We set out to describe the pattern of lung function growth in Mexican students from 8-20 years of age, using internationally accepted equipment and methodology, and to compare it to values reported for Mexican-American children. Out of a total of 6,803 students from primary school to high school studied cross-sectionally in the Mexico City metropolitan area, we selected 4,009 asymptomatic, nonobese, nonsmoker subjects to generate spirometric prediction equations. We describe regression equations for the main spirometric variables (log transformed) based on age, height, and weight, and separated for males and females. Spirometric function in the population studied was above that predicted for European (Quanjer et al. [1987] Pediatr Pulmonol 19:135-142) or Mexican-American children, for the same age, height, and gender. On average, forced expiratory volume in 1 sec (FEV(1)) in Mexican children was 9.5% above that of Europeans (Quanjer et al. [1987] Pediatr Pulmonol 19:135-142), 14% and 5% above Hispanics reported by (Coultas et al. [1988] Am Rev Respir Dis 138:1386-1392) and (Hsu et al. [1979] J Pediatr 95:14-23), respectively, and 5% above Mexican-Americans from the third National Health and Nutrition Examination Survey study. Similarly, FVC was 8%, 14%, 8%, and 5.6% above the figures predicted by the same authors. The largest errors of prediction of foreign equations occurred in extremely tall or short subjects, and therefore a single proportional adjustment is unfeasible.

IntroductionOur aim was to compare the longitudinal lung function growth of Mexican children and adolescents with the collated spirometric reference proposed for international use and with that of Mexican-Americans from the National Health State Examination Survey III (NHANES) III study.Materials and MethodsA cohort of Mexican children in third year of primary school was followed with spirometry twice a year through secondary school. Multilevel mixed-effects lineal models separated by gender were fit for the spirometric variables of 2,641 respiratory-healthy Mexican children expressed as Z-scores of tested reference equations. Impact of adjustment by sitting height on differences with Mexican-American children was observed in a subsample of 1,987 children.ResultsAt same gender, age, and height, Mexican children had increasingly higher forced expiratory volume in 1 s (FEV1) and Forced vital capacity (FVC) than the children from the collated reference study (mean Z-score, 0.68 for FEV1 and 0.51 for FVC) and than Mexican-American children (Z-score, 0.23 for FEV1 and 0.21 for FVC) respectively. Differences with Mexican-Americans were not reduced by adjusting by sitting height.ConclusionsFor reasons that remain unclear, the gender-, age-, and height-adjusted lung function of children from Mexico City is higher than that reported by several international studies.

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