Admission and fasting plasma glucose for estimating risk of death of diabetic and nondiabetic patients with acute coronary syndrome: nonlinearity of hazard ratios and time-dependent comparison.

BACKGROUND: In patients with acute coronary syndrome (ACS), increased plasma glucose levels are associated with worse outcome. Our aim is to ascertain the values of admission and fasting glucose for prediction of death among patients with ACS; and to compare their predictive capacities.
METHODS: The relationships of mortality to plasma glucose levels among 811 consecutive patients hospitalized with ACS were estimated using spline Cox models. Blood samples were obtained upon admission and after overnight fast. The predictive capacities of fasting and admission glucose were compared using time-dependent receiver operating characteristic curves.
RESULTS: Fasting and admission glucose levels were higher among the 151 patients who died (18.6%) than among survivors (P < .001). Among the 558 patients with no history of diabetes (68.8%) there was a J-shaped dependence of the all-time mortality hazard ratio on fasting glucose that persisted when adjusted for covariates: hazard was lowest at 110 mg/dL (6.1 mmol/L), and significantly greater at levels <90 mg/dL (5.0 mmol/L) or >117 mg/dL (6.5 mmol/L). Likewise among non-diabetic patients, the predictive capacities of admission and fasting glucose were similar for forecast times of up to about 1 year, but for later times the area under the receiver operating characteristic curve was larger for fasting glucose than admission glucose (P < .05). Neither admission nor fasting glucose levels discriminated among diabetic patients in regard to risk of death.
CONCLUSIONS: Both admission and fasting glucose may be used for triage of nondiabetic ACS patients; fasting glucose may additionally be useful for long-term management, for which the relationship with the all-time mortality hazard ratio is J-shaped.