Definition of index and reference standard tests
| Reference standard tests | Definition | |
| ABRS | Bacterial culture (any method) of fluid from antral puncture. | |
| Bacterial culture (any method) of endoscopically guided middle meatal aspiration. | ||
| Bacterial culture (any method) of endoscopically guided middle meatal swabs. | ||
| CT-confirmed ARS | Presence of fluid level or total opacification in any sinus on CT scan. | |
| Reference standard tests | Definition | Anticipated probability of outcome risk |
| Preceding URTI | History of preceding URTI as reported by patients or based on medical record. | Increase25 |
| Previous diagnosis of ARS | History of previous ARS episode as reported by patients or based on medical record. | Decrease25 |
| Maxillary pain | Pain (any, unilateral or bilateral) in maxillary sinus region as reported by patients. | Increase25 |
| Pain in teeth | Pain in teeth as reported by patients. | Increase4 25 |
| Anosmia | Loss of smell as reported by patients. | Increase25 |
| Cacosmia | Sensation of bad smell as reported by patients. | Increase4 |
| Double sickening | Worsening of symptoms after initial improvement of symptoms (‘two phases in the illness history’) as reported by patients or clinicians. | Increase4 |
| Clinical impression | Overall clinical impression of illness as reported by the clinician. | Increase4 |
| Purulent nasal discharge on examination | The presence of purulent nasal discharge on rhinoscopia anterior or endoscopy. | Increase4 25 |
| CRP | CRP levels from blood samples collected by vena puncture (laboratory analysis) or fingerprick (using validated POCT devices). | Increase25 |
| ESR | ESR levels from blood samples collected by vena puncture (laboratory analysis) or fingerprick (using validated POCT devices). | Increase20 |
| Duration of illness (>10 days) | Symptom duration of more than 10 days as reported by patients. | Unknown* |
| Fever (>38°C) | Presence of fever (body temperature above 38°C) as reported by patients or measured by clinician. | Unknown* |
| Severe pain | Pain score >8/10 or equivalent scores using other pain rating scales as reported by patients. | Unknown* |
*Candidate predictor selection based on clinical reasoning.
ABRS, acute bacterial rhinosinusitis; ARS, acute rhinosinusitis; CRP, C reactive protein; CT, computed tomography; ESR, erythrocyte sedimentation rate; POCT, point-of-care test; URTI, upper respiratory tract infection.