Spirometric reference values for healthy nonsmoking Saudi adults.

OBJECTIVES: To derive prediction equations of spirometric values of healthy Saudi adults and to compare the derived equations with equations reported in selected population.

METHODS: Cross-sectional study of healthy nonsmoking men and women Saudi adults. The measured spirometric values were the forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1 ), peak expiratory flow (PEF) and forced mid-expiratory flow (FEF 25%-75%).

RESULTS: A total of 621 spirometric tests were done. The prediction equations were derived using the following formula: Predicted spirometric value = constant + (b1 × age) + (b2 × height (cm)), where b1 and b2 represent the regression coefficients for age and height, respectively. Variable Constant Age (years) Height (cm) Variable Constant Age (years) Height (cm) Males (n = 292) Females (n = 175) FVC -2.933 -0.018 0.046 FVC -3.470 -0.016 0.045 FEV1 -1.886 -0.019 0.036 FEV1 -2.482 -0.018 0.036 FEV1 /FVC (%) 98.41 -0.095 -0.068 FEV1 /FVC (%) 100.67 -0.142 -0.072 PEF 17.274 -1.243 3.471 PEF -226.648 -0.499 4.076 FEF25%-75% 0.100 -0.024 0.027 FEF25%-75% -1.337 -0.021 0.031 The means of the measured FVC and FEV1 were significantly lower than the predicted values derived by the American equations of -7.2% and -4.6% among males, respectively (P value < 0.00001), and -4.7%, and -5.26% among females, respectively (P value < 0.00001).

CONCLUSION: The reference spirometric values derived in our study were significantly lower than the predicted values derived by the American equations.