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Table 2 Comparison of demographics and baseline spirometry parameters in patients with positive versus negative methacholine challenge test in the derivation cohort

From: Baseline spirometry parameters as predictors of airway hyperreactivity in adults with suspected asthma

  Methacholine negative (n = 1932) Methacholine positive (n = 305) P value
Mean SD Mean SD
Age (years) 24.10 3.65 24.50 3.80 0.16
Females 367 (19%) 67 (22%) 0.22*
Height (cm) 173.60 8.29 172.89 9.16 0.18
Weight (kg) 69.53 12.26 68.77 13.50 0.36
BMI (kg/m2) 23.01 3.44 22.80 3.46 0.56
Smoking n (%)**      0.26
 Non-smoker 176 (67)   42 (67)   
 Ex-smoker 12 (5)   6 (9)   
 Smoker 75 (28)   15 (24)   
 Total 263 (100)   63 (100)   
FEV1/FVC ratio (%pred) 84.10 7.40 80.10 7.50  < 0.01
FEV1 (%pred) 95.40 11.00 89.10 11.70  < 0.01
FEF50% (%pred) 89.80 22.80 75.10 18.00  < 0.01
FVC (%pred) 99.50 13.00 96.50 13.00  < 0.01
FEF25–75% (%pred) 86.90 23.10 82.70 22.80  < 0.01
angle β (°) 186.96 15.01 180.92 12.36  < 0.01
  1. Methacholine positive defined as PC20 ≤ 16 mg/ml; PC20, Concentration of methacholine causing a 20% decrease in FEV1. BMI, Body Mass Index; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; FEF50%, forced expiratory flow at 50% of FVC; FEF25–75%, forced expiratory flow at 25–75% of FVC; Relative values of spirometry parameters are given as percentage of the predicted value (% pred)
  2. *P value from Chi-squared analysis
  3. **Smoking status was available for 326 patients in the derivation cohort—263 from the MCT negative patients and 63 from the MCT positive patients