence of several socio-demographic and clinical variables on adherence in the two antipsychotic groups.

Two groups, one of 40 patients with schizophrenia on SGAs and the other with 30 patients on FGAs, were compared on clinician-rated and patient-rated measures of adherence over 6 months; a 3-month period prior to intake and a 3-month follow-up period. Mean scores on these measures and the proportion of adherent/non-adherent patients was estimated for both groups.

The two groups did not differ in the 3-month period prior to intake. Over the subsequent 3 months of follow-up, a-fifth of the patients on FGAs became non-adherent, while about 10% of those on SGAs became more adherent. These differences in continuation rates resulted in patients on SGAs being rated as significantly more adherent at the end of this 3-month follow-up period and over the entire 6 months of the study. Differences in adherence and continuation rates between the two groups were primarily driven by the differences between olanzapine and the FGAs. Supervision of treatment by relatives emerged as the only consistent determinant of adherence, but explained only 8% of the variance.

Patients on certain SGAs, notably olanzapine, are more likely to continue with their treatment that those on FGAs.