Relationship Between Vitamin D Levels with In-Hospital Complications and Morphofunctional Recovery in a Cohort of Patients After Severe COVID-19 Across Different Obesity Phenotypes

Background and objectives: the COVID-19 pandemic underscored the necessity of understanding the factors influencing susceptibility and disease severity, as well as a better recovery of functional status, especially in postcritical patients. evidence regarding the efficacy of vitamin D supplementation in reducing the severity of COVID-19 is still insufficient due to the lack of primary robust trial-based data and heterogeneous study designs. the principal aims of our study were to determine the impact of vitamin D deficiency or insufficiency on complications during intensive care unit (icu) stay, as well as its role in muscle mass and strength improvement as well as morphofunctional recovery during a multispecialty 6-month follow-up program based on adapted nutritional support and specific physical rehabilitation. as a secondary objective, we compared the association mentioned above between patients with sarcopenic obesity and non- sarcopenic obesity. methods: this prospective observational study included 94 outpatients postcritical COVID-19. two weeks after hospital discharge, patients were divided into sufficient (>= 30 ng/mL), insufficient (20.01-29.99 ng/mL), or deficient (<= 20 ng/mL) vitamin D levels. the differences in in-hospital complications and morphofunctional parameters including phase angle (PhA), body cell mass (BCM), handgrip strength (HGS), timed get-up-and-go (UAG), 6 min walk test (6MWT), and proinflammatory biochemical variables were analyzed. Incremental (Delta) changes in these parameters were also analyzed at the end of follow-up according to vitamin D levels and the presence vs. absence of sarcopenic obesity. A multivariate linear regression analysis was performed to detect possible confounding factors in the impact analysis of vitamin D changes on functional recovery in patients with obesity. Results: A total of 36.2% of patients exhibited vitamin D deficiency, 29.8% vitamin D insufficiency, and only 32.9% showed sufficient levels at hospital discharge. A total of 46.8% of patients had obesity, and 36.1% had sarcopenic obesity. Vitamin D deficiency was associated with longer hospital stays (p = 0.04), longer ICU stays (p = 0.04), more days of invasive mechanical ventilation (IMV) (p = 0.04), lower skeletal muscle mass/weight (SMM/w) (p = 0.04) and skeletal muscle index (SMI) (p = 0.047), higher fat mass percentage (FM%) (p = 0.04), C-reactive-protein (CRP) (p = 0.04), and glycated hemoglobin (HbA1c) (p = 0.03), and better performance in R-HGS (p = 0.04), UAG (p = 0.03), and 6MWT (p = 0.034) when compared with those with normal vitamin D levels. At six months, Delta vitamin D significantly correlated with Delta HbA1c (p = 0.002) and CRP (p = 0.049). Patients with normal vitamin D values showed better recovery of Delta SMI (p = 0.046), Delta SMM/w (p = 0.04), Delta R-HGS (p = 0.04), and Delta UAG (p = 0.04) compared to those with abnormal vitamin D levels, and these improvements in Delta R-HGS and Delta UAG were greater in the subgroup of sarcopenic obesity compared than in nonsarcopenic obesity (p = 0.04 and p = 0.04, respectively). Multivariate regression analysis detected that these results were also attributable to a longer hospital stay and lower Delta CRP in the subgroup of patients with sarcopenic obesity. Conclusions: Vitamin D deficiency was associated with longer hospital stays, longer VMI requirement, worse muscle health, and a higher degree of systemic inflammation. Furthermore, normal vitamin D levels at the end of the follow-up were associated with better morphofunctional recovery in postcritical COVID-19, particularly in patients with sarcopenic obesity partly due to a higher degree of inflammation as a result of a longer hospital stay.