6
Figures
Figure 3. Comparison of the ATS/ERS 2005
Recommendations to ATS/ERS 2022
Recommendations
a,b
A three-level system to assess the severity of lung function impairment using z-score values should
be used:
• z-score > −1.645 are normal
• z-scores between −1.65 and −2.5 are mild
• z-scores between −2.5 and −4 are moderate
• z-scores < −4 are severe.
a
ATS, American oracic Society; ERS, European Respiratory Society.
b
Uses 70%, 60%, 50% and 35% of predicted FEV
1
for eight individuals with the FEV
1
cut points
expressed as z-score values on the abscissa scale. e LLN at the 5th percentile (−1.645) is shown as
a vertical arrow, and the two new proposed cut levels of −4 and −2.5 z-score are shown as solid lines
with the new gradings above.
Very Severe
Very Severe
Very Severe
Very Severe Severe
Severe
Severe
Severe
Severe
M.
Severe
M.
Severe
M.
Severe
M.
Severe
M.
Severe
Mod.
Mod.
Mod.
Mod.
Mod.
Mild
Mild
Mild
Mild
Mild
Severe
M.
Severe
Mod.
Mild
Severe
Severe
M.
Severe
M.
Severe
Mod.
Mod.
Mild
Mild
V. Severe
V. Severe
V. Severe
V.
Severe
Female 80 yrs Ht 165 cm
Severe Moderate Mild Normal
Male 80 yrs Ht 175 cm
Female 50 yrs Ht 165 cm
Male 50 yrs Ht 175 cm
Female 25 yrs Ht 165 cm
Male 25 yrs Ht 175 cm
Female 15 yrs Ht 162 cm
Male 10 yrs Ht 137 cm
FEV
1
z-score
Lower limit
of normal
(LLN)
–6 –5 –4 –3 –2 –1 0
