title: Periostin - A Novel Systemic Biomarker for Eosinophilic Airway Inflammation: A Case Control Study.
abstract: BACKGROUND
  Chronic airway inflammation and remodelling are fundamental features of asthma. The molecular phenotypes in asthma are Th2 high and Th2 low. Serum periostin is a biomarker which aid in understanding Th2 high eosinophilic asthma.
  
  
  OBJECTIVE
  The present study aimed to identify whether or not serum periostin is a systemic biomarker for eosinophilic airway inflammation in asthmatics.
  
  
  METHODS
  The study was designed as a prospective, case control study. Patients who presented with consistent symptoms of asthma and confirmed by spirometry with reversibility were the cases. The controls were healthy subjects who had no history of lung disease with normal lung function. The sputum and blood samples were collected from both the groups. Sputum eosinophils, Absolute Eosinophil Counts (AEC) and serum periostin levels were compared between the groups.
  
  
  RESULTS
  The study comprised of 101 participants in which 30 were controls and 71 were cases. In the study group, mean post FEV1 was 64.45. There was a positive correlation of sputum eosinophils with severity of obstruction. The ROC curve analysis showed the cut-off value of 24.556 for serum periostin with the p-value of <0.001. As the severity of obstruction increased, the serum periostin levels were also found to be increased. Serum periostin had a sensitivity and specificity of 97.18% and 86.67% with a diagnostic accuracy of 94.06%.
  
  
  CONCLUSIONS
  Serum periostin appears to be a more sensitive tool for detection of airflow limitation in asthmatic patients with a Th2 high eosinophilic phenotype when compared to AEC and sputum eosinophils.
authors.affiliation: ESI Post Graduate Institute of Medical Sciences and Research (PGIMSR) , Rajajinagar, Bengaluru, India .
authors.forename: Viswanathan
authors.initials: V
authors.lastname: Emprm
authors.affiliation: Department of Pharmacy Practice, Faculty of Pharmacy, Sri Ramachandra University , Porur, Chennai, Tamil Nadu, India .
authors.forename: M G
authors.initials: MG
authors.lastname: Rajanandh
authors.affiliation: Professor and Head, Department of TB and Chest Diseases, Tagore Medical College & Hospital , Chennai, Tamil Nadu, India .
authors.forename: A D
authors.initials: AD
authors.lastname: Nageswari
keywords: Absolute eosinophil counts; Airway remodeling; Spirometry