Low vitamin D and risk of long COVID
Long COVID is an emerging syndrome that affects 50%-70% of COVID-19 survivors.
Low levels of vitamin D have been associated with increased likelihood of needing mechanical ventilation and worse survival in patients hospitalized with COVID-19, but the risk of long COVID associated with vitamin D has not been known.
Researchers analyzed data from adults aged 18 and older hospitalized at San Raffaele Hospital with a confirmed diagnosis of COVID-19 and discharged during the first pandemic wave, from March to May 2020, and then seen 6-months later for follow-up.
Patients were excluded if they had been admitted to the intensive care unit during hospitalization or had missing medical data or blood samples available to determine (OH) vitamin D levels, at admission and the 6-month follow-up.
Long COVID-19 was defined based on the U.K. National Institute for Health and Care Excellence guidelines as the concomitant presence of at least two or more of 17 signs and symptoms that were absent prior to the COVID-19 infection and could only be attributed to that acute disease.
Researchers identified 50 patients with long COVID at the 6-month follow-up and matched them with 50 patients without long COVID at that time point, based on age, sex, concomitant comorbidities, need for noninvasive mechanical ventilation, and week of evaluation.
Patients were a mean age of 61 years (range, 51-73) and 56% were men; 28% had been on a ventilator during hospitalization for COVID-19.
The most frequent signs and symptoms at 6 months in the patients with long COVID were asthenia (weakness, 38% of patients), dysgeusia (bad taste in the mouth, 34%), dyspnea (shortness of breath, 34%), and anosmia (loss of sense of smell, 24%).
Most symptoms were related to the cardiorespiratory system (42%), the feeling of well-being (42%), or the senses (36%), and fewer patients had symptoms related to neurocognitive impairment (headache or brain fog, 14%), or ear, nose, and throat (12%), or gastrointestinal system (4%).
Patients with long COVID had lower mean 25(OH) vitamin D levels than patients without long COVID (20.1 vs 23.2 ng/mL; P = .03). However, actual vitamin D deficiency levels were similar in both groups.
Two-thirds of patients with low vitamin D levels at hospital admission still presented with low levels at the 6-month follow-up.
Vitamin D levels were significantly lower in patients with neurocognitive symptoms at follow-up (n = 7) than in those without such symptoms (n = 93) (14.6 vs. 20.6 ng/mL; P = .042).
In patients with vitamin D deficiency (< 20 ng/mL) at admission and at follow-up (n = 42), those with long COVID (n = 22) had lower vitamin D levels at follow-up than those without long COVID (n = 20) (12.7 vs. 15.2 ng/mL; P = .041).
And in multiple regression analyses, a lower 25(OH) vitamin D level at follow-up was the only variable that was significantly associated with long COVID (odds ratio, 1.09; 95% confidence interval, 1.01-1.16; P = .008).
The findings “strongly reinforce the clinical usefulness of 25(OH) vitamin D evaluation as a possible modifiable pathophysiological factor underlying this emerging worldwide critical health issue,” the researchers concluded.
The study was supported by Abiogen Pharma. One study author is an employee at Abiogen. Dr. Giustina has reported being a consultant for Abiogen and Takeda and receiving a research grant to his institution from Takeda. Dr. Di Filippo and the other authors reported no relevant financial relationships.
A version of this article first appeared on Medscape.com.