The predictive value of admission blood glucose value and HbA1c on hospital length of stay and mortality in a general medical population — ASN Events
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  3. The predictive value of admission blood glucose value and HbA1c on hospital length of stay and mortality in a general medical population

The predictive value of admission blood glucose value and HbA1c on hospital length of stay and mortality in a general medical population (#263)

Kharis Burns 1 2 , David R Chipps 1 2 , Sylvia Lim-Tio 1 2 , N Wah Cheung 1 2
  1. Department of Diabetes and Endocrinology, Westmead Hospital, Westmead, NSW, Australia
  2. University of Sydney, Sydney, NSW, Australia

Introduction

Hyperglycaemia has been associated with higher in-hospital mortality in patients with and without diabetes. The value of HbA1c in predicting hospital length of stay (LOS) and mortality has been assessed in patients with diabetes though there is limited information in a general medical population. Furthermore, the relationship between admission HbA1c and blood glucose levels (BGL) in predicting outcomes has been little investigated to date. Is hyperglycaemia associated with higher mortality regardless of HbA1c?

Objectives

We aimed to examine the relationship between admission BGL and HbA1c, and outcomes of LOS and in-hospital mortality in a general medical population with hyperglycaemia (BGL>10mmol/L) when presenting to an emergency department (ED).

Methods

HbA1c levels were routinely collected for all Emergency Department patients with an admission blood glucose of >10mmol/L between 2012 and 2015. Data linkage with the hospital administrative database was performed for all patients to capture hospital outcome parameters including length of stay and discharge status (including mortality). Presentations for diabetic emergencies including DKA and Hyperosmolar hyperglycaemic states were excluded.  Simple descriptive statistics were used to assess population data and Spearman’s rank correlation coefficient was used to analyse the relationship between variables of admission glucose, HbA1c, age and length of stay. Association between mortality and HbA1c was assessed with Mann-Whitney U tests.

Results

Between 2012 and 2015 there were 739 presentations with a BGL >10mmol/L, for whom an HbA1c was collected in ED, excluding presentations for diabetic emergency. The mean admission BGL was 13.9 +4.7mmol/L and mean HbA1c was 7.5 +2.0%, (58.3+21.5mmol/mol). More than 1/3rd of the population presenting with hyperglycaemia had an HbA1c <6.5%, 48mmol/mol (259/739, 35.1%). The mortality rate was 44/739 (5.95%).

There was a negative correlation between admission HbA1c and LOS (r = -0.102, p=0.006), though there was no relationship between LOS and admission BGL (r= 0.012, p=0.738). In-hospital mortality was associated with a lower HbA1c (median 5.85% vs 7.20%, (p <0.05)).

Conclusions.

HbA1c is negatively associated with higher mortality amongst people with hyperglycaemia. Elevated glucose in association with normal HbA1c suggests hyperglycaemia is due to severe illness, rather than diabetes, and may thus predict higher mortality.