Spirometric Standards for Healthy Iranians Dwelling in the Centre of Iran


1 Department of Internal Medicine,

2 Faculty of Public Health, Kashan University of Medical Sciences and Health Services, KASHANIRAN.


Background: In order to determining spirometric reference values in healthy, nonsmoker adult subjects, this study was
performed on populations dwelling in the centre of Iran, Kashan city. The area was selected as the representative of a less
polluted area in Iran, as we intended to exclude possible effects of air pollution on spirometric values.
Materials and Methods: The study was performed on 550 subjects (295 Males, 255 Females) aged 17 to 82 years,
randomly selected from the general population, and assessed anthropometrically for age and height by using stepwise
regression analysis. The prediction equations were calculated on the basis of age and height for forced vital capacity (FVC),
forced expiratory volume in one second (FEV1), and forced expiratory flow during the middle half of the FVC (FEF25-75%).
Comparisons with predictions of other Caucasians studies are reported.
Results: A Comparative study of FVC and FEV1 values of our subjects, standardized for age and height was much closer to
FVC and FEV1 of other studies. The prediction equations (based on age and standing height) for FVC (liters) in males: -5.546
+ 0.065 height – 0.027 age; and females –3.214+ 0.046 height – 0.023 age; FEV1 (liters) in males: -2.853 + 0.046 height –
0.029 age; and females: - 2.430 + 0.039 height- 0.024 age; for FEF25-75% in males: + 1.987 + 0.027height – 0.044 age; and
females: - 0.769 + 0.037 height – 0.033 age.
Conclusion: A comparison between equation from the present study and other available reference data shows that our
prediction values were similar to those previously reported. The present regression equations for predicted values of lung
function measurements may be regarded as the definitive norms for adult population dwelling in the centre of Iran and will be
useful for diagnostic and research purposes. (Tanaffos 2005; 4(15): 19-26)