Improvement of Survival with Antihypertensive Drugs in Mild-to-Moderate Hypertension

A systematic review 1 including 7 RCTs with a total of 34,342 subjects (175,000 patient-years of follow-up) was abstracted in DARE. The analysis included patients with diastolic blood pressure in the range of 90 - 114 mmHg aged less than 60 years who had been without antihypertensive therapy before entry into the trial. In trials with a high all-cause mortality rate (> 6 per 1000 patient years) in the control group, antihypertensive treatment increased life expectancy. When all-cause mortality in the control group was low, treatment showed no effect or even an opposite effect. Findings from coronary heart disease was similar, whereas drug treatment decreased stroke mortality irrespectie of the incidence of stroke in the control group.

Another systematic review 2 including 22 studies with a follow-up period of 4 - 7 years was abstracted in DARE. Patients with mild (initial diastolic blood pressure 90 - 105 mmHg) and moderate (initial diastolic blood pressure 105 - 115 mmHg) hypertension were included. Significant reductions of stroke were found in 10 of the 22 studies (none of which were in the non-pharmacological studies). Incidence of CHD was significantly reduced in 5 of 22 studies (1 of which in a non-pharmacological study). Based on a previous meta-analysis it is concluded that the morbidity and mortality risk reduction for CHD is 16% and for stroke 38%.

The review concludes that positive effects of drug therapy are documented at a stable diastolic blood pressure of 95 mmHg or above. The positive effects of drug therapy are clearly demonstrated in older individuals with a stable systolic blood pressure of 160 mmHg or above. The absolute benefits from treating persons with diastolic blood pressures in the range 90 - 99 mmHg are small over a 5-year period, and the patient´s total risk factor profile must be taken into account. Only treatment based on diuretics and beta-blockers has been studied in relation to morbidity and mortality. Lifestyle-related therapies demonstrate the ability to reduce blood pressure for a limited time, but no studies have shown an effect on morbidity or mortality.

A third systematic review 3 including 17 studies (hypertension in older patients aged 65 or over, 7 trials, n=13,154; mild-to-moderate hypertension with an average diastolic BP of <105 mmHg in young patients, 5 trials, n=22,967; non-moderate hypertension with an average diastolic BP >105 mmHg, 3 trials, n=334; poststroke hypertension, 2 trials, n=551 patients) was abstracted in DARE. Odds ratios, ARR per 1000 patients, and number needed to treat (NNT) were reported.

Mortality: older people OR 0.90 (95% CI 0.81 to 1.00), ARR -3, NNT 382; mild-moderate hypertension in young people OR 0.98, NS; non-moderate hypertension OR 0.62, NS; poststroke hypertension OR 0.77, NS.

Cardiovascular death: Older people OR 0.77 (95% CI 0.67 to 0.89), ARR -4, NNT 225; mild-moderate hypertension in young people OR 0.96, NS; non-moderate hypertension OR 0.66, NS; poststroke hypertension OR 0.64, NS.

Stroke: Older people OR 0.66 (95% CI 0.56 to 0.77), ARR -5, NNT 197; mild-moderate hypertension in young people OR 0.51 (95% CI 0.39 to 0.69), NNT 833; non-moderate hypertension OR 0.62, NS; poststroke hypertension OR 0.65 (95% CI 0.43 to 0.99), NNT 31.

Major coronary event: Older people OR 0.79 (95% CI 0.68 to 0.92), ARR -3, NNT 362; mild-moderate hypertension in young people OR 0.96, NS; non-moderate hypertension OR 0.63, NS; poststroke hypertension OR 0.94, NS.

Congestive heart failure: Older people OR 0.54 (95% CI 0.43 to 0.68), ARR -5, NNT 190; mild-moderate hypertension in young people OR 0.22, NS; non-moderate hypertension OR 0.14 (95% CI 0.05 to 0.41); NNT 24; poststroke hypertension OR 0.31 (95% CI 0.10 to 2.95), NNT 88.

Comment: The duration of treatment for the reported effects is not given in the abstract.

The following decision support rules contain links to this evidence summary:

• Indications for antihypertensive drug therapy considering total cardiovascular risk http://www.ebmeds.org/ebmeds/ebmeds_home.asp?mode=scripts&submode=view&id=scr00434&country=UK

References

• Hoes AW, Grobbee DE, Lubsen J. Does drug treatment improve survival? Reconciling the trials in mild-to-moderate hypertension. J Hypertens 1995 Jul;13(7):805-11. [PubMed][DARE]
• The Swedish Council on Technology Assessment in Health Care. Moderately elevated blood pressure. J Intern Med 1995;238(suppl 737):1-255. [DARE]
• Gueyffier F, Froment A, Gouton M. New meta-analysis of treatment trials of hypertension: improving the estimate of therapeutic benefit. J Hum Hypertens 1996 Jan;10(1):1-8. [PubMed][DARE]