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Member Research and Reports

Georgia Study: New Proposed Clinical Decision Rule Could Curb Inappropriate Antibiotic Prescribing among Sinus Infection Patients

No one is a stranger to sinus infections, and they are one of the most common reasons patients walk out of the doctor’s office with an antibiotic prescription in hand. The problem is that only about one third of sinus infections are caused by bacteria, which means most patients are inappropriately receiving antibiotics.

[Photo: Dr. Mark Ebell]

In an effort to curb unnecessary antibiotic prescribing, physician and University of Georgia researcher Dr. Mark Ebell sought to develop a clinical decision rule for diagnosing sinus infections, or acute rhinosinusitis as it’s known clinically. In a study appearing in the Annals of Family Medicine, Dr. Ebell presents a series of simple clinical rules that assess patient symptoms and C-reactive protein level to accurately detect acute bacterial rhinosinusitis.

Determining whether bacteria is the cause of a sinus infection has historically been a challenge. “A lot of the signs and symptoms of a bacterial sinus infection can be similar to those of a viral respiratory infection,” said Dr. Ebell, who is a professor of epidemiology at the UGA’s College of Public Health. “It can be difficult to distinguish between the two just using individual signs and symptoms.”

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

“Patients have been conditioned to expect an antibiotic for sinus infections because that’s what doctors do,” said Dr. Ebell, “so the goal of our research was to help identify patients who didn’t need an antibiotic.”

To develop a clinical decision rule for acute bacterial sinusitis, Dr. Ebell needed to determine which combination of symptoms best predicted the presence of bacteria and compare the statistical predictor to a reference standard. A positive bacterial culture of sinus fluid is the preferred reference standard.

He and his colleague, Dr. Jens Hansen of Aarhaus University Hospital in Denmark, recorded the symptoms, C-reactive protein and three reference standards for 175 patients suspected of having sinus infections. Based on these data, Dr. Ebell created a point score that can be used to determine the likelihood that a patient is at low, moderate or high risk for bacterial infection.

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

Dr. Ebell explains that physicians can easily incorporate this point score into clinical practice. A nurse or medical assistant can identify whether patients are experiencing any of the five symptoms included in the score during the initial interview. Then, the physician could decide whether to order a C-reactive protein (CRP) test and determine a final score for sinus infection.

CRP tests detect inflammation in the body, which can indicate an infection. This is an important component of the point score, says Dr. Ebell, though CRP testing is currently unavailable in most primary care settings in the U.S.

“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.”

CRP tests have also been shown to help better diagnose lower respiratory infections, pneumonia and, now, acute bacterial sinusitis. Dr. Ebell hopes this study will encourage the Food and Drug Administration to loosen restrictions on its use in primary care clinics.

“If you can show a patient that his or her inflammation level is low, which makes bacteria an unlikely cause of infection, then I think patients might be more willing to accept not getting an antibiotic.”

Dr. Ebell’s next plan is 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,” said Dr. Ebell. “Using these kinds of tools, we can hopefully reduce unnecessary antibiotic use.”

The study “Proposed Clinical Decision Rules to Diagnose Acute Rhinosinusitis Among Adults in Primary Care” is available online at http://www.annfammed.org/content/15/4/347

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