Table 2.
Positive test thresholds for objective tests across international guidelines
| BTS [36] | NICE [17] | GINAa [6, 7] | |
|---|---|---|---|
| Spirometry |
Adults: FEV1/FVC ratio < LLN Children: as above |
Adults: FEV1/FVC ratio < 70% (or < LLN if available) Children: as above |
Adults: FEV1/FVC < LLN Children: as above |
| BDR |
Adults: FEV1 increase by ≥ 12% and ≥ 200 ml Children: (≤ 16 years): FEV1 increase by ≥ 12% |
Adults: FEV1 increase by ≥ 12% and ≥ 200 ml Children: (≤ 16 years): FEV1 increase by ≥ 12% |
Adults: FEV1 increase by > 12% and > 200 ml from baseline Children: (6–11 years) FEV1 increase by > 12% of predicted value |
| FeNO |
Adults: ≥ 40 ppb Children: ≥ 35 ppb |
Adults: ≥ 40 ppb Children: (≤ 16 years): ≥ 35 ppb |
Not included |
| PEFv |
Adults: > 20% variability (using minimum 2-week PEF diary—calculating percentage of the average PEF) Alternatively > 20% variability when symptomatic vs non-symptomatic Children: not recommended |
Adults: > 20% variability (using minimum 2-week PEF diary—calculating amplitude as a percentage of mean or highest value) Children: (≤ 16 years) as above |
Adults: > 10% variability (using minimum 2-week PEF diary—calculating days highest minus days lowest, divided by mean of days highest and lowest and averaged over the week) Children: (6–11 years) > 13% variability measured as above |
| BHR tests |
Adults: histamine or methacholine PC20 ≤ 8 mg/ml Alternatively mannitol (positive defined as drop in FEV1 > 15%) Children: as above |
Adults: histamine or methacholine PC20 ≤ 8 mg/ml Children: (≤ 16 years) not recommended |
Adults: histamine or methacholine dose PC20 (guideline states “using standard doses”) Alternatively eucapnic voluntary hyperventilation, hypertonic saline or mannitol PC15 Children: (≤ 16 years) not recommended |
| Exercise challenge test |
Adults: drop in FEV1 > 15% Children: as above |
Not included |
Adults: drop in FEV1 > 10% and > 200 ml from baseline Children: (≤ 16 years) drop in FEV1 > 12% predicted or PEF > 15% |
aThe GINA 2018 guideline report is used, plus updates have been extracted from the GINA Pocket Guide for Asthma Management and Prevention (updated 2019). The official GINA report for 2019 is not currently available