Comparison of lung function during different phases of the menstrual cycle among young female asthmatics and non-asthmatics
Bronchial asthma is a chronic lung disease that causes significant morbidity and poor quality of life. The incidence of asthma is higher in boys before puberty and higher in females following puberty. Female preponderance is maintained into adulthood and morbidity due to asthma is greater in females. With this background we assessed the lung function with spirometry parameters of young asthmatic and non-asthmatic healthy females during different phases of the menstrual cycle. A case control study was conducted among well controlled asthmatic (N=60) and comparable (age and BMI matched) non – asthmatic healthy females (N=60) between 19 -25 years from June 2017- June 2020. The asthmatics were recruited from the asthma clinic, National Hospital of Sri Lanka, the Family Practice Centre and the medical Centre, University of Sri Jayewardenepura (USJ) while the non-asthmatic females (controls) were recruited from volunteering undergraduates of the university. Although ethnicity was not a criterion for recruitment of participants, the final recruited participants were all from the Sinhalese ethnicity. The sociodemographic data and the relevant information on asthma were obtained through an interviewer administered questionnaire. Forced Expiratory Volume in the first second (FEV1), Forced Vital Capacity (FVC), FEV1/FVC ratio, Peak Expiratory Flow Rate (PEFR) and Forced Expiratory Flow Rates, were measured during menstrual, follicular and luteal phases of the menstrual cycle. Spirometry parameters (means), were compared in asthmatics and non-asthmatics, with independent sample t-test. Analysis of variance (ANOVA) was used to analyze differences within the menstrual cycle within the groups. In all three phases, all spirometry parameters (except FVC) were lower in asthmatics (p<0.05). The spirometry parameters showed a cyclical pattern but did not change significantly between the three phases of the menstrual cycle in both groups. In asthmatics, the mean values of FEV1, FEV1/FVC%, FEF 25-75, FEF50, FEF75 were lowest in the menstrual phase and highest in the luteal phase and in non-asthmatics, the FEV1 was lowest in the menstrual phase and highest in the luteal phase.
KEYWORDS: menstrual cycle, lung functions, spirometry, asthma, young females