presentation to national alliance for radiation readiness november 16, 2011 large-scale testing for...
TRANSCRIPT
Presentation to
National Alliance for Radiation ReadinessNovember 16, 2011
Large-Scale Testing for ARS after a Nuclear Detonation
• As a result of a ground burst 10kt nuclear detonation in a major city:– Many thousands of people would be exposed to life-
threatening doses of radiation from fallout – Medical interventions could save many of these people– Resources (medicines, hospital beds, transportation)
would be limited and therefore victims must be triaged
• How can the patients most likely to benefit from medical intervention be rapidly and accurately identified?
THE CHALLENGE
• Modeling estimates ~100,000 people may develop ARS from fallout
• It may not be obvious early on who these people are– early symptoms are non-specific and unreliable– Many other concurrent reasons for symptoms
• “Worried well”, stress reaction, normal illnesses, head injuries, ear drum rupture, etc
– Geographic information may not be sufficient
• Testing many times the 100,000 may be needed to identify all those with impending ARS.
• Reasonable to estimate that in a metro area of 3 million, 1 million people may need to be screened
TESTING ONE MILLION PEOPLE?
• Countermeasures (bone marrow stimulators) are most effective if given early—within 1-2 days.
• Getting patients to care (RITN or other) may take days.
• Many patients with ARS will have a latent period of several days before the onset of severe illness.
SHORT TIME FRAME FOR SCREENING
• Many of the people in the area of the detonation will evacuate (informed or not) and they may be on the move for days given transportation and lodging challenges.
• They may first present for screening in other cities or towns.
• They may not be in the same place if they need follow-up testing.
• They may not be in the same place when they become seriously ill.
A POPULATION ON THE MOVE
• Can 1 million people be screened for ARS over a 24 hour period (starting within 1-2 days of a nuclear detonation) regardless of where they are and have their results be immediately available to any clinician anywhere in the country using only existing technology and systems?
THE THOUGHT EXPERIMENT
• Time to vomiting– Most people exposed to >2 Sv will vomit within 4 hours– However, vomiting is non-specific and unreliable (many
false positives and false negatives)– Severe, repetitive vomiting may be more reliable– Absence of any nausea or vomiting indicates less risk of
significant exposure
POSSIBLE METHODS
• Chromosomal Dicentrics– Gold standard– Not performed in most laboratories– Specially trained personnel– Takes time for results– Current national capacity is 50-100 tests week. May be
able to increase to 1000 week in next few years.
POSSIBLE METHODS FOR SCREENING
• Investigational:– Electroparamagentic spin resonance (EPS) of dental
enamel-Ideally performed on extracted teeth but can be done one nails and teeth in head
– Stress gene and protein signature– Metabolomics (urine)– Ocular albumin– others
• All early stage R&D
POSSIBLE METHODS
• Predictable time-dependent decrease in ALC after radiation exposure– If time of exposure known, approximate whole body
dose can be estimated– For single test, measurement at 48 hour is most useful
• Serial testing adds value• Comparison to neutrophil count adds value
ABSOLUTE LYMPHOCYTE COUNT
• ALC enables prioritizing patients most like to benefit from treatment (hospitalization, G-CSF, blood products, antibiotics): – Too low to benefit from treatment (will die even with
treatment)– Too high to need treatment (will recover without
treatment)– Treatment can make the difference between life and
death
ALC: CATEGORIES OF TRIAGE
• Performed in all clinical laboratories as part of CBC/d
• Automation• No special training of technicians
ALC: ADVANTAGES
• After a nuclear detonation some local hospital labs may be destroyed
• Other hospitals’ labs may be overwhelmed with medical surge (trauma, prompt radiation, evacuated patients, etc)
• Deployable labs have limited capacity—– With people on the move, where to deploy to?
• Physician office and clinic labs: low volume and slow
• Need for ability to track/match results with patients as they move
WHO WOULD PERFORM ALCS?
• 2 major national laboratory chains serve the US– LabCorp (1700 patient care sites, 51 major laboratories)– Quest Diagnostics (2000 patient care sites, 37 major
laboratories)– Both possess transportation fleets including fixed-wing
aircraftTogether they believe that they possess have the capacity to do 1 million ALCs in a 24 hour periodBoth have extensive internet portals that allow patient tracking of results; most physicians and most Americans already are registered with one or both
NATIONAL LABORATORY CHAINS
• Many challenges to implementation– Reagent Supply Chain-JIT inventory principles– Interoperability between IT systems– Need to integrate smaller labs– Logistics of phlebotomy
• Phlebotomy supplies
– Physician order rules• Some states require Rx for labwork
• None seem insurmountable
• Next steps…….?
CHALLENGES