Clinical Briefs

Diuretics, Mortality, and Nonrecovery of Renal Function in Acute Renal Failure

Diuretics are commonly used in the setting of acute renal failure (ARF), based upon premises that they will reduce volume in extracellular volume overload and may convert oliguric ARF to nonoliguric ARF. To date, no randomized clinical trials have confirmed anticipated benefits in survival or restoration of renal function as a result of diuretic treatment. Mehta and associates postulated that diuretics in ARF would actually increase mortality and forestall recovery of renal function, and they studied critically ill ARF patients (n = 820) at 4 teaching hospitals. ARF was defined as BUN > 40 mg/dL, creatinine > 2.0 mg/dL, or an increase of creatinine > 1 mg/dL over baseline.

Using a covariate-adjusted model, diuretic use was associated with a 68% increase in in-hospital mortality, and a similar (77%) increase in likelihood of death or nonrecovery of renal function. Diuretics used included furosemide, bumetanide, metolazone, and HCTZ, with no demonstrable differences in outcomes dependent on any particular agent, whether used as monotherapy or combination therapy. Patients who were least responsive to diuretics (in terms of urinary output) were disproportionately at risk for adverse outcomes. Mehta et al posit that delay in using dialysis, while medical (diuretic) therapy is used, may indeed by injurious; they further suggest that diuretics, though not yet conclusively proven to be harmful by this single trial, are unlikely to provide benefit in the setting of ARF among critically ill patients.

Mehta RL, et al. JAMA. 2002;288: 2547-2553.

Nut and Peanut Butter Consumption and Risk of Type 2 Diabetes in Women

Recent trials have confirmed that both pharmacologic treatment (acarbose or metformin) and lifestyle intervention (weight loss and exercise) may prevent onset of type 2 diabetes (DM-2) in high-risk individuals. Recent data suggest that it is the type (saturated vs unsaturated) rather than the total fat percentage of diet that better predicts risk of DM-2. Higher intake of saturated fat and transfat negatively affect both glucose metabolism and insulin resistance. Since nuts contain primarily unsaturated fats, as well as fiber, magnesium, vitamins, minerals, and antioxidants, they theoretically provide a dietary substance that could favorably affect likelihood of developing DM-2.

To study the relationship between nuts and DM-2, Jiang and associates evaluated the participants in the Nurses Health Study (n = 121,700 women). Information collected on these women includes family history of diabetes, body weight, smoking, and physical activity; additionally, dietary questionnaires quantitated intake of nuts, dividing inquiry into peanuts, nuts, and peanut butter.

Women in the highest quartile of nut ingestion (at least 5 times weekly) when compared with those who almost never consumed nuts (lowest quartile) demonstrated an age-adjusted 0.55 relative risk (RR) for DM-2. A similar comparison specific to peanut butter showed an RR of 0.79 comparing quartile 1 to quartile 4. Because there has been some concern that increasing nuts in the diet might worsen weight management issues, the fact that this study found that ingestion of nuts in the highest quartile was not associated with significantly greater weight gain than those eating nuts less frequently is reassuring. When coupled with the epidemiologic studies suggesting favorable effects of nuts upon lipids and coronary heart disease, this study provides increasing impetus for clinician endorsement of nut consumption.

Jiang R, et al. JAMA. 2002;288: 2554-2560.

Optimal Diets for Prevention of CHD

The classic diet-heart hypothesis postulates that dietary saturated fat and cholesterol are causally associated with coronary heart disease (CHD). Though the evidence for this hypothesis is sufficiently compelling that few clinicians debate its veracity, other components of diet, or their effects in concert, may be equally pertinent to the development of CHD.

A MEDLINE search produced 147 trials assessing diverse dietary factors, which indicated that omega-3-fatty acids, trans-fatty acids, carbohydrates, glycemic index, fiber, folate, individual foods (eg, nuts), and specific dietary patterns demonstrate a relationship with cardiovascular disease. From these data, several strategies, in addition to cholesterol reduction, are well substantiated to be associated with lesser risk of CHD: substitution of unsaturated fat (especially polyunsaturated) for saturated fat, reduction of transfatty acids, increases of omega-3 fatty acids (ie, from fish oil or plant sources), and a diversified diet which includes high intake of fruits, vegetables, nuts, and whole grains (low in refined grains). Despite the fact that common practice for management of obesity, an important contributor to CHD, suggests restriction of dietary fat to < 30% of total energy intake, the data to support such intervention are lacking. Rather, it may be more prudent to focus upon the favorable dietary characteristics detailed above, contained within a moderately hypocaloric diet.

Hu FB, Willett WC. JAMA. 2002;288:2569-2578.