Cost Comparison and Clinical Evaluation of a Blood Test for Tuberculosis (TB) in a Correctional Setting

Transcription

1 Cost Comparison and Clinical Evaluation of a Blood Test for Tuberculosis (TB) in a Correctional Setting Princess Adaku Iroh, M.Sc. Academic and Health Policy Conference on Correctional Health March 20th, 2015

2 Disclosures Research Funding provided by QIAGEN

3 Educational Goals & Objectives 1) To describe the long term difference in costs between the Tuberculin Skin Test (TST) and QuantiFERON-TB Gold In-Tube (QFT-GIT) blood test for latent tuberculosis infection (LTBI) in the Dallas County Jail (DCJ) 2) To describe the prevalence of LTBI in the DCJ as measured by the TST and the QFT-GIT test 3) To describe the HIV positivity rate and HIV risk behaviors in the cohort tested for LTBI while entering the DCJ

4 Presentation Outline Background Methods Results Discussion Conclusion

5 Background Globally, 9 million people develop active TB annually United States in 2013: 9,582 active TB cases Four states (CA, TX, NY, and FL) accounted for half of these cases TX, 2013: 1,222 TB cases 164 (13.4%) dx in a correctional facility 53 (32.3%) occurred in local jails 4,300-5,900 TSTs are placed per month at Dallas County Jail Requiring 8 full time-equivalent nurses or medical aides Includes staff time for reading TST result at inmate s cell

6 TB screening Limitations Tuberculin Skin Test (TST) Variability in placement and interpretation of result Requires return visit after hrs. Cross reaction with BCG vaccine, Non TB Mycobacterium (NTM) No controls used Interferon-gamma release assays (IGRA) Standard interpretation of laboratory result Does not require a return visit Test is unaffected by BCG vaccine, limited NTM crossreactivity Positive and negative controls Sensitivity 59-97% 81-83% Specificity 70-89% 99% Cost/test $1 $37

7 Presentation Outline Background Methods Results Discussion Conclusion

8 Study Recruitment Single study site: Dallas County Jail (DCJ) Enrollment period: June October 2014 Goal Enrollment: 500 subjects Recruitment location: Classification area Inclusion criteria: Inmate, age 18 or older No prior LTBI or active TB Speak English and be able to provide informed consent Exclusion criteria: Completed and documented TST in past 3 months Ineligible to have TST placed

9 Dallas County Jail - Study Site 7th largest county jail Average daily intake of 275 new arrestees Average daily census of 6200 inmates 77% Male, 23% Female Health care delivery by Parkland Hospital

10 Study Procedures After recruitment, HIPPA and participation consent, each inmate completed: 1. TB/HIV Risk Questionnaire 2. Blood draw for HIV Ab then QFT-GIT 3. TST placement (per DCJ protocol) 4. QFT-GIT samples transported to the Children s Medical Center of Dallas (CMC) Laboratory 5. Research team notified of indeterminate results or insufficient sample, otherwise blinded

11 Time-in-Motion Sub-study Research assistant timed (with a stopwatch) multiple iterations of the following: TST placement (TB staff and security time) TST reading (TB staff and security time) QFT-GIT blood draw (phlebotomy and security time) Chest X-ray (radiology technician and security time, interpretation) Treatment/consultation (MD, nurse and pharmacist time)

12 Presentation Outline Background Methods Results Discussion Conclusion

13 Enrollment Details Inmates Screened (n=576) Consented (n=529) Refused (n=15) Fear of needles (6) Confidentiality concerns (2) Other (7) Ineligible (n=32) Age <18 (6) Recent TST placed (16) Prior LTBI/active TB (10) Blood Drawn (n=501) Unable to draw blood (n=28) Indeterminate (n=2) Lab Error (n=6) QFT-GIT Results (n=493)

14 Table 1. Baseline characteristics Characteristic Overall 529 (100%) Gender Male 397 (75%) Age, mean (years) (46%) (26%) (17%) >50 59 (11%) Ethnicity Hispanic 128 (24%) Non-Hispanic 303 (57%) Unknown 97 (18%) Race Black 244 (46%) White 151 (29%) Native American* 21 (4%) Asian 4 (1%) Pacific Islander** 1 (<1%) Other 122 (23%) Non US born 19 (4%) Stayed in homeless shelter 75 (14%) First incarceration 81 (15%) Ever Injected Drugs 89 (17%) MSM 20 (4%) HIV + 13 (2%) Tested for HIV in past 376 (71%) Past positive TB 6 (1%) Ever treated for TB 6 (1%) Vaccinated with BCG 63 (12%) Ever been exposed to TB 15 (3%) TB symptoms, any 7 (1%)

15 Table 2. Paired Results of testing with QFT and TST QFT + QFT - Total TST TST Total TST positivity rate: 9/351 = 2.6% QFT positivity rate: 47/351 = 13.4% Kappa score: 0.142

16 Table 3. HIV Ab Test Results Non-Reactive 471 (89.0%) Confirmed-known Positive 13 (2.5%) Preliminary Positive 1 (0.2%) Blood Draw Failure 26 (4.9%) Quantity Not Sufficient (QNS) 8 (1.5%) Refused 5 (0.9%) Missing Result 5 (0.9%) Total 529

17 Table 4. Time-in-Motion Procedure (# measurements) TST QFT TST placement (19) Nursing time 3 min 0 min Security time 1 min 0 min TST reading 3 towers (65) Nursing time 11 min 0 min Security time 2 min 0 min TST result entry (27) Nursing time 12 min 0 min QFT-GIT blood draw (23) Nursing time 0 min 3 min Security time 0 min 3 min Total Nursing time 26 min 3 min Total Security time 3 min 3 min

18 Presentation Outline Background Methods Results Conclusion Discussion

19 Conclusions QFT-GIT positivity was unexpectedly high (13.4%) and much higher than TST positivity (2.6%) Bundled QFT-GIT/ HIV testing was acceptable and 2.5% of individuals were HIV-infected (all prior known infections) Time-in-motion/Cost Analysis QFT testing more time-efficient, though overall cost higher Potentially a more accurate screening tool for LTBI If QFT-GIT better at identifying active TB than may result in cost savings QFT provides a platform to include screening for other public health infections

20 Why high QFT+ test results? False positives unlikely Average quantitative results well above positivity cut-off Validated 10 QFT tests same results from different lab Rikers reported initial QFT-GIT+ at 10% Recent TB outbreak in homeless shelters in Dallas County High discordance between TST & QFT TST re-reading Performed an internal audit on 73 inmates 7 (9.5%) initially read as negative had + TST QFT could be identifying more LTBI and/or active TB in a high risk population

21 Acknowledgements and Collaborating Agencies UT Southwestern Medical Center Ank Nijhawan Parkland Health and Hospital Systems/ Dallas County Jail Esmaeil Porsa Rolanda Williams, Walter Ramos Merilyne Aguwa, Yosha Franklin QIAGEN John Harborth, Brian Barron Children s Medical Center Laboratory Clay York, John Burns, Brenda Newton The National Center for Advancing Translational Sciences of the National Institutes of Health - award Number UL1TR Study data were collected and managed using REDCap electronic data capture tools hosted at UT Southwestern Medical Center