The association between critical illness and changes in bone turnover in adults: a systematic review

SUMMARY

Critical illness may lead to altered bone turnover and associated adverse health outcomes. This systematic review found moderate evidence for a positive association between critical illness and increased bone turnover. Prospective cohort studies that identify the extent and risk factors for critical illness related bone loss are required.

INTRODUCTION

Intensive care patients face health issues that extend beyond their critical illness and result in significant morbidity and mortality. Critical illness may result in altered bone turnover due to associated immobilisation, inflammation, exposure to medications that effect bone and calcium metabolism, and endocrine dysfunction. The aim of this study was to synthesise the existing evidence for altered bone turnover in adults admitted to intensive care.

METHODS

A literature search using MEDLINE and EMBASE was performed from 1965 to March 2013. Reviewed studies investigated the relationship between critical illness and evidence of altered bone turnover (bone turnover markers, bone mineral density, or fracture). Studies were rated upon their methodological quality, and a best-evidence synthesis was used to summarise the results.

RESULTS

Four cohort and seven case-control studies were identified for inclusion, of which five studies were rated as being of higher methodological quality. Ten of the studies measured bone turnover markers, and one study fracture rate. Findings were consistent across studies, and best-evidence analysis resulted in a conclusion that moderate evidence exists for an association between critical illness requiring admission to intensive care and altered bone turnover.

CONCLUSION

A positive association between critical illness requiring intensive care admission and bone turnover exists, although data are limited, and the risk factors and the nature of the relationship are not yet understood. Prospective cohort studies that identify risk factors and extent of critical illness related bone turnover changes are required.

Glycaemic control and long-term outcomes following transition from modified intensive insulin therapy to conventional glycaemic control

This retrospective observational cohort study compared glycaemic control and long-term outcomes following transition from a modified intensive insulin therapy (mIIT) regimen to conventional glycaemic control (CGC) in adult patients admitted to a tertiary adult general intensive care unit, during two 24-month periods, before and after the publication of the Normoglycemia in Intensive Care Evaluation and Surviving Using Glucose Algorithm Regulation (NICE-SUGAR) trial. The before NICE-SUGAR cohort received mIIT (target glycaemic ranges 4.4 to 7.0 mmol/l), while the after NICE-SUGAR cohort received CGC (target glycaemic range 7.1 to 9.0 mmol/l). A total of 5202 patients were included in the study. With transition from mIIT to CGC, the mean time-weighted glucose increased from 6.94 mmol/l to 8.2 mmol/l (P <0.0001). A similar increase was observed in other glycaemic indices (mean, highest and lowest glucose values, P <0.0001 for all). The adjusted 90-day odds ratio for mortality decreased by 47% with transition from mIIT to CGC (odds ratio 1.47 (95% confidence interval, 1.22 to 1.78) (P <0.0001). The rate of severe and moderate hypoglycaemia also decreased from 1.2 to 0.4% (P=0.004) and from 23.3 to 5.9% (P <0.0001), respectively. mIIT was associated with an increased risk of moderate and severe hypoglycaemia compared to CGC (odds ratio 3.1 (1.51 to 6.39) (P=0.002), 6.29 (5.1 to 7.75) (P <0.0001)). Changes in recommended glycaemic control were translated into practice, with increased glycaemic indices and decreased rates of severe and moderate hypoglycaemia after the introduction of CGC. The associated decrease in 90-day mortality suggests mIIT was not superior to CGC, despite a lower hypoglycaemia rate than in previous IIT trials. Our findings support the continued use of CGC.

Cardiac complications and mortality rates in diabetic patients following non-cardiac surgery in an Australian teaching hospital

This retrospective study of diabetic patients undergoing non-cardiac surgery has identified that a greater number of patients are at risk of cardiac complications and death in the perioperative period than had previously been suggested. As well as insulin-dependent diabetic patients and patients with elevated creatinine (> 178 micromol/l) as previously found, our study suggests that non-insulin-dependent diabetic patients and patients with creatinine > 120 micromol/l are also at increased risk of cardiac complications and death following non-cardiac surgery. This increases by a factor of six those diabetic patients at risk of perioperative complications from non-cardiac surgery and also increases the number of patients with renal failure similarly at risk. The study confirms similar risks of cardiac complications and death to other recently published data and suggests ongoing comparisons will contribute to quality assurance activities in anaesthesia and surgery.