Predictors of Pneumocystis carinii pneumonia in HIV-infected persons. Pulmonary Complications of HIV Infection Study Group.

The Pulmonary Complications of HIV Infection Study is a prospective, multicenter, observational study evaluating pulmonary disease among HIV-infected persons. For approximately 52 mo, 1,182 HIV-infected subjects were followed. All participants were evaluated for pulmonary disease on a predetermined schedule. There were 145 episodes of Pneumocystis carinii pneumonia (PCP). Low CD4 count correlated with risk of PCP (p < 0.0001); 79% had CD4 counts less than 100/microl and 95% had CD4 counts less than 200/microl. Subtle changes in diffusing capacity for carbon monoxide (DLCO) were associated with PCP. Univariate analysis identified recurrent undiagnosed fevers, night sweats, oropharyngeal thrush, and unintentional weight loss to be associated with risk among persons with CD4 counts above 200/microl. Subjects in whom CD4 counts declined to below 200/microl and who were not receiving preventive therapy were nine times more likely to develop PCP within 6 mo compared with subjects who received such therapy. A strong trend toward differences between the sexes was detected. Black subjects had less than one third the risk of developing PCP as did white subjects (p < 0.0001). There was no significant difference in risk by HIV transmission category, study site, frequency of follow-up, age, education, smoking history, or use of antiretroviral therapy. Multivariable analysis revealed low CD4 lymphocyte count (p < 0.0001), use of prophylaxis (p < 0.0001), racial differences (p < 0.0001), and declining DLCO (p = 0.015) to influence risk. Constitutional signs and symptoms indicate increased risk for PCP among HIV-infected persons with CD4 counts above 200/microl.

Predicting the annual concentration of indoor 222Rn from one or more short-term measurements.

Long-term and short-term measurements of indoor 222Rn from 480 houses located in eleven states were used to study the relationship between the annual living area average (ALAA) and 1) a single 2 d measurement and 2) the mean of multiple 2 d measurements (taken in different seasons). Of particular interest is the issue of using a short-term measurement(s) to predict the ALAA in a given house. The results indicate that with 95% confidence (approximately): 1) a single 2 d measurement gives an interval estimate of the true ALAA that is within a factor of 2.5 of the predicted ALAA; and 2) a mean of two 2 d measurements (taken in different seasons) gives an interval estimate that is within a factor of 2.2 of the predicted ALAA. If a more precise estimate of the ALAA is needed, then an alternative procedure to using 2 d measurements should be employed (e.g., measure the annual concentration directly).

Indoor 222Rn concentrations in a probability sample of 43,000 houses across 30 states.

The U.S. Environmental Protection Agency has assisted 30 of the 48 conterminous states in completing statistically designed surveys of indoor 222Rn over the past 4 y. In all states, the lowest livable level of 43,054 randomly selected houses was tested using charcoal canisters exposed for 48 h. The sampled population included owner-occupied ground-level houses having listed telephone numbers. Summary statistics along with the percentage of houses exceeding various concentration levels are given by state and over all states for houses with basements, for houses without basements, and for all houses. As expected, 222Rn concentration varies widely from one state to another and, in every state, basement houses exhibit higher concentrations than nonbasement houses. The lognormal distribution is shown to be a good approximation to the distribution of screening measurements over the 30-state area. There is, however, some evidence that the lognormal distribution underestimates, by a narrow margin, the upper tail of the observed distribution of basement measurements.

Multi-state surveys of indoor 222Rn.

The U.S. Environmental Protection Agency provides assistance to states in conducting surveys of indoor 222Rn. Alabama, Kentucky, Tennessee, Wisconsin, and Wyoming completed statistically designed surveys during the 1986-1987 heating season. In all states, probability-based samples of 5800 houses were tested using charcoal canisters exposed for 48 h. Thus, sample results can be validly extrapolated to the target population of all owner-occupied, ground-level houses having listed telephone numbers. Estimates of population parameters (e.g., median) and their associated confidence intervals are given for each state, for geographic regions within states, and for basement and nonbasement houses. Results confirm that 222Rn concentration varies widely from one state to another and from one geographic region to another within a state; however, the same pattern of differences was not evident in basement or nonbasement houses. Short-term 222Rn readings appear to follow a log-normal distribution.