Predicting asthma severity and control using YKL-40 biomarker at Kiruddu General Referral Hospital: a cross-sectional and retrospective cohort study

Abstract

Introduction: Asthma affects about 11% of Ugandans and about 67% of these have uncontrolled disease. The complexity of classifying asthma severity and predicting asthma control with the current guidelines calls for identification of biomarkers for this purpose. YKL-40 is a human glycoprotein implicated in asthma pathogenesis. It has been found to be elevated in asthma patients and showing a positive correlation with severity of asthma in some populations. Objectives: To establish the relationship between YKL-40 and asthma severity at entry into the study, and asthma control following one year of optimal treatment among asthma patients presenting to Kiruddu General Referral Hospital in 2016 to 2019. Methods: This was a cross sectional and retrospective cohort study among 99 asthma patients from a simple random sample of the 431 Ugandan participants of the African Severe Asthma Programme at Kiruddu general referral hospital. Bio-banked sera collected at entry into the primary study was used to determine YKL-40 quantities by means of ELISA test. The data was summarised using means or median. A modified Poisson model with robust standard errors was fitted controlling for socio-demographics and clinical parameters to associate YKL-40 with asthma severity at entry into the study and also determine its ability to predict asthma control following 12 months follow up. Results: The median (IQR) age was 35(20-47) years with a median(IQR) BMI of 23.9(19.6-30.7)kg/m2 . There was no statistically significant difference in the median concentration of YKL-40 in not severe asthma and severe asthma (130.46 Vs 127.82 pg/ml, p=0.606). Similarly, there was no significant difference in the median concentration of YKL-40 among those with controlled and uncontrolled asthma (129.06 Vs 128.57 pg/ml, p=0.837). At multivariate analysis, YKL-40 was not associated with severe asthma (aIRR=1.00; 95% CI 0.99-1.00). There was no association between YK-40 and asthma control. Conclusions: This study showed that serum YKL-40 is not associated with asthma severity among patients with asthma in Uganda. And there was no association between YKL-40 and asthma control following one year of treatment. Therefore YKL-40 is not useful as a biomarker for severe asthma or asthma control in this population.