Lifestyle variables (table 4)

The comparison of the two phenotypes showed no evidence of a difference in smoking (p=0.25) or home location (p=0.12), but did show a difference in alcohol consumption, with CRSwNP participants likely to drink more alcohol than those with CRSsNP (p=0.032).
Discussion
Key results:
No demonstrable differences were found for the key socioeconomic variables between the two groups, nor were there any differences in lifestyle variables other than alcohol consumption being higher in those with CRSwNP. Aside from confirmation of asthma being more common in CRSwNP, it was notable that this group complained less of URTIs. CRSsNP participants showed evidence of lower HRQoL scores in respect of body pain. The difference in alcohol consumption may be explained by the gender differences. In the UK men consume more alcohol than women. The 2018 Health Survey for England showed the mean male weekly alcohol consumption in units was 15.5 while for females it was 923. The same survey also found that 14% of male responders were teetotal compared to 21% of female responders. Our data shows that males are significantly more likely to suffer from CRwNP than females.
Interpretation:
CRES is the largest epidemiological study of CRS and the first study since the 2001 Sinonasal Audit (24) to collect detailed information on socioeconomic variables in the UK. As mentioned above, a systematic review in 2018 concluded that smoking, social deprivation and low socioeconomic level appear to have a direct correlation with rhinosinusitis10. They also concluded that education level, and exercise and diet appear to have a more complex relationship with CRS. In the Korean KNHANES study CRSwNP was more prevalent in rural areas and with a lower level of education, obesity, increased amounts of smoking and alcohol consumption, and comorbid asthma8. It is possible that some of these difference are accounted for by ethnic differences in the underlying pathophysiology25.
A small study (n=186) comparing patients with AFRS and CRS found that he CRS cases were predominantly white and older at the time of diagnosis with higher income levels. They found no associations between disease severity, socioeconomic status, and demographic factors within the CRS groups 26. In a North American study published in 2019, Beswick et al reported that their analysis of 392 patients showed that medical insurance status and male gender were significantly associated with worse smell test scores, and also that higher household income and lower age led to better outcomes on health related quality of life scores (SNOT-22) following sinus surgery (27). In this study 36% of the cases were CRS with nasal polyps (CRSwNP) and 37% reported asthma. Differing findings and differing diagnostic and sampling methods across various studies and healthcare systems suggest that the true picture has yet to be clarified.
Whilst our CRES study has not demonstrated any evidence that socioeconomic deprivation is a risk factor for CRS or either of the two main phenotypes, other related work on the cost of managing CRS has shown higher out-of-pocket expenditure, primary care and secondary care utilisation, and time lost from work compared to those without CRS28. This study estimated an annual average out of pocket expenses of £304.84 secondary to CRS over 3 months, with a 5.3-fold greater spending on over-the-counter medication when compared to the general population and an association with an average 18.7 missed workdays per year. For those in lower socioeconomic groups, they are more likely to be disadvantaged by this implication. This effect appears to have been more pronounced in a private healthcare system (27) but may be less apparent in the National Health Service where direct healthcare is free at the point of service, excluding prescription costs (England not Scotland).
It is an interesting observation that those with CRSwNP reported higher rates of alcohol consumption than those with CRSsNP given our previous analysis regarding symptom exacerbation with wine, which showed significantly higher rates in the CRSwNP phenotype (29). This association between dietary salicylates and symptom exacerbation requires further investigation to better understand the link and the presence of any dose-dependent response.

Limitations

The CRES study design has certain limitations, whilst the diagnosis was made by a clinician, the remaining data was self-reported and may therefore predispose to recall bias. Secondly although we collected information on household occupancy, we didn’t collect information on number of bedrooms and the potential for overcrowding. In asthma, overcrowding has been shown to have a positive 30 and a negative 31 correlation with respiratory symptoms with no clear relationship in other studies 32, so there is not a clear relationship in the lower respiratory tract. Our study has also sampled a mainly British White ethnic demographic and may not fully reflect the wider population in the UK today.

Generalisability

CRES is a cross sectional UK based study incorporating a variety of the CRS population from across the country presenting to secondary care. The CRES study does not necessarily capture the whole CRS spectrum as mild sufferers may be managed by primary care alone and may therefore be underrepresented. In contrast to other studies, CRS was diagnosed by ENT specialists according to accepted diagnostic guidelines (EPOS 2012) (16); other existing studies have relied on self-diagnosis and/or used different criteria making direct comparisons with the existing literature more complicated. Whilst we realise EPOS2020 (1) has now superseded EPOS2012, the former was relevant at the time of the study being conducted. In the current era making comparisons between endotypes such as those with or without Type 2 mediated inflammation may provide further clinical relevance, but for now these are perhaps not adequately defined.