Iron supplementation following bariatric surgery: A systematic review of current strategies.

Iron deficiency (ID) and iron deficiency anemia (IDA) are common following bariatric surgery; however, there are limited standardized treatment recommendations for their management. The purpose of this study was to review the current strategies for iron supplementation following bariatric surgery and assess their relative efficacy in managing ID and IDA. MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials were searched to January 2021. Primary outcomes of interest were prevention or improvement in ID or IDA with iron supplementation. Forty-nine studies with 12,880 patients were included. Most patients underwent Roux-en-Y gastric bypass (61.9%). Iron supplementation was most commonly administered orally for prevention of ID/IDA and was effective in 52% of studies. Both IV and oral iron were given for treatment of ID/IDA. Fifty percent (3/6) of the oral and 100% (3/3) of the IV supplementation strategies were effective at treating ID. Iron supplementation strategies employed following bariatric surgery are highly variable, and many do not provide sufficient iron to prevent the development of ID and IDA, potentially due to poor patient adherence. Further high-quality prospective trials, particularly comparing intravenous and oral iron, are warranted in order to determine the ideal dosage, route, and duration of iron supplementation.

Preoperative Vitamin D Concentration and Cardiac, Renal, and Infectious Morbidity after Noncardiac Surgery.

BACKGROUND: Low 25-hydroxyvitamin D is associated with cardiovascular, renal, and infectious risks. Postsurgical patients are susceptible to similar complications, but whether vitamin D deficiency contributes to postoperative complications remains unclear. We tested whether low preoperative vitamin D is associated with cardiovascular events within 30 days after noncardiac surgery. METHODS: We evaluated a subset of patients enrolled in the biobank substudy of the Vascular events In noncardiac Surgery patIents cOhort evaluatioN (VISION) study, who were at least 45 yr with at least an overnight hospitalization. Blood was collected preoperatively, and 25-hydroxyvitamin D was measured in stored samples. The primary outcome was the composite of cardiovascular events (death, myocardial injury, nonfatal cardiac arrest, stroke, congestive heart failure) within 30 postoperative days. Secondary outcomes were kidney injury and infectious complications. RESULTS: A total of 3,851 participants were eligible for analysis. Preoperative 25-hydroxyvitamin D concentration was 70 ± 30 nmol/l, and 62% of patients were vitamin D deficient. Overall, 26 (0.7%) patients died, 41 (1.1%) had congestive heart failure or nonfatal cardiac arrest, 540 (14%) had myocardial injury, and 15 (0.4%) had strokes. Preoperative vitamin D concentration was not associated with the primary outcome (average relative effect odds ratio [95% CI]: 0.93 [0.85, 1.01] per 10 nmol/l increase in preoperative vitamin D, P = 0.095). However, it was associated with postoperative infection (average relative effect odds ratio [95% CI]: 0.94 [0.90, 0.98] per 10 nmol/l increase in preoperative vitamin D, P adjusted value = 0.005) and kidney function (estimated mean change in postoperative estimated glomerular filtration rate [95% CI]: 0.29 [0.11, 0.48] ml min 1.73 m per 10 nmol/l increase in preoperative vitamin D, P adjusted value = 0.004). CONCLUSIONS: Preoperative vitamin D was not associated with a composite of postoperative 30-day cardiac outcomes. However, there was a significant association between vitamin D deficiency and a composite of infectious complications and decreased kidney function. While renal effects were not clinically meaningful, the effect of vitamin D supplementation on infectious complications requires further study.