Modifying Prescribing Behaviour of Angiotensin Receptor Blockers by Selectively Rescinding Managerial Prior Authorization Requirements for Losartan

Aims: To evaluate whether rescinding the prior authorization (PA) requirement (managerial pre-approval) for losartan in an health maintenance organization (HMO) could reduce prescribing of the more expensive angiotensin receptor blockers (ARBs).

Methods: HMO physicians were notified that losartan would no longer require PA, and appropriate changes were made to the electronic prescribing computer program. The monthly distribution by drug of the number of prescriptions for ARBs dispensed for new patients was calculated before and after the policy change from data captured from electronic records. The proportion of patients (percentage and 95% confidence interval) treated with losartan who met the criteria for treatment with ARBs (hypertension or cardiac insufficiency in patients who have developed adverse effects in response to angiotensin-converting enzyme inhibitors or macroproteinuria) during the first month after the PA requirement was rescinded was calculated.

Results: The total number of PA requests for ARBs declined by 48.6% from 961 in December 2008, the month before the policy change, to 494 the following January, rising again to 651 during January 2010. Prescription incidence changed from 121 to 255 patients treated per month (114% increase) for losartan, from 15 to 16 (6.7% increase) for candesartan, and from 89 to 71 (20.2% decrease) for valsartan. The duration of effect for decrease in ARB requests for the more expensive drugs was approximately 1 year. Only 23.3% (95% confidence interval 18.1-28.4) of patients receiving losartan met the criteria for receiving ARBs.

Conclusions: Rescinding the PA requirement for this drug alone was an effective limited-duration strategy for reduction of prescription of relatively expensive drugs.