Sinus infections are one of the most common reasons patients leave a doctor’s office with a prescription for antibiotics. But bacteria cause only about one-third of sinus infections—the rest are caused by viruses, which are not treatable with antibiotics.

To curb unnecessary antibiotic prescribing, physician and UGA researcher Mark Ebell developed a clinical decision rule for diagnosing sinus infections, or acute rhinosinusitis. In a study published in the Annals of Family Medicine, Dr. Ebell presented a series of clinical rules that integrate patient symptoms and a simple lab test to accurately detect acute bacterial rhinosinusitis.

“A lot of the signs and symptoms of a bacterial sinus infection can be similar to those of a viral respiratory infection,” said Ebell, professor of epidemiology at the College of Public Health. “It can be difficult to distinguish between the two.”

Primary practice guidelines recommend the use of antibiotics only for patients who have experienced prolonged or severe symptoms, but an estimated 72 percent of patients receive an antibiotic.

“Patients have been conditioned to expect an antibiotic for sinus infections,” Ebell said. “The goal of our research was to help identify patients who didn’t need an antibiotic because their infection is probably caused by a virus.”

To develop a clinical decision rule, Ebell needed to determine which combination of symptoms and tests best predicted the presence of bacteria and compare that prediction model to a reference standard used to confirm its accuracy. A positive bacterial culture of sinus fluid was the preferred reference standard in this study.

He and his colleague, Dr. Jens Hansen of Aarhaus University Hospital in Denmark, recorded the symptoms and C-reactive protein (CRP) levels for 175 patients suspected of having sinus infections. Based on these data, Ebell created a simple, six-item point score to determine whether a patient is at low, moderate or high risk for bacterial infection.

CRP tests detect inflammation in the body, which can indicate an infection. This is an important component of the point score, but CRP testing is not available in most primary care settings in the U.S., Ebell said.

“That’s one of the issues we wanted to call attention to,” he said. “This is a test that’s widely used by doctors in Europe, the U.K. and Australia and has been shown to decrease inappropriate antibiotic use for other respiratory infections as well.”

About half of patients in the study had a low score, meaning they were low risk for bacterial infection and most likely had a viral infection. Withholding antibiotics from this group could cut the proportion of patients receiving antibiotics in half.

Physicians can easily incorporate this point score into clinical practice, Ebell said. During an initial interview, a nurse or medical assistant can identify whether patients are experiencing any of five symptoms—previous upper respiratory or sinus infections, discolored mucus, pain in the area under the eyes, or a toothache. Then, the physician can decide whether to order a CRP test and determine a final score for sinus infection.

Ebell plans to perform a randomized clinical trial to test the effectiveness of the point score system, including the use of a CRP test, in clinical practice.

“We need to give physicians better tools to support their decision-making, and that can include clinical decision rules and point-of-care tests like CRP,” he said. “Using these kinds of tools, we can hopefully reduce unnecessary antibiotic use.

This story appeared in the fall 2017 issue of Research Magazine. The original press release is available at