Point of care testing for respiratory viruses Jen Kok Medical Virologist Centre for Infectious Diseases and Microbiology Laboratory Services Pathology West ICPMR Westmead Hospital jen.kok@health.nsw.gov.au
Outline rationale for testing, testing methods and impact of testing factors affecting performance of tests sample, transport, age of patient, novel virus examples of platforms ICT, FIA, LAMP, RT-PCR future of POCT
Why test those meeting clinical case definition of ILI (fever + cough/sore throat)? individual patient management antivirals obviates unnecessary tests and treatments infection control measures epidemiological purposes emerging pathogens monitoring of secular trends of existing pathogens pandemic preparedness planning
Novel antiviral agents for respiratory viruses Virus Existing agents Novel agents Influenza RSV NIs (Oseltamivir, Zanamivir, Laninamivir, Peramivir) Favipiravir Adamantanes Ribavirin Palivizumab Motavizumab VX-787 Fludase (DAS181) Monoclonal antibodies AVI-7100 Presatovir (GS-5806) ALS-008176 RI-001 ALN-RSV01 TMC353121 MDT-637 ALX-0171
Novel antiviral agents for respiratory viruses Virus Existing agents Novel agents in development Parainfluenza virus - DAS181 (Fludase ) Rhinovirus - Vapendavir (BTA798) SNG001 (IFN-β) Adenovirus Cidofovir Brincidofovir (CMX001)
Clinician s perspective: which diagnostic method? 24/7 Menu Accurate TAT Cost
Laboratory s perspective: which diagnostic method? Menu Workflow Automation Throughput Random access TAT Complexity Expertise Instruments Cost* *kits, reagents, labor, instruments, QAP, transport
Respiratory virus diagnostic methods Type of test Sensitivity Turn around time POCT 18-77% 15 mins Traditional nucleic acid ~98-100% ~4 hours detection icpmr Advantages Rapid Simple bedside test No need for specialised laboratory Typing possible Expanding menu Sensitive Typing and subtyping Can detect viable and nonviable virus Disadvantages (Expensive) Limited shelf life Lower sensitivity False positives and negatives Specimen quality important Requires technical expertise and specialised equipment Expensive
A positive RIDT alters outpatient pediatrician practices in ILIs Clearview Exact Influenza A + B o increase antiviral therapy o reduce antibiotic therapy Jennings IORV 2009
More tests, less optimal antimicrobial use, longer length of stay and more $$$ if no RIDT in ED MD aware RIDT positive (n=96) MD unaware RIDT positive (n=106) P value CBC 0 13 (12%) <0.001 BC 0 11 (13%) <0.001 Urinalysis 2 (2%) 12 (11%) 0.011 CXR 7 (7%) 26 (25%) 0.001 Antibiotic prescription Antiviral prescription Mean time from exam to discharge 7 (7%) 26 (25%) <0.001 18 (19%) 7 (7%) 0.02 25 minutes 49 minutes <0.001 Charge/patient $15.65 $92.37 <0.001 Bonner Pediatrics 2003
Impact of RIDT on adult hospital inpatients RIDT negative (n=80) RIDT positive (n=86) P value Antibiotic use 79 (99%) 74 (86%) 0.002 Antiviral use 6 (8%) 63 (73%) <0.001 Antibiotics ceased because of influenza Discharged from hospital whilst on antibiotics 2 (2%) 12 (14%) 0.004 51 (64%) 38 (44%) 0.006 multivariate analysis for discontinuing antibiotics positive RIDT OR of 6.90 (95% CI 2.0 32.70) p=0.005 Falsey Arch Intern Med 2007
Detection of influenza virus in samples collected, stored and transported using media at different temperatures 4 O C 22 O C Liquid Amies 37 O C Druce J Clin Microbiol 2012
Rate of detection of respiratory viruses differs according to age and samples tested DeByle J Virol Methods 2012 (n=314 children < 3 years) Munywoki J Clin Microbiol 2011 (n=299 children < 13 years) Hernes Eur J Clin Microbiol Infect Dis 2011 (n=223 adults) Recovery using flocked swabs 79 89% (nasopharyngeal) 89.6% (nasopharyngeal) 78% (nasopharyngeal) Recovery using comparator 69 94% (nasal wash) 79.2% (nasal wash) 63% (oropharyngeal flocked swabs) p values and Δ in CT values (- flocked swab comparator) p=0.069 1.0 0.6 7.0 p=0.0043-1 -2 p <0.01-5.75
Sensitivity of antigen tests stratified according to age groups and influenza A subtype in 2009 (n=2274) Age group 0-1 years (n=65 RIDT, 46 IFA) 2-5 years (n=61 RIDT, 25 IFA) 6-15 years (n=160 RIDT, 25 IFA) 16 years (n=1503 RIDT, 389 icpmr IFA) ph1n1 RIDT Non-pH1N1 ph1n1 IFA Non-pH1N1 87.5% 100% 86.7% 90% 70% 87.5% 100% 100% 69.3% 71.9% 86.7% 83.3% 42.4% 72.1% 39.8% 56.7% Unpublished data Kok ASID 2010
Reduced sensitivity of RIDT (QuickVue) for newly circulating pandemic influenza virus Kok J Clin Microbiol 2010
Should RIDT be performed in the lab or in the field? parallel testing of RIDT using NAT/viral culture as gold standard (n=124 samples) transported at 4 O C, tested within 24h inter-operator variability (WYD 2008) Operator Sensitivity (%) Specificity (%) PPV (%) NPV (%) Trained (n=59) 60* 96.6 94.7 70 Untrained (n=65) 34.6* 89.7 69.2 67.3 Foo J Clin Virol 2009 *p > 0.05
POCT platforms
Performance of POCT vs RT-PCR in real-life Turnaround times (minutes) Sensitivity Specificity ICT (BinaxNOW) 15 minutes Influenza A: 44% Influenza B: 25% RSV: 63 65% Influenza A: 100% Influenza B: 100% RSV: 100% FIA (Sofia) 15 minutes Influenza A: 71.4% Influenza B: 33.3% RSV: 92.9% Influenza A: 98.2% Influenza B: 99.5% RSV: 100% LAMP (Alere i) 15 minutes Influenza A: 77.8% Influenza B: 75% Influenza A: 100% Influenza B: 99% Hazelton J Med Virol 2014, IORV 2015
False positive influenza B using Sofia FIA (Northern Hemisphere 2013/2014) n=43 93% confirmed by GenMark esensor RVP n=66 only 1 specimen concordant 38% non influenza respiratory virus 14% positive for A(H1N1)pdm09 Iovine Clin Infect Dis 2014
Predominance of influenza B in NSW 2015 NSW Health 2015
PPV and NPV of RIDT (poor sensitivity but good specificity) depends on prevalence of flu If flu prevalence is and specificity is then PPV is very low (2.5%) good (98%) poor (39 56%) moderate (20%) good (98%) good (86-93%) If flu prevalence is and sensitivity is then NPV is moderate (20%) poor (50%) moderate (86 89%) high (40%) poor (50%) very good (93 94%)
Rapid respiratory virus NAT Turnaround times (minutes) Sensitivity Specificity Cobas Liat Influenza A/B (Roche Diagnostics) 20 minutes Influenza A: 99.2% Influenza B: 100% Influenza A: 100% Influenza B: 100% Xpert (Cepheid) 40 75 minutes Influenza A: 97.8% Influenza B: 100% RSV: 90.6% Influenza A: 100% Influenza B: 99.4% RSV: 99.4% FilmArray RP (BioFire/bioMerieux) 1 hour 17 viruses Up to 100% 17 viruses Up to 100% Simplexa Flu A/B + RSV Direct (Focus Diagnostics) 1 4 hours Influenza A: 91.7-100% Influenza B: 97.5-100% Influenza A: 99.4-100% Influenza B: 98.1-99.4% Binnicker J Clin Microbiol 2015, Popowitch J Clin Microbiol 2015, Babady Expert Rev Mol Diagn 2013, Ko J Med Virol 2013
Future of POCT laboratory diagnosis of viral infections important impact of availability of rapid test result novel antivirals for specific viruses technological advances multi-analyte rapid molecular based tests real-time surveillance model of centralized core laboratory vs bedside?patient self sampling costs laboratory vs bedside