1216 infection control & hospital epidemiology october 2015, vol. 36, no. 10
Using this information, we have identified an infection prevention strategy that can be used to increase detection and empiric treatment of infectious pulmonary TB patients and optimize utilization of AIIRs.
epidemiology Disease Burden
From 1993 to 2012, US TB incidence rates decreased from 9.7 TB cases per 100,000 population to 3.2 TB cases per 100,000 population.14 During 2012, nearly 50% of TB cases were reported in California, Florida, New York, and Texas; however, these states accounted for less than 33% of the US population.14 The distribution of TB within states is also heterogeneous. For instance, in California, TB cases were reported in 48 of 61 local health jurisdictions during 2012; however, 6 jurisdictions accounted for 68% of reported TB cases.15 In the United States, TB persists in specific populations.
Foreign-born persons are disproportionately affected by TB and accounted for 63% of TB cases during 2012.14 Important differences in demographic and clinical characteristics have been reported between foreign-born and US-born TB patients,16–20 and these differences need to be considered to rapidly diagnose TB and to reduce TB transmission. First, a higher proportion of foreign-born TB patients have immuno- suppressing conditions such as diabetes16 and end-stage renal disease18 at the time of TB diagnosis. Second, foreign-born TB patients may be less likely to have traditional TB risk factors such as human immunodeficiency virus (HIV) infection, homelessness, or substance abuse.19,20 Third, among culture- positive pulmonary TB patients, foreign-born persons were more likely to have negative acid-fast bacilli (AFB) sputum smears.17 Although no difference in mortality was noted according to sputum smear status,17 previous studies have reported that a negative AFB sputum smear result is associated with delays in initiation of TB treatment21 and is responsible for up to 17% of TB transmission.22 These characteristics of current TB epidemiology in the United States can inform approaches to diagnosis.
Hospitalizations
Cohort studies have estimated that 50%–75% of TB patients are hospitalized for TB,23,24 and 83% of these hospitalizations occur at the time of TB diagnosis.24 From 1995 to 2006, the number of hospitalizations with a principal diagnosis of TB decreased 41% from 15,000 to 8,800; the number of hospita- lizations with a secondary diagnosis of TB decreased 10% from 55,000 to 49,700.25 The average length of stay for a TB hospi- talization is between 9 to 17 days,23,25 and the estimated cost per hospitalization is $6,000 to $27,000.23,25,26An estimated 65%–80% of the total cost associated with TB hospitalization is borne by the public sector, which includes local, state, and federal governments as well as public hospitals.25,27
Patients hospitalized for TB are more likely to be homeless, to use alcohol or other drugs, and to have HIV infection compared with TB patients who were not hospitalized.23 Considerable geographic variation in hospitalization among TB patients has been reported,23 which may be attributed to local hospitalization practices or to coexisting medical conditions and severity of TB disease among patients. Despite the implementation of health department guidelines for hospitalization of patients with suspected or confirmed TB that incorporate medical and social factors, almost 40% of hospitalizations for TB patients in New York City could have been avoided.24 These findings suggest that partnerships between health departments and hospitals may be needed to ensure appropriate utilization of inpatient care for TB patients.
Mortality
From 1993 to 2010, TB mortality rates decreased from 0.6 TB deaths per 100,000 population to 0.2 TB deaths per 100,000 population.14 During 2010, 893 deaths were reported among patients with TB; 28% of these deaths occurred before initia- tion of TB treatment and 72% occurred during TB therapy.14 The substantial proportion of deaths that occur prior to treatment highlights the importance of timely diagnosis. Analyses of county and statewide TB surveillance data have identified several risk factors associated with death among TB patients28–34 that may be important to consider among hospitalized patients. Receipt of fluoroquinolones in the 6 months prior to TB diagnosis,28 HIV infection,28–32,34 excessive alcohol use,30,33 and age 65 years and older33,34 have all been identified as risk factors associated with death among patients with TB. Although the proportion of TB deaths that are preventable is unknown, interventions that could result in earlier TB diagnosis among patients hospitalized with risk factors and symptoms consistent with TB or death with TB may decrease the proportion of patients who die. These characteristics and outcomes of tuberculosis patients across the United States are important to consider in formulating a TB diagnostic and infection prevention strategy in diverse settings.
clinical prediction rules to identify culture-positive tb patients
Numerous CPRs for predicting patients who have culture- positive pulmonary TB in acute care facilities have been pub- lished.35–44 Although most published CPRs include clinical data routinely available at the time of admission to an acute care hospital,35–42 some CPRs include results for laboratory tests, such as the AFB sputum smear,43,44 which are often not available when a healthcare provider must make a decision to admit a patient to an AIIR. Studies evaluating CPRs that identify patients with culture-
positive pulmonary TB are summarized in Table 1.35–42 All studies were conducted in an academic or academically affiliated healthcare facility in an urban area in the United States
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