Clinical Impact and Cost-effectiveness of Xpert MTB/RIF Testing in Hospitalized Patients With Presumptive Pulmonary Tuberculosis in the United States.
Microscopic examination of acid-fast-stained sputum smears is the current standard of care in the United States to determine airborne infection isolation (AII) of inpatients with presumptive pulmonary tuberculosis (PTB). However, nucleic acid amplification testing (NAAT) with the Xpert MTB/RIF assay (Xpert) may be more efficient and less costly.



This prospective observational cohort study enrolled a consecutive sample of 318 AII-eligible inpatients from a public hospital in Seattle, Washington, from March 2012 to October 2013. Sputum samples were collected from each inpatient and analyzed using smear microscopy, culture, drug susceptibility testing, and NAAT. The performance, clinical utility (AII duration and survival), and cost-effectiveness from an institutional perspective were compared for 5 testing strategies.



Among the 318 admissions with presumptive PTB, 20 (6.3%) were culture-positive for Mycobacterium tuberculosis. The sensitivity of 1 Xpert, 2 Xperts, 2 smears, or 3 smears compared to culture was 0.85 (95% confidence interval [CI], .61–.96), 0.95 (95% CI, .73–1.0), 0.70 (95% CI, .46–.88), and 0.80 (95% CI, .56–.93), respectively. A cost-effectiveness analysis of the study results demonstrated that an Xpert test on 1 unconcentrated sputum sample (assuming equivalent results for unconcentrated and concentrated sputum samples) is the most cost-effective strategy (99.9% preferred at willingness-to-pay of US$50000) and on average would save 51.5 patient-hours in AII and up to $11466 relative to microscopy without a compromise in sensitivity.



In hospitalized patients with presumptive PTB in a low-burden setting, NAAT can reduce AII and is comparably sensitive, more specific, and more cost-effective than smear microscopy.
Department of Global Health, University of Washington Schools of Medicine and Public Health.
James F
JF
Cowan
Department of Medicine, University of Washington School of Medicine.
Aldine S
AS
Chandler
Department of Medicine, University of Washington School of Medicine.
Elizabeth
E
Kracen
Department of Global Health, University of Washington Schools of Medicine and Public Health.|Harborview Medical Center.
David R
DR
Park
Harborview Medical Center.|Department of Laboratory Medicine, University of Washington School of Medicine, Seattle.
Carolyn K
CK
Wallis
Cepheid, Sunnyvale, California.
Emelline
E
Liu
Cepheid, Sunnyvale, California.
Chao
C
Song
Cepheid, Sunnyvale, California.
David H
DH
Persing
Harborview Medical Center.|Department of Laboratory Medicine, University of Washington School of Medicine, Seattle.|Department of Microbiology, University of Washington School of Medicine, Seattle
Ferric C
FC
Fang
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003362:Cost-Benefit Analysis; D004269:DNA, Bacterial; D005260:Female; D006760:Hospitalization; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000302:isolation & purification; D021141:Nucleic Acid Amplification Techniques / Q000191:economics / Q000379:methods; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000382:microbiology* / Q000635:transmission; D014861:Washington; D055815:Young Adult
D004269:DNA, Bacterial