Ventilatory capacity indices in Malawian children

Objective: To compare ventilatory capacity indices in healthy Malawian school children with those of other ethnic Africans and Caucasians. Design: Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), peak expiratory flow rate (PEFR), FEV1 expressed as a percentage of FVC (FEV%), weight and height. Setting: Two primary schools in urban Blantyre, Malawi. Subjects: Five hundred and fourteen apparently healthy school children (230 boys and 284 girls) aged six to 17 years. Results: Ventilatory capacity indices (FEV1, FVC and PEFR) strongly and significantly correlated to body size and age of children of both sexes. The mean value of FEV% was 88.3% and it did not change significantly with increasing body size and age of children. The mean values of FEV1 and FVC were 9.8% and 10.8% higher in boys than in girls, respectively. The 1.4% gender difference in PEFR values was statistically non-significant. For FEV1 and FVC values, the average differences between Malawian and European children were between 20.5% and 23% while for PEFR the ethnic difference was about 12%. The Malawian children have similar ventilatory capacity indices to those of Nigerian, Jamaican and Tanzanian children. Conclusion: Prediction equations calculated in this study should be used for interpretation of ventilatory capacity indices in Malawian children instead of reference values for Caucasians or ethnic scaling factors. Computation of regional reference values for ventilatory capacity indices shall be continued. It shall embrace additional factors contributing to variance in respiratory functions such as customary physical activity, local environmental conditions, altitude of residence, nutritional status and smoking.