Objective laboratory parameters in determining childhood asthma control

Introduction: Asthma is the most frequent chronic disease in childhood and it is important that the control status of asthma is accurately determined in order for treatment to be effective. Global initiavite for Asthma (GINA 2016) guidelines and pediatric asthma control test parameters are used to determine asthma control which depends on patients and their relative's declarations and are usually subjective. In our study, we investigated the role of objective laboratory parameters such as serum periostin, tryptase, leukotriene E4 and exhaled nitric oxide, which play a role in pathogenesis of asthma, in determining asthma control. Methods: This single-centered study included asthma patients between the ages of 7 and 18 who were followed up for at least one year in Abant Izzet Baysal University Medical Faculty Hospital Child Allergy Immunology Clinic. The control level of the patients was determined according to GINA guidelines, the asthma control test (ACT) was applied and pulmonary function test were administered. Serum periostin, tyrptase, urinary leukotrien E4, exhaled nitric oxide levels were calculated for all patients. Patient groups with and without control (partially controlled+uncontrolled) according to GINA were compared in terms of these parameters. Results: A total of 160 asthmatic patients were included in the study, which 133 were allergic and 27 were non-allergic. 52.5% of the patients were female and the mean age of the participants was 10.6±3.7 years. The asthma control level of 31.9% of the participants was controlled according to GINA and the median pediatric ACT score was 20. The median pediatric ACT score, serum periostin value and exhaled nitric oxide levels were significantly different when compared to control and uncontrolled patients according to GINA (respectively; p<0.001, p<0.001, p=0.003), but no difference was found in terms of basal tryptase and urinary leukotriene E4 levels. As a result of ROC analysis, pediatric ACT (AUC:0.914, %95GA:0.86-0.97, vii p<0.001), serum periostin (AUC:669, %95GA:0.59-0.75, p=0.001), and exhaled nitric oxide (AUC:755, %95GA:0.67-0.84, p<0.001) have been shown to be diagnostic value foreseeing asthma uncontrollability. The optimal cut-off values were 21 for ACT, 17.5 ppm for exhaled NO and 75 ng/ml for periostin. When the cut-off value for ACT was taken 20, incompatibility rate between ACT and GINA was 28,7%; 21, it was found to be 13,8%. Periostin and exhaled NO levels were found to be high in 8,7% of GINA and ACT-controlled patients, whereas periostin and exhaled NO levels were below cut-off values in 25% of uncontrolled patients according to both methods. Conclusion: There is significant disagreement between the GINA and ACT used in the prediction of childhood asthma control. The high levels of two imflammatory markers (periostin and exhaled NO) in patients who were accepted as having controlled asthma by both methods, may be due to the presence of subclinical inflammation, the inability of patients to express their symptoms, or their concealment of their symptoms. On the contrary a significant proportion of uncontrolled patients had both imflammatory markers found to be low. GINA is basically a clinical classification based on symptoms expressed by patients or their relatives. Patients sometimes exaggerate and sometimes hide their symptoms. At this point, we believe that the use of objective laboratory parameters such as exhaled NO and serum periostin leves will contribute to preventing over or under treatment. Key words: asthma control, GINA, pediatric ACT, periostin, tryptase, urinary leukotriene E4, exhaled nitric oxide