SESSION TITLE: Pulmonary Function Testing
SESSION TYPE: Slide Presentations
PRESENTED ON: Sunday, March 23, 2014 at 04:15 PM - 05:15 PM
PURPOSE: Exhaled nitric oxide (FeNO) and Methacholine challenge (MCH) are both utilized in the detection and management of numerous pulmonary diseases. MCH is a measure of direct airway hyperresponsiveness. FeNO measures bronchial epithelial damage from eosinophilic bronchitis whether asthma or non-asthma related. FeNO has an attractive performance profile, as it is a cheaper and less invasive test. We hypothesize that FeNO can decrease the need for MCH testing.
METHODS: Retrospective chart review of patients ≥ 18 years presenting to a tertiary referral center seen between 11/01/2009 - 8/31/2013 who received FeNO and MCH within 2 weeks. Fischer exact test and diagnostic testing evaluations were used for analysis.
RESULTS: 1322 patients were identified. Demographics: 843 (63.7%) females and 479 (36.2%) males; 1288 (97.4%) Caucasian, 21 (1.6%) Black, 13 (1%) Asian. Average age was 54.1 years (SD +/- 15.5 years). Mean BMI 29.5 (SD +/-6.7). 89 patients were positive for both MCH and FeNO, 178 patients had a positive MCH but negative FeNO, 160 patients had a negative MCH but positive FeNO, and 895 patients had both a negative (p<0.01). Directly comparing FeNO to MCH yielded: sensitivity 33.33% (95% CI: 27.71 % to 39.34 %), specificity 84.83% (95% CI: 82.53 % to 86.95 %), positive likelihood ratio 2.2 (95% CI: 1.76 to 2.74), negative likelihood ratio 0.79 (95% CI: 0.72 to 0.86), positive predictive value 35.74% (95% CI: 29.79 % to 42.04 %), and negative predictive value 83.41% (95% CI: 81.05 % to 85.59 %).
CONCLUSIONS: In this large cohort of pulmonary patients, a strategy of FeNO at the point-of-care may reduce but does not eliminate the need for MCH testing. Likely this represents that FeNO and methacholine responsiveness measure different biological phenomenon. Further subgroup analysis is needed to determine if FeNO is more predicative in certain patient groups, such as steroid naïve patients.
CLINICAL IMPLICATIONS: Exhaled nitric oxide seems to represent a different biologic phenomena from methacholine challenge. Despite exhaled nitric oxide being non-invasive and having an attractive cost profile, it can not be used to replace methacholine challenge in the evaluation of the pulmonary patient.
DISCLOSURE: The following authors have nothing to disclose: Andrew Nickels, Kenneth Parker, Paul Scanlon, Kaiser Lim
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