David Spencer, pharmacist at the Update Pharmacy, carries out a quarterly analysis of a local GP practice’s prescribing data as part of a prescribing advice service.

David raises the issue of angiotensin-renin system drugs (ARSDs) with senior partner Dr Mo Merali.

David says: “I’ve noticed that the cost of ARBs (angiotensin II receptor antagonists or blockers) in this practice is quite high and it’s rising steadily. It’s rather above the Nice recommendations.”

David explains the relative rate of prescribing of ACE (angiotensin converting enzyme) inhibitors and ARBs in the practice and the relative costs of the drugs.
Mo replies: “Wow, I didn’t realise they were making such a hole in our budget.”

“Do you know why ARBs are being prescribed?” David asks.

“I would imagine they are mainly being substituted for ACE inhibitors for patients troubled with cough side effects. Also, I sometimes prescribe an ARB as an add-on if a patient’s BP is not being adequately controlled on an ACE inhibitor alone.”

 “As far as both those reasons are concerned, I think the evidence shows that prescribing ARBs is generally not necessary or justified,” David replies and goes on to demonstrate his points. 

 “Well, we don’t have a specific prescribing policy for this important group of drugs at the moment,” says Mo. “Perhaps it’s time you drew one up for us.”

Questions

1. What are the relative rates of prescribing and costs of ARSDs? 

2 What are the Nice recommendations on relative prescribing?

3. How necessary or justified is the substitution of ARBs for cough caused by ACE inhibitors?

4. How justified is prescribing of ARBs alone or in combination with ACE inhibitors for hypertension and other conditions?

Answers

1. In primary care in England, about 70 per cent of ARSD prescribing is for ACE inhibitors, with 30 per cent for ARBs. But ARBs account for 70 per cent of the total spend on ARSDs.

2. 80 per cent ACE inhibitors/20 per cent ARBs. This would represent a saving of around 23 per cent on the £300 million annual cost of ARSDs in England alone. Only about 12 per cent of GP practices achieve this.

3. The major benefit of ARBs over ACE inhibitors is their lower rate of cough. However, cough may not be as common with ACE inhibitors as is perceived: the percentage of people reporting cough in randomised controlled trials is about 10 per cent, and as low as 2 per cent in observational, real world studies. Discontinuation rates due to cough are lower: only 4.2 per cent of patients taking an ACE inhibitor stopped treatment because of cough compared with 1.1 per cent taking an ARB.1 Cough sometimes results from other, overlooked, causes, eg pulmonary oedema.

4. For hypertension and all other indications, ACE inhibitors are the first-line choice.2 An ARB alone is only indicated if an ACE inhibitor is discontinued because of intolerable cough. There is generally no benefit in prescribing an ACE inhibitor plus an ARB, and outcomes are often worse than with an ACE inhibitor alone.3  

References

1. Matchar, DB, et al. Systematic review: comparative effectiveness of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers for treating essential hypertension. Ann Intern Med 2008;148:16-29.

2. The ONTARGET investigators. Telmisartan, ramipril or both in patients at high risk for vascular events. N Engl J Med 2008;358:1547-59.

3. Mann, JFE, et al. Renal outcomes with telmisartan, ramipril, or both, in people at high vascular risk (the ONTARGET study): a multicentre, randomised, double-blind, controlled trial. Lancet 2008; 372:547-53.

Further reading

MeReC. Angiotensin-II receptor antagonists: what is the evidence for their place in therapy? MeReC Bulletin  2010; 20(2) www.npc.co.uk/ebt/merec/cardio/cdhyper/merec_bulletin_vol20_no2.html#REF