To the Editor:
Marchant et al. have found that patients with uncontrolled diabetes have worse perioperative outcomes after joint arthroplasty than patients with controlled diabetes who, in turn, have worse outcomes than those without diabetes (1). The classification of diabetes control was determined from ICD-9 codes. While this reflects glycemic control to a
degree, a better determinant would be a biochemical measure such as serum glucose at the time of hospital admission.
We have previously found a relationship between admission blood glucose levels, hospital mortality, and length of stay (LOS) in patients admitted through our Emergency Department (2). In light of the publication by Marchant et al., we analyzed our data for the subset of 489 patients who had a Diagnosis Related Group and ICD-10 code indicating their admission was related to a bone and joint disorder. As there were no deaths in this cohort, we used LOS as the outcome of interest.
Using linear regression, the relative LOS per unit increase in blood glucose level was 1.07 (95%CI 1.03-1.10, p<0.001), after adjustment for age and sex; i.e., for every one mmol/L increase in blood glucose level, LOS increased by 7%. The relative LOS for those with a blood glucose level over 8 mmol/L compared to those with a level under 8 mmol/L was 1.31 (95%CI 1.03-1.65), after adjustment; i.e., their average length of stay was 31% longer.
It seems likely that increased LOS in our study was related to increased hospital complications. Our data therefore support the finding that glucose control influences outcomes of patients admitted to hospital
for acute musculoskeletal conditions. In addition to increased morbidity, this has significant cost implications to the health system. Further research needs to be conducted to determine if interventions for hyperglycemia result in better outcomes for these patients.
The author did not receive any outside funding or grants in support of his research for or preparation of this work. Neither he nor a member of his immediate family received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the author, or a member of his immediate family, is affiliated or associated.
References
1. Marchant MH Jr, Viens NA, Cook C, Vail TP, Bolognesi MP. The impact of glycemic control and diabetes mellitus on perioperative outcomes after total joint arthroplasty. J Bone Joint Surg Am. 2009;91:1621-9.
2. Cheung NW, Li S, Ma G, Crampton R. The relationship between admission blood glucose levels and hospital mortality. Diabetologia. 2008;51:952-5.
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