Overview of antidepressant usage and cost 2004 until 2006
Van der Westhuizen, Elmarie
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Depression has an increasingly significant economic impact and quality of life burden on patients, employers and third party payers worldwide (Hylan et a/., 1998:53). Current projections indicate that the global burden of depression will rank second only to ischemic heart disease by the year 2020 (Hylan et a/., 1998:53). The prevalence of clinical depression in South Africa has been reported to range between 14 to 49 per cent of the general population (Triant, 2002:21). The cost of mental disorders in South Africa particularly when they are diagnosed late, are at least as high as R5 billion each year (The mental health information centre, 2002). According to the report of Mediscor medicines review for the year 2006 (Bester & Hammann, 2007) antidepressants contributed up to 5.0 per cent of the total medicine expenditure and was ranked third according to total medicine expenditure. The objective of this study was to review the prescribing patterns and cost of antidepressants in a section of the private health care sector of South Africa by using a medicine claims database for the years 2004 to 2006. A retrospective drug utilisation study was done on data provided by the database of a pharmaceutical benefit management (PBM) company. The cost savings attributable to generic substitution were calculated by means of a cost minimisation study. Comparisons and analyses were done for 2004 to 2006, using the Statistical Analysis System (SAS for Windows, 9.1, 2002-2003). Results of the study showed that antidepressant prescriptions accounted for 5.66% (n = 2 595 242), 5.05% (n = 1 621 739) and 4.51% (n = 996 787) of all prescriptions claimed during 2004, 2005 and 2006 respectively. The total cost for antidepressants for 2004 amounted to R 32 199 165.09; making depression the third most costly condition during 2004. During 2005 and 2006, these costs were ranked sixth and seventh respectively amongst all pharmacological classes on the database. Prescriptions of antidepressants to female patients represented 42.26% (n = 44 915) compared to 17.86% prescribed to male patients. Antidepressant prescriptions ranked the highest for the age group older than 19 and younger than 44 years of age with a percentage of 42.72% of all prescriptions (n = 44 915); followed by antidepressant prescriptions for the age group older than 44 and younger than 59 years of age with a percentage of 35.06% (n = 44 915). The most prevalent pharmacological category was the selective serotonin reuptake inhibitors (SSRIs) followed by tricyclic antidepressants. The most common prescribed antidepressants for 2004 was fluoxetine (18.87%, n = 157 810) while amitriptyline was the drug of choice during 2005 (19.11%, n = 86 521) and 2006 (20.09%, n = 47 740). Drug interactions with a significance rating of one and two according to Tatro (2002: xiv), were respectively 79.45% (n = 5 247) in 2004, 65.76% (n = 2 415) in 2005 and 51.56% (n = 1 470) in 2006. Generic antidepressants represented 58.67% (n = 157 810) of all prescriptions in its class in 2004, compared to 56.49% (n = 86 521) in 2005 and 63.30% (n = 47 470) in 2006. It was finally determined that the PBM company could have saved up to 10.87% (n = R 56 183 697.91) on mental health care cost during the study period if all innovator products on the database had been substituted with the least expensive generic product. Recommendations for future research in this field were also made.
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