In a retrospective study of patients tested for COVID-19, researchers at the University of Chicago Medicine found an association between vitamin D deficiency and the likelihood of becoming infected with the coronavirus.
"Vitamin D is important to the function of the immune system and vitamin D supplements have previously been shown to lower the risk of viral respiratory tract infections," said Dr David Meltzer, chief of hospital medicine at UChicago Medicine and lead author of the study. "Our statistical analysis suggests this may be true for the COVID-19 infection."
The research team looked at 489 UChicago Medicine patients whose vitamin D level was measured within a year before being tested for COVID-19. Patients who had vitamin D deficiency (< 20ng/ml) that was not treated were almost twice as likely to test positive for the COVID-19 coronavirus compared to patients who had sufficient levels of the vitamin.
The study findings were previously reported on medRxiv, a preprint server for the health sciences.
Half of Americans are deficient in Vitamin D, with much higher rates seen in African Americans, Hispanics and individuals living in areas like Chicago where it is difficult to get enough sun exposure in winter.
"Understanding whether treating Vitamin D deficiency changes COVID-19 risk could be of great importance locally, nationally and globally," Meltzer said. "Vitamin D is inexpensive, generally very safe to take, and can be widely scaled."
Meltzer and his team emphasize the importance of experimental studies to determine whether vitamin D supplementation can reduce the risk, and potentially severity, of COVID-19. They also highlight the need for studies of what strategies for vitamin D supplementation may be most appropriate in specific populations. They have initiated several clinical trials at UChicago Medicine and with partners locally.
Abstract
Importance: Vitamin D treatment has been found to decrease the incidence of viral respiratory tract infection, especially in patients with vitamin D deficiency. Whether vitamin D is associated with coronavirus disease 2019 (COVID-19) incidence is unknown.
Objective: To examine whether the last vitamin D status before COVID-19 testing is associated with COVID-19 test results.
Design, Setting, and Participants: This retrospective cohort study at an urban academic medical center included patients with a 25-hydroxycholecalciferol or 1,25-dihydroxycholecalciferol level measured within 1 year before being tested for COVID-19 from March 3 to April 10, 2020.
Exposures: Vitamin D deficiency was defined by the last measurement of 25-hydroxycholecalciferol less than 20 ng/mL or 1,25-dihydroxycholecalciferol less than 18 pg/mL before COVID-19 testing. Treatment changes were defined by changes in vitamin D type and dose between the date of the last vitamin D level measurement and the date of COVID-19 testing. Vitamin D deficiency and treatment changes were combined to categorize the most recent vitamin D status before COVID-19 testing as likely deficient (last level deficient and treatment not increased), likely sufficient (last level not deficient and treatment not decreased), and 2 groups with uncertain deficiency (last level deficient and treatment increased, and last level not deficient and treatment decreased).
Main Outcomes and Measures: The outcome was a positive COVID-19 polymerase chain reaction test result. Multivariable analysis tested whether vitamin D status before COVID-19 testing was associated with testing positive for COVID-19, controlling for demographic and comorbidity indicators.
Results: A total of 489 patients (mean [SD] age, 49.2 [18.4] years; 366 [75%] women; and 331 [68%] race other than White) had a vitamin D level measured in the year before COVID-19 testing. Vitamin D status before COVID-19 testing was categorized as likely deficient for 124 participants (25%), likely sufficient for 287 (59%), and uncertain for 78 (16%). Overall, 71 participants (15%) tested positive for COVID-19. In multivariate analysis, testing positive for COVID-19 was associated with increasing age up to age 50 years (relative risk, 1.06; 95% CI, 1.01-1.09; P = .02); non-White race (relative risk, 2.54; 95% CI, 1.26-5.12; P = .009), and likely deficient vitamin D status (relative risk, 1.77; 95% CI, 1.12-2.81; P = .02) compared with likely sufficient vitamin D status. Predicted COVID-19 rates in the deficient group were 21.6% (95% CI, 14.0%-29.2%) vs 12.2%(95% CI, 8.9%-15.4%) in the sufficient group.
Conclusions and Relevance: In this single-center, retrospective cohort study, likely deficient vitamin D status was associated with increased COVID-19 risk, a finding that suggests that randomized trials may be needed to determine whether vitamin D affects COVID-19 risk.
Authors
David O Meltzer, Thomas J Best, Hui Zhang, Tamara Vokes, Vineet Arora, Julian Solway
[link url="https://www.sciencedaily.com/releases/2020/09/200903133007.htm"]University of Chicago Medical Centre material[/link]
[link url="https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2770157"]JAMA Network Open abstract[/link]