Vitamin D supplementation in the critically ill: A systematic review and meta-analysis

The relevance of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D concentration for postoperative infections and postoperative organ dysfunctions in cardiac surgery patients: The eVIDenCe study

BACKGROUND & AIMS

Recent studies indicate that vitamin D deficiency is associated with increased morbidity and mortality in critically ill patients. Knowledge about the functional role and clinical relevance of vitamin D for patients undergoing cardiac surgery is sparse. Therefore, we investigated the clinical significance of vitamin D levels on outcome of cardiac surgery patients.

METHODS

92 patients undergoing elective cardiac surgery with cardiopulmonary arrest were included in this prospective observational pilot study. 25-hydroxyvitamin D (25OHD) and 1,25-dihydroxyvitamin D (1,25(OH)₂D) levels were measured prior to surgery, immediately postoperatively as well as 6, 12 and 24 h after surgery. We assessed postoperative organ dysfunctions, infections and death until hospital discharge.

RESULTS

The serum concentration of 1,25(OH)₂D significantly decreased intraoperatively by 29.3% (p < 0.001) and was significantly lower at any postoperative time point compared to baseline values, whereas 25OHD levels did not show significant changes during the observation period. Coronary artery bypass graft (CABG) patients had significant higher baseline 1,25(OH)₂D values than patients with valve surgery (39.7 ± 13.9 ng/l vs. 30.1 ± 14.1 ng/l, p = 0.010) or CABG + valve surgery (39.7 ± 13.9 ng/l vs. 32.6 ± 11.8 ng/l, p = 0.044). Our data showed a significant odds ratio to develop postoperative organ dysfunction (OR 0.95; p = 0.009) and PCT levels ≥5 μg/l (OR 0.94; p = 0.046) for every ng/l increment in 1,25(OH)₂D, when performing multivariable analysis and after adjusting for preoperative illness and demographics. In addition, multivariable-adjusted statistical analyses revealed that patients stayed significantly shorter on ICU (-0.21 h; p = 0.001) and in hospital (-2.6 days; p = 0.009) for every ng/l increment in 1,25(OH)₂D.

CONCLUSION

Our data highlight important evidence about the clinical significance of 1,25(OH)₂D levels in cardiac surgery patients. Higher levels were associated with significantly less postoperative organ dysfunctions, elevated PCT levels, death and prolonged hospital stay. 1,25(OH)₂D levels decreased significantly intra- and postoperatively, while serum levels of 25OHD did not.

TRIAL REGISTRATION

clinicaltrials.gov (NCT02488876), registered May 1, 2015.

Vitamin D and critical illness: what endocrinology can learn from intensive care and vice versa

The prevalence of vitamin D deficiency in intensive care units ranges typically between 40 and 70%. There are many reasons for being or becoming deficient in the ICU. Hepatic, parathyroid and renal dysfunction additionally increases the risk for developing vitamin D deficiency. Moreover, therapeutic interventions like fluid resuscitation, dialysis, surgery, extracorporeal membrane oxygenation, cardiopulmonary bypass and plasma exchange may significantly reduce vitamin D levels. Many observational studies have consistently shown an association between low vitamin D levels and poor clinical outcomes in critically ill adults and children, including excess mortality and morbidity such as acute kidney injury, acute respiratory failure, duration of mechanical ventilation and sepsis. It is biologically plausible that vitamin D deficiency is an important and modifiable contributor to poor prognosis during and after critical illness. Although vitamin D supplementation is inexpensive, simple and has an excellent safety profile, testing for and treating vitamin D deficiency is currently not routinely performed. Overall, less than 800 patients have been included in RCTs worldwide, but the available data suggest that high-dose vitamin D supplementation could be beneficial. Two large RCTs in Europe and the United States, together aiming to recruit >5000 patients, have started in 2017, and will greatly improve our knowledge in this field. This review aims to summarize current knowledge in this interdisciplinary topic and give an outlook on its highly dynamic future.

Vitamin D in the ICU: More sun for critically ill adult patients?

Critical illness in patients is characterized by systemic inflammation and oxidative stress. Vitamin D has a myriad of biological functions relevant to this population, including immunomodulation by the alteration of cytokine production and nuclear factor loop amplification. Low serum levels have consistently been found in observational studies conducted on critically ill patients, but the causality with mortality and worse outcomes has not been confirmed. The current focus is on interventional trials, whereas the pharmacokinetic profile of vitamin D administration remains sparse and the optimal strategy has not been confirmed. So far, high-dose oral or enteral supplementation is the most studied strategy. The largest randomized controlled trial published so far, the VITdAL-ICU (Effect of High-dose Vitamin D3 on Hospital Length of Stay in Critically Ill Patients with Vitamin D Deficiency) trial, showed no benefits on mortality in its primary analysis. However, secondary analysis suggested improvement in those patients with severe deficiency (i.e., 25-dihydroxyvitaminD <12 ng/mL). Smaller trials investigated intramuscular and intravenous administration and found interesting intermediate biochemical findings, including increased cathelicidins, but were not powered to investigate relevant clinical outcomes in the critically ill. The latest meta-analysis, which was recently published, does not support benefits of vitamin D supplementation in the heterogeneous population of critically ill patients. The European guidelines, published in the last year, suggest supplementing severely deficient patients with levels <12.5 ng/mL within the first week after ICU admission. However, other societies do not support such supplementation in their older recommendations. Large trials are currently recruiting ICU patients and could elucidate potential clinical benefits of vitamin D therapy in the critically ill.

A review of micronutrients in sepsis: the role of thiamine, l-carnitine, vitamin C, selenium and vitamin D

Sepsis is defined as the dysregulated host response to an infection resulting in life-threatening organ dysfunction. The metabolic demand from inefficiencies in anaerobic metabolism, mitochondrial and cellular dysfunction, increased cellular turnover, and free-radical damage result in the increased focus of micronutrients in sepsis as they play a pivotal role in these processes. In the present review, we will evaluate the potential role of micronutrients in sepsis, specifically, thiamine, l-carnitine, vitamin C, Se and vitamin D. Each micronutrient will be reviewed in a similar fashion, discussing its major role in normal physiology, suspected role in sepsis, use as a biomarker, discussion of the major basic science and human studies, and conclusion statement. Based on the current available data, we conclude that thiamine may be considered in all septic patients at risk for thiamine deficiency and l-carnitine and vitamin C to those in septic shock. Clinical trials are currently underway which may provide greater insight into the role of micronutrients in sepsis and validate standard utilisation.

Vitamin D status and its influence on outcomes following major burn injury and critical illness

Vitamin D deficiency is common among the general population. It is also observed in up to 76% of critically ill patients. Despite the high prevalence of hypovitaminosis D in critical illness, vitamin D is often overlooked by medical staff as the clinical implications and consequences of vitamin D deficiency in acute contexts remain to be fully understood. Vitamin D has a broad range of pleotropic effects on various processes and systems including the immune-inflammatory response. 1α,25-dihydroxyvitamin D (1,25(OH)₂D), has been shown to promote a tolerogenic immune response limiting deleterious inflammatory effects, modulation of the innate immune system, and enhancement of anti-microbial peptides. Vitamin D deficiency is frequently observed in critically ill patients and has been related to extrinsic causes (i.e., limited sunlight exposure), magnitude of injury/illness, or the treatment started by medical doctors including fluid resuscitation. Low levels of vitamin D in critically ill patients have been associated with sepsis, organ failure, and mortality. Despite this, there are subpopulations of critical illness, such as burn patients, where the literature regarding vitamin D status and its influence on outcomes remain insufficient. Thermal injury results in damage to both burned and non-burned tissues, as well as induces an exaggerated and persistent immune-inflammatory and hypermetabolic response. In this review, we propose potential mechanisms in which burn injury affects the vitamin D status and summarizes current literature investigating the influence of vitamin D status on outcomes. In addition, we reviewed the literature and trials investigating vitamin D supplementation in critically ill patients and discuss the therapeutic potential of vitamin D supplementation in burn and critically ill patients. We also highlight current limitations of studies that have investigated vitamin D status and supplementation in critical illness. Thermal injury influences vitamin D status. More studies investigating vitamin D depletion in burn patients and its influence on prognosis, via standardized methodology, are required to reach definitive conclusions and influence clinical practice.

Vitamin D deficiency in critically ill children: a systematic review and meta-analysis

BACKGROUND

Vitamin D deficiency (VDD) has been hypothesized not only to be common but also to represent a potentially modifiable risk factor for greater illness severity and clinical outcome during critical illness. The objective of this systematic review was to determine the frequency of VDD in pediatric critical illness and its association with clinical outcomes.

METHODS

MEDLINE, Embase, and CENTRAL were searched through December 12, 2016, with no date or language restrictions. The primary objective was to estimate the prevalence of VDD in the pediatric intensive care unit (PICU) and compare vitamin D status with healthy control populations. Secondary objectives were to evaluate whether VDD is associated with mortality, increased illness severity, PICU interventions, and patient clinical course. Random effects meta-analysis was used to calculate pooled VDD event rate, compare levels with those of control subjects, and evaluate for associations between VDD and clinical outcome.

RESULTS

Among 2700 citations, 17 studies meeting study eligibility were identified. The studies reported a total of 2783 critically ill children and had a median sample size of 120 (range 12-511). The majority of studies used a 25-hydroxyvitamin D [25(OH)D] level less than 50 nmol/L to define VDD, and the pooled VDD prevalence was 54.8 (95% CI 45.4-63.9). Average 25(OH)D levels were significantly lower in PICU patients than in healthy control subjects (pooled difference -17.3 nmol/L, 95% CI -14.0 to -20.6). In a meta-analysis calculation, we found that VDD was associated with increased mortality (OR 1.62, 95% CI 1.11-2.36), illness severity, and need for PICU interventions.

CONCLUSIONS

Approximately 50% of critically ill children have VDD at the time of PICU admission, defined as a blood total 25(OH)D concentration under 50 nmol/L. VDD was further determined to be associated with greater illness severity, multiple organ dysfunction, and mortality in the PICU setting. Clinical trials are required to determine if optimization of vitamin D status improves patient outcome.

TRIAL REGISTRATION

PROSPERO, CRD42016026617 . Registered on 11 January 2016.