1.
Dear Editor,
The letter by Panagiotou et al provides an interesting insight into potential associations between vitamin D deficiency (VDD) and COVID‐19 disease severity within their NHS foundation trust in the north of England.
It is important to clarify how disease severity has been defined in the study. According to the letter, ‘25(OH)D levels were not associated with increased oxygen requirements, NEWS‐ 2 score, COVID‐19 radiological findings, CRP levels or presence of comorbidities’; all of these parameters contribute to disease severity. 1 Panagiotou et al appear to have separated patients into one of two groups: the ITU group and the non‐ITU group. It is important to point out that those with ward‐based ceilings of care were included in the study data as part of the non‐ITU group.
It appears that those who received treatment on ITU were rightly believed to have severe disease, and those within the non‐ITU group, a milder form. It is potentially favourable to exclude those with ward‐based ceilings of care from the study. Defining disease severity is complicated by the inclusion of such patients. Perhaps mortality could be considered the clearest indicator of disease severity; however, this too would have to be corrected for ceilings of care to be able to interpret results. It would be interesting to see data published excluding these individuals and a comparison made with current findings. It is possible that by doing so, the results could show an even wider difference between VDD on ITU and on the wards; if it is to be believed that those with lower ceilings of care are also those more likely to have VDD, in particular the elderly. 2 , 3 It would also be useful if there was discussion regarding the proportions of patients from the ITU and non‐ITU groups that had been discharged, died or were still receiving inpatient treatment. This could provide further valuable insight.
Ethnicity could be an important covariate not explored in this study. This could prove particularly pertinent as the very people affected more severely by COVID‐19 disease—those of Black Asian and minority ethnic (BAME) groups—are also more at risk of VDD. 4 , 5 It would be of clear importance to expand the study to include data from other hospitals within the region, and indeed nationally, to further explore these potential demographic links. It would also be beneficial to increase the sample size in order to achieve statistical significance that was not apparent for mortality nor disease severity in this study.
REFERENCES
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