Effective patient selection for PCD diagnostics; the PICADAR score with nasal nitric oxide

Abstract

Primary ciliary dyskinesia (PCD) symptoms are non-specific and tools to aid patient selection for referral are needed. Objectives: To assess accuracy of a validated symptom score (PICADAR) [Behan, ERJ, 2016], in combination with nasal nitric oxide (nNO) to identify patients needing full diagnostics. Methods: Prospective data from 142 consecutive referrals for PCD diagnostics (33 PCD positive, 111 negative). Sensitivity/specifity calculated using either PICADAR score >5 or nNO below threshold (30, 77 or 100nl/min) as a positive test compared to final diagnosis of PCD. Results: PICADAR alone had sensitivity 0.88 and specificity 0.95. nNO+PICADAR improved identification of PCD positive patients. Accuracy was dependent on nNO threshold; sensitivities/specificities were 0.94/0.89, 0.94/0.78 and 1.0/0.73 using 30, 77 and 100nl/min. Conclusion: PICADAR effectively selects patients for referral to PCD diagnostics but some cases are missed. Addition of nNO provides a highly sensitive patient selection; 100nl/min nNO threshold gives a sensitivity and negative predictive value of 100%.