Prescribing trends and drug budget impact of the ARBs in the UK.

Objectives: Angiotensin II receptor blockers (ARBs) were introduced into the UK antihypertensive drug market at a premium price relative to other antihypertensives during a period of evolving evidence about hypertension treatment. This study aimed to determine the UK antihypertensive drug budget impact as the first ARB market launched in December 1994 and what proportion of the increase was directly attributable to ARBs.

Methods: Prescriptions for oral antihypertensives were identified from The Health Improvement Network database. Drug prices were based on the Chemist & Druggist January 2005 pricelist estimating real expenditure growth. Expenditure increases were disaggregated into the number of patients receiving antihypertensive drug prescriptions, the number of antihypertensive prescriptions per patient treated, and the average drug expenditure per antihypertensive prescription.

Results: The annual ARB prescription frequency increased from 0.04% in 1995 to 6.57% in 2004. Expenditure for antihypertensive drugs was estimated at pound465,862,416 in 1995 and pound1,458,268,104 in 2004 (2005 values), reflecting a 213% real rate of increase. Use of ARBs accounted for only 9.3% (range: 5.8%-12.5%) of the average drug expenditure. Treatment prevalence rose from 11.30% in 1995 to 16.90% in 2004, while the average number of antihypertensive drug prescriptions per patient increased from 9.34 to 13.46 per year. The average expenditure per antihypertensive drug prescription increased over time reflecting a product shift toward more expensive therapies.

Conclusions: ARBs accounted for only 9.3% of the 213% increase in antihypertensive drug expenditure after their introduction. A substantial portion of the impact reflected increases in treatment prevalence and in the number of prescriptions per patient.