ABSTRACT
The cost of managing schizophrenia per patient in Nigeria has increased in the last two decades, and about 95% of these patients do out of pocket payments for their medications. The study aim was a pharmacoeconomic evaluation of antipsychotics usage in Federal Neuro-Psychiatric Hospital, University of Benin Teaching Hospital and community pharmacies, all in Benin City, specifically to determine the utilization pattern of drugs, examine the inventory management of the antipsychotics, determine the pharmacoeconomics of typical and atypical antipsychotics and assess patient preference for antipsychotics. A retrospective drug utilization study of outpatient‘s prescriptions sheets from year 2013 - 2017 was carried out, then ABC-VED matrix analysis from year 2014 - 2018 and budget impact analysis of drugs from providers‘ perspective from year 2014 - 2017 were done, followed by a longitudinal study of cost-effectiveness analysis of antipsychotics conducted from patients‘ perspective with decision tree analytical model. Outcomes measured were socio-demographics, drug effectiveness using the Brief Psychiatric Rating Scale, and cost. In addition, a cross-sectional survey was done using two-stage cluster sampling procedure to measure the affordability of medications employing the impoverishment, catastrophic and minimum daily wage expenditure, lastly willingness to pay for antipsychotics by patients where a virtual market was created with the questionnaire of 20 payment options ranging from NGN5000 to NGN100 to the four antipsychotics whose attributes ranged from efficacy, duration and side effects. Results obtained showed that the most utilized antipsychotic in year 2013 was haloperidol (typical antipsychotic) and decreased in daily utilization in 2017 while that of olanzapine (atypical antipsychotic) from 2013 increased in drug utilization. ABC-VED matrix analysis of drugs revealed that category I items i.e., very expensive and vital drugs were averaged of 25 items (19.6%) and consumed NGN37,955,459 (73.8%) of Annual Drug Expenditure. The budget impact of introducing atypical antipsychotics has the least value of 8.8 million naira annually. Sensitivity analysis of CEA of medications; haloperidol 10mg (typical) is more cost effective than risperidone 3 mg (atypical antipsychotic) in the 1st scenario while in the second scenario, risperidone is more cost effective than haloperidol only when the savings of making one person free from schizophrenia in a month is worth more than NGN763.7. Purchasing atypical or typical antipsychotics caused the respondents to be further impoverished by more than 7% or less than 4% respectively, at the risk of catastrophic expenses by more than 60% or less than 30% respectively, while that of the number of days the least paid government worker will have to work to obtain medication that he or she will take for 30 days was more than 2 days or less than 1 day respectively. The Willingness to Pay (WTP) for all the medications except haloperidol indicated by most of the respondents was above their available market prices. Respondents with higher educational level and income gave p-values of 0.0251 and 0.009 respectively on antipsychotics effectiveness while; on WTP more for antipsychotics were 0.015 and 0.001 respectively. In conclusion, there is irrational prescribing of all antipsychotics. Atypical antipsychotics utilization is on the increase, it has a high budget impact, of strict inventory control while, its marginal cost effectiveness over xvi typical antipsychotics is not robust and respondents are not willing to pay for atypical antipsychotics because it is less affordable. Respondents with higher educational status, and income gave higher response rate to antipsychotic, and WTP.
