Cholesterol lowering, low cholesterol, and mortality

L-rhamnose and lactulose decrease serum triacylglycerols and their rates of synthesis, but do not affect serum cholesterol concentrations in men

Colonic short-chain fatty acids (SCFA) may affect hepatic lipid metabolism. Lactulose increases colonic acetate production, whereas L-rhamnose increases propionate. To test the effects of oral L-rhamnose and lactulose for 28 d on fasting concentrations and hepatic synthesis of lipids in humans, 18 men were administered 25 g/d of L-rhamnose, lactulose, or d-glucose for 4 wk in a partially randomized crossover design, with blood collected from fasting subjects on the first and last day of each period. Cholesterol and triacylglycerol (TG) synthesis rates were determined using deuterated water uptake rate over the last 24 h of each period. Postprandial blood lipids, and glucose and insulin were assessed in 11 subjects on d 28. Fasting serum cholesterol was unchanged; however, when expressed as a percentage change, TG were decreased, relative to baseline (P < 0.04), by L-rhamnose (-10%) and lactulose (-10%), compared with D-glucose, which increased serum TG (+11%). Net TG-fatty acid (TGFA) synthesis on d 28 was lower with L-rhamnose (2.42 +/- 0.38 g/d) and lactulose (2.62 +/- 0.35 g/d) than with D-glucose (2.96 +/- 0.31 g/d, P < 0.01). We conclude that these results do not support a primary role for propionate in the cholesterol-lowering effect of soluble fiber. However, both lactulose and L-rhamnose lowered serum TG (expressed as a percentage change) and TGFA synthesis, compared with d-glucose, which increased them. Although these data are consistent with inhibition of TGFA synthesis by SCFA, other aspects of the metabolism of these sugars cannot be ruled out as putative agents of their TG-lowering effects.

Clinical Practice Guidelines and Performance Indicators as Related—But Often Misunderstood—Tools

BACKGROUND

Widespread variation in medical practice indicates that existing scientific evidence is often not translated into appropriate clinical care. Two tools have evolved that try to address this variation: clinical practice guidelines (CPGs) and performance indicators (PIs).

TENSIONS BETWEEN CPGS AND PIS

CPGs present available evidence that is subsequently reviewed and frequently adopted by professional organizations, so that clinicians may judge whether specific management recommendations are appropriate for each patient. PIs are devised to measure and document performance to motivate organizations to improve through the use of common metrics.

IMPLICATIONS OF THESE TENSIONS

The increasingly widespread use of PIs with CPGs (and clinicians' confusion of them with CPGs) risks lowering the standards of clinical care. PIs are not intended to set optimal standards of care for any individual patient. Clinicians should not restrict their quality monitoring to a focus on PIs because they could miss important opportunities to learn and to improve the care they deliver to their individual patients.

CONCLUSION

Tensions between CPGs and PIs do not mean that these tools should be abandoned but rather that they need to be refined. Recognition of the imperfections of CPGs and PIs should not blind clinicians to the ultimate goals of these tools--to promote quality (through changes in practice and/or selection) and ensure that medical care is based on scientific evidence.

Understanding the neurobiology of suicidal behavior

Our current knowledge about the neurobiology of suicide is still limited. Technical limitations and the complexity of the CNS are major obstacles. However, there is evidence for a hereditary disposition to suicide, which appears to be independent of diagnosis. Clinical, postmortem, genetic, and animal studies suggest that serotonin has a central role. The main regions of interest in the CNS have been the dorsal and median raphe nuclei in the midbrain that host the main serotonergic cell bodies and the prefrontal cortex, particularly the ventral PFC, innervated by the serotonergic system. In vivo and postmortem studies indicate serotonergic hypofunction in suicide and serious suicide attempts. This deficiency in turn can lead to a predisposition to impulsive and aggressive behavior, probably due to a breakdown in the inhibitory function of the ventral prefrontal cortex as a result of less serotonin input. In the context of this predisposition and the development of mental illness or other life stressors, the individual is at risk of acting on suicidal thoughts. Such deficient serotonin input into the PFC may arise as a result of genetic, parenting, head injury, and other effects. Identifying psychiatric, social, and environmental predictors of suicide are studied to improve prediction and prevention of suicide. A better understanding of the neurobiology of suicide can help detect at risk populations and help develop better treatment interventions.

The impact of cholesterol lowering on patients' mood

This study compared mood changes in 212 patients treated for hypercholesterolemia, as a function of their level of adherence to dietary recommendations. Assessments of mood (anxiety, depression, and hostility), measured by the Profile of Mood States, were obtained at baseline and 3-, 6-, and 12-month follow-up. Adherence to diet was categorized as low, medium, or high based on the Food Record Rating. Repeated-measures ANOVAs showed a significant decrease over time for anxiety, total cholesterol (TC), and low-density lipoproteins (LDL). A multiple regression was performed to determine if reductions in TC or LDL were associated with the anxiety decrease. The model for anxiety change was highly significant and included gender, baseline anxiety, number of stressful events, psychological stress, baseline level of adherence to diet, gender x adherence interaction, and change in TC x adherence interaction. In conclusion, cholesterol lowering did not negatively affect patients' moods. However, those who adhered poorly but nonetheless showed stable or reduced TC exhibited a greater decrease in anxiety.

The association of low serum cholesterol with depression and suicidal behaviours: new hypotheses for the missing link

Several observational studies indicate that reduction of serum cholesterol levels is related to an increase in violent deaths and suicide but the nature of this possible relationship remains unclear. Many confounding factors, e.g. poor health, depression and loss of appetite may play a role in the apparent relationship between serum cholesterol levels and suicide. Two separate phenomena should be considered: lowering total cholesterol and low total cholesterol. This review considers the evidence from epidemiological studies on serum cholesterol lowering and psychiatric disturbances. The available evidence does not seem to substantiate the view that large-scale intervention to reduce cholesterol concentrations could lead to more violent and aggressive behaviour, and generally greater unhappiness. In recent trials using statin treatment, there were slightly fewer deaths from accidents and suicide in the treated group compared with the placebo group. We believe that clinicians should not be deterred from prescribing cholesterol-lowering drugs, to reduce the risk of death from coronary heart disease, when they are indicated.

Current concepts in secondary prevention after acute myocardial infarction

Acute myocardial infarction (MI) is the leading cause of death around the globe. Advances in the field of cardiology have identified several effective treatments that have lead to decrease in mortality from this cause over the past 3 decades. The purpose of this article is to review the existing literature in regards to secondary prevention after acute MI. A search of MEDLINE through August of 1999 was carried out to identify any available publications on secondary prevention after MI. Evidence on the use of both pharmacological and nonpharmacological interventions that was shown to be effective in improving morbidity and mortality was sought. Recommendations for the treatment of patients with acute MI are made based on existing evidence. Betablockers, aspirin and lipid-lowering agents for patients with low density lipoprotein-cholesterol > 130 mg% should be used for all patients following a MI. Angiotensin converting enzyme inhibitors are indicated for patients with congestive heart failure and/or reduced left ventricular ejection fraction and are likely protective in most patients. Calcium channel blockers (Verapamil and Diltiazem) are indicated as second-line therapy for patients who have contraindications or are intolerant to betablockers. The routine prophylactic use of antiarrhythmic drugs to suppress ventricular ectopic beats should be avoided. Recommendations regarding diet, smoking cessation and achievement of ideal body weight should be an integral part of patient management. Referral for outpatient rehabilitation should also be strongly encouraged. Finally, adequate control of blood pressure and diabetes cannot be overemphasized. Adherence to these goals in patients with acute MI will lead to better long-term outcomes and reduction in cardiac death, recurrent MI, stroke, and need for coronary revascularization.

Effects of chronic combined treatment with captopril and pravastatin on the progression of insulin resistance and cardiovascular alterations in an experimental model of obesity in dogs

Obesity is a metabolic disorder in which multiple clinical and biochemical alterations coexist. However, the progression of these alterations in relation to weight gain has not been investigated in detail. Therefore, we studied the evolution of insulin resistance and associated risk factors in a model of experimental obesity in dogs. We also studied whether chronic exposure to these pathogenic factors could induce cardiac and vascular alterations. Twenty male age- and body weight-matched beagle dogs were divided into four groups (n = 5), according to diet and pharmacologic therapy received, and followed for 2 years. Control animals were maintained with a regular diet, while the 15 remaining animals were fed a high-fat diet. The Obese group of dogs received no therapy, whereas the Capto group received 25 mg/12 h captopril, and the Prava+Capto was treated with 10 mg/24 h pravastatin plus the same dose of captopril throughout the study. Periodical determinations of clinical and biochemical parameters were made, and the degree of insulin resistance was also estimated. After the 2-year follow-up, the dogs were killed and vascular thickening in the aorta and the coronary arteries was evaluated. In addition, cardiac hypertrophy was estimated by heart weight and free-wall left ventricular width. Chronic pravastatin plus captopril treatment, together with decreasing weight gain rate, ameliorated the progression of insulin resistance and associated risk factors (hyperinsulinemia, hypercholesterolemia) related to this severe model. In addition, this combined therapy showed cardioprotective action, as cardiac and vascular hypertrophy observed in the Obese group was prevented. These positive results seems to emerge from the synergistic effects of both drugs, as captopril as monotherapy induced only a slight benefit on these parameters.

Assessing the observed relationship between low cholesterol and violence-related mortality. Implications for suicide risk

Health advocacy groups advise all Americans to restrict their dietary intake of saturated fat and cholesterol as an efficacious and safe way to lower plasma cholesterol concentrations and thus reduce the risk of coronary heart disease and other atherosclerotic disorders. However, accumulating evidence suggests that naturally low or clinically reduced cholesterol is associated with increased nonillness mortality (principally suicide and accidents). Other evidence suggests that such increases in suicide and traumatic death may be mediated by the adverse changes in behavior and mood that sometimes accompany low or reduced cholesterol. These observations provided the rationale for an ongoing series of studies in monkeys designed to explore the hypothesis that alterations in dietary or plasma cholesterol influence behavior and that such effects are potentiated by lipid-induced changes in brain chemistry. In fact, the investigations in monkeys reveal that reductions in plasma cholesterol increase the tendency to engage in impulsive or violent behavior through a mechanism involving central serotonergic activity. It is speculated that the cholesterol-serotonin-behavior association represents a mechanism evolved to increase hunting or competitive foraging behavior in the face of nutritional threats signaled by a decline in total serum cholesterol (TC). The epidemiological and experimental data could be interpreted as having two implications for public health: (1) low-cholesterol may be a marker for risk of suicide or traumatic death and (2) cholesterol lowering may have adverse effects for some individuals under some circumstances.

Prognostic value of cholesterol in women of different ages

We assessed the short-term and long-term prognostic relationship between cholesterol and mortality in women of different ages with the aid of statistical graphics. Our population-based cohort study involved 2873 women in the Framingham Heart Study, with a median follow-up of 31 years. The primary outcome was all-cause mortality. Secondary outcome measures were coronary heart disease, noncoronary heart disease, and stroke mortality. We found that significant age interactions were present in the relationships between total cholesterol and mortality from all causes, coronary heart disease (CHD), stroke, and non-CHD causes. For women ages < or = 55, cholesterol is related positively to both short-term (p > 0.05) and long-term (p = 0.05) all-cause mortality. For women ages 56-70, there are significant U-shaped relationships between cholesterol and both short-term and long-term all-cause mortality (p < 0.01). Lowest short-term and long-term mortality rates for women in this age group are at cholesterol values between 240 and 280 mg/dl. For women ages > 70, cholesterol < 240 mg/dl is associated with increased short-term mortality (p < 0.01), and no significant long-term association was detected. These cholesterol/mortality relationships and age interactions can be explained by patterns of association between mortality and both high- and low-density lipoprotein cholesterol among women in the different age groups. These results do not support the hypothesis that cholesterol < 200 mg/dl leads to decreased mortality in women > 55 years old.

Variations in cholesterol management practices of U.S. physicians

OBJECTIVES

This study sought to evaluate national cholesterol management practices of U.S. physicians.

BACKGROUND

Past studies show that nonclinical factors affect physician practices. We tested the hypothesis that physician and patient characteristics influence cholesterol management.

METHODS

We used a stratified, random sample of 2,332 office-based physicians providing 56,215 visits to adults in the 1991-1992 National Ambulatory Medical Care Surveys. We investigated physicians' reporting of cholesterol-related screening, counseling or medications during office visits and used multiple logistic regression to assess independent predictors.

RESULTS

An estimated 1.12 billion adult office visits occurred in 1991 and 1992 (95% confidence interval 1.06 to 1.18 billion). For the 1.03 billion visits by patients without reported hyperlipidemia, cholesterol screening (2.8% of visits) and counseling (1.2%) were not frequent. The likelihood of screening increased with older age, cardiovascular disease risk factors, white race and private insurance. We estimate that only 1 in 12 adults received cholesterol screening annually. In the 85 million visits by patients with hyperlipidemia, cholesterol testing was reported in 22.9%, cholesterol counseling in 34.4% and lipid-lowering medications in 23.1%. Testing was more likely in diabetic and nonobese patients. Counseling was more likely with younger age, cardiovascular disease and private insurance. Medications use was associated with cardiovascular disease, Northeast region of the United States, nonobese patients and visits to internists. Physician practices did not differ by patient gender.

CONCLUSIONS

Although clinical conditions strongly influence cholesterol management, the appropriateness of variations noted by payment source, geographic region and physician specialty deserve further evaluation. These variations and the low estimated volume of services suggest that physicians have not fully adopted recommended cholesterol management practices.

Multicenter comparison of micronized fenofibrate and simvastatin in patients with primary type IIA or IIB hyperlipoproteinemia

In 12 weeks of active treatment, we compared the efficacy and safety of a new (micronized) formulation of fenofibrate (F) (200 mg/day) with that of simvastatin (S) (20 mg/day), an inhibitor of hydroxy-methyl-glutaryl coenzyme A (HMG-CoA)-reductase. Men and women with primary hyperlipoproteinemia (HLP) with low-density lipoprotein (LDL) cholesterol level 180-300 mg/dl and triglyceride level < 500 mg/dl had dietary treatment for 8 weeks, and 133 (2 of 3 type IIa, 1 of 3 type IIb HLP) were randomized. The decrease in total cholesterol differed between type IIa patients (F - 17.9 vs. S - 25.8%), the decrease in triglyceride levels between the type II b groups (F - 52.8 vs. S - 14%), whereas the degree of decrease in LDL cholesterol (F - 20.9 vs. S - 34.9%) differed among all patients. Despite the difference in LDL cholesterol decrease, no difference was noted in total apolipoprotein (apo) B lowering (F - 20.8 and S - 26.5%). Increases in high-density lipoprotein (HDL) cholesterol (F + 18.5 vs. S + 15%) differed specifically in type IIb patients (F + 33.6 vs. S + 11.4%), accompanied by a more pronounced increase in apo AI with fenofibrate (F + 10.5% vs. S no change). Improvement in the ratios of total cholesterol/HDL cholesterol and apo AI/apo B occurred similarly with both drugs. Only fenofibrate, not simvastatin, decreased both fibrinogen (-10.3 vs. + 3.6%) and uric acid (-25% vs. no change) in type IIa and type IIb patients. Safety parameters reflected drug-specific known side effects, underscoring the safety of both drugs in addition to their efficacy in lipid lowering. Besides its advantages in type IIb hyperlipidemia, micronized fenofibrate proved a potent drug in decreasing total and LDL cholesterol and in very effectively decreasing apo B-containing lipoproteins, which is a recommendation for its use in primary hypercholesterolemia.

Influence of dietary lipids on agonistic and affiliative behavior in Macaca fascicularis

The current study evaluates the hypothesis, derived from previous investigations, that alterations in dietary fat and cholesterol influence the social behavior of monkeys. Subjects were 62 adult male, cynomolgus macaques (Macaca fascicularis) assigned originally to an investigation of atherosclerosis regression. This study thus involves a secondary analysis of data derived from an investigation conducted for another purpose. Animals were housed for 14 months' in social groups of five individuals each and initially fed a diet very high in saturated fat and cholesterol to induce coronary artery atherosclerosis. Monkeys were then exposed for 28 months to one of three conditions; (1) a moderately high-fat, high-cholesterol diet and an unstable social environment (in which monkeys were switched among groups monthly); (2) a low-fat, low-cholesterol diet and an unstable social environment; and (3) a low-fat, low-cholesterol diet and a stable social environment. A comparison of animals living in unstable groups revealed that those consuming the low-fat diet exhibited more overt aggression (P < 0.001) and overt submission (P < 0.01) than did monkeys eating the high-fat diet. A second comparison involved only those animals living in stable social units. These monkeys, while consuming the low-fat diet, engaged in more aggression and submission (P_s < 0.05), spent less time in passive body contact or within touching distance (P_s < 0.001), and spent more time alone (P < 0.001) than they had initially while consuming a very high-fat diet. The current investigation is the first on this topic to include measures of social behavior in animals both before and after a reduction in dietary fat. The findings that such a reduction is associated with increased agonism and decreased affiliation may help explain the epidemiologic association in human beings between low or reduced plasma cholesterol concentrations and a high incidence of violence-related mortality. More generally, the data are consistent with the hypothesis that there is a negative feedback adaptation providing for appropriate changes in behavior in response to periodic dietary privation. © 1996 Wiley-Liss, Inc.

Clinical perspectives on primary and secondary prevention of coronary atherosclerosis

Several clinical trials have provided compelling evidence in support of the benefits of lipid-lowering therapy for primary and secondary prevention of atherosclerosis. The results of primary prevention trials have demonstrated that coronary morbidity can be reduced and survival improved with effective lipid-lowering regimens. There has been concern, however, regarding harmful effects (e.g., increased rate of suicide and increased risk of gastrointestinal cancer) of cholesterol-lowering therapies in primary prevention trials. These concerns are not well supported by strong evidence, and there has been lack of a dose-response relationship. It is generally believed that for 1% reduction in serum cholesterol, there is a 2% reduction in the risk of coronary events. The results of numerous secondary prevention trials have clearly demonstrated the benefit of lipid-lowering therapies in reducing the risk of future cardiac events and cardiac mortality in patients with preexistent coronary artery disease. Several studies have shown that treatment regimens effective in reducing LDL cholesterol levels lead to regression of atherosclerotic plaques as well as retard the progression of the disease process. Interestingly, some of these studies have also shown that when measured angiographically, the luminal diameter at the site of stenotic lesions might improve only by an average of 2% to 3%; however, this small degree of improvement is associated with a remarkable reduction by 35% to 25% in the risk of future coronary events. These findings further corroborate the hypothesis about the importance of a lipid-rich cap of the vulnerable plaques and suggest that the reduction in lipid levels is associated with the efflux of lipids from the plaque, thus converting it from a vulnerable to a stable state. The most recent data from the 4S trial have unequivocally demonstrated the benefits of treatment with HMG coenzyme-A reductase inhibitors in reducing the risk of future coronary events and improving the overall survival in patients with established CHD. Although there is still ongoing controversy regarding the precise course of action for primary prevention of CHD, the results of a large number of studies provide overwhelming evidence in support of aggressive lipid-lowering therapy for secondary prevention of CHD. Based on the findings of these studies, it seems prudent that clinicians become actively involved in the evaluation and management of lipid abnormalities and other risk factors in patients with CHD.