Controlling tuberculosis in an urban emergency department: a rapid decision instrument for patient isolation

Hospital Practices for Respiratory Isolation for Patients With Suspected Tuberculosis and Potential Application of Prediction Models

Hospitalized persons with suspected pulmonary tuberculosis (PTB) are placed in airborne isolation to prevent nosocomial infection, as recommended by the Centers for Disease Control and Prevention (CDC). There is significant evidence that clinicians overuse this resource due to an abundance of caution when confronted with a patient with possible PTB. Many researchers have developed predictive tools based on clinical and radiographic data to assist clinicians in deciding which patients to place in respiratory isolation. We assessed the isolation practices for an urban hospital serving a large immigrant population and then retrospectively applied seven previously derived prediction models of isolation of PTB to our population. Our current clinical practice results in 76% of patients with PTB being placed in isolation on admission. However, 208 patients without PTB were placed in isolation unnecessarily for a total of 584 days. Four models had sensitivities greater than 90%, and two models had sensitivities of 100%. The use of these models would have potentially saved more than 150 days of patient isolation per year.

Individual and public health consequences associated with a missed diagnosis of pulmonary tuberculosis in the emergency department: A retrospective cohort study

Objectives

To determine: i) the emergency department (ED) utilization history of pulmonary tuberculosis (PTB) patients, and ii) the potential individual and public health consequences of a missed diagnosis of PTB in this setting.

Design

Retrospective observational cohort study.

Participants

Patients with PTB aged >16 years diagnosed between April 1, 2010 and December 31, 2016 in the Province of Alberta, Canada.

Methods

We identified valid new cases of PTB from a provincial registry and linked them to ED attendees in administrative databases. Visits are considered ‘PTB’, pulmonary ‘other’, and non-pulmonary based on the most responsible discharge diagnosis. Individual consequences of a missed diagnosis included health system delay and PTB-related death; public health consequences included nosocomial ED exposure time and secondary cases.

Results

Of 711 PTB patients, 378 (53%) made 845 ED visits in the six months immediately preceding the date of diagnosis. The most responsible ED discharge diagnosis was PTB in 92 (10.9%), pulmonary ‘other’ in 273 (32%) and non-pulmonary in 480 (56.8%). ED attendees had a median (IQR) health system delay of 27 (7,180) days and, compared to non-ED attendees were more likely to die a TB-related death 5.9% vs 1.2%, p = 0.001. Emergency attendees generated 3812 hours of ED nosocomial exposure time, and 31 secondary cases (60.8% of all secondary cases reported). Mycobacterium tuberculosis isolates from ED-attendees were more likely than non-attendees to be clustered–i.e., have an identical DNA fingerprint with another isolate (27% vs. 21%, p = 0.037).

Conclusions

ED utilization by PTB patients, and related consequences, are substantial. EDs are a potential resource for earlier PTB diagnosis.

Improving natural ventilation in hospital waiting and consulting rooms to reduce nosocomial tuberculosis transmission risk in a low resource setting

Background

TB transmission in healthcare facilities is an important public health problem, especially in the often-overcrowded settings of HIV treatment scale-up. The problem is compounded by the emergence of drug resistant TB. Natural ventilation is a low-cost environmental control measure for TB infection control where climate permits that is suited to many different areas in healthcare facilities. There are no published data on the effect of simple structural modifications to existing hospital infrastructure to improve natural ventilation and reduce the risk of nosocomial TB transmission.

The purpose of this study was to measure the effect of simple architectural modifications to existing hospital waiting and consulting rooms in a low resource setting on (a) improving natural ventilation and (b) reducing modelled TB transmission risk.

Methods

Room ventilation was measured pre- and post-modification using a carbon dioxide tracer-gas technique in four waiting rooms and two consulting rooms in two hospitals in Lima, Peru. Modifications included additional windows for cross-ventilation (n = 2 rooms); removing glass from unopenable windows (n = 2); creation of an open skylight (n = 1); re-building a waiting-room in the open air (n = 1). Changes in TB transmission risk for waiting patients, or healthcare workers in consulting rooms, were estimated using mathematical modelling.

Results

As a result of the infrastructure modifications, room ventilation in the four waiting rooms increased from mean 5.5 to 15; 11 to 16; 10 to 17; and 9 to 66 air-changes/hour respectively; and in the two consulting rooms from mean 3.6 to 17; and 2.7 to 12 air-changes/hour respectively. There was a median 72% reduction (inter-quartile range 51–82%) in calculated TB transmission risk for healthcare workers or waiting patients. The modifications cost <US$75 in four rooms, and US$1000 and US$7000 in the remaining two rooms.

Conclusions

Simple modifications to existing hospital infrastructure considerably increased natural ventilation, and greatly reduced modelled TB transmission risk at little cost.

Systematic review with meta-analyses and critical appraisal of clinical prediction rules for pulmonary tuberculosis in hospitals

OBJECTIVE

To systematically review studies evaluating clinical prediction rules (CPRs) for adult inpatients suspected to have pulmonary tuberculosis.

DESIGN

Systematic review with meta-analyses.

SETTING

Hospitals. Patients Inpatients at least 15 years of age admitted to acute care.

METHODS

A search was conducted in 5 indexed electronic databases with no language or year of publication restrictions. We performed a meta-analysis for those CPRs with at least 2 validation studies. Results were reported according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

RESULTS

Of the 461 abstracts selected, 36 articles were fully analyzed and 11 articles were included, yielding 8 CPRs derived in 4 countries. Broad validation studies were identified for 2 CPRs. The most frequent clinical predictors were fever and weight loss. All CPRs included chest imaging signs. Most CPRs were derived in countries with a low prevalence of pulmonary tuberculosis and included homeless, immigrants, and those who reacted to the purified protein derivative test. Both of the CPRs derived in countries with a high prevalence of pulmonary tuberculosis strongly relied on chest radiograph predictors. Accuracy of the different CPRs was high (area under receiver operating characteristic curve, 0.79-0.91). Meta-analysis of 4 validation studies for Wisnivesky's CPR indicates optimistic pooled results: sensitivity, 94.1% (95% CI, 89.7%-96.7%); negative likelihood ratio, 0.22 (95% CI, 0.12-0.40).

CONCLUSION

On the basis of a critical appraisal of the 2 best validated CPRs, the presence of weight loss and/or fever in inpatients warrants obtaining a chest radiograph, regardless of the presence of productive cough. If the chest radiograph is abnormal, the patient should be placed in isolation until more specific test results are available. Validation in different settings is required to maximize external generalization of existing CPRs.

Active case finding of tuberculosis (TB) in an emergency room in a region with high prevalence of TB in Brazil

SETTING

Public hospital emergency room (ER) in Porto Alegre, Brazil, a setting with high prevalence of tuberculosis (TB) and human immunodeficiency virus (HIV) infection.

OBJECTIVE

To determine the prevalence of PTB, using a symptom based active case finding (ACF) strategy in the ER of a public hospital in an area with high prevalence of TB and HIV, as well as variables associated with pulmonary TB diagnosis.

METHODS

Cross sectional study. All patients ≥ 18 years seeking care at the ER were screened for respiratory symptoms and those with cough ≥ 2 weeks were invited to provide a chest radiograph and two unsupervised samples of sputum for acid-fast bacilli smear and culture.

RESULTS

Among 31,267 admissions, 6,273 (20.1%) reported respiratory symptoms; 197 reported cough ≥ 2 weeks, of which pulmonary TB was diagnosed in 30. In multivariate analysis, the variables associated with a pulmonary tuberculosis diagnosis were: age (OR 0.94, 95% CI: 0.92-0.97; p<0.0001), sputum production (OR 0.18, 95% CI 0.06-0.56; p = 0.003), and radiographic findings typical of TB (OR 12.11, 95% CI 4.45-32.93; p<0.0001).

CONCLUSIONS

This study identified a high prevalence of pulmonary TB among patients who sought care at the emergency department of a tertiary hospital, emphasizing the importance of regular screening of all comers for active TB in this setting.

Understanding the burden of tuberculosis among American Indians/Alaska Natives in the U.S.: a validation study

OBJECTIVE

We validated cases of active tuberculosis (TB) recorded in the Indian Health Service (IHS) National Patient Information Reporting System (NPIRS) and evaluated the completeness of TB case reporting from IHS facilities to state health departments.

METHODS

We reviewed the medical records of American Indian/Alaska Native (AI/AN) patients at IHS health facilities who were classified as having active TB using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnostic codes from 2006 to 2009 for clinical and laboratory evidence of TB disease. Individuals were reclassified as having active TB disease; recent latent TB infection (LTBI); past positive tuberculin skin test (TST) only; or as having no evidence of TB, LTBI, or a past positive TST. We compared validated active TB cases with corresponding state records to determine if they were reported.

RESULTS

The study included 596 patients with active TB as per ICD-9-CM codes. Based on chart review, 111 (18.6%) had active TB; 156 (26.2%) had LTBI; 104 (17.4%) had a past positive TST; and 221 (37.1%) had no evidence of TB disease, LTBI, or a past positive TST. Of the 111 confirmed cases of active TB, 89 (80.2%) resided in participating states; 81 of 89 (91.2%) were verified as reported TB cases.

CONCLUSIONS

ICD-9-CM codes for active TB disease in the IHS NPIRS do not accurately reflect the burden of TB among AI/ANs. Most confirmed active TB cases in the IHS health system were reported to the state; the national TB surveillance system may accurately represent the burden of TB in the AI/AN population.

Emergency department presentation of children with tuberculosis

OBJECTIVES

The objectives were to describe emergency department (ED) presentations of children with tuberculosis (TB) disease and assess the utility in children of TB screening tools developed for adults.

METHODS

Children at most 18 years old with confirmed or probable TB seen at the Children's TB Clinic from 2005 to 2009 who were initially evaluated in the ED for symptoms compatible with TB in the preceding month were included. TB was classified as microbiologically confirmed disease or probable TB disease, as defined by the World Health Organization.

RESULTS

Sixty children (29 with confirmed TB and 31 with probable TB) were identified after presentation to the ED, representing 35% of all children diagnosed with TB at the two hospitals during this interval. Eighty-eight percent were previously healthy. Fifty-five percent were Hispanic, 30% were black or African American, 12% were Asian, and 3% were white. Forty-four (73%) had intrathoracic disease (37 pulmonary parenchymal or pleural disease, four miliary disease, two endobronchial, one pericarditis). Sixteen (27%) had extrathoracic disease (eight meningitis, five cervical lymphadenopathy, two gastrointestinal, one interstitial keratitis), 11 of whom also had abnormal chest radiographs, including all eight children with TB meningitis. Most (76.7%) were diagnosed at the time of their first ED visit or during their first hospital admission, 12% after their second ED visit, 10% after their third ED visit, and one patient after six ED visits to various facilities. In 33 case (55%), the diagnosis was suspected in the ED because of epidemiologic risk factors (15), radiographic evaluation (11), or symptoms (7). Hemoptysis (12%) and night sweats (10%) were uncommon. Neither cavitary lesions (seen in two children) nor apical lesions (seen in 42%) predominated. The five screening tools validated for adults with pulmonary disease were 77% to 98% sensitive in identifying children with intrathoracic TB and 50% to 100% sensitive for extrathoracic TB.

CONCLUSIONS

The point of entry to health care for many children with TB is the ED. The more protean manifestations of TB in children can decrease the utility of screening tools developed to identify adults with TB. While TB in adults often is a microbiologic diagnosis, childhood TB often is an epidemiologic diagnosis. Therefore, questioning caregivers about TB risk factors in the family may identify a higher percentage of children with possible TB.

Evaluation of clinical prediction rules for respiratory isolation of inpatients with suspected pulmonary tuberculosis

BACKGROUND

In the framework of hospital infection control, various clinical prediction rules (CPRs) for respiratory isolation of patients with suspected pulmonary tuberculosis (PTB) have been developed. Our aim was to evaluate their performance in an emergency department setting with a high prevalence of PTB.

METHODS

We searched the MEDLINE and OVID databases to identify CPRs to predict PTB. We used a previously collected database containing clinical, radiographical, and microbiological information on patients attending an emergency department with respiratory complaints, and we applied each CPR to every patient and compared the result with culture for Mycobacterium tuberculosis as the reference standard. We also simulated the proportion of isolated suspects and missed cases for PTB prevalences of 5% and 30%.

RESULTS

We withheld 13 CPRs for evaluation. We had complete data on 345 patients. Most CPRs achieved a high sensitivity but very low specificity and very low positive predictive value. Mylotte's score, which includes results of sputum smear as a predictive finding, was the best-performing CPR. It attained a sensitivity of 88.9% and a specificity of 63.9%. However, at a 30% PTB prevalence, 498 of 1000 individuals with suspected PTB would have to be isolated; 267 of these cases would be true PTB cases, and 33 cases would be missed. Two consecutive sputum smears had a sensitivity of 75.6% and a specificity of 99.7%.

CONCLUSIONS

In a setting with a high prevalence of PTB, only 1 of the 13 assessed CPRs demonstrated high sensitivity combined with satisfactory specificity. Our results highlight the need for local validation of CPRs before their application.

Communicable respiratory threats in the ED: tuberculosis, influenza, SARS, and other aerosolized infections

Respiratory infections are the most common communicable infectious diseases. EDs are the front line for patients with respiratory infections because of their acute nature and because the ED is the principal site of health care for those at highest risk. These diseases include influenza, tuberculosis, and measles, together accounting for 25% of infectious causes of death worldwide. These are emerging and biothreat agents that follow the same route of transmission, such as pneumonic plague. We discuss epidemiology, pathogenesis, diagnosis, and treatment of each agent. Emphasis is on the ED's role as a public health prevention arena, with attention to education and disease prevention, early identification of disease in patients at risk, and reduction of illnesses.

Validity of clinical prediction rules for isolating inpatients with suspected tuberculosis. A systematic review

OBJECTIVE

Declining rates of tuberculosis (TB) in the United States has resulted in a low prevalence of the disease among patients placed on respiratory isolation. The purpose of this study is to systematically review decision rules to predict the patient's risk for active pulmonary TB at the time of admission to the hospital.

DATA SOURCES

We searched MEDLINE (1975 to 2003) supplemented by reference tracking. We included studies that reported the sensitivity and specificity of clinical variables for predicting pulmonary TB, used Mycobacterium TB culture as the reference standard, and included at least 50 patients.

REVIEW METHOD

Two reviewers independently assessed study quality and abstracted data regarding the sensitivity and specificity of the prediction rules.

RESULTS

Nine studies met inclusion criteria. These studies included 2,194 participants. Most studies found that the presence of TB risk factors, chronic symptoms, positive tuberculin skin test (TST), fever, and upper lobe abnormalities on chest radiograph were associated with TB. Positive TST and a chest radiograph consistent with TB were the predictors showing the strongest association with TB (odds ratio: 5.7 to 13.2 and 2.9 to 31.7, respectively). The sensitivity of the prediction rules for identifying patients with active pulmonary TB varied from 81% to 100%; specificity ranged from 19% to 84%.

CONCLUSIONS

Our analysis suggests that clinicians can use prediction rules to identify patients with very low risk of infection among those suspected for TB on admission to the hospital, and thus reduce isolation of patients without TB.

Miniature chest radiograph screening for tuberculosis in jails: a cost-effectiveness analysis

Jails are an important reservoir of tuberculosis infection in the United States. Screening for active disease in these high-risk settings is difficult. We used decision analysis to assess the cost effectiveness of routine miniature chest radiography for screening for tuberculosis on admission to jail. Infection rates, probabilities, and costs associated with detecting and treating tuberculosis were derived from published studies. We calculated an average total cost of $6.60 per inmate for routine radiograph screening on admission to jail. The cost of screening for active tuberculosis with miniature chest radiography was estimated to be $9,600 per case identified, compared with $32,100 per case with tuberculin skin testing and $54,100 per case with symptom screening. Chest radiography would also identify substantially more cases than other methods of screening. Screening for tuberculosis with miniature chest radiography is cost effective even under a wide range of assumptions regarding risk factors and prevalence of disease. Miniature chest radiography should be strongly considered as an important tool in the fight to eliminate tuberculosis from the high-risk populations that may be reached through screening in jails.

Implementation of an emergency department triage procedure for the detection and isolation of patients with active pulmonary tuberculosis

STUDY OBJECTIVES

To investigate the ability of an emergency department screening protocol to initiate respiratory isolation of patients with pulmonary tuberculosis at ED triage before chest radiography.

METHODS

We conducted a prospective cohort study with retrospective medical record review of adult patients who presented for care to an urban, university-affiliated hospital in Los Angeles County over a 4-month period. Ambulatory patients were administered a triage screening protocol that used patient-reported tuberculosis risk factors and symptoms in combination with selective chest radiography to screen patients at ED triage for active pulmonary tuberculosis.

RESULTS

A total of 10,674 patients were screened; 2, 218 were isolated at triage and underwent chest radiography, and 378 were kept in isolation in the ED. The respiratory isolation of pulmonary tuberculosis (RIPT) protocol detected 17 of 27 visits made by patients with unsuspected pulmonary tuberculosis, yielding a sensitivity of 63% (95% confidence interval [CI] 42% to 81%). The estimated specificity was 78%. For each patient with tuberculosis who was detected by the RIPT protocol, 624 patients were screened at triage, 130 chest radiographs were taken, and 22 patients were placed in respiratory isolation in the ED. Patients with undetected pulmonary tuberculosis more commonly had nonpulmonary chief complaints (76% versus 20%; odds ratio [OR] 13, 95% CI 2.1 to 78.3), and only 60% (95% CI 26% to 88%) were ultimately isolated in the hospital. Among RIPT screen-positive patients, radiographic findings predictive of pulmonary tuberculosis were cavitary lesions (OR 84.3, 95% CI 22.6 to 315), upper lobe infiltrates (OR 24.2, 95% CI 9.1 to 64.4), pleural effusions (OR 8.9, 95% CI 2.5 to 31.8), diffuse/interstitial infiltrates (OR 5.7, 95% CI 1.8 to 17.9), and non-upper lobe infiltrates (OR 3.1, 95% CI 1.0 to 9.5).

CONCLUSION

The RIPT screening protocol was only moderately sensitive for isolating patients with pulmonary tuberculosis at ED triage. Future studies should evaluate modified and abridged screening protocols, as well as the cost-effectiveness of triage screening.