Guidelines on vitamin D replacement in bariatric surgery: Identification and systematic appraisal

Abstract

Introduction Bariatric surgery is the most effective therapeutic option to reduce weight in morbidly obese individuals, but it results in a number of mineral and vitamin deficiencies. Clinical Practice Guidelines (CPGs) attempt to balance those benefits and harms to provide guidance to physicians and patients. Objectives We compare and evaluate the quality of the evidence and of the development process of current CPGs that provide recommendations on vitamin D replacement in patients undergoing bariatric surgery, using a validated tool. Methods We searched 4 databases, with no time restriction, to identify relevant and current CPGs. Two reviewers assessed eligibility and abstracted data, in duplicate. They evaluated the quality of CPGs development process using the Appraisal of Guidelines, Research, and Evaluation II (AGREE II) tool that consists of 6 domains. A content expert verified those assessments. Results We identified 3 eligible CPGs: (1) the Endocrine Society (ES) guidelines (2010); (2) the American Association of Clinical Endocrinologists (AACE), The Obesity Society (TOS), and the American Society for Metabolic & Bariatric Surgery (ASBMS) guidelines (update 2013); and (3) the Interdisciplinary European (IE) guidelines on Metabolic and Bariatric Surgery (latest update 2014). The ES and the AACE/TOS/ASBMS guidelines recommended high doses of vitamin D, varying from 3,000 IU daily to 50,000 IU 1-3 times weekly. Vitamin D doses were not mentioned in the IE guidelines. The recommendations were based on a low quality of evidence, if any, or limited to a single high quality trial, for some outcomes. In terms of quality, only the IE guidelines described their search methodology but none of the CPGs provided details on evidence selection and appraisal. None of the three CPGs rigorously assessed the preferences of the target population, resource implications, and the applicability of these guidelines. According to the AGREE II tool, we rated the ES guidelines as average in quality, and the other two as low in quality. Conclusion Current CPGs recommendations on vitamin D supplementation in bariatric surgery differ between societies. They do not fulfill criteria for optimal guideline development, in part possibly due to limited resources, and are based on expert opinion. Thus, the pressing need for high quality randomized trials to inform CPGs, to be developed based on recommended standards.

Vitamin D and intestinal calcium transport after bariatric surgery

“…However, deficiencies do occur postoperatively [72,76,77], likely because those undergoing sleeve gastrectomy may have suboptimal vitamin D status preoperatively and then are subject to restricted dietary intake postoperatively. Because of this uncertainty, clinical guidelines about vitamin D supplementation and monitoring after sleeve gastrectomy are extremely limited at this time [73–75,78]. …”

The Impact of Fat and Obesity on Bone Microarchitecture and Strength in Children

“…Vitamin D deficiency, hyperparathyroidism and calcium malabsorption following malabsorptive procedures such as RYGB is of concern [99] particularly in a background of vitamin D deficiency in obese patients pre-operatively [100]. However, across clinical practice guidelines there remains lack of agreement as to the post-operative supplementation of vitamin D with recommended doses ranging from 3000 IU daily to 50,000 IU 1–3 times weekly [101]. There are very few studies in adolescents assessing the impact of profound weight loss on bone secondary to bariatric surgery.…”

Unlicensed medicines use: a UK guideline analysis using AGREE II†

“…Organisations who use ‘working party’ methodology, such as the National Institute of Health and Clinical Excellence and the Scottish Intercollegiate Guideline Network, generally score well in this domain. The Stakeholder Involvement domain also identified a deficit in patient involvement in guideline development, similar to other findings using AGREE II …”

“…This could make implementation of such guidelines difficult and is reflected in low scores in the ‘applicability’ domain. Other analyses have also found a wide variability in the consideration of the use of guidelines in practice …”