Treatment Patterns among Schizophrenia Patients on Paliperidone Palmitate or Atypical Oral Antipsychotics in Community Behavioral Health Organizations
Objective: Non-adherence to antipsychotic medication increases the likelihood of relapse among patients with schizophrenia. Atypical long-acting injectable antipsychotics may increase adherence. We assessed treatment patterns among schizophrenia patients treated with paliperidone palmitate (PP) versus atypical oral antipsychotics (OATs) in community behavioral health organizations. Methods: We evaluated 763 schizophrenia patients who were new (PP-N; N=174) or continuing (PP-C; N=308) users of PP, or new users of OAT (N=281) at enrollment in the REACH-OUT registry (2010-2013). Discontinuation, switching, and adherence were assessed for one year; where adherence was measured by proportion of days covered (PDC) or medication possession ratio (MPR). Reverse Engineering and Forward Simulation (REFSTM) was used to identify predictors of discontinuation, switching, and adherence. Multivariable Cox or generalized linear regression was used to estimate adjusted hazard ratios (HRs) or odds ratios (ORs), with 95% confidence intervals. Results: Among PP-N users, 27% discontinued and 23% switched from their initial treatment regimen, vs. 51% (p<0.001) and 27% (p=0.493) of OAT users, respectively. After covariate adjustment, PP-N users (vs. OAT, HR=0.49 [0.31-0.76]) and males (HR=0.65 [0.46-0.92]) had significantly lower rates of discontinuation. Predictors of switching included: OAT (vs. PP-C users, OR=2.50 [1.39-4.55]), unfavorable attitude toward medications (Drug Attitude Inventory-10 score <8 vs. ≥8, OR=1.85 [1.04-3.33]), African-American race (vs. Caucasian, OR=2.07 [1.16-3.72]), and substance abuse (OR=1.86 [1.13-3.09]). Relative to OAT, PP-N had a 36% [31%-42%] higher MPR, and a 10-fold increased achievement of PDC ≥80% (OR=10.46 [5.72-19.76]). Conclusions: PP was associated with improved adherence, and less frequent treatment discontinuation and switching, compared to OATs.