Spirometric reference values for Hopi Native American children ages 4-13 years.

Spirometry is the most important tool in diagnosing pulmonary disease and is the most frequently performed pulmonary function test. Respiratory disease is also one of the greatest causes for morbidity and mortality on the Hopi Nation, but no specific reference equations exist for this unique population. The purpose of this study was to determine if population reference equations were necessary for these children and, if needed, to create new age and race-specific pulmonary nomograms for Hopi children. Two hundred and ninety-two healthy children, ages 4-13 years, attending Hopi Nation elementary schools in Arizona, were asked to perform spirometry for a full battery of pulmonary volumes and capacities of which the following were analyzed: forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1 ), FEV1 % (FEV1 /FVC), FEF25-75% and peak expiratory flow rate (PEFR). Spirometric data from Navajo children living in the same geographical region as the Hopi children were compared as well as spirometric data from common reference values used for other ethnic groups in the USA. Spirometry tests from 165 girls and 127 boys met American Thoracic Society quality control standards. We found that the natural log of height, body mass and age were significant predictors of FEV1 , FVC, and FEF25-75% in the gender-specific models and that lung function values all increased with height and age as expected. The predictions using the equations derived for Navajo, Caucasian, Mexican-American, African-American youth were significantly different (P ≤ 0.05) from the predictions derived from the Hopi equations for all of the variables across both genders, with the exceptions of Hopi versus Navajo FEV1 /FVC in the males and Hopi versus Caucasians FEF25-75% in the females. Thus it would appear for this population important to have specific formulae to provide more accurate reference values.

Maximal respiratory pressure reference values for Navajo children ages 6-14.

BACKGROUND: Since anthropometric variables are critical to the creation of pulmonary nomograms for FVC, FEV1, and other volumes and capacities, it is logical that anthropometric variables also influence the values of the maximal respiratory pressures (MRPs). Since nomograms are race-specific, it is important that tribe-specific tables of normal maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) be developed. To date normal tables for MRPs do not exist for Navajo children. OBJECTIVE: Therefore the purpose of this study was to derive MRP normative reference values for Navajo children in the age range of 6-14 years. METHODS-PARTICIPANTS AND MEASUREMENTS: A cross-sectional study was undertaken with a representative sample of 534 healthy children, ages 6-14 years, attending Navajo Nation elementary schools in Arizona. MIP and MEP were measured. RESULTS: Test results from 275 girls and 259 boys met American Thoracic Society quality control standards and showed that MRPs all increased with height. Mean MIP in cm H2 O was 77 for boys and 67 for girls with lower limits of 44 and 40, respectively. Mean MEP in cm H2 O was 75 for boys and 66 for girls with the lower limits of 42 and 38, respectively. CONCLUSION: Since the data were collected from the population of interest, the resulting MIP and MEP reference equations should be used when testing Navajo children ages 6-14 years.

Spirometry reference values for Navajo children ages 6-14 years.

Spirometry is the most important tool in diagnosing pulmonary disease and is the most frequently performed pulmonary function test. Since respiratory disease is the single greatest cause for morbidity and mortality on the Navajo Nation, the purpose of this study was to create new age and race-specific pulmonary nomograms for Navajo children. Five hundred fifty-eight healthy children, ages 6-14 years, attending Navajo Nation elementary schools in Arizona, were asked to perform spirometry to develop population-specific and tribe-specific nomograms for forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1), and FEV1 Ratio (FEV1/FVC). Spirometry tests from 284 girls and 274 boys met American Thoracic Society quality control standards. Lung function values, except for FEV1/FVC, all increased with height. The lower limit of the normal range for FEV1/FVC was 80%. The spirometry reference equations from the healthy boys and girls were developed. Height and the natural log of height were significant predictors of FEV1, FVC, and FEF(25-75%) in the gender-specific models. The resulting population-specific spirometry reference equations should be used when testing Navajo children ages 6-14 years. However, the use of the NHANES III spirometry reference equations for Caucasian children may not result in significant misclassification in clinical settings providing that a maximal effort is given by the Navajo child being tested.

Obesity and pulmonary function in Navajo and Hopi children.

BACKGROUND: Although several reports have shown an adverse cardiovascular and metabolic risk profile associated with childhood obesity, few reports have examined the effects of childhood obesity on pulmonary function. OBJECTIVE: The purpose of this study was to examine the influence of obesity on pulmonary function in Navajo and Hopi children. METHODS: Subjects included 256 (110 males, 146 females) Hopi children 6-12 years of age and 557 (274 males, 283 females) Navajo children 6-12 years of age (N = 813). The body mass index was used to classify subjects as normal weight, overweight, or obese on the basis of international reference values. Forced vital capacity (FVC), forced expired volume in one second (FEV1), FEV1% (FEV1 to FVC ratio; FEV1/FVC), and forced expiratory flow between 25%-75% of vital capacity (FEF25-75) were determined according to the American Thoracic Society recommendations. RESULTS: Approximately 26% of Navajo and Hopi children were defined as overweight additional 16% (14.6% of boys and 17.7% of girls) were defined as obese. In general, the patterns showed an increase in pulmonary function between normal weight and overweight children and a decrease in pulmonary function of obese children. Significant differences among groups existed for FEV1% and FEF25-75 in boys and FVC and FEV1 in girls. CONCLUSIONS: The results indicate the pulmonary consequences of obesity in children and provide further evidence of the adverse consequences of pediatric obesity among Native Americans.

Growth status and obesity of Hopi children.

The purpose of this study was to examine the growth status and prevalence of underweight, overweight, and obesity in Hopi children. Subjects were 263 (117 males, 146 females) Hopi children 6-12 years of age. Stature and mass were measured and the body mass index (BMI) was calculated. Body size variables were plotted relative to age- and sex-specific reference data and the prevalence rates for underweight, overweight, and obesity were estimated using the BMI as the criterion. Age-specific sex differences were compared using independent samples t-tests. In both sexes, mean age-specific stature appeared to be relatively stable around the 50th percentile of reference values. Mean age-specific mass appeared to be relatively stable between the 50th and 90th percentiles of the reference values, while the mean BMI tended to fluctuate about the 85th percentile. Approximately 23% of Hopi children were classified as overweight and an additional 24% were classified as obese. Only two subjects were categorized as underweight. The results are consistent with other reports that childhood obesity is a serious public health concern among Native Americans. Further study is warranted to examine the causes of the high prevalence rates of pediatric obesity among Native Americans and the effectiveness of prevention and intervention programs.