By Lilian Anekwe
Patients with high blood pressure from different ethnic backgrounds may require different second-line drugs, according to UK research showing optimal treatment combinations may vary between ethnic groups.
An analysis by the ASCOT researchers found white, black and South Asian patients responses differently to both first and second-line antihypertensives, calling current guidance into question.
Black patients were less responsive to ACE inhibitors and more responsive to a diuretic when used as second-line agents. In contrast, South Asian patients were more responsive to ACE inhibitors than white and black patients when used as a second-line agent.
The researchers, including several members of forthcoming JBS3 hypertension guideline development group, said the research suggested that current guidance ‘may not be applicable to black and South Asian patients', and indicated future guidance could include recommendations for GPs to ‘use tailored combinations' of drugs in different ethnic groups.
Current joint guidance by NICE and the British Hypertension Society takes ethnicity into account when recommending first-line drugs. Black patients, as well as those aged over 55, should be treated with calcium-channel blockers or thiazides, while other patients can be given an ACE inhibitor.
But second-line therapies are also important in the treatment of hypertension, as most patients will require two or more drugs for adequate control of their blood pressure.
Researchers randomised 5,800 UK patients – 5,400 white, 250 black and 150 of South Asian origin – to either atenolol or amlodipine as monotherapy.
3,459 went on to receive bendroflumethiazide added to atenolol, or perindopril added to amlodipine as second-line therapy and 2,868 continued with their allocated drugs and were used for a per-protocol analysis.
Adding thiazide to atenolol resulted in similar mean systolic and diastolic blood pressure lowering in all ethnic groups.
But adding perindopril to amlodipine resulted in an average systolic blood pressure reduction of just 3.2 mm Hg in blacks, compared to 10.2 and 11.2 mm Hg in whites and South Asians, respectively.
Among those on amlodipine monotherapy, addition of perindopril reduced the average diastolic blood pressure by 5.6, 2.5, and 4.8 mm Hg in whites, blacks, and South-Asians, respectively.
Compared to the reference group of whites on atenolol and bendroflumethiazide, adding a diuretic reduced diastolic blood pressure by 1.7 mm Hg in blacks and 2.8 mm Hg higher in South-Asians, but these differences were not statistically different.
However, compared to the reference group, when perindopril was added to amlodipine, whites responded with a further 1.7 mm Hg reduction, whereas the systolic blood pressure increased in blacks by 0.8 mm Hg and decreased by 6.2 mm Hg in South-Asians.
Lead researcher Dr Ajay Gupta, clinical research fellow at the national heart and lung institute at Imperial College concluded in the American Journal of Hypertension: ‘These differential effects raise the possibility that current British guidance for optimal two-drug combinations of antihypertensive therapy may not be applicable to South-Asian and black patients.
He told Pulse: ‘We have shown that heterogeneity in response to blood pressure medications remain with add-on therapy. Hence, current guidelines suggesting calcium channel blockers and an ACE inhibitor or angiotensin-receptor blocker for blacks may have to be changed to calcium channel blocker and a diuretic.
‘More importantly, we have shown importance of ACE inhibitors in South Asians, a high risk group, so far not properly addressed in British guidance.'
In an accompanying editorial, Professor Morris Brown, professor of clinical pharmacology at the University of Cambridge and chair of the JBS2 guidance, wrote the research ‘demonstrate that not only initial therapy but also add-on drugs vary in efficacy with age and/or ethnicity, and that ignoring this truth can at the extreme lead to paradoxical rises in blood pressure when an inappropriate drug is prescribed.'
American Journal of Hypertension, published online August 18 2010.There are differential responses to antihypertensives among ethnic groups Pulse seminar