Respiratory isolation of patients with suspected pulmonary tuberculosis in an inner-city hospital

Objective: To identify clinical factors that predict which patients presenting to the ED with pneumonia will require respiratory isolation for suspected tuberculosis and to evaluate a protocol for rapid identification of patients at risk for pulmonary tuberculosis (PTB). Methods: To identify potential clinical indicators of PTB, a case-control study was performed using patients admitted to an urban teaching hospital with the ED diagnosis of pneumonia (derivation sample). These predictors were then evaluated in a separate prospective observational study of 103 patients admitted to the same institution from July 1994 to February 1995. Adult patients with the admitting diagnosis of pneumonia were admitted to a respiratory isolation bed if they met 1 of the following criteria: 1) HIV-positive or unknown HIV status with a history of injection drug use; 2) chest x-ray consistent with PTB; or 3) pneumonia with 1 of the following: PPD conversion within 2 years, recent exposure to PTB, previous PTB, or hemoptysis, Patients who did not meet isolation criteria were admitted to the medical ward and had a PPD and anergy panel placed. Those who were anergic or PPD-positive were transferred to respiratory isolation. Results: Predictor variables identified during the first study phase were incorporated into the isolation guidelines noted above. Only 36 of 50 (72%) PTB patients were admitted to an isolation bed during this phase. During the second phase, 103 patients were admitted with the ED diagnosis of pneumonia-rule out PTB; 22 patients (22%) were culture-confirmed positive for PTB. The guidelines predicted PTB as follows: sensitivity, 0.96 (95% CI, 0.88-1.0); specificity, 0.14 (95% CI, 0.08-0.24); positive-predictive value, 0.23 (95% CI, 0.17-0.35); and negative predictive value, 0.92 (95% CI, 0.77-1.0). The 1 patient who Was not isolated was found to be anergic after 48 hours and subsequently isolated. Conclusion: Respiratory isolation guidelines for patients admitted from the ED with pneumonia were developed and validated. These guidelines provide satisfactory guidance for isolation of patients at risk for PTB in a high-PTB-prevalence population.