Table 5.

Accuracy of Simple Heuristics for the Clinical Diagnosis of Influenza

Rule and StudyaHeuristicSensitivity, %Specificity, %PPV, %NPV, %LR+LR−LR+/ LR−
ILI=influenza-like illness; LR− = negative likelihood ratio; LR+ = positive likelihood ratio; NPV = negative predictive value; PPV = positive predictive value; RTI=respiratory tract infection.
a Study population and prevalence of influenza are shown in Table 2.
b Odds ratio in logistic regression model was 6.7 for cough and 3.1 for temperature greater than 38°C.
c Odds ratio in logistic regression model was 7.2 for cough, 4.3 for headache, and 3.9 for pharyngitis.
Fever and cough rule
Stein et al,8 2005Fever (≥37.8°C) and cough409258845.10.77.3
Govaert et al,13 1998Fever (>38°C) and cough309426955.00.746.8
Boivin et al,12 2000bFever (≥37.8°C) and cough785587391.70.44.3
Monto et al,11 2000Fever (≥37.8°C) and cough646779491.940.543.6
van den Dool et al,22 2008Fever (>38.3°C) and cough429026954.20.646.5
Fever, cough, and acute onset rule
Stein et al,8 2005Fever (≥37.8°C), cough, and duration ≤48 hr758965936.50.321.7
Walsh et al,21 2002Fever (≥38°C), cough, and duration <7 days787347912.90.39.7
Govaert et al,13 1998Fever (>38°C), cough, and acute onset279530955.90.767.8
Monto et al,11 2000Fever (≥37.8°C), cough, and acute onset636877511.950.543.6
Cough, headache, and pharyngitis rule
Friedman and Attia,20 2004cCough, headache, and pharyngitis807877813.70.2614.2