Assessment of the Association of Vitamin D Level With SARS-CoV-2 Seropositivity Among Working-Age Adults
Cohort study of 18,148 patients in the USA showing low vitamin D associated with COVID-19 PCR+ status before adjustments but not after.
Authors state that "low vitamin D levels were not independently associated with the
risk of seropositivity", however there is significant correlation between some adjustment variables and vitamin D levels in the logistic regression that prevent drawing this conclusion [statisticsbyjim.com]
. Details of the logistic regression in the matched sample set are not provided.
Authors analyze only 20ng/mL and 30ng/mL cutoff points, other studies use 10ng/mL (or 12), where more significant differences are typically seen.
risk of case, 8.6% lower, RR 0.91, p = 0.24, high D levels 610 of 13,650 (4.5%), low D levels 290 of 4,498 (6.4%), adjusted per study, inverted to make RR<1 favor high D levels, odds ratio converted to relative risk, >20ng/mL, Figure 2.
risk of case, 12.4% lower, RR 0.88, p = 0.07, high D levels 289 of 7,272 (4.0%), low D levels 611 of 10,876 (5.6%), adjusted per study, inverted to make RR<1 favor high D levels, odds ratio converted to relative risk, >30ng/mL, Figure 2.
Effect extraction follows pre-specified rules prioritizing more serious outcomes. Submit updates
Li et al., 19 May 2021, retrospective, USA, peer-reviewed, 4 authors.
Abstract: Original Investigation | Infectious Diseases
Assessment of the Association of Vitamin D Level With SARS-CoV-2 Seropositivity
Among Working-Age Adults
Yonghong Li, PhD; Carmen H. Tong, MS; Lance A. Bare, PhD; James J. Devlin, PhD
IMPORTANCE Low vitamin D levels have been reported to be associated with increased risk of
SARS-CoV-2 infection. Independent, well-powered studies could further our understanding of this
Question Are low levels of vitamin D
independently associated with the risk
of SARS-CoV-2 seropositivity?
Findings In this cohort study of 18 148
OBJECTIVE To examine whether low levels of vitamin D are associated with SARS-CoV-2
individuals whose vitamin D levels were
seropositivity, an indicator of previous infection.
measured before the COVID-19
pandemic, low levels of vitamin D were
DESIGN, SETTING, AND PARTICIPANTS This is a cohort study of employees and spouses who
associated with SARS-CoV-2
elected to be tested for SARS-CoV-2 IgG as part of an annual employer-sponsored health screening
seropositivity in unadjusted univariable
program conducted in August to November 2020. This program includes commonly assessed
analysis. However, after adjusting for
demographic, biometric, and laboratory variables, including total vitamin D measurement. Baseline
potentially confounding factors,
(prepandemic) levels of vitamin D and potential confounders were obtained from screening results
including age, sex, race/ethnicity,
from the previous year (September 2019 to January 2020). Data analysis was performed from
education, body mass index, blood
December 2020 to March 2021.
pressure, smoking status, and
geographical location, vitamin D level
EXPOSURES Low total serum 25-hydroxyvitamin D, defined as either less than 20 ng/mL or less
was not associated with SARS-CoV-2
than 30 ng/mL.
Meaning Although SARS-CoV-2–
MAIN OUTCOMES AND MEASURES The main outcome was SARS-CoV-2 seropositivity, as
determined with US Food and Drug Administration emergency use–authorized assays. The
seropositive individuals did have lower
vitamin D levels than seronegative
association of SARS-CoV-2 seropositivity with vitamin D levels was assessed by multivariable logistic
regression analyses and propensity score analyses.
individuals, low vitamin D levels were
not independently associated with the
risk of seropositivity.
RESULTS The 18 148 individuals included in this study had test results for SARS-CoV-2 IgG in 2020
and vitamin D levels from the prepandemic and pandemic periods. Their median (interquartile range)
age was 47 (37-56) years, 12 170 (67.1%) were women, 900 (5.0%) were seropositive, 4498 (24.8%)
had a vitamin D level less than 20 ng/mL, and 10 876 (59.9%) had a vitamin D level less than 30
ng/mL before the pandemic. In multivariable models adjusting for age, sex, race/ethnicity, education,
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body mass index, blood pressure, smoking status, and geographical location, SARS-CoV-2
seropositivity was not associated with having a vitamin D level less than 20 ng/mL before (odds ratio
[OR], 1.04; 95% CI, 0.88-1.22) or during (OR, 0.93; 95% CI, 0.79-1.09) the pandemic; it was also not
associated with having a vitamin D level less than 30 ng/mL before (OR, 1.09; 95% CI, 0.93-1.27) or
during (OR, 1.05; 95% CI, 0.91-1.23) the pandemic. Similar results were..
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