Search PubMed⌕ Search

Biomedical subjects

B M Rifkind

Publications and source records attributed to B M Rifkind.

At least 37 records · Page 2Linked to original sources
PubMed1990

Does lowering serum cholesterol levels lower coronary heart disease risk?

Many lines of evidence converge toward the conclusion that low-density lipoprotein cholesterol (LDLC) is indeed a causal factor in the genesis of CHD. These range from animal studies, pathology studies, inborn errors of metabolism, clinical observations, and the existence of plausible biologic mechanisms, to the vast body of epidemiologic evidence. Observations of the association of LDLC with CHD hold between different populations, in the same population at different times, and to studies of individuals within populations. Finally, the clinical trials of cholesterol lowering, together with regression studies in animals and angiographic studies in humans, provide compelling evidence that the progress of atherosclerosis can be halted and the clinical sequelae can be reduced. The newly available results from more recent intervention studies have reinforced the validity of this conclusion. The intervention studies reduced the CHD incidence rate by approximately 2% for every 1% reduction in total cholesterol (TC) even though the studies were of relatively short duration (typically 5 years). More prolonged exposure to lower TC levels can be expected to yield even greater ultimate benefit. The benefit is most clearcut for men at highest risk. The combined data indicate that both fatal and nonfatal CHD can be reduced. More data on the extremes of age, on subjects with moderate elevations of TC, and on women would be valuable, but it is reasonable to proceed with advice to the general population aimed at reducing average cholesterol levels, and also to identify and treat those at high risk. There is good reason to expect that these measures will further reduce MI events and in all likelihood also MI deaths. Whether they will also reduce overall mortality is at present a moot point; however, a reduction in the burden of nonfatal MI would in itself be a very desirable objective.

Animals↗
PubMed1989

Treating high blood cholesterol in the older patient.

Although the general importance of treating high blood cholesterol to prevent coronary heart disease (CHD) is now widely accepted, its application to the older patient has not been well-defined. The association between total blood cholesterol levels and CHD morbidity and mortality weakens with age. However, because age itself is a major risk factor for CHD, treatment of hypercholesterolemia in the elderly may bring about a greater reduction in absolute risk than is obtained in younger persons. More research that directly addresses the benefits of the treatment of hypercholesterolemia in the elderly is needed.

Adult↗
PubMed1989

Cholesterol and coronary heart disease prevention--a transatlantic consensus.

Recent research findings have enhanced interest in coronary heart disease prevention. Three expert panels, one in the United States and two in Europe, have addressed the subject and recommended appropriate action. The report of the United States Consensus Conference on Lowering Blood Cholesterol appeared in 1985, and the reports of the European Atherosclerosis Society and British Cardiac Society appeared in 1987. We discuss these reports and emphasize the proposals concerning cholesterol. We review the scientific background to the decisions of the expert panels, high-risk and population-based strategies, cholesterol screening and cholesterol reference levels for the initiation of treatment and therapeutic goals. Dietary recommendations are highlighted and the attention given to special groups such as women, the elderly and children is appraised. Finally, the recommendations of the reports regarding the other risk factors are discussed. We note the general consensus among them and outline the strategies and guidelines which advocate concerted effort to reduce the burden of coronary heart disease.

Adolescent↗
PubMed1989

The place of HDL in cholesterol management. A perspective from the National Cholesterol Educational Program.

The guidelines developed by the Adult Treatment Panel of the National Cholesterol Education Program identified low density lipoprotein (LDL) as the major atherogenic lipoprotein, and high levels of LDL-cholesterol as the primary target for cholesterol-lowering therapy. Low levels of high density lipoprotein (HDL)-cholesterol were recognized as a major risk factor for coronary heart disease. This report reexamines in depth the recommendations of the Adult Treatment Panel on HDL-cholesterol. Two major questions are discussed: (1) Should HDL-cholesterol levels be measured in all adults, as recommended for total cholesterol? (2) Should patients found to have a low serum HDL [corrected]-cholesterol level (less than 35 mg/dL [less than 0.91 mmol/L]) enter medical therapy to raise the level? The guidelines of the Adult Treatment Panel are reaffirmed as appropriate from the current perspective. These guidelines recommend that HDL-cholesterol levels be determined in patients deemed to be at high risk for coronary heart disease and suggest that HDL measurement is optional for individuals with borderline-high total levels. The guidelines of the Adult Treatment Panel recommend that low HDL-cholesterol levels be raised mainly by hygienic means (ie, smoking cessation, weight loss, aerobic exercise). When drug therapy is required for high LDL-cholesterol levels in the presence of low HDL levels, cholesterol-lowering drugs that concomitantly raise HDL should be given first priority.

Cholesterol, Dietary↗
PubMed1989

Lowering blood cholesterol to reduce coronary heart disease risk.

Key recent findings provide definitive evidence that lowering blood cholesterol in humans reduces coronary heart disease risk. These research advances serve as the basis for national guidelines concerning the medical and public health implications of lowering blood cholesterol to prevent heart disease.

Cholesterol↗
PubMed1988

Biological and cultural sources of familial resemblance in plasma lipids: a comparison between North America and Israel--the Lipid Research Clinics Program.

Heterogeneity in determinants of familial resemblance of lipid and lipoprotein levels between populations in North America and Israel was investigated using path analysis. A common protocol, identical measurement techniques, and the same statistical procedures were used in the two samples. Both genetic (h2) and cultural (c2) determinants of inheritance were significant for all lipid variables in the two studies. Genetic and cultural heritability of total cholesterol (h2 = 0.61, c2 = 0.02), low-density lipoprotein cholesterol (h2 = 0.59, c2 = 0.02), and high-density lipoprotein cholesterol (h2 = 0.55, c2 = 0.06) did not differ significantly between North America and Israel, while there was a significant difference for triglyceride (h2 = 0.41, c2 = 0.07 in North America; h2 = 0.61, c2 = 0.05 in Israel). Secondary parameters of the path model describing intrafamilial environmental relationships differed between the two countries. In particular, there was a higher correlation between marital environments in Israel for all traits except triglyceride, and a larger effect of father's environment on offspring's environment in Israel for all traits. Within both populations, variation of plasma lipids and lipoproteins was mostly explained by genetic factors and random unmeasured environmental factors. The contribution of common family environment was found to be small, though statistically significant. This is probably due to homogeneity of the distribution of familial environmental determinants within both countries.

Cholesterol↗
PubMed1988

Comparing mean levels of total cholesterol from visit 2 of the Lipid Research Clinics Prevalence Study with the second National Health and Nutrition Examination Survey.

Mean levels of total cholesterol by sex and age were compared between groups of whites in visit 2 of the Lipid Research Clinics Program Prevalence Study and in the second National Health and Nutrition Examination Survey (NHANES II). NHANES II estimates were found to be higher than comparable visit 2 estimates by 3-14 mg/dl for males and by 11-21 mg/dl for females. Adjustment for the use of differing components of blood in making the lipid determinations in the two studies (plasma in visit 2 and serum in NHANES II) reduced the original differences by roughly one half. Other adjustments--for operational differences among laboratories that performed the blood sample analysis in the two studies, for educational differences in the study populations, and for inclusion of data from a Toronto clinic in the visit 2 data--were collectively found to explain most of the remaining differences between visit 2 and NHANES II, especially for males.

Adult↗
PubMed1987

Change in physician perspective on cholesterol and heart disease. Results from two national surveys.

The National Heart, Lung, and Blood Institute sponsored national telephone surveys of practicing physicians in 1983 (N = 1610) and 1986 (N = 1277) to assess attitudes and practices regarding elevated serum cholesterol levels. The 1983 survey was conducted just before the release of the results of the Lipid Research Clinics Coronary Primary Prevention Trial, which showed that a reduction in the blood cholesterol level reduced coronary heart disease. In 1986, 64% of physicians thought that reducing high blood cholesterol levels would have a large effect on heart disease, up considerably from 39% in 1983. Whereas in 1983, physicians attributed considerably less preventive value to reducing the cholesterol level than to reducing blood pressure or smoking, this disparity was substantially smaller in 1986. The median range of blood cholesterol at which diet therapy was initiated was 6.21 to 6.70 mmol/L (240 to 259 mg/dL) in 1986, down from 6.72 to 7.21 mmol/L (260 to 279 mg/dL) in 1983; the median for drug therapy was 7.76 to 8.25 mmol/L. (300 to 319 mg/dL) in 1986 and 8.79 to 9.28 mmol/L (340 to 359 mg/dL) in 1983. In 1986, 87% of physicians surveyed felt that medical evidence warranted the recommended treatment levels set forth in the 1984 National Institutes of Health Consensus Conference on Lowering Blood Cholesterol. These changes indicate that by 1986, physicians were more convinced of the benefit of lowering high blood cholesterol levels and were treating patients accordingly. The data also suggest areas for continued educational initiatives.

Adult↗
PubMed1987

Parent-offspring aggregation of plasma lipids in selected populations in North America and Israel. The Lipid Research Clinics Prevalence Study.

Parent-offspring associations of total cholesterol and triglycerides were compared between family dyads in six North American populations examined between 1972 and 1976 as part of the North American Lipid Research Clinics Prevalence Study and those from families examined between 1976 and 1979 at the Lipid Research Clinic located in Jerusalem. Common study design, protocol, and laboratory techniques were used by all Lipid Research Clinics. The authors first examined homogeneity of familial correlations across clinics in the North American population and across origin groups in the Israeli sample. In general, correlations were homogeneous across clinics and origin groups, except for parent-daughter pairs for triglycerides in North America. The pooled familial correlations were similar in the two study populations. There was no asymmetry in parent-offspring correlations by the sex of the offspring. The pooled mother-child correlations were significantly higher than father-child values in the North American sample only. The strength of parent-offspring similarity showed no consistent pattern of change with level of education of parents in either study group. Patterns of familial similarity are discussed in relation to genetic, cultural, and environmental differences between the two study populations.

Adolescent↗
PubMed1987

Cardiovascular mortality and noncontraceptive use of estrogen in women: results from the Lipid Research Clinics Program Follow-up Study.

A cohort of 2270 white women, aged 40-69 years at baseline, were followed for an average of 8.5 years in the Lipid Research Clinics Program Follow-up Study. There were 44 deaths due to cardiovascular disease among the 1677 nonusers of estrogens and six cardiovascular disease deaths among the 593 estrogen users. The age-adjusted relative risk (RR) of cardiovascular disease deaths in users compared with nonusers was 0.34 (95% confidence limits 0.12 to 0.81). After multivariable adjustment for potential confounding factors (age, blood pressure, and smoking), the estimated RR for estrogen use was 0.37 (95% confidence limits 0.16 to 0.88). Analyses were done to explore whether these results could be due to selection bias for estrogen use. However, the prevalence of cardiovascular disease at baseline was slightly higher in estrogen users (12%) than in nonusers (10%); furthermore, the exclusion of all women with prevalent cardiovascular disease at baseline did not alter the apparent protective effect of estrogen use on cardiovascular disease mortality (RR = 0.42, 95% confidence limits 0.13 to 1.10). Additional analyses examining the complex association between estrogen use, lipoprotein levels, and cardiovascular disease mortality suggest that the protective effect of estrogen is substantially mediated through increased high-density lipoprotein levels.

Adult↗
PubMed1987

Segregation analysis of low levels of high-density lipoprotein cholesterol in the collaborative Lipid Research Clinics Program Family Study.

Complex segregation analysis with the unified mixed model in white families from nine lipid research clinics was carried out to delineate the mode of familial transmission of plasma high-density-lipoprotein cholesterol (HDL-C). Three groups of families from the collaborative Lipid Research Clinics Program Family Study were assessed: 1,146 selected at random, 483 obtained through hypercholesterolemic probands, and 177 selected from the random sample because a number had low HDL-C, the sample sizes being 4,279, 1,807 and 735, respectively. The data were first transformed and adjusted for effects of covariates. Analyses were performed within clinic and selection strata and also pooled across clinics within strata. The results were consistent across strata and identified two major HDL-C clusters with means separated by approximately 3 SD. There was significant evidence of transmission of a major factor for low HDL-C, but transmission did not conform to Mendelian segregation expectations. There was also evidence of significant multifactorial transmission. Since low HDL-C levels are a major independent risk factor for coronary heart disease, the association of a major factor with familial aggregation of low HDL-C emphasizes the importance of detailed within-family sampling for low HDL-C after identifying a proband whose predominant dyslipoproteinemia is low HDL-C.

Cholesterol, HDL↗
PubMed1986

A comparison of methods for the estimation of plasma low- and very low-density lipoprotein cholesterol. The Lipid Research Clinics Prevalence Study.

Using data from over 10 000 men, women, and children who participated in the Lipid Research Clinics prevalence studies, we have examined the formula adopted by Friedewald et al for estimating plasma or serum concentrations of low-density lipoprotein cholesterol (LDL-C) when (for economy, or in the absence of an ultracentrifuge) only fasting total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and triglyceride (TG) concentrations are measured in milligrams per liter, ie, LDL-C = TC-(HDL-C + 0.20 X TG). Values for LDL-C obtained by use of the Friedewald formula were compared with values derived from the Lipid Research Clinics ultracentrifugal procedure for LDL-C, which was used as a reference. Participants who were pregnant, who had not fasted, or whose plasma contained chylomicrons or floating beta-lipoproteins were excluded. We concluded that a better estimator for LDL-C was provided by the equation LDL-C = TC-(HDL-C + 0.16 X TG), since it produced an error (relative to the reference method) of lesser magnitude than the previous formula. The expression 0.16 X TG (0.37 X TG when measurements are reported in millimoles per liter) also produced a more accurate estimate of very low-density lipoprotein cholesterol relative to values obtained by the standard Lipid Research Clinics procedure for this component. The proposed formula is more precise for plasmas or sera with a TG concentration within the normal range.

Adolescent↗