Prescribing patterns of biologic immunomodulating medicine in the South African private health care sector
Advances in molecular immunology and rapid technical evolution during the past two decades have led to a new class of medicines called biologics. Recently, a large number of biologics, or biologic immunomodulators, directed towards an array of immune–mediated diseases, have entered the market. This has lead to a dramatic change in the immunotherapy of autoimmune diseases, as biologics present new potential to improve or substitute conventional immunosuppressive therapies. According to literature, biologics are used by only a small number of a health plan’s members, (approximately one per cent), but a single occurrence can be relatively expensive. Furthermore, there is an indication that the frequency of use and cost of biologics are on the rise, and as more biologics enter the market, health plans and employers face the challenge of controlling costs while ensuring that biologics are affordable. The general objective of this study was to determine the prevalence and cost of biologic immunomodulating medicine in the treatment of certain autoimmune diseases during the period 2005 to 2008 in a section of the private health care sector of South Africa, by employing a medicine claims database as a source to obtain necessary information. A quantitative, retrospective drug utilisation review (rDUR) was performed on computerised medication records (medicine claims data) for four consecutive years (i.e. 2005 to 2008) provided by a pharmacy benefit management company (PBM). The study population consisted of all patients on the database who received at least one medicine item with adalimumab, etanercept, infliximab, interferon beta–1a, interferon 1–b or rituximab as active ingredient and who were diagnosed with either rheumatoid arthritis (RA), multiple sclerosis (MS) or Crohn’s disease between 1 January 2005 and 31 December 2008. Between 2005 and 2008, an average of 1,305,201 patients appeared on the total database, and of these 0.055% (n = 713) received biologic immunomodulating medicine. More than two thirds of biological users were female and most patients who received these medicine items were between the ages of 39 and 64 years, followed by those patients aged between 25 and 39 years. Biologic immunomodulating medicine items (n = 11,914) and biologic prescriptions (n = 9,537) represented 0.016% of the total number of medicine items (N = 76,129,173) and 0.030% of the total number of prescriptions (N = 31,985,153). The percentage contribution of biologic immunomodulators to the total number of medicine items and prescriptions on the total database increased each year, and in four years’ time the percentage of all the medicine items on the total database that included biologic immunomodulators had tripled, from 0.009% to 0.023%. The total cost of biologic immunomodulating medicine accounted for 1.278% of the total cost (N = R7, 483,759,176.23) of all medication claimed through the PBM between 2005 and 2008. The percentage contribution of biologic immunomodulators to the total medicine expenditure also increased from one year to another for the four–year study period. The average cost of a biologic immunomodulating medicine item increased with 71.10% from 2005 (R5602.71 ± 2166.61) to (R9586.25 ± 5956.56) in 2008. The CPI for biologic immunomodulators, (CPI = 60.00 for 2005; CPI = 74.62.17 for 2006; CPI = 85.26 for 2007; and CPI = 86.96 for 2008) indicated that biologic immunomodulating medicine items were relatively expensive and the d–value between the average cost per biologic immunomodulator and the average cost per non–biological medicine item (d–value = 2.54 in 2005, d–value = 3.32 in 2006, d–value = 2.23 in 2007 and d–value = 1.59 in 2008) furthermore indicated that the impact of biological therapies was large and practically significant. Rheumatoid arthritis patients represented 19.78% of the total number of patients (n = 713) who claimed the biologic immunomodulators during the four–year period, MS patients (n = 172) represented 24.12% and Crohn’s patients (n = 11) represented 1.5%. Biological drugs prescribed to RA patients represented 0.28% (n = R20, 708,818.82) of the total cost (N = R7, 483,759,176.23) of all medication claimed through the PBM during the four–year period, while those prescribed to MS patients represented 0.41% (R30, 922,520.07) and those prescribed to Crohn’s disease patients represented 0.015% (R1, 108,568.02). Although biologic immunomodulating medicine items used in the treatment of RA, MS and Crohn’s disease are relatively expensive, it seems that the number of other medication prescribed to patients with these diseases decreased after treatment with biologics, which may influence the medicine treatment cost of these patients. It can be concluded that even though biologic immunomodulators are used by only a very small percentage of the total patient population in a section of the private health care sector of South Africa, they are relatively expensive and have a considerable impact not only the medical aid scheme, but also on the patient.
- ETD@PUK