Use of nasal inspiratory flow rates in the measurement of aspirin-induced respiratory reactions.

Background: Nasal ketorolac challenge with modified oral aspirin challenge is a safe and effective alternative for desensitizing patients with aspirin-exacerbated respiratory disease. In addition to clinical judgment, objective tests assessing nasal flow may help in diagnosing nasal reactions.

Objective: To evaluate the feasibility of peak nasal inspiratory flow (PNIF) as an objective measurement in the assessment of a reaction to nasal ketorolac and to determine changes in PNIF that have adequate sensitivity and specificity.

Methods: One hundred fifty-one patients referred to the Scripps Clinic for aspirin challenge and desensitization and 14 healthy controls participated in the study. Percentages of decrease in PNIF during reactions were compared with the nonreactors' measurements. A receiver operating characteristic curve was constructed to assess the diagnostic performance of PNIF measurement during a clinically positive nasal challenge.

Results: A total of 165 subjects participated in the study. One hundred fourteen patients (69.1%) clinically reacted to the nasal ketorolac challenge. There was no statistical difference between nasal reactors and nonreactors regarding sex, baseline forced expiratory volume in 1 second, and use of systemic steroid before challenge. The mean percentage of decrease in PNIF was significantly higher in the reactor group (-0.30 ± 0.29 vs -0.07 ± 0.16, P < .001). A cutoff value of 25% decrease in PNIF had the maximum sensitivity and specificity (56.1% and 94.1%).

Conclusion: The high specificity of a 25% decrease in PNIF found in receiver operating characteristic curve analysis indicated that PNIF measurements can be useful for assessing nasal reactions during nasal ketorolac challenges in the diagnosis of aspirin-exacerbated respiratory disease.