Reference values for spirometry in Brazilian children.

OBJECTIVE: To generate reference values for spirometry in Brazilian children 3-12 years of age and to compare those values with the values employed in the equations currently in use in Brazil. METHODS: This study involved healthy children, 3-12 years of age, recruited from 14 centers (primary data) and spirometry results from children with the same characteristics in six databases (secondary data). Reference equations by quantile regressions were generated after log transformation of the spirometric and anthropometric data. Skin color was classified as self-reported by the participants. To determine the suitability of the results obtained, they were compared with those predicted by the equations currently in use in Brazil. RESULTS: We included 1,990 individuals from a total of 21 primary and secondary data sources. Of those, 1,059 (53%) were female. Equations for FEV1, FVC, the FEV1/FVC ratio, FEF between 25% and 75% of the FVC (FEF25-75%) and the FEF25-75%/FVC ratio were generated for white-, black-, and brown-skinned children. The logarithms for height and age, together with skin color, were the best predictors of FEV1 and FVC. The reference values obtained were significantly higher than those employed in the equations currently in use in Brazil, for predicted values, as well as for the lower limit of normality, particularly in children with self-reported black or brown skin. CONCLUSIONS: New spirometric equations were generated for Brazilian children 3-12 years of age, in the three skin-color categories defined. The equations currently in use in Brazil seem to underestimate the lung function of Brazilian children 3-12 years of age and should be replaced by the equations proposed in this study.

Reference values for spirometry in Brazilian children / Valores de referência de espirometria para crianças brasileiras

ABSTRACT Objective: To generate reference values for spirometry in Brazilian children 3-12 years of age and to compare those values with the values employed in the equations currently in use in Brazil. Methods: This study involved healthy children, 3-12 years of age, recruited from 14 centers (primary data) and spirometry results from children with the same characteristics in six databases (secondary data). Reference equations by quantile regressions were generated after log transformation of the spirometric and anthropometric data. Skin color was classified as self-reported by the participants. To determine the suitability of the results obtained, they were compared with those predicted by the equations currently in use in Brazil. Results: We included 1,990 individuals from a total of 21 primary and secondary data sources. Of those, 1,059 (53%) were female. Equations for FEV1, FVC, the FEV1/FVC ratio, FEF between 25% and 75% of the FVC (FEF25-75%) and the FEF25-75%/FVC ratio were generated for white-, black-, and brown-skinned children. The logarithms for height and age, together with skin color, were the best predictors of FEV1 and FVC. The reference values obtained were significantly higher than those employed in the equations currently in use in Brazil, for predicted values, as well as for the lower limit of normality, particularly in children with self-reported black or brown skin. Conclusions: New spirometric equations were generated for Brazilian children 3-12 years of age, in the three skin-color categories defined. The equations currently in use in Brazil seem to underestimate the lung function of Brazilian children 3-12 years of age and should be replaced by the equations proposed in this study.

RESUMO Objetivo: Gerar valores de referência para espirometria em crianças brasileiras de 3-12 anos de idade e comparar os resultados obtidos com as equações em uso no Brasil. Métodos: Foram incluídas crianças sadias de 3-12 anos recrutadas em 14 centros (dados primários) e resultados de espirometria de crianças com as mesmas características de seis bancos de dados (dados secundários). As equações quantílicas foram geradas após transformações logarítmicas dos dados espirométricos e antropométricos. A classificação por cor da pele foi autodeclarada. Os resultados obtidos foram comparados com os previstos nas equações em uso no Brasil para testar sua adequação. Resultados: Foram incluídos 1.990 indivíduos de 21 fontes de dados primários e secundários, sendo 1.059 (53%) do sexo feminino. Equações para VEF1, CVF, VEF1/CVF, FEF25-75% e FEF25-75%/CVF foram geradas para crianças brancas e para crianças negras e pardas. Os logaritmos da estatura e da idade e a cor da pele foram os melhores preditores para VEF1 e CVF. Os resultados obtidos foram significativamente maiores do que as estimativas geradas pelas equações em uso no Brasil, tanto para valores previstos quanto para o limite inferior da normalidade, particularmente em crianças negras e pardas. Conclusões: Novas equações espirométricas foram geradas para crianças brasileiras de 3-12 anos de cor branca, negra e parda. As equações atualmente em uso no Brasil parecem subestimar a função pulmonar de crianças brasileiras menores de 12 anos de idade e deveriam ser substituídas pelas equações propostas neste estudo.

Bronchodilator response cut-off points and FEV 0.75 reference values for spirometry in preschoolers.

OBJECTIVE:: To determine the cut-off points for FEV1, FEV0.75, FEV0.5, and FEF25-75% bronchodilator responses in healthy preschool children and to generate reference values for FEV0.75. METHODS:: This was a cross-sectional community-based study involving children 3-5 years of age. Healthy preschool children were selected by a standardized questionnaire. Spirometry was performed before and after bronchodilator use. The cut-off point of the response was defined as the 95th percentile of the change in each parameter. RESULTS:: We recruited 266 children, 160 (60%) of whom were able to perform acceptable, reproducible expiratory maneuvers before and after bronchodilator use. The mean age and height were 57.78 ± 7.86 months and 106.56 ± 6.43 cm, respectively. The success rate for FEV0.5 was 35%, 68%, and 70% in the 3-, 4-, and 5-year-olds, respectively. The 95th percentile of the change in the percentage of the predicted value in response to bronchodilator use was 11.6%, 16.0%, 8.5%, and 35.5% for FEV1, FEV0.75, FEV0.5, and FEF25-75%, respectively. CONCLUSIONS:: Our results provide cut-off points for bronchodilator responsiveness for FEV1, FEV0.75, FEV0.5, and FEF25-75% in healthy preschool children. In addition, we proposed gender-specific reference equations for FEV0.75. Our findings could improve the physiological assessment of respiratory function in preschool children. OBJETIVO:: Determinar os pontos de corte de resposta ao broncodilatador do VEF1, VEF0,75, VEF0,5 e FEF25-75% em crianças pré-escolares saudáveis e gerar valores de referência para o VEF0,75. MÉTODOS:: Foi realizado um estudo transversal de base comunitária em crianças de 3-5 anos de idade. Pré-escolares saudáveis foram selecionados por um questionário padronizado. Foi realizada espirometria antes e depois do uso de broncodilatador. Foram definidos os pontos de corte dessa resposta como o percentil 95 de variação em cada parâmetro. RESULTADOS:: Foram recrutadas 266 crianças, e 160 (60,0%) foram capazes de gerar manobras expiratórias aceitáveis e reprodutíveis antes e depois do uso de broncodilatador. As médias de idade e estatura dos participantes foram 57,78 ± 7,86 meses e 106,56 ± 6,43 cm, respectivamente. A taxa de sucesso para o VEF0,5 foi de 35%, 68% e 70%, respectivamente, nos participantes com 3, 4 e 5 anos de idade. O percentil 95 de variação percentual do valor previsto na resposta ao broncodilatador foram, respectivamente, de 11,6%, 16,0%, 8,5% e 35,5%, para VEF1, VEF0,75, VEF0,5 e FEF25-75%. CONCLUSÕES:: Nossos resultados definiram pontos de corte de resposta ao broncodilatador para o VEF1, VEF0,75, VEF0,5 e FEF25-75 em crianças pré-escolares saudáveis. Adicionalmente, foram propostas equações de referência para o VEF0,75, separadas por sexo. Os achados deste estudo podem melhorar a avaliação fisiológica da função respiratória em pré-escolares.

Bronchodilator response cut-off points and FEV 0. 75 reference values for spirometry in preschoolers / Pontos de corte da resposta ao broncodilatador e valores de referência para VEF 0. 75 em espirometria de pré-escolares

ABSTRACT Objective: To determine the cut-off points for FEV1, FEV0.75, FEV0.5, and FEF25-75% bronchodilator responses in healthy preschool children and to generate reference values for FEV0.75. Methods: This was a cross-sectional community-based study involving children 3-5 years of age. Healthy preschool children were selected by a standardized questionnaire. Spirometry was performed before and after bronchodilator use. The cut-off point of the response was defined as the 95th percentile of the change in each parameter. Results: We recruited 266 children, 160 (60%) of whom were able to perform acceptable, reproducible expiratory maneuvers before and after bronchodilator use. The mean age and height were 57.78 ± 7.86 months and 106.56 ± 6.43 cm, respectively. The success rate for FEV0.5 was 35%, 68%, and 70% in the 3-, 4-, and 5-year-olds, respectively. The 95th percentile of the change in the percentage of the predicted value in response to bronchodilator use was 11.6%, 16.0%, 8.5%, and 35.5% for FEV1, FEV0.75, FEV0.5, and FEF25-75%, respectively. Conclusions: Our results provide cut-off points for bronchodilator responsiveness for FEV1, FEV0.75, FEV0.5, and FEF25-75% in healthy preschool children. In addition, we proposed gender-specific reference equations for FEV0.75. Our findings could improve the physiological assessment of respiratory function in preschool children.

RESUMO Objetivo: Determinar os pontos de corte de resposta ao broncodilatador do VEF1, VEF0,75, VEF0,5 e FEF25-75% em crianças pré-escolares saudáveis e gerar valores de referência para o VEF0,75. Métodos: Foi realizado um estudo transversal de base comunitária em crianças de 3-5 anos de idade. Pré-escolares saudáveis foram selecionados por um questionário padronizado. Foi realizada espirometria antes e depois do uso de broncodilatador. Foram definidos os pontos de corte dessa resposta como o percentil 95 de variação em cada parâmetro. Resultados: Foram recrutadas 266 crianças, e 160 (60,0%) foram capazes de gerar manobras expiratórias aceitáveis e reprodutíveis antes e depois do uso de broncodilatador. As médias de idade e estatura dos participantes foram 57,78 ± 7,86 meses e 106,56 ± 6,43 cm, respectivamente. A taxa de sucesso para o VEF0,5 foi de 35%, 68% e 70%, respectivamente, nos participantes com 3, 4 e 5 anos de idade. O percentil 95 de variação percentual do valor previsto na resposta ao broncodilatador foram, respectivamente, de 11,6%, 16,0%, 8,5% e 35,5%, para VEF1, VEF0,75, VEF0,5 e FEF25-75%. Conclusões: Nossos resultados definiram pontos de corte de resposta ao broncodilatador para o VEF1, VEF0,75, VEF0,5 e FEF25-75 em crianças pré-escolares saudáveis. Adicionalmente, foram propostas equações de referência para o VEF0,75, separadas por sexo. Os achados deste estudo podem melhorar a avaliação fisiológica da função respiratória em pré-escolares.

Early termination of exhalation: effect on spirometric parameters in healthy preschool children.

OBJECTIVE: To evaluate the acceptability and reproducibility of spirometry in preschool children; to estimate the effect size of early termination of exhalation (ETE) on FVC, FEV(1) and FEV(0.5); and to evaluate the validity of FEV(0.5) in curves with ETE. METHODS: Spirometric data were obtained from 240 healthy preschool children, who were selected by simple sampling. On the basis of the best curve from each child according to the end of exhalation, three groups were formed: no ETE (nETE); ETE and flow ≤ 10% of the highest PEF (ETE≤10); and ETE and flow > 10% of the highest PEF value (ETE>10). The reproducibility of FVC, FEV(1) and FEV(0.5) was compared among the three groups. The effect of ETE on FVC, FEV(1), and FEV(0.5) was assessed. RESULTS: Of the 240 children tested, 112 (46.5%)-82 (34.0%) of those in the nETE group and 30 (12.5%) of those in the ETE≤10 group--had acceptable curves for all the parameters. In 64 (27.0%) of those in the ETE>10 group, the curves were acceptable only for FEV(0.5), increasing the proportion of children with valid FEV(0.5) to 73.0%. There were no significant differences between the nETE and ETE≤10 groups in terms of the mean values of the parameters assessed. CONCLUSIONS: Maneuvers with ETE and flow ≤ 10% of the highest PEF are valid. In individuals with a flow > 10% of the highest PEF value, these maneuvers are only valid for FEV(0.5).

Efeito da terminação precoce da expiração nos parâmetros espirométricos em crianças pré-escolares saudáveis / Early termination of exhalation: effect on spirometric parameters in healthy preschool children

OBJETIVO: Avaliar a aceitabilidade e a reprodutibilidade da espirometria em pré-escolares; estimar o tamanho do efeito da terminação precoce da expiração (TPE) nos valores de CVF, VEF1 e VEF0,5; e avaliar a validade do VEF0,5 em curvas com TPE. MÉTODOS: Espirometrias foram obtidas em 240 pré-escolares saudáveis, selecionados por amostragem simples. Três grupos foram formados com base na melhor curva de cada criança de acordo com o término da expiração: sem TPE (sTPE); com TPE e fluxo < 10 por cento do maior PFE (TPE<10); e com TPE e fluxo > 10 por cento do maior PFE (TPE>10). Foram comparadas a reprodutibilidade da CVF, VEF1 e VEF0,5 nos três grupos. Foi avaliado o efeito da TPE em CVF, VEF1 e VEF0,5. RESULTADOS: Das 240 crianças testadas, 112 (46.5 por cento) realizaram curvas aceitáveis para todos os parâmetros - 82 (34,0 por cento) no grupo sTPE e 30 (12,5 por cento) no grupo TPE<10. Em 64 (27,0 por cento) no grupo TPE>10, as curvas foram aceitáveis apenas para VEF0,5, aumentando para 73,0 por cento a proporção de crianças com VEF0,5 válido. Não houve diferenças significantes nas médias dos parâmetros avaliados entre os grupos sTPE e TPE<10. CONCLUSÕES: Manobras com TPE e fluxo < 10 por cento do maior PFE são válidas. Em indivíduos com fluxo > 10 por cento do maior PFE, essas manobras são válidas somente para VEF0,5.

OBJECTIVE: To evaluate the acceptability and reproducibility of spirometry in preschool children; to estimate the effect size of early termination of exhalation (ETE) on FVC, FEV1 and FEV0.5; and to evaluate the validity of FEV0.5 in curves with ETE. METHODS: Spirometric data were obtained from 240 healthy preschool children, who were selected by simple sampling. On the basis of the best curve from each child according to the end of exhalation, three groups were formed: no ETE (nETE); ETE and flow < 10 percent of the highest PEF (ETE<10); and ETE and flow > 10 percent of the highest PEF value (ETE>10). The reproducibility of FVC, FEV1 and FEV0.5 was compared among the three groups. The effect of ETE on FVC, FEV1, and FEV0.5 was assessed. RESULTS: Of the 240 children tested, 112 (46.5 percent)-82 (34.0 percent) of those in the nETE group and 30 (12.5 percent) of those in the ETE<10 group-had acceptable curves for all the parameters. In 64 (27.0 percent) of those in the ETE>10 group, the curves were acceptable only for FEV0.5, increasing the proportion of children with valid FEV0.5 to 73.0 percent. There were no significant differences between the nETE and ETE<10 groups in terms of the mean values of the parameters assessed. CONCLUSIONS: Maneuvers with ETE and flow < 10 percent of the highest PEF are valid. In individuals with a flow > 10 percent of the highest PEF value, these maneuvers are only valid for FEV0.5.