Renal function as an indicator of prognosis in malignant essential hypertension

Is the rule of halves still relevant today? A cross-sectional analysis of hypertension detection, treatment and control in an urban community

AIMS

To estimate percentages of patients with undiagnosed hypertension, diagnosed untreated hypertension and diagnosed, treated and uncontrolled hypertension and to identify sociodemographic factors for diagnosed, uncontrolled hypertension and not having a blood pressure (BP) reading recorded.

METHODS

Data from 320 094 patients aged 18 to less than 80 years from general practices in inner London was analysed using both last recorded BP (blood pressure) and mean BP. Logistic regression models identified factors associated with uncontrolled hypertension and no recorded BP.

RESULTS

Twenty-nine thousand, seven hundred and nineteen (9.3%) patients had a recorded diagnosis of hypertension. On the basis of analysis of the last BP value, 14.2% (n = 4207) were untreated and 46.3% (n = 13 749) had uncontrolled hypertension; 10.0% (n = 28 274) without a prior hypertension diagnosis had undiagnosed hypertension. Corresponding values based on mean BP analysis were 8.9% (n = 2367) untreated, 51.5% (n = 13 734) uncontrolled; 4.1% (n = 11 446) undiagnosed. 17.5% (n = 55 960) had no recorded BP value.Black ethnicity was a predictor of uncontrolled hypertension: compared with the White British population, the adjusted odds ratio (AOR) for the Black African population was 1.39 (95% CI: 1.25-1.53) and for the Black Caribbean was 1.31 (95% CI: 1.19-1.45). The White Other group were most likely to have no record of BP measurement (AOR: 1.52; 95% CI: 1.47-1.57); conversely, unrecorded BP was less likely in the Black African (AOR: 0.79; CI: 0.74-0.83) and Black Caribbean (AOR: 0.71; CI: 0.66-0.76) groups, relative to the White British population.

CONCLUSION

In an inner-city, multiethnic population, the 'rule of halves' still broadly applies to the diagnosis and control of hypertension, although only a small proportion were untreated.

ACE inhibition preserves renal function better than beta-blockade in the treatment of essential hypertension

Antihypertensive treatment can slow down the decline in glomerular filtration rate (GFR) with time. In patients with diabetic nephropathy, angiotensin converting enzyme (ACE) inhibition has been shown to be more effective in this regard than conventional antihypertensive therapy. Whether this applies to the much larger population of patients with essential hypertension is not yet known. In the present study, the effects of two different antihypertensive therapies on the loss of GFR with time, determined with Cr51-EDTA clearance after 6, 12 and 24 months of treatment, were assessed in a prospective, randomised, double-blind trial in 257 patients with essential hypertension. All had normal renal function and none had diabetes mellitus or glucosuria. Proteinuria (dipstick positive or trace) was detected in 7 patients initially. The two therapeutic modalities were the ACE inhibitor cilazapril and the beta-adrenoceptor blocking agent atenolol. Both therapies were equally effective in lowering systolic blood pressure (e.g. from 168 mmHg to 152 mmHg with cilazapril and from 170 mmHg to 155 mmHg with atenolol after 6 months, p < 0.001 for both). However, atenolol was slightly but significantly more effective in lowering the diastolic blood pressure at 6, 12 and 24 months. The decline in GFR with time was significantly smaller with cilazapril than with atenolol. After 6 months the reduction in GFR was 1.0 vs. 4.0 ml/min x 1.73 m2, p = 0.008 (cilazapril vs. atenolol) and after 12 months the corresponding changes were 2.0 vs. 4.5 ml/min x 1.73 m2, p = 0.04 and after 24 months 3.0 vs. 4.0 ml/min x 1.73 m2, respectively (n.s.).(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical evaluation of felodipine in patients with refractory hypertension

The calcium antagonist, felodipine, was used to treat 21 patients with severe uncontrolled hypertension: 13 had renoparenchymatous hypertension, 5 essential hypertension and 3 renovascular hypertension. Mean arterial blood pressure of patients was 195 +/- 8/122 +/- 3mm Hg in spite of treatment with 3 or more antihypertensive drugs. The majority of the patients (n = 17) were treated with an ACE inhibitor. Mean glomerular filtration rate (GFR) for 20 patients was 39 +/- 6 ml/min/1.73m2 body surface area (Cr-EDTA clearance) before felodipine administration. All patients had an immediate blood pressure fall after 5-10mg of felodipine administered orally. This fall persisted when the drug was given 2 or 3 times daily in combination with previous medication except the former vasodilating drugs. 15 patients are on long term treatment with felodipine and their blood pressure after 1 year (n = 14) was 152 +/- 4/89 +/- 2mm Hg. Patients with moderately impaired renal function and no signs of progressive kidney disease (n = 8) improved their GFR significantly after 1 year on felodipine. Six patients stopped felodipine therapy within 3 months (4 because of adverse reactions, 1 died of scleroderma and 1 became normotensive after the start of dialysis treatment). In patients with renoparenchymatous disease and documented progressive deterioration of renal function the addition of felodipine did not prevent a decline in filtration rate but did slow the rate of deterioration (from 9 +/- 2 to 5 +/- 1 ml/min/year).(ABSTRACT TRUNCATED AT 250 WORDS)