Factors associated with prescribing and dispensing of schizophrenia treatment in the private health sector of South Africa

Abstract

The aim of this study was to determine the prevalence, medicine prescribing patterns and maximum potential savings through generic substitution in direct treatment costs associated with schizophrenia in the private health sector of South Africa. A literature review and an empirical investigation were employed to achieve the objectives stated in the study. A retrospective drug utilisation study was conducted in order to analyse antipsychotic medicine prescribing patterns during the period 1 January 2008 to December 31, 2013. Data were obtained from a Pharmaceutical Benefit Management Company while active ingredients used for this study were identified using the MIMS classification system. Results from the study were presented in the form of two manuscripts. Manuscript one employed two study populations. The study population used to determine prescribing patterns consisted of all patients with an ICD-10 code (F20-F20.9) with paid medicine claims from their prescribed minimum benefits (N = 4 410). The population employed to determine dispensing patterns (manuscript one) included all patients with more than two claims reimbursed from their prescribed minimum benefits for antipsychotics in conjunction with ICD-10 codes F20 to F20.9 on claims (N = 1 780). The study population used to determine prescribing patterns (N = 4 410) was also used for manuscript two, for the calculation of potential cost-savings due to generic substitution. Prescribing patterns were observed by comparing the actual prescribed daily doses (PDDs) with the maximum recommended daily doses (MRDDs) allowed as well as through evaluating the prescribing volume of antipsychotics by prescriber speciality. The medicine possession ratio (MPR) calculation was used as proxy to determine patient compliance related to the antipsychotics prescribed. The maximum potential direct cost-savings were determined by generically substituting all originator and more expensive generic drugs with the least expensive generic item that was available on the dataset during the study period. In this study, female patients showed a higher prevalence of schizophrenia than males overall; however, patients presented with a higher prevalence between the ages 18 to 35 years, whereas women had a higher prevalence above the age of 35 years. The majority of prescriptions were prescribed by psychiatrists (60.88%). Several antipsychotics were prescribed above the maximum recommended doses. Factors that played a significant role in compliance were the type of active ingredient (p < 0.0001; Cramer‘s V = 0.1287) and length of treatment period (p < 0.0001; Cramer‘s V = 0.2477). Clozapine (59.61%) and haloperidol (56.95%) had the highest compliance status categorised in the compliance group. Compliance increased for patients on antipsychotic treatment for longer than four months (54.76%). The total cost of antipsychotic treatment amounted to R 52 647 520.38 during the study period. If generic substitution was fully applied R 4 642 685.45 (39.21%) could have been saved. As the availability of generic items on the South African market increased, the number of generic items claimed also increased 60.31%) during the study period; however, psychiatrists still favoured prescribing of non-generic items (40.63%) during 2013. This may also be one of the factors that caused the large increase in patient contribution (726.94%) during the study period. In conclusion, this study emphasised possible factors that impact on patient compliance towards antipsychotic treatment and the economic strain schizophrenia medicine treatment places on patients and healthcare systems. Factors influencing a prescriber‘s choice of drug, including factors influencing a patient‘s compliance and the potential economic impact of schizophrenia were highlighted.