Is there a role for up-to-date imaging in patients awaiting sinus surgery?

Introduction

Chronic rhinosinusitis (CRS) is defined as inflammation of the paranasal sinuses and nasal mucosa lasting twelve weeks or longer (1). Rhinosinusitis is characterised by two or more symptoms of nasal congestion, nasal discharge, post-nasal drip, facial pain or pressure and reduction or loss of smell (1). The European Position Paper on Rhinosinusitis and Nasal Polyps and the Clinical Practice Guideline by the American Academy of Otolaryngology state that symptoms should be corroborated with either positive endoscopic findings or computed tomography (CT) changes to confirm the diagnosis (1,2). A CT scan is mandatory if the patient is to undergo surgery in order to guide the surgeon on disease extent and variations in anatomy. The Lund-Mackay scoring system (LMS) was first described in 1993 to determine the radiological severity of sinus disease on CT scans (3). It is easy to perform with high inter-observer and intra-observer reliability and therefore has been widely accepted by clinicians without specialist radiological training (3,4).

CRS affects an estimated 1.9 million Australians (5). It markedly impacts on patients’ quality of life and increases the economic burden on the public health system (6-8). In Australia, there is a public health system which is funded by the government while the private health system is funded by the patient and/or their health insurance. Due to the limitations in capacity, there is a significant waiting time for patients to be seen and treated in the public sector after being referred by their primary care physician (9,10). CRS is considered non-urgent and patients may wait up to 5 years to be seen. The patient may have an initial CT sinus scan from their primary care physician but this scan could have been done several years ago due to the waiting time to be seen in the public outpatient clinic. While there is no guidance in the literature whether the delay to surgical treatment may cause radiological progression of CRS, patients often complain of worsening symptoms. Therefore, some otolaryngology doctors may decide to repeat the CT sinus scan when they initially consult on the patient in the public outpatient clinic. It is unclear whether the repeat CT scan would demonstrate a radiological change in LMS and secondarily whether it changes the extent of planned ESS.

The aim of this study is to determine if there is a difference in the LMS between two CT scans performed at least a year apart while waiting to be seen by a specialist in the public health system. The secondary aim is to determine whether the repeat CT scan changes the planned extent of sinus surgery. We present the following article in accordance with the STROBE reporting checklist (available at http://dx.doi.org/10.21037/ajo.2020.03.04).

Methods

Ethical approval was granted by the Human Research Ethics Committee as a clinical audit (HREC 65.18). This is a retrospective multicentre study performed at Flinders Medical Centre in South Australia and Monash Health in Victoria. Patients who underwent ESS from January 2016 to November 2018 were identified from the hospital electronic operating database system.

Inclusion criteria were:

• Eighteen years old and above;
• Elective ESS for CRS;
• Patients with two CT scans of the paranasal sinuses prior to surgery which were at least 12 months apart.
• No ESS performed prior to the repeat CT scan.

The exclusion criteria were:

• Emergency surgery;
• Patients with known diseases that may affect the paranasal sinuses (e.g., granulomatosis with polyangiitis, sinonasal tumours, cystic fibrosis, facial trauma).

We chose an inclusion criterion of 12 months between CT scans for our study because an audit identified that patients with CRS regularly wait for more than 12 months before they are seen for consultation in the public outpatient clinic. All CT scans were de-identified and coded such that reviewers were blinded to the identities and the dates of the scans. Experienced rhinologists (J Rimmer and EH Ooi) of similar experience from each site scored the CT scans from their own centre. Each scan was scored using the LMS. The frontal, maxillary, anterior ethmoid, posterior ethmoid and sphenoid sinuses, for both left and right sides, were scored zero (no opacity), one (partial opacity) or two (complete opacity) per sinus. The ostiomeatal complex (OMC) is scored zero (patent) or two (obstructed). The maximum LMS for a CT scan is 24. Prior to reviewing the scans, the reviewers reached a consensus of scoring one for any mucosal opacification and scoring two only if the sinus was completely opacified. Five randomly selected scans, a total of ten, scored by both reviewers were used to determine inter-rater variability. For each CT scan, the reviewers also proposed the surgery they would perform, scoring one for each sinus they would operate on, and zero for those they would not operate on (with a maximum score of ten for the planned extent of sinus surgery). In general, the practice is to perform a mini-functional endoscopic sinus surgery (FESS) for maxillary and ethmoid disease or a full-house FESS if the sphenoid and frontal sinus was also involved in regards to extent of surgery performed. The patient demographics (age, gender), relevant medical history (smoking history, aspirin intolerance, asthma), patient reported symptoms using the Sino-Nasal Outcome Test (SNOT-22), post-operative follow up (complications, revision surgery) and reasons for repeating CT scans were also collected from case notes.

Statistical analysis

The data was not normally distributed therefore non-parametric statistical tests were employed (Related Samples Wilcoxon Signed Rank test). Spearman’s rank order coefficient was used to determine the correlation of the LMS of the second scan with SNOT-22 and the extent of the planned ESS. Cohen’s kappa was used to determine the inter-rater variability between the two examiners for the LMS and the proposed operation related to each CT scan. The interpretation for kappa is as follows: <0 less than chance agreement; 0.01–0.20 slight agreement; 0.21–0.40 fair agreement; 0.41–0.60 moderate agreement; 0.61–0.80 substantial agreement; and 0.81–0.99 almost perfect agreement (11).

Results

There was a total of 56 patients in this study who met the inclusion criteria, 44 patients from South Australia and 12 patients from Victoria resulting in 112 CT sinus scans for analysis. The median [interquartile range (IQR)] age of the patients was 51.0 (39.0–64.8) years old. There were 36 males and 20 females. Relevant medical history is presented in Table 1.

The median (IQR) waiting time between the date of referral and the first outpatient clinic appointment was 2.7 (1.2–4.1) years. The median (IQR) time difference between the two scans was 2.1 (1.5–3.7) years. The median (IQR) time from first outpatient appointment to ESS was 0.8 (0.2–1.2) years.

The median (IQR) LMS of the first and second CT scans were 11 [6–14] and 12 [7–14] with no statistically significant difference between them (P=0.431), nor was there a significant difference in the extent of planned ESS based on the first and second scans (P=0.948). There was also no significant difference between each individual sinus when analysing the LMS or planned ESS between scans (Table 2). No changes to the anatomy were observed between the two scans in this study.

There was good correlation between the LMS for both CT scans and the extent of planned surgery (n=112, Spearman’s ρ 0.769, P<0.0001). Pre-operative SNOT-22 was recorded in 21/56 patients. There was no correlation between the LMS of the second CT and the patients’ perspective of their disease when using the SNOT-22 (n=21, Spearman’s ρ −0.079, P=0.73).

One patient required revision ESS due to recurrent polyps obstructing their frontal sinus drainage pathway resulting in ongoing symptoms. The rate of surgical complication was 5.4% (3/56). Three complications were recorded in three patients: two complications (septal haematoma and septal perforation) were related to the septoplasty performed in conjunction with ESS, and one patient had lateralisation of both middle turbinates with adhesions requiring revision ESS.

Inter-rater variability

The inter-rater variability of the LMS for each sinus is presented in Table 3 and the likelihood of operation on each sinus is presented in Table 4. The right anterior ethmoid for comparison of LMS and the left anterior ethmoid for planned ESS were unable to be calculated using Cohen’s kappa as the scores for one reviewer were constant with no variation.

Discussion

CRS is a disease that greatly impacts on quality of life (12). Delay in accessing appropriate medical and surgical treatment can potentially increase long term health care costs along with loss of productivity (12,13). We hypothesised that lengthy delays in accessing specialist treatment in the public health system in Australia result in increased LMS and change in the extent of planned sinus surgery. This retrospective cohort study found no significant evidence of LMS worsening while patients are on the waiting list to be seen in the outpatient clinic. The subsequent decision about the extent of planned ESS was also unchanged, with the rhinologists in this study blinded to the dates of the scans. These results are similar to those of Fraczek et al. who also demonstrated no significant changes in mucosal thickening on CT scans over approximately 1 year (mean time interval of 338 days) (14). Despite a longer duration between CT scans in this study, of approximately 2.1 years (median time interval 782 days), there were still no significant changes in radiological scores.

Unnecessarily repeated scans of the paranasal sinuses not only incur additional costs to both patients and the health service but also expose patients to further radiation. Current low dose CT protocols reduces the radiation exposure for scans dedicated to the sinuses, but certain risks remain due to the cumulative effect on biological tissue (14). The most likely affected tissue is the lens, in which repeated exposure may result in radiation-induced cataract (15). The thyroid gland is the most radiosensitive organ in the body and may be affected by scattering even though it is not within the scanning field (15,16). With low dose protocols at 40 mA, the lens and thyroid are exposed to a mean radiation dose of 5.53 and 0.63 mGy respectively (17). A cumulative dose of 500 to 2,000 mGy is required to cause corneal opacities and over 5,000 mGy to cause cataract, while the risk of developing thyroid cancer increases after exposure to radiation dose of more than 50 to 100 mGy (17,18).

Benninger et al. demonstrated an almost linear increase in post-operative healthcare utilisation the longer a patient waited for ESS (13), suggesting that patients potentially have worse post-operative outcome and co-morbidities the longer they suffer from CRS. However, Benninger’s study was retrospective in nature and based on medical and drug insurance claims, with no association to the actual severity of the disease (13). We did not find evidence of worsening of LMS in our patients experiencing symptoms for longer than 12 months which indirectly indicates that radiology alone is not sufficient to assess the severity or worsening of CRS. Hence repeating the CT sinus scan because patients have been waiting for many years to be seen in the public outpatient clinic is not supported by the findings of our study.

The SNOT-22 score has been recommended as the most suitable patient-reported outcome tool for CRS (19). As SNOT-22 was not completed when patients received their first CT scan during the initial presentation to their primary care physician, it is not possible to correlate the patients’ symptoms with the first CT. In this study, there was no correlation between the LMS and the patient’s perspective of their disease when using the SNOT-22 with the second CT scan. These findings are consistent with the literature regarding patients’ symptomology and the LMS (4,20). Patient outcome measures are subjective and multiple factors play a role in the patient’s perspective of their disease, resulting in poor correlation with objective measurements such as the LMS.

CT of the paranasal sinuses is an invaluable tool to not only assess the site and extent of sinus disease but also anatomical variations of the sinus and its relationship to the skull base and the orbit. The anatomy is unlikely to change over time unless complications related to sinus disease occur. When assessing the extent of sinus disease, the LMS has previously been shown to have high inter-rater and intra-rater reliability due to its simplicity (21). Inter-rater variability was assessed in the current study showing moderate to almost perfect agreement. However, the OMC and the left anterior ethmoid sinuses had lower inter-rater variability than expected despite the reviewers being of equivalent experience. This contradicts Julkunen et al. who demonstrated moderate inter-rater agreement for the OMC and anterior ethmoid sinuses (22). The inter-rater decision to operate on individual sinuses were generally consistent, except for the frontal sinuses. The decision to operate on the frontal sinuses was variable despite having substantial agreement on the LMS of the frontal sinuses. This may be a result of the recognised differences in the approach to frontal sinus surgery by different rhinologists (23). The limitations of the LMS is that it does not assess important considerations for ESS such as mucoceles or dehiscent lamina papyracea. The decision to operate on a particular sinus is also unlikely to change regardless of whether the LMS is scored one or two for that sinus. However, in the literature the LMS is used as a surrogate for comparing radiological disease when assessing the outcomes of ESS (8,20). Therefore, we felt that it was important to use the LMS to evaluate the evidence of repeating CT sinus scans in an Australian public healthcare system.

There are recognised limitations to this study. The retrospective nature of the study means there is missing data when collecting information from case notes. Some patients in this study did not have a SNOT-22 recorded. Even though the two reviewers are both senior rhinologists of equivalent experience, there may still be differences in their management approaches. We attempted to assess the reasons for the decision to request a repeat CT scan but the reasons were often not recorded in the outpatient notes. The reason, when recorded, was due to the initial CT scan being performed years ago. It is conceivable that there could be other clinical reasons for ordering a repeat CT sinus scan such as a need for stealth guided sinus surgery, however, no patients were identified requiring this in our study. The hypothetical decision to operate on the individual sinus was based purely on the appearance of the individual sinus on the CT scan. This acts as a surrogate for the extent of treatment to allow statistical analysis. However, this does not fully reflect the decision making when performing ESS where consideration of other factors such as surrounding sinuses, drainage pathway and phenotype of CRS also play a role.

Conclusions

This Australian multi-institutional study demonstrates the LMS for CT sinus scans at least 1 year apart in patients undergoing ESS was not significantly different between scans. It is also important to be aware that other factors such as the pathophysiology of the underlying CRS that determines the extent of surgery. Therefore, we conclude from our study that the practice of routinely repeating a CT sinus scan is not recommended. CT scans should be repeated if the patient’s symptoms and signs have significantly changed, surgery has been performed or suspected sinusitis-related complications have developed since the original scan.

Acknowledgments

We thank Dr. Nuwan Dharmawardana for help with the statistical analysis.

Funding: None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at http://dx.doi.org/10.21037/ajo.2020.03.04

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/ajo.2020.03.04). JR serves as an unpaid editorial board member of Australian Journal of Otolaryngology. EHO serves as an unpaid editorial board member of Australian Journal of Otolaryngology. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). Ethical approval was granted by the Human Research Ethics Committee as a clinical audit (HREC 65.18). Informed consent was waived due to the retrospective nature of the study.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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