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NHS prescribing advisers urge GPs to ignore BP rules

By Nigel Praities

NHS prescribing advisers have shocked leading cardiologists by urging GPs to ignore NICE guidance and use thiazide diuretics first line in older patients and in many younger patients too.

The National Prescribing Centre said thiazides were better supported by recent evidence than either calcium channel blockers or ACE inhibitors and also questioned the benefits of intensive blood pressure control.

Its advice essentially urges GPs to tear up the NICE ACD algorithm, and follows two recent gold-standard reviews that came out against lowering blood pressure below 140/90mmHg. The Cochrane reviews found low-dose thiazides were the best initial therapy for hypertension.

In response, the NPC warned that rigorous blood-pressure targets recommended by NICE in high-risk patients were ‘not proven' and should be balanced against possible harm, such as side-effects and hypotension.

The centre also concluded diuretics should be the preferred agent in the over-55s, and in younger patients were equal first choice with an ACE inhibitor.

‘The review found thiazides had the most robust evidence base, more so than ACE inhibitors or calcium channel blockers, and there was no evidence to support first-line use of angiotensin receptor blockers,' the advice concludes.

But the advice prompted a furious response from cardiology experts, who questioned the role of the NPC in issuing advice contradicting NICE guidelines.

Professor Peter Sever, professor of clinical pharmacology and therapeutics at Imperial College London, said the NPC advice was ‘simply wrong' and based on ‘dubious' data.

‘The Blood Pressure Lowering Treatment Trialists Collaboration clearly showed in those with diabetes lower BP was advantageous on most, if not all, cardiovascular end-points.'

‘The recommendation of the NPC on low-dose thiazides beggars belief – there are no outcome trials I am aware of with low-dose bendroflumethiazide, yet that's what they recommend. The NPC advice should be ignored and buried,' he said.

Professor Neil Poulter, professor of preventive cardiovascular medicine at Imperial College London and a board member of the British Hypertension Society, also said the advice on thiazides went against recent evidence, such as the ACCOMPLISH trial. ‘In short, the NPC is talking bollocks – low-dose thiazides have no evidence in any trials. All diuretic evidence is for chlorthalidone and indapamide – and neither are thiazides – or for high-dose thiazides with a potassium- sparing component,' he said.

Dr Mark Davis, a BHS member and a GP in Leeds, said the blood pressure targets for high-risk groups were based on ‘the limited evidence available' and urged GPs to follow NICE guidelines. ‘I can see no need for the NPC to add to the debate and possibly cause confusion in primary care,' he said.

Dr Neal Maskrey, director of evidence-based therapeutics at the National Prescribing Centre, said: ‘I can only presume any commentators have not fully read our summary, or the primary sources.'

How the NPC advice stacks up

Use of low dose thiazides

FOR
- Cochrane review shows thiazide threatment reduces cardiovascular events by more than other BP drugs, with a reduction of 30%

AGAINST
- Major analysis released at the European Meeting on Hypertension in Milan this year found ‘paltry' evidence for thiazide diuretics as first-line therapy
- The ACCOMPLISH study – published last year – found a combination of an ACE inhibitor with a calcium channel blocker was more effective at reducing the risk of CV events than an ACE inhibitor with a diuretic

Rigorous BP control

FOR
- Various studies and analyses showing benefit in high risk groups – such as those with diabetes and end-organ damage or chronic kidney disease – including the Blood Pressure Lowering Treatment Trialists Collaboration, HOT and ADVANCE studies

AGAINST
- Cochrane review showing ‘the net health effect of lower targets could not be fully assessed due to lack of information regarding serious side-effects'

The National Prescribing Centre says evidence supports use of low-dose thiazide diuretics, even in younger patients The National Prescribing Centre says evidence supports use of low-dose thiazide diuretics, even in younger patients

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