Validation of Previous Spirometric Reference Equations and New Equations

Reference Equations for Impulse Oscillometric and Respiratory System Model Parameters in Anglo and Hispanic Children / Ecuaciones de referencia para parámetros de oscilometría de impulsos y de modelo del sistema respiratorio en niños anglos e hispanos

Abstract The Impulse Oscillometry System (IOS) has been recognized as a useful diagnostic tool. Previous research by our group has shown that R5 (Resistance at 5 Hz), R5-R20 (frequency dependence of resistance), AX (the "Goldman Triangle") and the extended Resistor-Inductor-Capacitor (eRIC) model-derived parameter Cp (peripheral Compliance) are reliable measures that track respiratory system function. Here we determined the predictive equations from 112 asthmatic and non-asthmatic Anglo and Hispanic children data, that were previously classified into four groups: Normal, PSAI (Probable Small Airway Impairment), SAI (Small Airway Impairment), and Asthma by using regression analysis of IOS and eRIC model parameters as dependent variables regressed against age, height, and weight. Height showed the greatest correlation with IOS and eRIC model parameters and provided the most significant reference values for these measures in Anglo and Hispanic children. These values could serve as a useful framework for diagnosis, early interventions, and treatment of respiratory diseases in this population.

Resumen El Sistema de Oscilometría Impulsos (por sus siglas en Inglés: IOS) ha sido reconocido como una herramienta de diagnóstico útil. Investigaciones previas realizadas por nuestro grupo han demostrado que R5 (Resistencia a 5 Hz), R5-R20 (dependencia a la frecuencia de la resistencia), AX (el "Triángulo de Goldman") y el párametro Cp (Capacitancia periférica) derivado del modelo extendido Resistencia-inductor-condensador (eRIC) son medidas fiables que monitorean la función del sistema respiratorio. El presente estudio determina las ecuaciones de predicción de 112 niños Anglo e Hispanos asmáticos y no asmáticos, que previamente clasificados en cuatro grupos: Normal, PSAI (por su nombre en inglés: Probable daño en las vías aéreas menores), SAI (por su nombre en inglés: Daño en las vías aéreas menores), y Asma. Las ecuaciones de predicción se determinaron mediante análisis de regresión de parámetros del IOS y del modelo eRIC (variables dependientes) contra edad, estatura y peso. La estatura mostró la mejor correlación con los parámetros del IOS y del modelo eRIC, proporcionando los valores de referencia más significativos para estas medidas en niños Anglos e Hispanos. Estos valores podrían servir como un marco de referencia útil para el diagnóstico, intervenciones tempranas, y tratamiento de las enfermedades respiratorias en esta población.

O impacto dos valores previstos nos testes de função pulmonar / The impact of predicted values in pulmonary function tests

A interpretação dos testes de função pulmonar é resultado da comparação de valores obtidos com valores previstos para um determinado indivíduo. Os valores previstos são obtidos através de equações de referência, sendo estas determinadas por dados antropométricos e demográficos dos indivíduos. A presente revisão de literatura pretende identificar quais as equações referência mais utilizadas para os testes de função pulmonar, comparar estudos entre equações com ênfase nas publicações de equações de referência brasileiras.

Lung function test interpretation is based on the comparison between values measured according to the predicted values for each individual. The predicted values come from reference equations, which depend on anthropometric and demographic data of individuals. The present review aims to identify the most commonly used reference equations for pulmonary function tests, interpret comparative studies between equations and emphasizes publications with Brazilian reference equations.

The effect of applying ethnicity-specific spirometric reference equations to Asian migrant workers in Korea

OBJECTIVES: Asian migrant workers in Korea have various ethnicities. The purpose of this study was to evaluate the difference in spirometric interpretation made using the set of third National Health and Nutrition Examination Survey (NHANES III) reference equations and the relevant ethnicity-specific reference sets. METHODS: Spirometry was performed on 166 migrant and 498 Korean male workers between March and November 2012. We analyzed the spirometric data of healthy never-smokers. Spirometric patterns were evaluated using the NHANES III reference set and some relevant ethnicity-specific equations (Eom's equation for Koreans, Ip's equation for East Asians, Crapo's equation for Central Asians, Memon's equation for South Asians, and Gnanou's equation for Southeast Asian people). RESULTS: In all migrant groups except the Central Asian group, the forced expiratory volume in 1 second percentage (FEV1%) and forced vital capacity percentage (FVC%) calculated using each of the ethnicity-specific reference equations considered were significantly higher than those calculated using the NHANES III reference set. This study showed that in the evaluation of the spirometric result of subjects from Southeast Asia or South Asia, the percentage of cases with an abnormal FEV1 or FVC increased when the NHANES III set of equations was used as compared to when the ethnicity-specific equations were used. CONCLUSIONS: We found that the spirometric results of all ethnic groups were higher and the composition of the abnormal spirometric result was lower when the ethnicity-specific reference equations were used instead of the NHANES III reference set.

Clinical Usefulness and the Accuracy of Korean Reference Equation for Diffusing Capacity / 결핵및호흡기질환

BACKGROUND: Park et al. developed the Korean reference equation for the measurement of diffusing capacity in 1985. However, the equation has not been widely used in Korea and foreign reference equations have been popularly used. We intended to compare the clinical usefulness and the accuracy of the the Korean reference equation (Park's equation) with that of the foreign equation (Burrows' equation) that is commonly used in Korea. METHODS: 1. Evaluation of clinical usefulness; Among 1,584 patients who underwent diffusing capacity (D(L)CO) at the Asan Medical Center from July to December 2006, group A subjects included 276 patients who had different interpretations of D(L)CO in trials employing Burrows' equation and Park's equation. Clinical assessment was decided by consensus of two respiratory physicians. In order to evaluate the clinical usefulness of Burrows' equation and Park's equation, agreement of clinical assessment and DLCO interpretation were measured. 2. Evaluation of accuracy; Group B subjects were 81 patients with interstitial lung disease (ILD) and 39 normal subjects. The 81 ILD patients were diagnosed following a surgical lung biopsy. The accuracy of diagnosing ILD as well as sensitivity and specificity were evaluated according to the use of the reference equations (Burrows' equation and Park's equation) for DLCO. RESULTS: Agreement between clinical assessment and interpretation of D(L)CO was 22% for the use of Burrows' equation and 78% for the use of Park's equation. The sensitivity and specificity of the Burrows' equation for diagnosing ILD were 64.2% and 100%. The sensitivity and specificity of the Park's equation for diagnosing ILD were 90.1% and 100%. The sensitivity of the Park's equation for diagnosing ILD was significantly higher than that of Burrows' equation (p<0.001). CONCLUSION: The Korean reference equation (Park's equation) was more clinically useful and had higher sensitivity for diagnosing ILD than the foreign reference equation (Burrows' equation).