Assessment of Standardized Peak Expiratory Flow Rate using the Fawibe Reference Equation and Associated Factors among Sawmill Workers in Osogbo, Nigeria

Peak Expiratory Flow Rate (PEFR) is a safe, easy, quick test of lung function that is commonly applied in clinical and occupational health. PEFR values vary with physiological factors like age, height and sex, and hence the use of a reference equation is necessary to interpret the values accurately. This study aimed to determine PEFR and its correlates among sawmill workers in Osogbo, Nigeria, using the Fawibe reference equation for Nigerian adults. The study design used was descriptive cross sectional, comprising of 250 sawmill workers that were obtained by multistage sampling. PEFR was measured with the use of portable peak flow meter and highest of three measurements was recorded for each participant. The Fawibe equations that take  three measurements was recorded for each participant. The Fawibe equations that take into account age, sex, and height were used to calculate predicted PEFR values, and measured PEFR values were reported as % of predicted PEFR. Respiratory function  was classified as normal (≥80% predicted) or reduced (<80% predicted). Associations between PEFR status and selected variables were assessed using chi-square tests, with statistical significance set at p<0.05. The mean observed PEFR among respondents was 437.1 ± 60.49 L/min, with 42.4% recording a reduced PEFR and 57.6% a normal lung function. The bivariate analysis demonstrated that gender (p = 0.040), regular participation in milling activities (p = 0.001), daily hours spent on milling (p = 0.029) and BMI (p = 0.001) were significantly associated with reduced PEFR. After standardization with the Fawibe reference equation, a significant number of sawmill workers had a reduced PEFR linked to specific demographic, anthropometric and/or occupational factors. The study underscores the importance of routine respiratory health monitoring and strengthening occupational dust control among workers exposed to wood dust.