Morton D. Schweitzer

Genetic factors in primary hypertension and coronary artery disease a reappraisal

Abstract There is evidence of familial concentration in primary hypertension, but it is not known to what extent genetic factors are responsible. Data on genetic factors in coronary artery disease are meager, and interpretations are speculative. There is need for studies in which genetic and other factors are studied together. Study of the family characteristics of relatives of patients and controls can provide information on the interaction of genetic and environmental factors and offer suggestions for the interception of causes and the prevention of these diseases.

The epidemiology of primary hypertension. Present status.

Abstract Hypertension is defined as elevated arterial pressure, above the ranges encountered generally in the population. Although a variety of underlying pathological processes may give rise to a secondary elevation of blood pressure, the great majority of hypertensives have what is termed primary (or essential) hypertension which may be one disease or a group of diseases of unknown origin, but have no other evident condition to account for it. Current mortality statistics indicate that hypertension and hypertensive heart disease account for nearly 10 per cent of the deaths attributed to cardiovascularrenal diseases. There is agreement among clinicians and epidemiologists that hypertension is of even greater importance, although reliable statistics are lacking. One estimate is that hypertension is reported in fewer than 20 per cent of the deaths in which it is known to the attending physician. During the decade 1950–1960, there was a decline of 40 per cent in mortality reported in the United States in rubrics 440–447. Although some writers have attributed the decline to the widespread use of anti-hypertensive drugs, the poor quality of current mortality statistics makes this interpretation speculative. Primary hypertension is widespread in the adult American population. While exact statistics on its prevalence are not available, surveys among selected groups suggest that 5–25 per cent of the adult population are affected. It is more common among women, but more severe in men. Primary hypertension appears to be more prevalent in highly industrialized regions than in industrially underdeveloped ones. There is no clear indication of a secular trend in the occurrence of primary hypertension, but there is a suggestion that the number of cases is increasing in newly industrialized countries. Community studies and clinical observations have suggested association of primary hypertension with a number of factors including heredity, diet (particularly electrolyte intake), obesity, occupation and psychological and social characteristics. Although data are lacking to identify clearly the etiological importance of any of these variables, the most promising hypotheses are related to obesity, occupation, and especially to family concentration. Improvements are necessary in the reporting of mortality statistics. Changes in death certification and multiple cause coding could improve the usefulness of mortality statistics for epidemiological studies. Studies of blood pressure levels are not an efficient substitute for diagnostic examinations for the presence of primary hyptertension. Agreement on classification procedures would facilitate comparisons among studies. A major need in hypertension research is the conduct of long-term community and family studies.

Studies in hypertension. III. Analysis of individual blood pressure changes.

The results of a questionnaire on conditions of blood pressure measurement, 5ent out prior to the reported study, revealed wide diversity of opinion as to the most satisfactory conditions for blood pressure measurement. This is an analysis of individual blood pressure changes over a period of 312 weeks measured daily at the same hour among 21 subjects observed at 5-minute intervals during a 25-minute period of rest. Fifteen subjects were examined three times on one or more days (9 a.m., 1:30 p.m. and 4:30 p.m.). Although a few of the subjects in the study had occasional readings above 90 mm. diastolic or 140 mm. systolic, none had sustained pressures above these levels. Among the 383 sessions, the initial casual diastolic reading (within 4 mm.) was the lowest in two-thirds of the sessions. There was little change in readings after 15 minutes of rest. In comparing the observations extending over 312 weeks, it was found that the majority of the subjects had reached both their lowest and highest levels within the first five days. Although there was some tendency for midday readings to be lower than the other, this pattern was not consistent.

A family study of primary hypertension—Final report☆

Abstract A study was made of 1,056 spouses, siblings and children of 100 patients with primary hypertension and of 121 normotensives to ascertain the prevalence of hypertension among relatives and the characteristics of those who develop it. Women were found to be more susceptible, a familial concentration was confirmed and mating combinations appeared related to disease in offspring. Hypertensives and normotensives could not be differentiated on the basis of personal or environmental factors. In close to one-fifth of the relatives the presence or absence of primary hypertension could not be ascertained with certainty from a single examination and, even after repeated observations, remained uncertain in 7 per cent. The findings are consistent with but do not establish a genetic etiology.