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Background <p>The methacholine challenge requires a 20% fall in forced expiratory volume in one second (FEV<sub>1</sub>). The fall is measured as litre (L) change from the pre-challenge (baseline) value. A higher baseline FEV<sub>1</sub> requires a greater volume change to reach a 20% fall. The aim of this study was to evaluate change using percent predicted, which may remove dependence on the baseline value.</p> Methods <p>Challenge data from a cohort of 114 asthma patients was re-analysed. The dose causing an 20% fall from baseline (PD<sub>20</sub>) was compared to a 15% fall in predicted value (PD<sub>15%</sub>) for the classification of bronchial hyperresponsiveness.</p> Results <p>There was significant agreement between PD<sub>20</sub> and PD<sub>15%</sub> (r = 0.95, <i>p</i> &lt; 0.0001), with an ICC of 0.97. PD<sub>20</sub> was significantly higher than PD<sub>15</sub><sub>%</sub> (0.0055&#xa0;mg, <i>p</i> &lt; 0.0001). Greater decreases in FEV<sub>1</sub> were observed with PD<sub>20</sub> versus PD<sub>15%</sub> (21.4% pred vs 19.1% pred respectively, <i>p</i> = 0.0004), with 29% of patients requiring at least one additional dose of methacholine to achieve PD<sub>20</sub> compared to PD<sub>15%</sub>. A higher baseline FEV<sub>1</sub> resulted in higher PD<sub>20</sub> values, whereas no relationship was found for PD<sub>15%</sub>. Variability in FEV<sub>1</sub> between repeated visits (n = 15) was associated with the change in PD<sub>20</sub>, but not the change in PD<sub>15%</sub>.</p> Conclusion <p>We suggest a PD criteria based on 15% predicted change should be used for bronchial challenge testing. This method is less influenced by baseline airflow obstruction, and is a more efficient and safer way of measuring airway hyperresponsiveness.</p>

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The Advantages of FEV1 Percent Predicted Change During Bronchial Challenge Testing

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年7月5日

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  • James Dean,
  • Augusta Beech,
  • Dave Singh

摘要

Background

The methacholine challenge requires a 20% fall in forced expiratory volume in one second (FEV1). The fall is measured as litre (L) change from the pre-challenge (baseline) value. A higher baseline FEV1 requires a greater volume change to reach a 20% fall. The aim of this study was to evaluate change using percent predicted, which may remove dependence on the baseline value.

Methods

Challenge data from a cohort of 114 asthma patients was re-analysed. The dose causing an 20% fall from baseline (PD20) was compared to a 15% fall in predicted value (PD15%) for the classification of bronchial hyperresponsiveness.

Results

There was significant agreement between PD20 and PD15% (r = 0.95, p < 0.0001), with an ICC of 0.97. PD20 was significantly higher than PD15% (0.0055 mg, p < 0.0001). Greater decreases in FEV1 were observed with PD20 versus PD15% (21.4% pred vs 19.1% pred respectively, p = 0.0004), with 29% of patients requiring at least one additional dose of methacholine to achieve PD20 compared to PD15%. A higher baseline FEV1 resulted in higher PD20 values, whereas no relationship was found for PD15%. Variability in FEV1 between repeated visits (n = 15) was associated with the change in PD20, but not the change in PD15%.

Conclusion

We suggest a PD criteria based on 15% predicted change should be used for bronchial challenge testing. This method is less influenced by baseline airflow obstruction, and is a more efficient and safer way of measuring airway hyperresponsiveness.