Figures
- FIGURE 1
Mean values for total lung capacity (TLC), functional residual capacity (FRC) and residual volume (RV) in each of the four study groups, expressed as fractions of 100% predicted TLC for each group as measured by plethysmography. The Lean Control group slightly exceeded 100% predicted TLC. Mean TLC in each of the remaining groups was <100% predicted by amounts that are potentially attributable to volumes of atelectatic (non-recruitable) lung (grey).
- FIGURE 2
Closed symbols show the parameters derived from multiple breath nitrogen washout pertaining to lung size (a: functional residual capacity (FRC) and b: dead space volume (VD)) for each of the four study groups (means shown as horizontal bars). FRC from nitrogen washout was significantly lower in the late-onset nonallergic (LONA) obese asthma group compared to FRC from nitrogen washout in the other groups (*: ANOVA and paired t-test, p<0.05).
- FIGURE 3
Parameters derived from multiple breath nitrogen washout pertaining to lung heterogeneity (a: the coefficient of variation of regional specific ventilation CV,V′E and b: a measure of structural asymmetry at the level of the acinus (sacin)) for each of the four study groups (means shown as horizontal bars). There were no significant differences between groups for either parameter.
Tables
- TABLE 1
Baseline demographic data
Lean Obese p-value Control (n=11) Asthma (n=11) Control (n=11) Asthma (n=10) Sex n 8F/3M 9F/2M 8F/3M 7F/3M 0.92 Age years 41.7±6.1 23.1±1.6 44.6±4.1 45.2±6.9 <0.01 BMI kg·m−2 22.5±1.5 23.1±1.7 44.8±4.1 42.4±9.1 <0.01 Smoking pack-years 0.14 ±0.31 0 2.05±2.31 2.14±4.75 0.12 Waist circumference cm 86.6±9.8 82.6±8.1 139.0±9.5 117.4±23.7 <0.01 Age of asthma onset years – 4 (1,16) – 27 (18,50) Data are presented as mean±sd or median (range), unless otherwise stated. F: female; M: male; BMI: body mass index.
- TABLE 2
Baseline medication use and asthma control score
Lean Obese p-value Medication use ICS-LABA-LAMA 0 1 0.31 ICS-LABA 2 2 1 ICS 1 2 0.53 LTRA 2 0 0.14 No controller therapy 6 7 0.86 Asthma control score ACQ score# 0.84 ±0.71 1.63±0.63 0.01¶ Urgent asthma care in the prior 12 months ED visit 0 1 0.31 Urgent care (non-ED) visit 0 4 0.03 Systemic corticosteroids 1 2 0.53 Data are presented as number of participants or mean±sd, unless otherwise stated. ICS: inhaled corticosteroid; LABA: long-acting beta-agonist; LAMA: long-acting muscarinic antagonist; LTRA: leukotriene receptor antagonist; ACQ: Asthma Control Questionnaire; ED: emergency department. p-values were calculated using the Chi-squared test, except ¶, which was calculated using the t-test. #: higher score is indicative of worse asthma control.
- TABLE 3
Lung function data
Lean Obese p-value# Control Asthma Control Asthma FEV1 % pred 99.1±9.2* 89.2±16.6 99.0±12.3 83.0±13.6 0.02 FVC % pred 104.3±5.4* 98.5±14.7* 96.9±11.9* 80.9±9.8 <0.001 FEV1/FVC % 77.0±5.7 76.7±8.5 82.0±6.9 83.1±4.2 0.051 ERV % pred 62.5±39.8 69.1±29.7 44.3±35.4 51.4±46.5 0.53 TLC % pred 103.4±8.72* 98.2±14.0 96.1±12.8 87.4±8.9 0.02 RV % pred 132.4±39.4* 129.1±36.5* 99.5±30.4 82.7±36.9 <0.01 RV/TLC % pred 128.3±30.2 136.3±42.5* 102.5±26.8 93.9±35.5 0.02 FRC % pred 96.0±22.8+ 98.6±10.0+ 76.2±11.9 73.9±16.6 <0.001 sGaw % pred 119±92.0 127.9±72.6 107.8±78.1 156.6±92.9 0.59 PC20 mg·mL−1 methacholine 50 (22.2–64)¶ 2.8 (0.1–12.8) 64 (64–64)¶ 1.4(0.03,16) <0.0001 Data are presented as mean±sd or median (range), unless otherwise stated. Predicted values for spirometry are based on NHANES III [21], and those for lung volumes are based on Goldman and Becklake [22]. FEV1: forced expiratory volume in 1 s; % pred: % predicted; FVC: forced vital capacity; ERV: expiratory reserve volume; TLC: total lung capacity; RV: residual volume; FRC: functional residual capacity; sGaw: specific airway conductance; PC20: provocative concentration causing a 20% fall in FEV1. #: p-value shown for one-way analysis of variance for normally distributed variables, and Kruskal–Wallis test for non-parametric variables; *: p<0.05 compared with Obese Asthma group, post hoc comparison with Bonferroni correction; ¶: p<0.05 compared with asthma groups, post hoc comparison with Bonferroni correction; +: p<0.05 compared with obese groups, post hoc comparison with Bonferroni correction.
