Changes in bone mineral density in the year after critical illness

RATIONALE: Critical illness may be associated with increased bone turnover and loss of bone mineral density. Prospective evidence describing long-term changes in bone mineral density after critical illness is needed to further define this relationship. <br /><br />OBJECTIVES: To measure the change in bone mineral density and bone turnover markers in patients one year after critical illness compared to population-based controls. <br /><br />METHODS: We studied adult patients admitted to a tertiary intensive care unit (ICU) and requiring mechanical ventilation for at least 24 hours. We measured clinical characteristics, bone turnover markers and bone mineral density during admission and one year after ICU discharge. We compared change in bone mineral density to age and sex-matched controls from the Geelong Osteoporosis Study. <br /><br />MEASUREMENTS AND MAIN RESULTS: Sixty-six patients completed bone mineral density testing. Bone mineral density decreased significantly in the year after critical illness at both femoral neck and anterior-posterior spine site. The annual decrease was significantly greater in the ICU cohort compared to matched controls (anterior-posterior spine -1.59%, 95% CI -2.18, -1.01, p< 0.001, femoral neck -1.20%, 95% CI -1.69, -0.70, p <0.001). There was a significant increase in 10-year fracture risk for major fractures (4.85+5.25 vs 5.50+5.52, p<0.001) and hip fractures (1.57+2.40 vs 1.79+2.69, p=0.001). The pattern of bone resorption markers was consistent with accelerated bone turnover. <br /><br />CONCLUSIONS: Critically ill patients experience a significantly greater decrease in bone mineral density in the year after admission compared to population-based controls. Their bone turnover biomarkers pattern is consistent with increased rate of bone loss.