Factors influencing the clinical diagnosis of sinusitis

This study was conducted to determine the influence of various clinical factors on the physician's diagnosis of sinusitis. Although the "clinical impression" appears to be a valid method of diagnosis in the literature, the specific factors that influence it have not been explored.

Seven factors selected from the literature were incorporated into 128 simulated case histories of patients with possible sinusitis. These cases were presented to 40 local family physicians who were asked to assess whether sinusitis was present and whether antibiotic therapy would be prescribed. Logistic regression was performed to determine the influence of each factor. These results were compared with a 30-item Likert-type scale that asked the physicians to rate a variety of factors in terms of their importance to the diagnosis of sinusitis.

The diagnosis of sinusitis and the decision to prescribe antibiotics were strongly influenced by the number of factors present. Physicians placed the most emphasis on purulent drainage seen on examination and sinus tenderness, and the least emphasis on smoking history and the failure to respond to decongestants. Transillumination and x-ray examinations were less useful to these physicians in establishing the diagnosis.

The surveyed physicians based their diagnosis of sinusitis on the number of symptoms present, especially if the presentation included purulent drainage seen on examination or sinus tenderness. These results are consistent with studies that have approached the question using other designs.