Comparative Evaluation of Cost – Effectiveness and Medication Adherence Between Olanzapine and Iloperidone in Patients of Psychosis

ABSTRACT

Background: To assess the cost – effectiveness between Iloperidone and Olanzapine in relation to different measures of effectiveness and to evaluate significance of medication adherence and costs and outcomes. Methods: A prospective, randomized, comparative, flexible dose clinical study of 1 year duration was conducted in 100 first episode (drug naïve) cases of psychosis attending to psychiatric outdoor patient department of Rohilkhand Medical College and Hospital, Bareilly. 50 patients each in olanzapine (OLZ) and Iloperidone (ILO) group comprised the sample size. Patients were regularly evaluated by senior psychiatrist for dose titration. OLZ 10-20mg/day and ILO 6-12mg/day were used. Least expensive brands available in our hospital pharmacy were used. Cost – effectiveness and medication adherence were measured as per the formula. Results: It was observed that ILO (8mg/day) controlled 65-75% cases and 12mg/day dose controlled > 90% cases of psychosis. Whereas OLZ showed this level of control respectively with 10 – 15mg/day (average 12.5mg/day) and 15-20mg/day (average 17.5mg/d). Since olanzapine in 15-20mg/day dose cause more metabolic adverse events particularly obesity, hyperglycemia and dyslipidemia which need further management hence overall olanzapine is not cost-effective. 42(87.5%) cases had medication possession ratio (MPR) >90% in ILO group compared to 18 (37.5%) cases in OLZ group. Increased medication adherence led to better control and outcomes. Patients with <90% MPR had developed more adverse events and were mostly living in rural areas. Conclusions: Iloperidone is comparatively more cost-effective than olanzapine to control > 90% of patients on long term use.