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Table 4 The sensitivity, specificity, likelihood ratios of the positive (LR+) and negative test result (LR-) of single and combined symptoms, signs and context for the diagnosis of influenza (95%CI)a.

From: Clinical prediction rules combining signs, symptoms and epidemiological context to distinguish influenza from influenza-like illnesses in primary care: a cross sectional study

Symptoms. signs and context

Sensitivity

(95% CI)

Specificity

(95% CI)

LR+

(95% CI)

Cumulative b

LR+

(95% CI)

LR-

(95% CI)

Cumulative b

LR-

(95% CI)

Influenza epidemic

0.88 (0.86 to 0.89)

0.42 (0.39 to 0.44)

1.50 (1.43 to 1.57)

 

0.30 (0.26 to 0.33)

 

During an epidemic

  

1.50 (1.43 to 1.57)

 

1.50 (1.43 to 1.57)

 

Prediction rule 1

      

+ILI contact

0.42 (0.38 to 0.46)

0.63 (0.58 to 0.68)

1.12 (1.01 to 1.24)

1.68 (1.49 to 1.88)

0.93 (0.87 to 0.98)

1.38 (1.28 to 1.49)

+cough

0.81 (0.79 to 0.84)

0.40 (0.36 to 0.44)

1.35 (1.29 to 1.40)

2.27 (2.01 to 2.53)

0.47 (0.42 to 0.52)

0.65 (0.56 to 0.74)

+expectoration day1

0.10 (0.00 to 0.40)

0.93 (0.67 to 1.00)

1.30 (1.08 to 1.53)

2.96 (2.38 to 3.54)

0.93 (0.86 to 1.00)

0.54 (0.40 to 0.68)

+body temp > 37.8°C

0.90 (0.87 to 0.92)

0.21 (0.16 to 0.26)

1.13 (1.08 to 1.19)

3.35 (2.67 to 4.03)

0.49 (0.41 to 0.58)

0.26 (0.18 to 0.34)

Prediction rule 2

      

+ cough

0.82 (0.81 to 0.84)

0.39 (0.36 to 0.42)

1.34 (1.29 to 1.39)

2.01 (1.90 to 2.13)

0.46 (0.41 to 0.51)

0.69 (0.60 to 0.78)

+body temp > 37.8°C

0.91 (0.89 to 0.92)

0.19 (0.16 to 0.22)

1.12 (1.08 to 1.16)

2.26 (2.11 to 2.40)

0.49 (0.40 to 0.58)

0.34 (0.27 to 0.41)

Pre/post an epidemic

  

0.30 (0.26 to 0.33)

 

0.30 (0.26 to 0.33)

 

Prediction rule 1

      

+ ILI contact

0.42 (0.36 to 0.47)

0.82 (0.80 to 0.85)

2.36 (1.93 to 2.79)

0.69 (0.54 to 0.85)

0.71 (0.64 to 0.78)

0.21 (0.18 to 0.24)

+cough

0.81 (0.78 to 0.85)

0.40 (0.34 to 0.46)

1.35 (1.28 to 1.42)

0.93 (0.73 to 1.14)

0.47 (0.41 to 0.53)

0.11 (0.09 to 0.13)

+expectoration day1

0.11 (0.00 to 0.42)

0.92 (0.65 to 1.00)

1.30 (1.08 to 1.53)

1.21 (0.89 to 1.54)

0.93 (0.85 to 1.00)

0.09 (0.06 to 0.11)

+body temp > 37.8°C

0.92 (0.88 to 0.95)

0.17 (0.11 to 0.23)

1.11 (1.05 to 1.16)

1.34 (0.97 to 1.72)

0.48 (0.39 to 0.57)

0.04 (0.03 to 0.05)

Prediction rule 2

      

+cough

0.78 (0.76 to 0.81)

0.45 (0.42 to 0.48)

1.42 (1.37 to 1.47)

0.42 (0.38 to 0.47)

0.49 (0.43 to 0.54)

0.14 (0.12 to 0.17)

+body temp > 37.8°C

0.93 (0.91 to 0.95)

0.15 (0.12 to 0.17)

1.09 (1.06 to 1.12)

0.46 (0.41 to 0.51)

0.48 (0.39 to 0.57)

0.07 (0.05 to 0.08)

  1. CI = confidence interval
  2. a analysis was performed on the database with full and imputed records n = 4584
  3. b cumulative = combined diagnostic value of all the symptoms. signs or context taken into account so far