Table 3.

Summary of findings, including the seven studies comparing nasal nitric oxide with an extended reference standard of electron microscopy and/or genetics^*

Outcome	Studies (n), Patients (n)	Study Design	Factors That May Decrease Quality of Evidence					Effect per 100 Patients Tested (Pretest Probability of 35%)	Test accuracy QoE	Importance
			Risk of Bias	Indirectness	Inconsistency	Imprecision	Publication Bias
True positives (patients with PCD)	7 studies, 423 patients	Cohort and case–control-type studies	Serious†	Not serious	Not serious‡	Not serious	None	34 (31–35)	⊕⊕⊕◯MODERATE	Critical
False negatives (patients incorrectly classified as not having PCD)								1 (0–4)		Critical
True negatives (patients without PCD)	7 studies, 636 patients	Cohort and case–control studies	Serious†	Not serious	Not serious‡	Not serious	None	63 (55–64)	⊕⊕⊕◯MODERATE	Critical
False positives (patients incorrectly classified as having PCD)								2 (1–10)		Important
Inconclusive	7 studies, 27 patients	—	—	—	—	—	—		—	Important

Definition of abbreviations: PCD = primary ciliary dyskinesia; QOE = quality of evidence.

^*Sensitivity, 0.96 (95% confidence interval, 0.89–0.99); specificity, 0.96 (95% confidence interval, 0.85–0.99); prevalence 35%.

^†Four studies were case–control studies, among which one study included only healthy patients in the control group. Two studies did not prespecify the nasal nitric oxide cutoff before performing measurements and were not blinded to the reference standard.

^‡Not downgraded for inconsistency since the residual heterogeneity was explained by the difference in the risk of bias between studies.