Interferon-gamma release assays for diagnosing mycobacterium tuberculosis infection in renal dialysis patients.
OBJECTIVE
End-stage renal disease (ESRD) patients are at high risk for tuberculosis (TB). IFN-gamma release assays that assess immune responses to specific TB antigens offer potential advantages over tuberculin skin testing (TST) in screening such patients for Mycobacterium tuberculosis infection. This study sought to determine whether IFN-gamma release assay results are more closely associated with recent TB exposure than TST results.


METHODS
Prospective cohort investigation of patients at a hemodialysis center with a smear-positive case of TB. Patients without a history of TB underwent initial and repeat testing with TST, and with the IFN-gamma assays QuantiFERON-TB Gold (QFT-G) and ELISPOT test. Outcome measures included the prevalence of positive test results, identification of factors associated with positive results, and test result discordance.


RESULTS
A total of 100 (47% foreign born; median age, 55 yr; age range, 18 to 83 yr) of 124 eligible patients were enrolled. Twenty-six persons had positive TST results, 21 had positive QFT-G results, and 27 had positive ELISPOT results. Patients with TB case contact were likely to have a positive QFT-G result (P = 0.02) and ELISPOT results (P = 0.04), whereas TB case contact was not associated with positive TST results (P = 0.7). Positive TST results were associated with foreign birth (P = 0.04) and having had a TST in the previous year (P = 0.04).


CONCLUSIONS
Positive IFN-gamma assay results were more closely associated with recent TB exposure than were positive TST results. QFT-G and ELISPOT might offer a better method for detecting TB infection in ESRD patients.
Winthrop
Kevin L
KL
Division of Tuberculosis Elimination, National Center for HIV, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, USA. Winthrop@ohsu.edu
Nyendak
Melissa
M
Calvet
Helene
H
Oh
Peter
P
Lo
Melanie
M
Swarbrick
Gwendolyn
G
Johnson
Carol
C
Lewinsohn
Deborah A
DA
Lewinsohn
David M
DM
Mazurek
Gerald H
GH
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000942:Antigens, Bacterial / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000097:blood*; D007676:Kidney Failure, Chronic / Q000150:complications / Q000276:immunology / Q000382:microbiology / Q000628:therapy*; D008214:Lymphocytes / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000276:immunology* / Q000302:isolation & purification; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011933:Reagent Kits, Diagnostic; D006435:Renal Dialysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014374:Tuberculin Test; D014376:Tuberculosis / Q000175:diagnosis* / Q000276:immunology / Q000382:microbiology
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C117940:CFP-10 protein, Mycobacterium tuberculosis; C093276:ESAT-6 protein, Mycobacterium tuberculosis; D011933:Reagent Kits, Diagnostic; D007371:Interferon-gamma