key: cord-0733671-nix1knre
authors: Juraj, Smaha; Martin, Kužma; Kristína, Brázdilová; Samuel, Nachtmann; Martin, Jankovský; Katarína, Pastírov á; Andrea, Gažová; Peter, Jackuliak; Zdenko, Killinger; Ján, Kyselovič; Tomáš, Koller; Neil, Binkley; Juraj, Payer
title: COVID-19 pneumonia patients with 25(OH)D levels lower than 12 ng/ml are at increased risk of death
date: 2022-01-22
journal: Int J Infect Dis
DOI: 10.1016/j.ijid.2022.01.044
sha: 76aafa2148eb522b45e050af964eb112731c8203
doc_id: 733671
cord_uid: nix1knre

Objectives There is no consensus about specific serum 25(OH)D levels associated with higher risk of severe outcome in COVID-19 patients. According to the literature patients with serum 25(OH)D levels < 12 ng/ml are clearly deficient at all ages. Our aim was to assess COVID-19 mortality in the settings of severe 25(OH)D deficiency. Methods A cohort study of 357 COVID-19 patients was conducted. Subjects were monitored until discharge or in-hospital death. At admission, severity parameters (CRP, IL-6, Charlson Comorbidity Index etc.) were assessed. These parameters were compared regarding 25(OH)D levels threshold 12 ng/ml, where values below 12 ng/ml were considered absolute vitamin D deficiency. Results 25(OH)D levels at the time of admission were independently associated with mortality (p<0.05). Non-survivors (N=168) had lower 25(OH)D levels, SO2, higher age, CRP, viral load, and Charlson Comorbidity Index in comparison to survivors. Patients with serum 25(OH)D levels < 12 ng/ml had higher mortality (55% vs. 45 %), viral load (21.5 vs 23.1) and Charlson Comorbidity Index (5.3 vs 4.4) in comparison to those with serum 25(OH)D levels >12 ng/ml (p<0.05). Conclusions COVID-19 patients with serum 25(OH)D levels < 12 ng/ml have higher mortality. Among other factors, severe vitamin D deficiency likely leads to poor outcome.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) uses the angiotensinconverting enzyme 2 (ACE2) receptor to enter macrophages and monocytes, resulting in macrophage activation (Merad, Martin, 2020) . In some patients this leads to a hyperinflammatory syndrome, acute respiratory distress syndrome and end-organ damage (Webb et al., 2020) . It has been hypothesized that vitamin D sufficiency may modulate this excessive inflammatory response in Coronavirus Disease 2019 (COVID-19) (Grant et al., 2020) . Indeed, low vitamin D levels in COVID-19 patients has been reported to adversely affect disease severity and course (Pereira et al., 2020) . However, not all published literature supports this conclusion. Very recently a meta-analysis showed that vitamin D deficiency (< 20 ng/ml) or insufficiency (< 30 ng/ml) was not associated with a significantly increased risk of COVID-19 infection or in-hospital death (Chen et al., 2021) . In the context of the possible immunomodulatory role of vitamin D in COVID-19, the problem of reverse causality has also been proposed. Thus, it is possible that 25-hydroxy vitamin D (25(OH)D) is a negative acute phase reactant with low levels indicating greater inflammation. As such, the relationship between vitamin D status and COVID-19 severity remains controversial (Martineau, Forouhi, 2020) .

Although 25(OH)D is widely accepted as the best marker for assessing vitamin D status, the definition and relevance of vitamin D deficiency are still under debate (Amrein et al., 2020) . However, there is high level of agreement on two points: 25(OH)D levels < 12 ng/ml are clearly deficient at all ages and levels above 30 ng/ml are clearly sufficient (Giustina et al., 2020) . Severe vitamin D deficiency with a 25(OH)D concentration < 12 ng/ml increases risk of mortality, infections, and other diseases, and should be prevented with a public health approach (Amrein et al., 2020; Cashman, 2020; Lips et al., 2019) . Specifically, regarding respiratory infections Martineau et al. (2017) showed that vitamin D supplementation was protective against acute respiratory tract infections and patients, who were severely 25(OH)D deficient, experienced the most benefit. More recently, a small study reported that elderly COVID-19 patients with 25(OH)D levels < 12 ng/ml are at higher risk of non-invasive ventilation requirement in comparison to those with 25(OH)D levels > 12 ng/ml. The effect on mortality was not proven (Baktash et al., 2021) . To our knowledge, there is no study defining serum 25(OH)D level of 12 ng/ml as a specific cut-off point associated with excessive mortality in patients with COVID-19 pneumonia.

This study assessed COVID-19 mortality in the settings of absolute 25(OH)D deficiency. We speculate that in severely vitamin D deficient patients, their peripheral tissues including lung parenchyma are depleted of 25(OH)D. In this scenario, the immune system is unable to exert proper lung-protective immune response which ultimately leads to severe course and higher mortality in COVID-19 patients.

This study was undertaken as a longitudinal cohort study in a single center, the 5th

Internal medicine department of Comenius University and University Hospital Bratislava, Slovakia. The study included all consecutive patients who were admitted to our department between 1 November 2020 and 30 April 2021.

Inclusion criteria were as follows:

• COVID-19 pneumonia as a main diagnosis at admission,

• positive real-time reverse transcriptase-polymerase chain reaction (RT-PCR) test for SARS-CoV-2 on nasopharyngeal swab

• specimen for serum 25(OH)D level obtained on admission.

The patients were monitored until discharge (survivors) or in-hospital death (nonsurvivors).

Demographic characteristics, comorbidities, hematological and biochemical laboratory results on admission, information regarding intensity of care during hospitalization and information regarding pharmacological treatment before and during hospitalization were collected from electronic medical records and discharge summaries by two physicians using a standardized approach. The Charlson Comorbidity Index was used to provide a single score reflecting a range of comorbidities in our cohort of patients. An online calculator (www.mdcalc.com/charlsoncomorbidity-index-cci.com) was used for its calculation.

Laboratory evaluation 1) COVID-19 severity parameters: complete blood count, serum C-reactive protein (CRP), interleukin 6 (IL-6), procalcitonin (PCT), D-dimer, fibrinogen. Other standard tests such as liver tests, kidney functions, serum minerals, or fasting plasma glucose tests and basic coagulation tests were performed in each patient. All measures were assessed with commercial standardized tests and blood sampling was done between 7:00-8:00 a.m., 2) viral load: SARS-COV-2 virus load was assessed by RT-PCR using cycle threshold,

3) blood oxygen saturation was assessed using arterial blood sampling +/-2 hour from venous blood sampling. Table 1 . Overall, low serum 25(OH)D was common, with 80% of patients being 25(OH)D either insufficient or deficient according to existing guidelines, i.e., 25(OH)D < 30 ng/ml.

Lower 25(OH)D levels, platelets, oxygen saturation and higher age, CRP, viral load, white blood cells, neutrophils and Charlson Comorbidity Index in non-survivors compared to survivors were observed (all p<0.005). Arterial hypertension, chronic kidney disease, diabetes mellitus with complications, chronic heart failure and chronic kidney disease were more prevalent in non-survivors compared to survivors (p<0.05) (see Table 1 ). Non-survivors ended more frequently on high-flow nasal cannula and invasive mechanical ventilation (p<0.0001). There was no difference in gender, BMI, liver cirrhosis prevalence, lymphocyte count, PCT, D-Dimer, vitamin D use before hospitalization and IL-6 in survivors compared to non-survivors.

In multivariate linear regression analysis (see Table 2 ) serum level of 25(OH)D remained independently associated with in-hospital mortality (p=0.0398). Among other independent variables, age, CRP, blood oxygen level saturation, platelets count, Charlson Comorbidity Index and BMI were significantly independently associated with mortality (all p<0.05).

Patients within the group of 25(OH)D < 12 ng/ml (N=74) had more prevalent chronic kidney disease, higher Charlson Comorbidity Index and higher viral load in comparison to those with vitamin D > 12 ng/ml (N=283). Mortality was 11% higher within the group of vitamin D < 12 ng/ml (~55% vs ~44%; p<0.05) (see Table 3 and Figure 2 ). There was no difference in age, BMI, other comorbidities, blood count parameters, CRP, D-dimer, PCT, IL-6, oxygen saturation, use of vitamin D supplements prior hospitalization or ventilation outcome between groups according to 25(OH)D threshold.

A considerable number of studies, even from pre-COVID era, have suggested that vitamin D may play an important role in minimizing lung tissue inflammation and improving antiviral state thus maintaining local respiratory homeostasis (Hansdottir, Monick, 2011) .

In this study we found that a low serum level of 25(OH)D is highly prevalent in This study has several limitations. Firstly, the enormous burden of COVID-19 outbreak on healthcare personnel and resources at our center did not allow us to repeatedly assess serum levels of 25(OH)D during the disease, thus potentially better establishing the evolving relationship between levels of inflammatory biomarkers and 25(OH)D. Secondly, we did not know the preexisting vitamin D status in patients of our study cohort. Therefore, the possibility of so-called reverse causality to explain the relationship of 25(OH)D with COVID-19, i.e., that more severe disease produces greater 25(OH)D reduction must still be considered. Very recently, a small but elegant study documented that 25(OH)D declines within 2 hours of onset of inflammatory reaction, thus we can speculate that patients that were ill for a longer time prior to admission had lower 25(OH)D levels (Smolders et al., 2021) . Lastly, vitamin D supplementation during hospitalization could in fact influence mortality. All our patients were supplemented with vitamin D according to the treatment protocol at our institution, regardless of baseline 25(OH)D serum levels (loading dose: 30 000 IU of cholecalciferol daily for the first three days, followed by 7500 IU cholecalciferol daily).

We didn´t have control group of patients without supplementation. Vitamin D is a threshold nutrient, therefore patients with severe 25(OH)D deficiency are most likely to benefit from vitamin D supplementation. Given this, we could speculate that some severely 25(OH)D deficient patients could improve their nutritional status upon supplementation and thus exhibit milder course of the disease. Our study also has several strengths. Notably, this is a real-world study that prospectively evaluated a large homogeneous, properly defined group of acutely ill Finally, to our knowledge, this study for the first time described increased mortality specifically among COVID-19 patients with severe vitamin D deficiency, as defined by 25(OH)D levels less than 12 ng/ml.

In conclusion, this study shows that 25(OH)D insufficiency or deficiency is prevalent among acutely ill patients hospitalized for COVID-19 pneumonia. Importantly, serum level of 25(OH)D is an independent risk factor for mortality. In addition, serum 25(OH)D level < 12 ng/ml at the time of admission seems to be a good indicator for morbidity and mortality in COVID-19 patients and is associated with 11% increased mortality rate in comparison with patients with serum level above 12 ng/ml. According to these results, routine 25(OH)D assessment at admission could be relevant for the risk stratification and planning for treatment strategy in patients with COVID-19.

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

There was no financial support for the conduct of the research and/or preparation of the article. All authors of the manuscript have nothing to disclose.

The study was conducted in accordance with the Declaration of Helsinki and was approved by The Ethics Committee of the University Hospital Bratislava. An informed and written consent was obtained either from the participants or a first degree relative. 

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Figure 2. The difference in mortality between groups according to the specific 12 ng/ml cut-off level of 25(OH)D, representing servere 25(OH)D deficiency