1. The Research Question
Performance of a Rapid Influenza Detection Test (RIDT) in Ambulatory Primary Care Wisconsin:
Temte JL, Barlow S, Greene P, Haupt T, Reisdorf E, Wedig M, Shult P, Giorgi A, Fowlkes A. University of Wisconsin
What patient, illness and pathogen characteristics affect performance of rapid influenza detection tests?
Why this is important?
RIDTs are designed to provide point-of-care diagnosis of influenza to inform treatment and guidance decisions in a meaningful timeframe
RIDTs have been limited by some performance measures – primarily sensitivity
Package inserts suggest that age can affect sensitivity
BP34 Adherence to Antibiotic Prescribing for LRTI and Association With Recovery (Oral Presentation On Completed Research) Nick Francis, MD, PhD, Cardiff University; David Gillespie; Jacqueline Nuttall; Paul Little; Theo Verheij; Samuel Coenen; Jochen Cals; Kerenza Hood; Herman Goossens; Christopher Butler

2. What the Researchers Did
Population/Subjects
Primary care patients with acute respiratory infections
N = 1,219 (age 0 to 88.1 years)
November 2009 to April 2013
Four family medicine clinics in Wisconsin
Design:
Prospective respiratory virus surveillance
Pragmatic (multiple sites, 90 clinicians, diverse ARIs)
Basic Method/Intervention
Comparison of sensitivity of RIDT to gold standard PCR
RIDT: Quidel QuickVue Influenza A+B
CDC influenza RT-PCR primers and Qiagen Resplex II Multiplex PCR
Uniform demographic, epidemiologic and symptom data on all patients
aged ≥18 years, consulting with an illness where an acute or worsened cough was the main or dominant symptom, or had a clinical presentation that suggested a lower respiratory tract infection that had been present for ≥28 days.

3. What the Researchers Found Factors associated with Sensitivity
univariate analysis
(Chi Square)
Sex of Patient N.S
Male > Female
Age of patient P=0.001
younger > older (7 age groups)
ILI vs. ARI N.S.
ILI > ARI
Days from onset P=0.001
earlier > later (5 time groups
Vaccinated N.S.
Unvaccinated > vaccinated
Influenza strain N.S.
B > AH3 > AH1
mulitvariate analysis
(Binary Logistic Regression)
Age of patient
Sensitivity drops by 20% for each decade of life
Odds ratio = 0.80
P = 0.004
Days from Onset
Sensitivity drops by 26% for each passing day after onset
Odds ratio = 0.74
P = 0.01

4. What This Means for Clinical Practice
Rapid Influenza Diagnostic Test performance is complex and requires appropriate patient selection
Patient Age and Time from Illness Onset are key parameters
Sensitivity drops by 20% for each decade of life
Sensitivity drops by 26% for each passing day after illness onset
The messiness and chaos allowed by a Primary Care Surveillance Platform offers an excellent means to evaluate the effectiveness of diagnostic technology