Misdiagnosis of systemic hypertension and recommendations for improvement

Left ventricular hypertrophy in treated hypertensive patients with good blood pressure control outside the clinic, but poor clinic blood pressure control

OBJECTIVE

The aim of the study was to evaluate the prevalence of left ventricular hypertrophy (LVH) in treated patients with good blood pressure (BP) control during multiple home BP (HBP) measurements and during 24-h ambulatory BP monitoring (ABPM), but with unsatisfactory BP control in the clinic. These patients were compared with treated hypertensives whose BP was well controlled under the three circumstances.

METHODS

Seventy-two treated consecutive patients (group I, age 56 +/- 10 years) with clinic BP values > or = 140/90 mmHg, and a difference between clinic and self-measured HBP > 10 mmHg for diastolic blood pressure (DBP) and/or > 20 mmHg for systolic blood pressure (SBP), underwent the following procedures: (1) clinic BP measurement; (2) routine diagnostic work-up; (3) HBP monitoring; (4) 24-h ABPM; (5) echocardiography. Thirty-five hypertensive patients with satisfactory BP control according to clinic (< 140/90 mmHg), HBP (< or = 131/82 mmHg) and ABP criteria (< or = 125/79 mmHg) were included as the control group (group II, age 55 +/- 9 years).

RESULTS

In group I, 33 subjects out of the 72 (46%) with clinic BP > 140/90 mmHg had BP values controlled outside the clinic (23 according to HBP criteria and 22 according to ABP criteria). The prevalence of LVH (LV mass index > 134 g/m2 in men and > 110 g/m2 in women) was significantly higher in these patients (15.1 versus 2.8%, P < 0.01) than in group II (BP also controlled in the clinic), despite the fact that HBP and ABP were reduced to similar levels in the two groups. CONCLUSIONS Our data provide evidence that treated hypertensive patients with good BP control at home or during ambulatory monitoring, but incomplete BP control in the clinic, have more pronounced cardiac alterations than patients with both clinic and out of the clinic BP control. This finding offers a new piece of information about the diagnostic value of BP measurement in the clinic to assess BP control during antihypertensive treatment.

Comparison of nurse- and physician-determined clinic blood pressure levels in patients referred to a hypertension clinic: implications for subsequent management

BACKGROUND

When measuring BP, the physician induces a transient pressor response triggered by an alarm reaction. This 'white-coat effect' can influence therapeutic decisions. Whether it depends on the characteristics of the physician has not been evaluated.

OBJECTIVE

To assess the 'white-coat effect' induced by several physicians in a large sample of patients, using the blood pressure measured by trained nurses as a reference.

SETTING

Referral hypertension clinic.

METHODS

Patients were selected for the study if they had been referred for the first time to the clinic and if they had had their supine systolic/diastolic blood pressure measured by a trained nurse (mean of the last two of three measurements taken every 1 min by an oscillometric device) and a physician (auscultatory method using a standard mercury sphygmomanometer). Physicians were included in the study provided they had seen at least 25 patients during the study period. The between-physician difference was assessed using linear regression analysis. Physician blood pressure was the dependent and nurse blood pressure was the independent variable.

RESULTS

From 1 January 1997 to 15 September 1997, 1062 patients (50% male, aged 52 +/- 14 years), seen by 10 physicians (26-187 patients per physician) and one nurse were included for analysis. The mean systolic/diastolic blood pressure for physicians was 162 +/- 27/ 97 +/- 15 mmHg and that for the nurse was 155 +/- 24/ 88 +/- 14 mmHg. The nurse-physician differences were -6 mmHg (range -67 to +66) for systolic and -8 mmHg (-44 to +31) for diastolic blood pressures. Major differences were observed between individual physicians. Intercepts of the physician blood pressure versus nurse blood pressure relationship ranged from 0.1 -60.7 mmHg for systolic and from 13.3-55.3 mmHg for diastolic pressures. The slopes of this relationship differed less between physicians for systolic (0.72-1) than for diastolic pressures (0.56-0.97). There was no difference between the patients seen by physicians in patients' age, sex, tobacco consumption, anti-hypertensive treatment or target-organ damage.

CONCLUSION

Large between-physician differences exist in the magnitude of the white-coat effect that cannot be explained by patient characteristics. Physicians should therefore not make any decisions based on blood pressure measured manually during a first encounter.

Theatre monitor alarm settings: a pilot survey in Scotland and Belgium

The use of alarms on operating theatre equipment was explored in a questionnaire to anaesthetists in Belgium and Scotland. They were presented with a scenario of a fit male having an anaesthetic for an abdominal operation. The overall response rate was 72%, giving 100 records for analysis. The responses from Scottish and Belgian anaesthetists were similar except for views on setting an upper limit for systolic arterial pressure; Scottish anaesthetists seemed relatively unwilling to set an upper systolic arterial pressure limit. Beyond this, the respondents considered alarms to be a method of detecting problems before they occur and they readjust alarms for each patient. They would set systolic arterial pressure alarms 30 mmHg above and below the patients normal pressure, the heart rate alarms 30 bpm above and 20 bpm below the actual rate, and the peripheral oxygen saturation lower alarm limit to 90%.

Clinical evaluation of the Philips 5306B electronic blood pressure monitor

A patient-recorded home blood pressure series using an electronic manometer is used increasingly to provide a representative sample of blood pressure (BP) and to avoid frequent office visits and office rises in BP. Few of the many available electronic manometers have undergone rigorous testing and validation against a standard mercury manometer. We have evaluated fully the commonly used Philips 5306B electronic manometer against a Hawksley random zero mercury manometer employing a randomized, single-blind, crossover design and statistical analyses that have been validated previously. Although correlation coefficients greater than 0.9 were achieved for both systolic and diastolic pressure, the electronic manometer gave systolic and diastolic readings that differed from the mercury manometer by greater than or equal to +/- 5 mmHg in some 33% of patients and by greater than or equal to +/- 1- mmHg in some 18% of patients. Thus, in common with most electronic manometers, the Philips 5306B needs to be improved to correlate more closely with the standard mercury manometer to enhance its clinical usefulness.

Bayesian statistics as applied to hypertension diagnosis

This paper deals with the following hypertension diagnoses: essential hypertension and five types of secondary hypertension: fibrodysplasic renal artery stenosis, atheromatous renal artery stenosis, Conn's syndrome, renal cystic disease, and pheochromocytoma. Only blood pressures, general information and general biochemical data are taken into account. Nineteen items were finally selected, by statistical investigation of experimental data, as being both discriminative and independent. The marginal density distributions of every item, and then joint density distribution functions were determined within six types of hypertension. The frequency of a given hypertension type within the hypertensive patients was used as prior probability of this state. The loss matrix was established by medical arguments. The expected loss corresponding to six possible decisions could thus be calculated for all cases. Both the ratio of secondary hypertensions that could be inferred from our set of data (not including the results of complementary tests) and that of correct "essential" hypertension diagnosis proved to be satisfactory.