title: The validity of peak nasal inspiratory flow as a screening tool for nasal obstruction.
abstract: BACKGROUND
  The peak nasal inspiratory flow (PNIF) is used as an outcome measure in post-treatment clinical and research evaluation. It is simple and cost effective. The validity of the use as a screening tool has never been assessed
  
  
  OBJECTIVE
  To assess its validity and to define the cut-off point of determining the nasal obstruction
  
  
  METHODS
  The nasal patency of 141 ambulatory subjects with or without sino-nasal diseases was measured by the PNIF and active anterior rhinomanometry. Inclusion criteria was all subjects aged 18 to 75-years-old, sinonasal diseases/ symptoms(nasal congestion, nasal discharge, nasal polyp, deviated nasal septum, nasal tumor inferior turbinate hypertrophy, sinusitis, and allergic rhinitis), instant sensation of nasal obstruction, and nasal endoscopy finding were recorded. All subjects signed written consent. Compared with the active anterior rhinomanometry as the gold standard, the sensitivity, specificity, likelihood ratio, positive predictive value, and negative predictive value of the PNIF was analyzed. The cut-off point of nasal obstruction was defined from the Receiver Operating Characteristic curve analysis. The agreement between the PNIF and the stuffiness and between the PNIF and the presence of sino-nasal diseases were assessed by using Kappa.
  
  
  RESULTS
  With the cut-off point of 90 L/min, the sensitivity of the peak nasal inspiratory flow was 0.87 (0.753-0.989). The specificity was 0.52 (0.429-0.617). The negative predictive value was 0.93 (0.872-0.997). The positive predictive value was 0.34 (0.237-0.446). The likelihood ratio was 1.81 (1.438-2.318). The mean of the PNIF in normal subjects was 97.11 +/- 31.15. The agreement between the PNIF and the instant sensation of nasal blockage was 0.14 (-0.024-0.321) and the agreement between the PNIF and the sino-nasal diseases was 0.09 (-0.083-0.265).
  
  
  CONCLUSIONS
  The PNIF regarding the cut-off point of 90 L/min, revealed good sensitivity and high negative predictive value but it had low specificity and low positive predictive value. The nasal peak flow did not agree well with the subjects' symptoms of blockage and sino-nasal diseases.
authors.affiliation: Department of Otolaryngology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. Rujanavej@gmail.com
authors.forename: Valin
authors.initials: V
authors.lastname: Rujanavej
authors.forename: Kornkiat
authors.initials: K
authors.lastname: Snidvongs
authors.forename: Supinda
authors.initials: S
authors.lastname: Chusakul
authors.forename: Songklot
authors.initials: S
authors.lastname: Aeumjaturapat
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000403:Airway Resistance; D005260:Female; D006801:Humans; D001239:Inhalation; D008297:Male; D008875:Middle Aged; D015508:Nasal Obstruction / Q000175:diagnosis*; D011237:Predictive Value of Tests; D012372:ROC Curve; D025363:Rhinomanometry; D012680:Sensitivity and Specificity; D055815:Young Adult