| Summary: | The objective of this study was to develop certain cost thresholds for the purpose of decision–making in the private health–care sector of South Africa, with specific reference to the treatment of hypertensive patients.
This research was embedded in a drug utilisation review approach supported by various other measuring instruments, classification systems, arithmetical formulas and descriptive statistical methods. This study was done on a medicine claims database ranging over a four–year study period from 1 January 2005 to 31 December 2008. The total medicine claims database was divided into cardiovascular medicine items and then into antihypertensive medicine items. These were analysed according to treatment categories: treatment category 1 (TC1) consisted of medicine items listed in MIMS® group 7.3; treatment category 2 (TC2) consisted of medicine items listed in MIMS® group 16.1 and treatment category 3 (TC3) consisted of medicine items listed in both MIMS® group 7.3 and 16.1;, age groups: age group 1 (patients ?18 years), age group 2 (>18 and ?45 years), age group 3 (>45 years), and gender. Analysis included general cost analysis, adherence to antihypertensive medicine items, combination treatment with antihypertensive medicine items, and the calculation of cost threshold ranges (with an upper and lower limit) and cost ratio thresholds. The refill–based adherence rate (RAR) was calculated per individual medicine item for all antihypertensive (AH) medicine items that had been prescribed more than once. A cost threshold range was developed from a fraction of the standard deviation (50% or 33%) that had been added or subtracted from the average cost per item to determine the upper and lower limits. To obtain a medicine cost ratio threshold, the estimated number of high–income households and total medication cost were used as applied in the private health–care sector of SA. This estimated total medication cost was used to calculate a net cost. This resulted in the cost ratio threshold as applied in this study.
The results showed that antihypertensive medicine items accounted for 7,68% to 9,69% of all medicine items on the database at an associated cost of 10,94% to 11,10% of the total cost during the four study years. Antihypertensive medicine items represented 7 695 151 (70,04% N = 10 986 407) of all the cardiovascular medicine items and 59,94% of the total cost of cardiovascular medicine items for all four study years collectively for these medicine items.
Between 16,6% and 19,7% of all prescriptions contained antihypertensive medicine items, at a cost of 11,5% to 11,7% of the total cost of all medicine items claimed during the four–year study period. An analysis of combination antihypertensive treatment revealed that most observations were made for prescriptions consisting of two and three–item antihypertensive medications respectively. Generic antihypertensive medicine items accounted for more than 50% of all the antihypertensive medicine items throughout the four–year study period. Cost savings to the amount of R22 685 689,65 and R50 412 643,73 could have been possible with generic substitution at levels of 45% and 100% respectively during the total study period. The usage of generic antihypertensive medicine items increased by 17,26% over the four year study period. Average refill–based adherence rates calculated across all treatment categories indicated that treatment category 1 and treatment category 3 had acceptable refill adherence rates at 86,20% and 85,50% respectively.
Cost threshold ranges of R68,50 ? R142,00 and R80,90 ? R129,50 were calculated for total antihypertensive medicine items for the year 2008. For male patients a higher cost threshold range was calculated than for their female counterparts (R72,14 ? R147,66 and R84,98 ? R134,82 vs. R67,01 ? R137,75 and R78,24 ? R125,56). On the basis of the cost threshold ratio method, a higher cost ratio threshold was calculated for female patients vs. male patients (R59,73 vs. R50,49).
In conclusion, this study described not only the prescribing patterns and costs of antihypertensive medicine items, but also the cost implications of over– and under–utilisation of these medicine items. Different cost threshold ranges and cost ratio thresholds were calculated for implementation in the private health–care sector of South Africa.
It is recommended that threshold development in the public health–care sector be investigated further. === Thesis (PhD (Pharmacy Practice))--North-West University, Potchefstroom Campus, 2012.
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