Evaluating the diagnosis of chronic rhinosinusitis based on clinical guidelines and endoscopy

To validate the diagnosis of chronic rhinosinusitis (CRS) according to recent clinical practice guidelines and determine the added utility of nasal endoscopy.

Prospective diagnostic cohort study.

Academic medical center.

A consecutive series of adult patients presenting for evaluation of CRS were prospectively studied with the use of the rhinosinusitis symptom inventory (RSI), nasal endoscopy, and sinus computed tomography (CT). Symptom scores were tabulated from the RSI. Nasal endoscopy was performed to evaluate for purulence or polyps. Sinus CT scans were scored with the Lund system, with the reviewers blinded to the RSI scores and endoscopic findings. The clinical diagnosis of CRS was determined on the basis of the published adult sinusitis guideline criteria and compared with the diagnostic gold standard, CT.

A total of 202 patients were studied. The prevalence of CRS was 39.6 percent, as defined by CT (Lund score > or = 4). For symptom criteria alone, the sensitivity, specificity, positive predictive value, and negative predictive value were 88.7, 12.3, 39.9, and 62.5 percent, respectively, for CRS (P = 0.82). The addition of endoscopic findings to symptom criteria significantly improved the specificity, predictive value, and negative predictive value to 84.1, 66.0, and 70.3 percent (P < 0.0001). The odds ratio of a true diagnosis of CRS improved from 1.1 to 4.6 (95% confidence interval, 2.3-9.2). Sensitivity analysis adjusting symptom severity did not significantly alter diagnostic accuracy.

In patients meeting current guideline symptom criteria for CRS, the addition of nasal endoscopy improves diagnostic accuracy and should be emphasized as an early diagnostic tool. Diagnostic endoscopy may help reduce the use of CT, reducing costs and radiation exposure.