The diagnosis of bronchial obstruction, the early identification of lung diseases, the monitoring of lung growth, and the apogee and decline in lung function over time are all important characteristics to consider in the clinical management of respiratory disease. The assessment and management of respiratory diseases require reliable spirometry reference points for both static and dynamic lung volumes. To accomplish this, the effects of disease and of environmental influences on lung growth must be understood to avoid misdiagnoses. Ventilatory parameters observed in measurements of respiratory mechanics should be compared with spirometric reference values
This was a multicenter study that was conducted from February to May 2011 on school children and students in five elementary schools and one secondary school in Porto-Novo (Benin). There were no health risks associated with participation in this study when a previously undiagnosed respiratory impairment was discovered; the individual was referred to a specialist for consultation and monitoring. All participants were fully informed about the purpose and ongoing progress of the study.
On the day of the experiment, subjects completed a health status questionnaire; parents signed informed consent forms for younger participants (the ages under which parental consent was required were 11, 12, and 13). Individual subjects were weighed, and their height was measured and recorded. The same day, after 10 minutes passive rest, spirometric measurements were recorded. Due to possible influences that can induce alterations in biorhythms, spirometric measurements were always taken in the morning from 10 to 12 a.m. This study was approved by the Scientific Committee on Sectoral and Technical Sciences of Physical Activity and Sports (CSS/STAPS), University of Abomey, in accordance with the Helsinki Act of 1975.
The number of subjects required for the study was determined using the following formula:
The subjects were all students recruited by the Beninese simple probabilistic method and comprised a total of 274 Beninese boys and 210 Beninese girls, aged from 11 to 16 years. (Table
Anthropometric characteristics and ventilatory parameters by sex and age from 11 to 16 years.
Age |
11 yrs | 12 yrs | 13 yrs | 14 yrs | 15 yrs | 16 yrs | |
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Height (cm) | (Girls) |
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BM (kg) | (Girls) |
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BMI (kg/m²) | (Girls) |
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FVC (L) | (Girls) |
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FEV1 (L) | (Girls) |
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BM: body mass; BMI: body mass index; FVC: force vital capacity; FEV1: Force expiratory in one second. Values
Both boys and girls subjects from Benin who were regularly enrolled in schools in Porto-Novo and aged from 11 to 16 years were selected to participate in the study. Exclusion criteria included history of smoking; current cardiovascular respiratory diseases; rheumatic diseases; subjects who are chronically exposed to automotive pollutants and biomass fuels; subjects undergoing treatment known to induce interference with any aspect of lung function; and subjects who were unable to perform the required respiratory maneuvers.
Clinical data observed in the subjects were recorded using a respiratory questionnaire based on the questionnaire of the ATS [
Flow/volume variables (FVC and FEV1) were measured using the MicroQuark Spirometer (Cosmed Ltd., Rome, Italy). Every morning, the spirometer was calibrated using a calibration syringe (Cosmed SARL, Rome, Italy) with a capacity of three liters of atmospheric air. The MicroQuark met the criteria of the ATS/ERS for measuring individuals of African origin. Indeed, the selection of “African origin” refers to the spirometer equations of African-American subject [
The magnitude of the FVC and FEV1 values measured in the subjects from each age group and sex was subjected to univariate analysis to determine means as well as confidence interval (our results). The mean heights were then introduced into the ERS-93 [
For girls children aged 18 years and under,
For girls children aged 18 years and under,
Table
Dynamic growth of Height, Body mass, FVC and FEV, by sex and age from 11 to 16 years.
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Height (%) | (Girls) |
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0.00 | 3.18 | 0.51 | 1.35 |
(Boys) |
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4.21 | 2.31 | 1.63 | 1.36 | |
BM (%) | (Girls) |
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6.86 | 7.57 | 0.00 | 6.40 |
(Boys) |
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10.13 | 9.20 | 3.24 | 4.81 | |
FVC (%) | (Girls) | 4.86 | 12.89 | 4.57 | 4.37 |
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(Boys) | 7.77 |
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8.17 | 7.55 | 7.36 | |
FEV1 (%) | (Girls) | 1.36 |
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12.21 | −2.59 | 9.04 |
(Boys) | 9.43 |
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9.85 | −3.14 | 1.85 |
BM: body mass; BMI: body mass index; FVC: force vital capacity; FEV: force expiratory in one second. Values
Tables
FVC and FEV1 values measured from our study compared to those calculated using the ITS-Black equations.
(A) |
(B) |
(C) |
(D) |
(E) |
(F) |
(G) |
(H) |
(I) |
(J) |
(K) |
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11 yrs |
[140.7; 145.5] | 143.1 | [1.91; 2.21] | 2.06 |
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+7.53 | [1.46; 1.72] | 1.59 | 2.03* | +27.62 |
12 yrs |
[147.0; 152.2] | 149.6 | [2.08; 2.36] | 2.22 | 2.52* | +13.65 | [1.62; 1.86] | 1.73 | 2.31* | +33.53 |
13 yrs |
[152.6; 159.3] | 155.9 | [2.36; 2.78] | 2.57 | 2.85* | +10.79 | [1.84; 2.21] | 2.03 | 2.61* | +28.37 |
14 yrs |
[156.5; 162.4] | 159.4 | [2.59; 2.97] | 2.78 | 3.04* | +9.30 | [2.06; 2.41] | 2.23 | 2.78* | +24.68 |
15 yrs |
[159.4; 164.9] | 162.1 | [2.79; 3.19] | 2.99 |
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+6.75 | [2.00; 2.31] | 2.16 | 2.92* | +35.19 |
16 yrs |
[160.7; 168.0] | 164.3 | [2.95; 3.46] | 3.21 |
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+3.44 | [1.99; 2.42] | 2.20 | 3.04* | +38.06 |
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11 yrs |
[143.1; 146.8] | 144.9 | [1.72; 1.98] | 1.85 | 2.30* | +24.16 | [1.35; 1.58] | 1.47 | 2.01* | +36.48 |
12 yrs |
[149.1; 153.8] | 151.4 | [1.80; 2.08] | 1.94 | 2.62* | +34.94 | [1.34; 1.64] | 1.49 | 2.28* | +52.86 |
13 yrs |
[148.8; 153.2] | 151.0 | [2.04; 2.34] | 2.19 | 2.60* | +18.60 | [1.58; 1.85] | 1.72 | 2.26* | +31.41 |
14 yrs |
[139.3; 161.5] | 150.4 | [2.16; 2.42] | 2.29 | 2.57* | +12.08 | [1.77; 2.10] | 1.93 | 2.23* | +15.77 |
15 yrs |
[153.3; 156.7] | 154.9 | [2.24; 2.54] | 2.39 | 2.80* | +17.25 | [1.75; 2.01] | 1.88 | 2.43* | +29.42 |
16 yrs |
[153.8; 160.4] | 157.0 | [2.46; 2.96] | 2.71 |
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+7.64 | [1.76; 2.35] | 2.05 | 2.53* | +23.40 |
(A): different categories of age, year, and sex (B); confidence intervals (CI) of height; (C): reference values
FVC and FEV1 values measured from our study compared to that calculated using the ERS-93 equations.
(A) |
(B) |
(C) |
(D) |
(E) |
(F) |
(G) |
(H) |
(I) |
(J) |
(K) |
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11 yrs (Boys) | [140.7; 145.5] | 143.1 | [1.91; 2.21] | 2.06 | 2.48* | +20.52 | [1.46; 1.72] | 1.59 | 2.17* | +36.24 |
12 yrs (Boys) | [147.0; 152.2] | 149.6 | [2.08; 2.36] | 2.22 | 2.82* | +27.06 | [1.62; 1.86] | 1.73 | 2.45* | +41.54 |
13 yrs (Boys) | [152.6; 159.3] | 155.9 | [2.36; 2.78] | 2.57 | 3.20* | +24.40 | [1.84; 2.21] | 2.03 | 2.76* | +36.09 |
14 yrs (Boys) | [156.5; 162.4] | 159.4 | [2.59; 2.97] | 2.78 | 3.43* | +23.27 | [2.06; 2.41] | 2.23 | 2.95* | +32.47 |
15 yrs (Boys) | [159.4; 164.9] | 162.1 | [2.79; 3.19] | 2.99 | 3.61* | +20.88 | [2.00; 2.31] | 2.16 | 3.11* | +43.99 |
16 yrs (Boys) | [160.7; 168.0] | 164.3 | [2.95; 3.46] | 3.21 | 3.77* | +17.56 | [1.99; 2.42] | 2.20 | 3.24* | +47.40 |
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11 yrs (Girls) | [143.1; 146.8] | 144.9 | [1.72; 1.98] | 1.85 | 2.37* | +28.31 | [1.35; 1.58] | 1.46 | 2.24* | +53.19 |
12 yrs (Girls) | [149.1; 153.8] | 151.4 | [1.80; 2.08] | 1.94 | 2.66* | +37.05 | [1.34; 1.64] | 1.49 | 2.47* | +65.98 |
13 yrs (Girls) | [148.8; 153.2] | 151.0 | [2.04; 2.34] | 2.19 | 2.64* | +20.58 | [1.58; 1.85] | 1.72 | 2.46* | +42.94 |
14 yrs (Girls) | [139.3; 161.5] | 150.4 | [2.16; 2.42] | 2.29 | 2.61* | +14.14 | [1.77; 2.10] | 1.93 | 2.44* | +26.26 |
15 yrs (Girls) | [153.3; 156.7] | 154.9 | [2.24; 2.54] | 2.39 | 2.82* | +17.94 | [1.75; 2.01] | 1.88 | 2.60* | +38.33 |
16 yrs (Girls) | [153.8; 160.4] | 157.0 | [2.46; 2.96] | 2.71 | 2.98* | +7.64 | [1.76; 2.35] | 2.05 | 2.68* | +30.59 |
(A): different categories of age, year, and sex; (B): confidence intervals (CI) of height; (C): reference values
The FVCs of 11-, 15-, and 16-year-old boys and those of 16-year-old girls in our study were not significantly different (
FEV1 and FVC values
The percentages of variations from these standards serve as correction factors for pulmonary function of children in Benin. All of the corrections lowered individual ventilatory variables (Table
Correction ethnic factors suggested by our study in Beninese children after using the microQuark Spirometer (Cosmed, Italy) with “African origin” option.
(A) |
(B) |
(C) |
(D) |
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11 yrs (Boys) | [140.7; 145.5] | −7.53 | −27.62 |
12 yrs (Boys) | [147.0; 152.2] | −13.65 | −33.53 |
13 yrs (Boys) | [152.6; 159.3] | −10.79 | −28.37 |
14 yrs (Boys) | [156.5; 162.4] | −9.30 | −24.68 |
15 yrs (Boys) | [159.4; 164.9] | −6.75 | −35.19 |
16 yrs (Boys) | [160.7; 168.0] | −3.44 | −38.06 |
11 yrs (Girls) | [143.1; 146.8] | −24.16 | −36.48 |
12 yrs (Girls) | [149.1; 153.8] | −34.94 | −52.86 |
13 yrs (Girls) | [148.8; 153.2] | −18.60 | −31.41 |
14 yrs (Girls) | [139.3; 161.5] | −12.08 | −15.77 |
15 yrs (Girls) | [153.3; 156.7] | −17.25 | −29.42 |
16 yrs (Girls) | [153.8; 160.4] | −7.64 | −23.40 |
(A): different categories of age, year, and sex, (B): confidence intervals (CI) of height, (C) and (D): correction ethnic values
The major findings of this study show that ERS-93 [
In sum, the variable FVC observed in Beninese children can be predicted using the ITS-Black standard for the 11-, 15-, and 16-year-old age groups. It should be noted that the ITS-Black reference standard values were established using the physical characteristics of African-American subjects. Studies show that the ancestors of African-Americans were slaves who were forcibly brought from Africa to the Americas. The work of Jordan [
In conclusion, the present study assessed growth dynamics, morphological spirometry, and standard FVC and FEV1 values that were adapted to the physical characteristics, ethnicity and specific environments of Beninese children. These reference values,