Nickan Research Institute Immunopathologia Persa 2423-8015 10 1 2024 01 01 The positive association between various demographic characteristics and peak expiratory flow in employees of Zanjan university of medical sciences e33402 e33402 10.34172/ipp.2022.33402 EN Samad Ghodrati https://orcid.org/0000-0002-9597-0493 Jafar Kiasatfar Negin Parsamanesh https://orcid.org/0000-0002-1925-9165 Shohreh Alian Samakkhah Masoud Asadi-Khiavi https://orcid.org/0000-0002-4457-954X Aiyoub Pezeshgi https://orcid.org/0000-0001-9694-7394 Journal Article 10.34172/ipp.2022.33402 2022 05 01 2022 06 14 Introduction: Peak expiratory flow (PEF) is a reliable criterion for assessing respiratory capacity, and has a wide range of clinical application as a marker of asthma control. However, its wide variability undermines its efficacy. Objectives: This study was designed to evaluate PEF changes in staff of Zanjan University of Medical Sciences. Patients and Methods: Four hundred employees of this university participated in this cross-sectional study. Their PEF values were measured using peak flow meter in the morning at 8 AM and in the afternoon at 2 PM by three times for each individual, and then the highest amount of PEF was recorded about for measurement. Results: Obviously, PEF values were higher in the afternoon (43865 L/min) in comparison to the morning measurements (404.60 L/min) by paired t test (P<0.001). In addition, mean of PEF in the males was higher than the females in the morning (469.77 L/min, versus 355.94 L/min; independent t test, P<0.001), and also PEF mean of the morning and afternoon was higher in the males than females (404.6 L/min, versus 338.65 L/min, independent t test, P<0.001). Additionally, the variability level in the males and females was 8.39±6 and 8.47±4 L/min, respectively. There was a high correlation between the level of PEF variability and height (5.1). Meanwhile, a moderate correlation between PEF level and body mass index (BMI) was detected (1.47). There was not any correlation between the level of PEF and age. Conclusion: Based on our findings, PEF inter-individual variability depends on age, gender height, and BMI however, it is worthwhile that this PEF inter-individual variability to be measured just until 4 PM. All these variables were obtained under the range of 20%; however, relying on references, the variability of 20% is considered as normal.