The FEV1-to-FVC ratio is the volume of air expired in the first second, expressed as a percent of FVC.
FEV1-to-FVC ratio =
= (FEV1) / (FVC ) * 100%
FEV1 to FVC in percent for White males 15-91 years (Crapo, 1981) =
= ((-0.13) * (height in cm)) - (0.152 * (age in years)) + 110.49
FEV1 to FVC in percent for White females 15-84 years (Crapo, 1981) =
= ((-0.202) * (height in cm)) - (0.252 * (age in years)) + 126.58
FEV1 to FVC in percent for Hispanic males 25-75 years (Crapo, 1990) =
=(-0.1160 * (age in years)) + 86.5881
FEV1 to FVC in percent for Hispanic females 20-80 years (Crapo, 1990) =
=(-0.1862 * (age in years)) + 91.7259
FEV1 to FVC in percent for White males 65-85 years (Enright, 1993) =
= (-0.294 * (age in years)) + 93.8
FEV1 to FVC in percent for White females 65-85 years (Enright, 1993) =
= (-0.242 * (age in years)) + 92.3
FEV1 to FVC in percent for White males 18-86 years (Roberts, 1991) =
= (-21.476 * (height in meters)) - (0.242* (age in years)) + 126.252
FEV1 to FVC in percent for White females 18-86 years (Roberts, 1991) =
= (-0.172 * (age in years)) + 88.134
Interpretation:
• The FEV1/FVC ratio reflects the severity of pulmonary impairment in obstruction.
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FEV1 to FVC ratio
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Interpretation
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>= 70% of predicted
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normal
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61 - 69% of predicted
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mild obstruction
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45 - 60% of predicted
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moderate obstruction
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< 45% of predicted
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severe obstruction
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