Weight loss as a predictor of survival and disease progression in HIV infection. Terry Beirn Community Programs for Clinical Research on AIDS

Severe weight loss in HIV is associated with decreased length of survival. It is unclear whether mild weight loss is associated with an increased risk of death or opportunistic complications of HIV. Participants in four interventional studies (n = 2382) conducted by a community-based clinical trials network were evaluated for percentage change in weight during their first 4 months in the study. Proportional hazards models were performed for the occurrence of opportunistic complications and death subsequent to the 4-month visit. The relative risk of death and opportunistic complications for those with 5% to 10% weight loss over 4 months was 2.22 (p < .001) and 1.89 (p < .001), respectively, and 1.26 (p < .01) and 1.19 (p < .01) among those who lost 0% to 5% of their body weight, respectively, when compared with those with no weight loss. Among those who lost 5% to 10% of their body weight, the relative risk of individual opportunistic complications increased significantly, including Pneumocystis carinii pneumonia (PCP) (1.61; p < .01), cytomegalovirus (CMV) (2.33; p < .001), and Mycobacterium avium complex (MAC) (1.81; p < .01). As little as 5%t weight loss over a 4-month period is associated with increased risk of death and opportunistic complications in HIV. A weight loss of 5% to 10% is also associated with an increased risk of individual opportunistic complications.

A graphical assessment of the potential impact of losses to follow-up on the validity of study results. The Terry Beirn Community Programs for Clinical Research on AIDS

Losses to follow-up in clinical trials-patients for whom we do not know if the outcome of interest has occurred-can bias study results. If we investigate extreme case scenarios and find the study results do not change much, impact is negligible. If not, we may need to interpret the study's results with caution. At issue is how much caution do we need? We describe a graphical approach to assess the potential impact of losses to follow-up on the validity of study results. One can create the graphs using design estimates and interim or final data. We give two examples using design parameters and another example modelled after observed data from clinical trials conducted by the Terry Beirn Community Programs for Clinical Research on AIDS. The examples illustrate that tolerable levels of losses to follow-up change depending on the overall outcome and direction of differential losses.

Urinary albumin and N-acetyl-beta-D-glucosaminidase excretions in mild hypertension

Renal effects of mild hypertension and therapy have not been established. Since urinary albumin and N-acetyl-beta-D-glucosaminidase excretions reflect renal effects of hypertension, they were related to blood pressure, other cardiovascular risk factors, cardiac target organ effects, and response to therapy in mild hypertension (diastolic blood pressure 85-99 mm Hg). Participants were from two clinics of the Treatment of Mild Hypertension Study (TOMHS), a multicenter randomized, double-blind, controlled trial. Participants received nutritional-hygienic therapy and one of five active drugs or placebo. Urinary albumin and N-acetyl-beta-D-glucosaminidase excretions were assessed prospectively using office "spot" collections from one clinic (n = 213) and retrospectively using overnight collections from the other clinic (n = 210). Relationships were determined between protein excretions and blood pressure, age, gender, race, blood glucose, cholesterol concentrations, and indices of body mass and left ventricular mass and function at baseline. Treatment effects were assessed after 3 to 12 months. Spot and overnight albumin excretions related positively to baseline systolic blood pressure by univariate analyses. Spot albumin excretion related positively to systolic blood pressure, age, creatinine clearance, and left ventricular function while overnight albumin excretion related positively to left ventricular mass and female gender by multiple regression analyses. Spot, but not overnight, albumin excretion declined significantly with active drug therapy. N-acetyl-beta-D-glucosaminidase excretion did not relate to blood pressure or decline with therapy. The combined results suggest albumin excretion correlates with blood pressure, decreases with antihypertensive drug therapy, and is associated with greater left ventricular function and mass, as well as glomerular filtration rate, even at mild levels of hypertension.

Racial and ethnic modifiers of the salt-blood pressure response

The relation between sodium and blood pressure is a centuries-old question. A substantial body of epidemiological and experimental data has accumulated that strongly implicates NaCl as having a causal role in the genesis of arterial hypertension. Prospective studies that have been performed in diverse populations that have manipulated NaCl exposure by diet or infusion have repeatedly documented an NaCl pressor effect. Further, similar studies in biracial populations have also demonstrated a greater prevalence of "salt sensitivity" in blacks compared with whites. The reasons for this observation are not entirely clear; however, intrinsic or hypertension-induced renal abnormalities that limit natriuretic capacity, reduced Na+,K(+)-ATPase pump activity, other membrane ion transport disturbances, differential exposure to psychological stressors, greater insulin resistance, and dietary factors (reduced Ca+ and K+ intake) have all been suggested as possibly playing a role. Salt sensitivity appears to be a widespread phenomenon. However, it is critically important to determine what factors account for racial differences in salt sensitivity. Moreover, the prevalence of salt sensitivity in the general population is unknown. Current definitions of salt sensitivity are varied and unidirectional. In comparison with bidirectional criteria (blood pressure increase with salt loading and blood pressure decrease with salt restriction), they are probably inadequate to identify salt-sensitive individuals who manifest less extreme blood pressure change after dietary sodium or plasma volume manipulations. More sensitive criteria for diagnosing salt sensitivity will facilitate a better understanding of racial and ethnic differences in the prevalence of salt sensitivity.