Does vitamin D serum level affect prognosis of COVID-19 patients?

In a cross-sectional study of 329 hospitalized COVID-19 patients in Iran from March–July 2020, there was a significant association between hospital stay and lower serum vitamin D levels. In other words, the lower the vitamin D status the longer the stay. However, the relationship between vitamin D status and death rate or the time interval to return to normal oxygen levels was not significant.

• The mean hospital stay was 8.27±04 days, ranging 1–38 days.
• A total of 297 patients (90.3%) were discharged and 32 patients (9.7%) died.
• The three most common COVID-19 symptoms were 58.7% dyspnea, 46.5% cough (7.3% productive) and 38.3% fever.
• The three most common underlying conditions were 39.8% hypertension, 25.8% diabetes mellitus and 22.6% heart disease.
• The mean serum 25(OH)D concentration was 53.70±13 ng/ml (134.3±90.3 nmol/l), ranging from 4 to 193.4 ng/ml (10-483.5 nmol/l). Of the 329 patients, 72.3% were 25(OH)D sufficient (>30 ng/ml or >75 nmol/l), 14.6% were insufficient (20–30 ng/ml or 50-75 nmol/l) and 13.1% were deficient (<20 ng/ml or <50 nmol/l).
• There was a significant difference in the durations of hospital stay between patients with sufficient (>30 ng/ml or >75 nmol/l) and insufficient (<30 ng/ml or <75 nmol/l) serum 25(OH)D levels. After adjusting vitamin D levels for confounding variables such as age, sex and underlying conditions, linear regression underscored significant differences in the association between length of hospitalization and serum 25(OH)D levels, with a longer stay found in insufficient groups.
• There was no significant difference in the time interval to return to normal oxygen level (from SpO2 < 93%) or death rate between serum 25(OH)D sufficient and insufficient groups.

Three-hundred twenty-nine patients (167 men, 50.8%; 162 women, 49.2%) with a positive nasal swab RT-PCR test for SARS-CoV-2 were enrolled in the study. The mean age was 64.7±18.5 years, ranging 15–99 years. Age was <20 years in 13.1%, 20–30 years in 14.6% and >30 years in 72.3% of the patients.

• The observational design of the study cannot substantiate causality between serum vitamin D levels and severity of COVID-19 disease.
• No control group was included in the study. Similar vitamin D deficiency rates may be expected in subjects with baseline characteristics similar to the COVID-19 patients.
• This study had a small sample size. A larger sample size would increase the power and robustness of the study.

There was a significant association between hospital stay and lower serum 25(OH)D levels. However, the relationship between vitamin D status and death rate or the time interval to return to normal oxygen levels was not significant.

• This was a cross-sectional study of 329 COVID-19 patients who were admitted to Kamkar-ArabNia Hospital in Qom city, Iran from March–July 2020.
• Background data including age, sex, social history, underlying disease or medical condition, including renal transplantation/dialysis, chemotherapy and others were recorded in addition to COVID-19 symptoms.
• Serum 25-OH-vitamin D [25(OH)D] levels were measured by routine blood sampling on the first day of hospitalization. Patients were categorized into three groups: sufficient (>30 ng/ml or 75 nmol/l), insufficient (20–30 ng/ml or 50-75 nmol/l) and deficient (<20 ng/ml or 50 nmol/l) serum 25(OH)D levels.
• Peripheral capillary oxygen saturation levels (SpO2) were obtained. Normal SpO2 was set at 93% and patients with abnormal findings were followed until measurements returned to normal levels.

Nasiri M, Khodadadi J, Molaei S. Does vitamin D serum level affect prognosis of COVID-19 patients? Int J Infect Dis. 2021 Apr 30;107:264-267. doi: 10.1016/j.ijid.2021.04.083. Epub ahead of print. PMID: 33940189; PMCID: PMC8086264.