Blood Pressure Lowering Treatment Trialists’ Collaboration. Effects of different regimens to lower blood pressure on major cardiovascular events in older and younger adults: meta-analysis of randomised trials. BMJ 2008; 336: 1121-23 (17 May), doi:10.39548.738368.BE (published 14 May 2008)
May 22nd 2008
Reducing blood pressure with antihypertensive drugs reduces cardiovascular risk to a similar degree in both younger (<65 years) and older (>65 years) people irrespective of which drug regimen is used.
What action should you take?
This study supports the advice given by NICE in its guideline on the management of hypertension in primary care (CG34). Treatment of hypertension should be considered as part of an overall strategy to reduce CV risk in people at high risk of CV events. As with all patients, treatment in the elderly should be individualised and take into account the preferences and general health of the patient. Comorbidities and other drugs being taken will need to be considered carefully.
With regard to the drug choice, the NICE guideline should be followed. NICE recommends that diuretics or calcium channel blockers are appropriate first-line choices to consider in people aged 55 years or older. There are no indications from this study that one is preferable to the other. However, diuretics (e.g. bendroflumethiazide) are less expensive than calcium channel blockers and will be an appropriate first-line choice for most people (see MeReC Bulletin Vol. 17 No. 1 2006)
What was the study and what did it find?
This study evaluated data from 31 trials, involving more than 190,000 people with hypertension. A series of analyses identified no effect of age on the reduction in risk of major cardiovascular (CV) events achieved by blood pressure (BP) reduction and that there were no differences between antihypertensive regimens with regard to the reduction in CV risk achieved.
This was an analysis of data from 31 randomised trials (n=190,606) that compared the effect of an antihypertensive drug with placebo or a less intensive blood pressure treatment. The primary outcome was total major CV events. Meta-analyses compared effects of treatment for subgroups of patients who were either >65 years old or younger, the outcome being a reduction in major CV events. A meta-regression analysis explored the association between BP lowering and the reduction in CV risks achieved for each of the two subgroups. The effect of age on reduction in risk achieved by drug treatments was also assessed.
The meta-analyses showed no clear difference between age groups in the effects of lowering BP or any difference between the effects of the drug classes on major CV events (all P>0.24). Neither was there any significant interaction between age and treatment when age was fitted as a continuous variable (all P>0.09). Meta-regression also showed no difference in effects between the two age groups for the outcome of major CV events (<65 vs >65; P=0.38). See the full paper for more details.
What are the limitations of the study?
Despite the large number of patients included in the studies, their age ranges were limited to about 15 years either side of the arbitrary 65 year threshold used for assigning subgroups for analysis. It does not provide conclusive evidence that very elderly patients (e.g. above 80 years) will receive the same benefits as younger patients. The recent HYVET study (see NPC blog) provides some direct evidence for a benefit of antihypertensive treatment in this age group. There are many potentially confounding influences that may have affected the results. These included differences in base-line patient characteristics (e.g. the higher proportion of comorbidities in the elderly and their higher use of additional medication) and the propensity for older people to suffer a higher proportion of strokes.
This study was funded by the National Health and Medical Research Council of Australia.