Prospective 6-month follow-up of patients prescribed risperidone long-acting injection: factors predicting favourable outcome.

Risperidone long-acting injection (RLAI) is the first depot preparation of the so-called atypical antipsychotics. Efficacy is well established but effectiveness and factors predicting favourable outcome have only tentatively been evaluated. Our aim was to evaluate naturalistic outcome in patients given RLAI in normal clinical practice and to uncover factors predicting favourable outcome. Prescribers provided details of all patients prescribed RLAI on starting treatment and fortnightly thereafter. Patients were followed up for 6 months or until RLAI was discontinued. Main outcome measures were continuation with RLAI at 6 months and improvement in Clinical Global Impression (CGI) score. These outcomes were compared with clinical and patient data. Of 250 patients starting RLAI, 118 (47.2%) were still receiving it at 6 months. Patients were more likely to continue treatment with RLAI to 6 months if older than 55 yr [odds ratio (OR) 3.13, 95% CI 1.32-7.40, p=0.006] and if receiving a dose of >25 mg/2 wk RLAI (OR 2.37, 95% CI 1.40-3.99, p<0.001). An improvement of one point on the CGI scale (first vs. last assessment) was more likely in those prescribed RLAI because of poor prior adherence (OR 2.28, 95% CI 1.35-3.86, p=0.002) and less likely in those who had previously been prescribed clozapine (OR 0.29, 95% CI 0.14-0.61, p=0.001). Overall outcome of RLAI treatment is moderately good but better still when prescribed because of prior poor adherence and for more elderly patients. RLAI is less suitable for those who have previously received clozapine.