الفهرس 
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Abstract
Asthma is a complex genetic disorder with a heterogeneous phenotype; its incidence has risen over the past three decades across all age and ethnic groups to emerge as a global epidemic that affects nearly 155 million individuals worldwide. Asthma-related morbidity and mortality is disproportionately high among children making it the most common chronic disease in children in all developed countries.
The aim of the present study was to demonstrate the role of YKL-40 in the assessment of the severity of bronchial asthma which may have an impact on the choice of therapeutic regimen.
This study was conducted on 60 adult female patients suffering from bronchial asthma (group І). Group І was sub-divided according to the different degrees of severity of bronchial asthma based on GINA Classification (2009) into (22) patients with mild bronchial asthma (sub-group Іa), (20) patients with moderate bronchial asthma (sub-group Іb), and (18) patients with severe bronchial asthma (sub-group Іc). These patients were compared to twenty (20) age and sex matched apparently healthy control subjects (group ІІ).
Our study revealed a significant increase of serum YKL-40 when compared with the control group (P<0.001). In addition, serum YKl-40 was able to discriminate the different sub-groups of bronchial asthma (mild, moderate and severe).
A comparative study between the different degrees of severity of patients’ group (subgroup Ιa, subgroup Ιb, subgroup Ιc ) and group II regarding YKL-40 revealed a highly-significant difference between the subgroup Ιb and subgroup Ιc when compared with group II (P = <0.001 ) while there was no significant difference between the subgroup Ιa, and group II (P = >0.05).
As regard correlation analysis, a highly significant negative correlation was found between serum YKL-40 and FEV1. Moreover, a highly significant positive correlation was found between serum YKL-40 and frequency of symptoms, nighttime symptoms and the frequency of use of the short-acting B2 agonist.
The diagnostic performance of serum YKL-40 in discriminating group I from group II shows the best diagnostic cut off for serum YKL-40 in differentiation of group I from group II is 35ng/mL. The diagnostic sensitivity, specificity, PPV, NPV and total efficacy were 71%, 55 %, 83%, 37.9 % and 67.1 % respectively.
The diagnostic performance of serum YKL-40 in discriminating the different degrees of severity of bronchial asthma patients was assessed. The best diagnostic cut off for serum YKL-40 in differentiating subgroup Ιa from the other subgroups was 40ng/mL. The diagnostic sensitivity, specificity, PPV, NPV and total efficacy were 92%, 75%, 85.4%, 85.7% and 85.5%, respectively. In addition, the best diagnostic cut off for serum YKL-40 in differentiation between subgroup Ιb and subgroup Ιc was 100ng/mL. The diagnostic sensitivity, specificity, PPV, NPV and total efficacy were 88.9%, 90%, 88.9%, 90% and 89.5% respectively. Accordingly serum YKL-40 can be applied in the differentiation between different degrees of severity of bronchial asthma. This could help in planning the therapy modalities especially severe and refractory asthmatic patients as treatment failure in this group of patients is associated with continued airway inflammation which lead to a higher patient morbidity rate.
To achieve the highest efficacy in differentiating group І from group ІІ measuring YKL-40 and FEV1 were used combined together. It was found that the best diagnostic cut off of YKl-40 is 55ng/mL and FEV1 is 86%. This had a diagnostic sensitivity of 100%, specificity 95%, PPV 98.4 %, NPV 100 % and efficacy 98.8 %.
Finally, this study concluded that YKL-40 can assess the severity of bronchial asthma which can affect the choice of therapy modalities. Moreover, it can differentiate between asthma patients and healthy individuals especially when combined with FEV1 done by spirometer.