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.

Response of CD4 lymphocytes and clinical consequences of treatment using ddI or ddC in patients with advanced HIV infection.

The value of CD4 lymphocyte counts as a surrogate marker in persons with advanced human immunodeficiency virus infection during antiretroviral treatment was assessed using longitudinal models and data from the Terry Beirn Community Programs for Clinical Research on AIDS didanosine/zalcitabine trial of 467 HIV-infected patients. Patients with AIDS or two CD4 counts of < or = 300 who fulfilled specific criteria for zidovudine intolerance or failure were randomized to receive either 500 mg didanosine (ddl) daily or 2.25 mg zalcitabine (ddC) per day. Absolute CD4 counts were recorded at study entry and at as many as four visits. Patients were followed for clinical disease progression and survival. At 2 months, the difference in mean CD4 count from baseline was +15.4 cells/mm3 in the ddI group but -1.3 cells/mm3 in the ddC group. Patients assigned to ddI had a greater chance of a CD4 response at 2 months than those on ddC, yet only those in the ddC group with a response showed significant improvement in progression of disease or survival compared with ddC nonresponders, ddI responders, and ddI nonresponders (p = 0.03). We conclude that a CD4 response does not necessarily correlate with improved outcome and is therefore not a useful surrogate marker in these patients.

Insights from monitoring the CPCRA didanosine/zalcitabine trial. Terry Beirn Community Programs for Clinical Research on AIDS.

The design, conduct, and analysis of clinical trials that evaluate the safety and efficacy of treatment interventions in patients with HIV infection provide many scientific challenges. A recently completed randomized trial of didanosine (ddI) and zalcitabine (ddC), sponsored by the Terry Beirn Community Programs for Clinical Research on AIDS (CPCRA), is an especially valuable resource for illustrating these challenging issues and for providing insights into how they might be properly addressed. Establishing equivalence of treatment effects on clinical efficacy end points is illustrated through the use of the confidence interval approach. The striking changes in treatment efficacy results that occurred during the course of the CPCRA trial provide important insights into how a data and safety monitoring board can reduce the risk of inappropriate early study termination. The trial also provides valuable insights into how treatment effects should be assessed, revealing inconsistencies between effects on the CD4 surrogate end point and effects on primary clinical efficacy end points and showing the incompleteness of the standardly employed definition of AIDS progression. Finally, the results of this ddI/ddC trial are used to examine the role of covariate adjustment.

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.

A comparative trial of didanosine or zalcitabine after treatment with zidovudine in patients with human immunodeficiency virus infection. The Terry Beirn Community Programs for Clinical Research on AIDS.

BACKGROUND: Both didanosine and zalcitabine are commonly used to treat patients with human immunodeficiency virus (HIV) infection who cannot tolerate zidovudine treatment or who have had disease progression despite it. The relative efficacy and safety of these second-line therapies are not well defined. METHODS: In this multicenter, open-label trial we randomly assigned 467 patients who previously received zidovudine and had 300 or fewer CD4 cells per cubic millimeter or a diagnosis of the acquired immunodeficiency syndrome (AIDS) to treatment with either didanosine (500 mg per day) or zalcitabine (2.25 mg per day). RESULTS: After a median follow-up of 16 months, disease progression or death occurred in 157 of 230 patients assigned to didanosine and 152 of 237 patients assigned to zalcitabine, for a relative risk of 0.93 for the zalcitabine group as compared with the didanosine group (P = 0.56), which decreased to 0.84 (P = 0.15) after adjustment for the CD4 count, Karnofsky score, and presence of AIDS at base line. There were 100 deaths in the didanosine group and 88 in the zalcitabine group, for a relative risk of 0.78 (P = 0.09) and an adjusted relative risk of 0.63 (P = 0.003). A majority of patients in each group (66 percent) had at least one adverse event during treatment (153 patients taking didanosine and 157 taking zalcitabine). Peripheral neuropathy and stomatitis occurred more often with zalcitabine and diarrhea and abdominal pain more frequently with didanosine. CONCLUSIONS: For patients with HIV infection who have not responded to treatment with zidovudine, zalcitabine is at least as efficacious as didanosine in delaying disease progression and death.

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.

Sodium chloride raises blood pressure in normotensive subjects. The study of sodium and blood pressure.

The effects of dietary sodium on blood pressure in normotensive adults is not well characterized. The Study of Sodium and Blood Pressure (SNaP) is a randomized, double-blind crossover trial using a placebo or 96 meq sodium in 4-week treatment periods separated by a 2-week washout period. Before capsule treatment periods, participants were instructed in a low sodium diet for 10 weeks to reduce urinary sodium excretion to less than 35 meq/8 hr. The low sodium diet was continued throughout the capsule treatment periods. Participants (n = 48; 47 white, 1 black) were 79% male and had an average age of 52 years, a body mass index of 27.6, and a baseline blood pressure of 131/84 mm Hg. Baseline overnight urinary sodium excretion was 51 meq/8 hr and 19 meq/8 hr after the low sodium diet run-in period, before the capsule treatment periods began. Resting, seated blood pressure was measured twice at each visit in a standard fashion. Differences between sodium and placebo treatment periods were as follows: systolic blood pressure, 123.9 versus 120.3 mm Hg, respectively (p less than 0.001); diastolic blood pressure, 78.7 versus 76.4 mm Hg, respectively (p = 0.005); and sodium excretion, 51.3 versus 30.9 meq/8 hr, respectively (p less than 0.001). Both systolic and diastolic blood pressures increased significant amounts in normotensive adults on a low sodium diet supplemented with 96 meq/day sodium. Long-term effects and dose-response relations need further study.