Table 2.

Characteristics and main results of manuscripts that considered chest X-rays for active TB case finding, by study type and year of publication.

References	Country (incidence level)	Study type	Sample size and methodology	Results
Li et al. (8)	China (Intermediate: (article definition)/(high: WHO definition)	Cost-effectiveness modeling	Derived from Markov model, a decision analytic process was created using an imagined 65-years-old sample and a 20 years time frame. Four different screening strategies were analyzed: (i) no screening, (ii) TB screening (CXR), and (iii) TB screening (Xpert) represent screening for TB in symptomatic elderly by chest X-ray and Xpert® MTB/RIF, respectively, and (iv) LTBI/TB by QuantiFERON®-TB Gold In-Tube and chest X-ray. No screening was the reference. US $50,000 per QALYs gained was used as the threshold for cost-effectiveness.	No screening was the most cost-saving strategy. However, in 1,000 iterations of Monte Carlo simulation, the probabilities of no screening, TB screening (CXR), TB screening (Xpert), and LTBI/TB screening to be cost-effective were 0, 1.3, 20.1, and 78.6%, respectively. Also LTBI/TB screening was the most effective strategy with highest life-years (LYs) and life-years and QALYs.
Kowada (9)	Japan (Low)	Cost-effectiveness modeling	Population studied was comprised of fictitious 84-years-old LTCF residents, some with various comorbidities. Markov models and decision trees were created for seven different screening strategies. Quality-adjusted life-years (QALYs) were used as primary outcome for effectiveness.	The most cost-effective screening practice was QFT (US$ 50,000/QALY), while TST then QFT was best for residents with comorbidities. Diagnosing and treating LTBI is a more efficient procedure than active case-finding, as concerns the mitigation of TB in LTCFs.
Verma et al. (7)	Canada (Low)	Cost-effectiveness modeling	A Markov model was constructed for the three screening strategies to be assessed [no screening, two-step TST (LTBI), and CXR (active TB)] on entry to LTCFs. Alberta LTCF resident TB screenings from 2000 to 2010, and historical charts of TB patients from 1990 to 1996 made up the sample for this analysis. Outcomes for this model were TB cases averted, cases of active TB found with each strategy, and amount saved per case found. One-way sensitivity analysis done for all factors; 95% CIs and reasonable ranges for data-based probabilities and literature-derived values, respectively.	It required 1410 screenings with the LTBI approach to avert one active case, at a cost of $10,9913 CAD; it took 1266 screenings with the CXR approach to avert one active case, at a cost of $67,2298 CAD. Generally speaking, the authors note that both costs required to identify one case are quite high.
Kowada et al. (10)	Japan (Low)	Cost-effectiveness modeling	They constructed a Markov model to evaluate the cost effectiveness one time TB/LTBI screening of those aged over 65 years with QFT (two steps: detection of TB/LTBI by QFT, followed by detection of TB by CXR) vs. one-step detection of TB by CXR, or a no screening strategy, using a hypothetical cohort of 1,000 immunocompetent 65 years-old, vaccinated people. The main outcome measure was quality-adjusted life-years (QALYs) gained, using a lifetime horizon.	The no-screening strategy was the least costly ($US 303.51), while QFT was the most effective (14.6516 QALYs) compared with CXR (14.6477QALYs). QFT may become more cost effective than no screening when the sensitivity of QFT is over 0.89 and the prevalence of disease is higher.
Piccazzo et al. (11)	N/A (N/A)	Systematic Review	A systematic review of the literature concerning the utility of CXR for LTBI screening and uncovering TB cases was carried out, beginning with retrieval of 1,111 articles from PubMed, and concluding with a final review of 67 papers.	To reliably diagnose active TB, CXR must be examined “on the basis of temporal evolution of pulmonary lesions.” Normal CXR is not infrequent for patients presenting with TB symptoms and culture-positive. It is essential that a CXR is carried out after a positive TST/IGRA.
Marciniuk et al. (12)	Canada (Low)	Retrospective Cohort Study	518 patients who were culture-positive for TB were identified between 1988 and 1997. Medical history, symptoms, test results (CXR, cultures), and demographic data were reviewed and explained through descriptive statistics.	Positive cases of TB with normal CXR are not infrequent, and may be on the rise. 25 (4.8%) of the sample classified as having culture-positive TB had regular CXRs; 23 of these 25 had symptoms indicative of TB, while contact tracing was used to diagnose the remaining 2.
Thrupp et al. (4)	United States (low)	Review and position statement	A review of evidence and analysis as background for a position statement and recommendations to prevent and control TB in LTCF. No method described.	Newly admitted patients should undergo TST unless a prior positive result is already on record. A chest radiograph and clinical diagnostic evaluation should be performed for those with a positive TST result. If the initial TST result is negative, the second step of a two-step test should be done. Patients with known prior positive TST results with normal findings on chest radiographs or those with stable old changes on chest radiograph should be re-evaluated periodically for change in symptoms suggestive of TB. Chest radiographs should be repeated only if clinically indicated.

CXR, Chest X-ray; TB, tuberculosis; TST, tuberculin skin test; IGRA, Interferon-Gamma Release Assays; N/A, Not applicable; QFT, QuantiFERON®-TB Gold In-Tube; QALYs, quality adjusted life-years gained.