Annals of Family Medicine

Study Identifies Best Predictors of Bacterial Sinus Infection

April 05, 2019 02:21 pm Chris Crawford

Although acute rhinosinusitis (ARS) is the most common reason for outpatient prescription of antibiotics, only about one-third of patients with sinus symptoms have a confirmed bacterial infection, or acute bacterial rhinosinusitis (ABRS).

[physician examining woman's throat]

That's according to a study published in the March/April issue(www.annfammed.org) of Annals of Family Medicine that evaluated the accuracy of signs and symptoms used to diagnose ARS.

The authors searched Medline to identify studies of outpatients with clinically suspected ARS that reported enough data to calculate sensitivity and specificity of various signs and symptoms in making the diagnosis. Of the 1,649 studies they initially identified and evaluated, 17 met inclusion criteria.

The researchers found that studies used a number of reference standards, including various imaging modalities and inspection or culture of antral puncture fluid. Although ARS was diagnosed by any valid reference standard, ABRS was diagnosed only by purulence on antral puncture or positive bacterial culture.

The authors also noted that ARS, as diagnosed by any abnormal reference standard, is significantly less likely in patients with no nasal discharge, those without a complaint of purulent nasal discharge and those in whom transillumination is normal.

Story Highlights
  • A study published in the March/April issue of Annals of Family Medicine identified three predictors that best helped clinicians diagnose patients with acute bacterial rhinosinusitis: overall clinical impression, pain in the teeth and fetid breath.
  • Although acute rhinosinusitis (ARS) is the most common reason for outpatient prescription of antibiotics, only about one-third of patients with sinus symptoms have a confirmed bacterial infection.
  • The authors based their conclusions on studies of outpatients with clinically suspected ARS that reported enough data to calculate sensitivity and specificity of various signs and symptoms in making the diagnosis.  

Most importantly, the authors' analysis identified three predictors that best helped clinicians diagnose patients with ABRS: overall clinical impression, pain in the teeth and fetid breath.

Clinical Decision Rules

Lead study author Mark Ebell, M.D., M.S., a professor of epidemiology and biostatistics at the University of Georgia's College of Public Health in Athens, told AAFP News that in a previous study published in the July/August 2017 issue(www.annfammed.org) of Annals of Family Medicine, he and co-author Jens Hansen, M.D., a lecturer in the clinical epidemiology department at Aarhus University Hospital in Denmark, identified a number of clinical prediction rules that combined signs and symptoms to improve diagnosis of ARS and ABRS in adults.

This includes one Ebell described as "a very promising rule with five signs and symptoms plus a point-of-care measurement of C-reactive protein."

Those specific rule components are

  • preceding upper respiratory tract infections,
  • previous sinusitis diagnosis,
  • tender maxillary sinus (unilateral),
  • maxillary toothache,
  • purulent nasal discharge and
  • C-reactive protein greater than 15 mg/L.

Using two different analytic models (multivariate analysis and classification and regression tree analysis) to develop the clinical decision rules and positive bacterial culture of antral puncture fluid as the reference standard yielded low, moderate and high ranges of risk for ARBS that were 6-16%, 31-49% and 59-73%, respectively. However, as with all the rules identified in the systematic review, prospective validation in a new population is still needed.

"While C-reactive protein is accurate and widely used in some countries at the point of care to identify patients more or less likely to have a bacterial respiratory infection, it is not currently available in most U.S. outpatient settings," the most recent study said.

"We think this kind of information could help physicians avoid unnecessary antibiotics, but it should be prospectively validated in a new population as well," Ebell noted.

Another potentially useful point-of-care test is use of a urine dipstick to detect leukocyte esterase or nitrites in nasal discharge, the study noted. However, it, too, has not been prospectively validated.

Finally, the study noted that another recent systematic review that examined ultrasound found that the diagnostic imaging technique was about 80% sensitive for ARS.

"Patients who do not have any sinus fluid detected are therefore at low risk for ARS," the authors stated. "Thus, studies that evaluate the ability of modern handheld ultrasound devices to detect sinus fluid are needed."

Additional Author Notes

Ebell reiterated that a foul odor on the breath, pain in the maxillary teeth and the physician's overall clinical impression were most strongly associated with detection of bacteria in the sinus fluid in patients with sinus symptoms.

"The latter (clinical impression) was actually the best at ruling in and ruling out bacterial rhinosinusitis, which tells us that family physicians should trust their clinical examination and experience when ruling in, or just as importantly, ruling out a bacterial cause," he said.

Ebell also notes that these findings give family physicians ammunition in the ongoing battle for patient trust.

"Patients should be told to use symptomatic treatment like decongestants and should listen to their experienced family physician when he or she doesn't think they need antibiotics, because their overall clinical impression is quite accurate."

Related AAFP News Coverage
Is That Antibiotic Prescription Really Necessary?
Study Finds One in Four Prescriptions Are for Inappropriate Indications

(2/14/2019)

Study Shows Antibiotic Prescribing Lowest in Medical Offices
(8/2/2018)

AAFP Joins CDC, Other Groups in Fighting Antibiotic Resistance
(10/7/2016)

More From AAFP
American Family Physician: Interventions to Improve Antibiotic Prescribing for Uncomplicated Acute RTIs
(12/1/2016)

American Family Physician: Editorial: Curbing Inappropriate Antibiotic Prescribing: What Works?
(8/1/2016)

American Family Physician: Current Concepts in Adult Acute Rhinosinusitis
(7/15/2016)

FamilyDoctor.org: Antibiotics: When They Can and Can't Help(familydoctor.org)

FamilyDoctor.org: Sinusitis(familydoctor.org)