Abstract: Received: 29 January 2021 | Revised: 26 August 2021 | Accepted: 27 August 2021 DOI: 10.1002/fsn3.2591 ORIGINAL RESEARCH The predictive power of serum vitamin D for poor outcomes in COVID-­19 patients Hoda Derakhshanian1,2 | Hadith Rastad3 | Sanjoy Ghosh4 | Marjan Zeinali5 | Mahsa Ziaee5 | Tara Khoeini5 | Mohsen Farrokhpour6 | Mostafa Qorbani3 | 7 8 5,9 Mona Ramezani Ghamsari | Hossein Hasani | Zahra Mirzaasgari 1 Department of Biochemistry Genetics and Nutrition, School of Medicine, Alborz University of Medical Sciences, Karaj, Iran 2 Abstract Considering the high prevalence of vitamin D deficiency worldwide and its rela- Dietary Supplements and Probiotic Research Center, Alborz University of Medical Sciences, Karaj, Iran tionship with immune response to viral infections, this study attempted to identify 3 patients. This retrospective cohort study included all patients with confirmed Non-­communicable Diseases Research Center, Alborz University of Medical Sciences, Karaj, Iran 4 Department of Biology Okanagan Campus, University of British Columbia, Kelowna, BC, Canada 5 Department of Neurology, Firoozgar Hospital, Iran University of Medical Sciences, Tehran, Iran 6 Department of Internal Medicine, Firoozgar Hospital, Iran University of Medical Sciences, Tehran, Iran 7 Clinical Research Development Unit, Shahid Rajaei Educational and Medical Center, Alborz University of Medical Sciences, Karaj, Iran 8 Department of Community Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran, Iran 9 Shefa Neuroscience Research Center, Tehran, Iran Correspondence Zahra Mirzaasgari, Department of Neurology, Firoozgar Hospital, Iran University of Medical Sciences, Tehran, Iran. Email: mirzaasgari@gmail.com the predictive power of serum vitamin D for poor outcomes among the COVID-­19 COVID-­19 hospitalized between February 20, 2020, and April 20, 2020, at a designated COVID-­19 hospital, located in Tehran province, Iran. General characteristics, medical history and clinical symptoms were recorded by trained physicians. Blood parameters including complete blood count, creatinine, lactate dehydrogenase, creatine phosphokinase, erythrocyte sedimentation rate, C-­reactive protein and vitamin D were tested. This study included 290 hospitalized patients with COVID-­19 (the mean age [SD]: 61.6 [16.9], 56.6% males), of whom 142 had vitamin D concentrations less than 20 ng/ml, defined as vitamin D deficiency. COVID-­19 patients with vitamin D deficiency were more likely to die (Crude OR [95% CI]: 2.30 [1.25–­4.26]), require ICU (2.06 [1.22–­3.46]) and invasive mechanical ventilation (2.03 [1.04–­3.93]) based on univariate logistic regression results. Although, after adjusting for potentials confounders such as gender and age, the association between vitamin D and need to invasive mechanical ventilation lost its significance, adjusted values for the risk of death and ICU requirement were still statistically significant. Vitamin D deficiency can be considered as a predictor of poor outcomes and mortality in COVID-­19 patients. Therefore, checking serum 25 (OH) D on admission and taking vitamin D supplements according to the prophylactic or treatment protocols is recommended for all COVID-­19 patients. KEYWORDS Funding information This study was funded by Iran University of Medical Sciences and Alborz University of Medical Sciences coronavirus infections, COVID-­19, SARS-­CoV-­2, vitamin D This..