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  1. Novel regression equations predicting lung age for Mediterranean population Ben Saad H1,2, Selmi H2, Hadj Mabrouk K2, Maatoug C2, Rouatbi S1 1Department of Physiology and Functional Explorations. Farhat HACHED Hospital. 2Functional Exploration Laboratory. Occupational Medicine Group of Sousse. Tunisia. Rational Results Aim Conclusion Methods Abbreviations Validation of prediction equations: CLAs are compared with ELAs: i) Wilcoxon matched pairs test (ELA vs. CLA of groupsI-III). ii) Bland and Altman (group II)..iii) Scatterplots and paired T-tests: CLA vs. ELA of group II. iv) One-way ANOVA and Turkey test: .difference between the four COPD grades. It have been demonstrated that published reference equations predicting estimated lung age (ELA) (Morris and Temple1985, Newbury2010, Hansen2010, Yamaguchi2012) didn’t reliably predict chronological lung age (CLA) data in Tunisian healthy adults representing a sample of a Mediterranean population. To develop and to validate novel equations for ELA from varied anthropometric data and FEV1. Fig 1. Comparison of ELA determined from the retained Tunisian reference equations with CLA in group II. r2: determination coefficient; r: correlation coefficient; p: probability; n=number of subjects. Fig A: male. Fig B: female. : regression line. : identity line. Design: cross sectional study. Subjects:Group I (equation group): healthy never-smokers aged 19-90 Yrs with normal spirometry (176 ♂, 364 ♀). Group II (healthy subject’s validation group): healthy never-smokers aged 22-89 Yrs with normal spirometry (20 ♂; 41 ♀). Group III (patients’ validation group): COPD patients aged 19-80 Yrs (65 ♂; 26 ♀): post-bronchodilator FEV1/FVC < 0.70. Collected data: dependent variable (CLA), independent variables [sex, age, weight, height, BMI, FVC, FEV1, PEF, MMEF, FEFx, FEV1/FVC] and ELAs from the published studies. Spirometry function tests according ATS/ERS-2005. ELA influencing factors T-tests: associations CLA and categorical variables (sex). Pearson product-moment correlation coefficients: CLA and continuous measures. ELA simplified reference equations: ELA (Yrs) = a0 + a1 x Sex + a2 x Height + a03 x Weight + a4 x BMI + a5 x BSA + a6 x FEV1 Upper and lower limit of normal (ULN, LLN): calculated. Fig 2. CLA minus ELA in COPD patients.  : mean. : 95% CI. Dotted line: average ULN for (CLA-ELA) (+16 Yrs). P < 0.05: one-way ANOVA (and multiple comparison of the Turkey test) between the 4 COPD grades. a: larger than grade I. b: larger than grade II. c: larger than grade III. ELA simplifiedreferenceequations ♀: ELA (Yr) = 64.64 - 8.00xFEV1 (L) - 0.17xBMI (kg/m2) + 8.82xHeight (m); r2: 0.38; ULN/LLN= 14.77 Yrs. ♂: ELA (Yr)= 42.85 - 20.74xFEV1 (L)+ 47.41xBSA (m2) - 0.62xBMI (kg/m2); r2: 0.56; ULN/LLN= 16.0 Yrs. Novel regression equations allowing prediction of reference value of ELA and normal limits of difference between ELA and CLA age were elaborated in both sexes for Tunisian adult’s population. In additional groups of adult-healthy or adult-patients prospectively assessed, our reference equations yielded satisfactory predictions. Validation of the retained reference equations ELA in group II (fig 1): males and females means±SD (CLA-ELA) weren’t significant (respectively, 3±13 vs. -3±9 Yrs). ELA group III (fig 2): (CLA-ELA) averaged -1.84 Yrs in COPD-grade I, +13.34 Yrs in COPD-grade II, +21.68 Yrs in COPD-grade III, or +26.42 Yrs in COPD-grade IV. FEFx: forced expiratory flow when x% of FVC has been exhaled. FEV1: first second forced expiratory volume. FVC: forced vital capacity. LLN: lower-limit-of-normal. MMEF: maximal mid-expiratory flow. PEF: peak expiratory flow. BMI: body mass index.