Background:
Sinonasal symptoms are common and can have several underlying causes. When symptoms occur in specified patterns lasting three months or more they meet criteria for chronic rhinosinusitis (CRS). Approaches to CRS symptom measurement do not specify how to measure symptoms and treat six sinonasal symptoms as generally interchangeable, suggesting that such symptoms should cluster on one or two latent factors.
Methods:
We used questionnaire responses to 37 questions on presence, severity, bother, and frequency of cardinal sinonasal and related symptoms lasting three months, from 3535 subjects at three time points over 16 months. We completed five exploratory factor analyses (EFA) to identify symptom clustering, one for each time point and two for the differences between adjacent questionnaires. The baseline EFA was used to provide factor scores that were described longitudinally and examined by CRS status.
Results:
Five EFAs identified the same five factors (blockage and discharge, pain and pressure, asthma and cold/flu symptoms, smell loss, and ear and eye [mainly allergy] symptoms), with clustering determined by symptom frequency, severity, and degree of bother. Responses to individual questions showed changes over time but when combined into factor scores showed less longitudinal change. All symptom factor scores were progressively higher from never to past to current CRS status.
Conclusions:
Although the current approaches to symptom characterization in CRS imply a single underlying latent construct, our results suggest that there are at least three latent constructs relevant to CRS. Further studies are needed to evaluate if these clusters have identifiable underlying pathobiologies.