Discriminating inhalational anthrax from community-acquired pneumonia using chest radiograph findings and a clinical algorithm.

BACKGROUND: Limiting the effects of a large-scale bioterrorist anthrax attack will require rapid and accurate detection of the earliest victims. We undertook this study to improve physicians' ability to rapidly detect inhalational anthrax victims. METHODS: We conducted a case-control study to compare chest radiograph findings from 47 patients from historical inhalational anthrax cases and 188 community-acquired pneumonia control subjects. We then used classification tree analyses to derive an algorithm of chest radiograph findings and clinical characteristics that accurately and explicitly discriminated between inhalational anthrax and community-acquired pneumonia. RESULTS: Twenty-two of the 47 patients from historical inhalational anthrax cases (46.8%) had reported chest radiograph findings. All 22 case patients (100%) had mediastinal widening, pleural effusion, or both. However, 16 case patients (72.7%) also had infiltrates. In comparison, all 188 community-acquired control subjects had reported chest radiographs. Of these, 127 control subjects (67.6%) had infiltrates, 43 control subjects (22.9%) had pleural effusions, and 15 control subjects (8.0%) had mediastinal widening. A derived algorithm with three predictor variables (chest radiograph finding of mediastinal widening, altered mental status, and elevated hematocrit) is 100% sensitive (95% confidence interval [CI], 73.5 to 100) and 98.3% specific (95% CI, 95.1 to 99.6). The derivation process used 12 patients with inhalational anthrax and 177 control subjects with community-acquired pneumonia who had information available for all three variables. CONCLUSIONS: There are significant chest radiograph differences between inhalational anthrax and community-acquired pneumonia, but none of the chest radiograph findings are both highly sensitive and highly specific. The derived clinical algorithm can improve physicians' ability to discriminate inhalational anthrax from community-acquired pneumonia, but its utility is limited to previously healthy individuals and its accuracy may be limited by missing values.

Clinical predictors of bioterrorism-related inhalational anthrax.

Limitation of a bioterrorist anthrax attack will require rapid and accurate recognition of the earliest victims. To identify clinical characteristics of inhalational anthrax, we compared 47 historical cases (including 11 cases of bioterrorism-related anthrax) with 376 controls with community-acquired pneumonia or influenza-like illness. Nausea, vomiting, pallor or cyanosis, diaphoresis, altered mental status, and raised haematocrit were more frequently recorded in the inhalational anthrax cases than in either the community-acquired pneumonia or influenza-like illness controls. The most accurate predictor of anthrax was mediastinal widening or pleural effusion on a chest radiograph. This finding was 100% sensitive (95% CI 84.6-100.0) for inhalational anthrax, 71.8% specific (64.8-78.1) compared with community-acquired pneumonia, and 95.6% specific (90.0-98.5) compared with influenza-like illness. Our findings represent preliminary efforts toward identifying clinical predictors of inhalational anthrax.

Acceptance of HIV testing and counseling among unmarried young adults in Northern Thailand.

A cluster randomized trial was used to assess the effect of an active group intervention in promoting utilization of voluntary HIV testing and counseling (HIV-TC). Villagers from 40 clusters were sampled to represent the premarital age population and assigned into two groups, intervention and comparison. The intervention was designed to enhance risk perception and increase knowledge about HIV testing. Interviews were performed before and after the intervention. At baseline, 23% of 398 participants had been tested for HIV at least once and 90% reported testing positive. Most participants perceived that they had no chance of being infected with HIV. Among the intervention group, 71% participated in the intervention activities. The risk ratio of HIV-TC acceptance among the intervention group was 2.92, but the risk difference was only 8.11%. Factors associated with HIV-TC acceptance were ever having had a sexually transmitted disease, being previously married, intention to get tested, and having partici pated in AIDS-related activities.