NAAT

Is it Time for a New Option in California?

Background

• CDC 2009 guidelines recommend NAAT for each patient with suspected TB for whom the test result would alter treatment or TB control activities

• Experience in several settings has found significant efficiencies with NAAT by reducing unnecessary– treatment– isolation– contact investigation

Challenges

• Test characteristics– limited sensitivity for smear negative – laboratory complexity (MTD)– variable performance (home brew)

• Availability

• Delay in results

GeneXpert (Cepheid)

• New platform for TB NAAT• Platform used for other diseases• Technically simple• Performance similar to MTD

– very high specificity– very high sensitivity for smear positive– ~75% sensitivity for smear negative

• Provides rapid rifampin susceptibility• FDA approval possible

Luke Davis. MD

Under-treatment is rare in SFDPH TB Clinic…• 426 TB suspects (TB5) in 2009 • 65 (15%) TB3

– Only 2 (3%) not started on empiric treatment

Luke Davis. MD

…Over-treatment is common in SFDPH TB Clinic• 109/426 TB5s were treated

– 46/109 (42%) did not have TB • 31 (29%) received unnecessary DOT • Median 47 days of unnecessary treatment

• 29/63 (46%) contact investigations initiated unnecessarily– 87/321 (27%) “case” contacts unnecessarily identified

Luke Davis. MD

TB GeneXpert Protocol at SFDPH• Included

– Pulmonary TB Suspect High/Moderate starting TB treatment– Pulmonary TB Suspect Low in congregate housing

• Excluded– Prior TB treatment within last 12 months

• Procedures– Sputum x 3 for routine AFB smear/culture– Sputum x 1 for TB GeneXpert

• Testing – Performed at SFDPH 2-3 days week, results within 1-2 days

• Monthly follow-up until confirmed final diagnosis if treatment held

Luke Davis. MD

15 High & Moderate TB Suspects on Treatment• Xpert changed treatment in 9

– 4 AFB+, Xpert+ M. TB, empiric treatment continued– 1 AFB+, Xpert- M. kansasii, empiric treatment changed– 10 AFB-, Xpert-

• 8 empiric treatments changed– 6 TB0 Stopped when Xpert-– 2 TB4 Tailored to INH+RIF for TB4

• 2 empiric treatments continued– 1 TB0 Stopped after 2 months– 1 TB3 Continued when BAL +

• Contact investigation suspended in all 11 Xpert- – In 1 AFB-, BAL MTB+ patient, contact investigation started later

Luke Davis. MD

4 TB5 Low

• 3 not on treatment– All AFB-, Xpert-

• Sent to MH/SA programs

• 1 on treatment – AFB-, Xpert-

• Treatment discontinued• Sent to MH/SA program

TB controllersHow birds see the world

Why Now?

• APHL/CDC funding opportunity for equipment and supply purchase

• New system with better characteristics

• Importance of efficiency in current resource setting

• Continued requests for NAAT

Options

• Local public health labs could implement—likely not feasible for all

• Some hospitals may offer—availability unclear

• CDPH could implement, either at state or a local lab

State Option

• GeneXpert system– rapid diagnosis of M. tb complex (NAAT)– expanded rapid rifampin resistance testing

• Follow up culture and DST

• Prepaid shipping contract

What Will it Take?

• Funds available for initial investment

• Recurrent costs (staff, supplies, shipping): $215,000/year

• Some funds may come from other sources– CDCR?– CDC?

• Balance from local assistance/detention– used for emergency funding requests

Discussion