Spirometric “Lung Age” estimation for North African population

Abstract

Background: Published reference equations predicting Estimated-Lung-Age (ELA) did not reliably predict Chronological-Lung-Age (CLA) data in North African population. Aims: To develop and to validate novel reference equations for ELA from varied anthropometric data and FEV1. Methods: Applying multiple regression analysis, equations predicting ELA were invented using data from 540 never-smokers with normal spirometry (group I). Validation was made based on data from 41 never-smokers with normal spirometry (group II). Equations were further applied for 91 subjects with confirmed COPD. Results: Novel regression equations allowing prediction of reference value of ELA and normal limits of difference between ELA and CLA were elaborated in both sexes. In males, ELA (yrs) = 42.85 − 20.74 × FEV1 (L) + 47.41 × Body Surface Area (m2) − 0.62 × Body-Mass-Index (BMI, kg/m2). In females, ELA (yrs) = 64.64 − 8.00 × FEV1 (L) − 0.17 × BMI (kg/m2) + 8.82 × Height (m). Normal limits of difference between ELA and CLA were ±16.9 yrs in males and ±14.8 yrs in females. Established equations predicted ELA of group II with no significant difference between CLA and ELA in either sex (respectively, 42.9 ± 16.6 vs. 40.3 ± 13.7 yrs in males, 42.0 ± 13.5 vs. 45.6 ± 7.7 yrs in females) ELA was significantly older than CLA age only in COPD with grades III and IV ((ELA minus CLA) (yrs) averaged, respectively, +21.7, +26.4). Conclusion: North African reference equations enrich the World Bank of reference equations from which the physician should choose according to the patient’s ethnic background.

Keywords

• Lung Age
• Spirometry
• Reference value
• Normal limits
• Tunisia
• North Africa