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Journal of Postgraduate Medicine, Vol. 49, No. 4, Oct-Dec, 2003, pp. 307-310 The Impact of Diabetes Mellitus on In-hospital Stroke Mortality Hamidon BB, Raymond AA
Department of Medicine, Faculty of Medicine Universiti
Kebangsaan Malaysia (UKM), Kuala Lumpur Code Number: jp03086
BACKGROUND AND PURPOSE: Diabetes mellitus is a strong risk factor for stroke.
However, the prognosis in terms of mortality after a stroke is still unclear,
especially in diabetic patients. The main purpose of this study was to compare
and evaluate the features of stroke in patients having diabetes mellitus with
those without diabetes mellitus and to identify factors that influence survival
following a stroke. Key Words: Stroke, Diabetes mellitus, Hyperglycaemia, Mortality. In Malaysia, there is limited information related to the prevalence and mortality of stroke. Diabetes mellitus (DM), which confers a two to three- fold increase in the risk of developing “first ever” and recurrent stroke, is one of the most important risk factors. DM has also been reported to be an independent risk factor for mortality in patients with stroke.[1],[2],[3] However, some investigators after performing multivariate analysis have found that diabetes is not an independent risk factor for the development of stroke.[4] Whether acute diabetic hyperglycaemia independently affects patient outcome is also still debated upon.[5] This study was, therefore, undertaken to determine the effect of hyperglycaemia on the mortality in patients with stroke. The study was undertaken after obtaining sanction from the institution's research and ethics committee. Consecutive patients who were admitted to the general medical ward, high-dependency ward or the intensive care unit in a single hospital with a clinical diagnosis of acute stroke (first ever or recurrent within one week of onset of symptoms) or those who suffered a stroke in the hospital during the period June 2000 to January 2001 were enrolled in the study after obtaining an informed consent. They were managed according to a standardised critical pathway. The description provided by the World Health Organisation (WHO) was used to define acute stroke: “rapidly developing clinical signs of focal (or global) disturbance of cerebral function, with symptoms lasting 24 hours or longer or leading to death, with no apparent cause other than of vascular origin”.[6] A standardised data sheet was used to record the demographic variables including age, sex and presence of DM. DM was defined as a fasting plasma glucose level of > 7.8 mmol/l, random plasma glucose of > 11.1 mmol/l, or the requirement of regular hypoglycaemic drug(s). History of hypertension, hypercholesterolaemia, smoking and ischaemic heart disease was also recorded. Hypertension was defined as a previous record of at least two blood pressure readings of >140/90 mmHg or the requirement of regular intake of anti-hypertensive drugs. Hypercholesterolaemia was defined as having a total cholesterol of > 6.5 mmol/l or the requirement of regular anti-cholesterol drug(s). All study subjects were identified during the first 24 hours of admission and were observed prospectively by a single observer (first author). Using predefined diagnostic criteria, the type and time of the onset of stroke and death that occurred during the inpatient period were recorded using the standardised data sheet. The subjects were seen every morning by the observer (or if called) until they were discharged or they died. The parameters on admission, including the blood pressure, glucose levels, Glasgow coma score and the Barthel activities of daily living (ADL) index were recorded. Severe disability was defined as Barthel index less than 5 (out of 20). Stroke types were classified into ischaemic or haemorrhagic. Ischaemic stroke subtypes were divided into lacunar infarcts (infarct size less than 15 mm on brain CT) or territorial infarcts. The territorial infarcts were further classified as anterior cerebral artery (ACA) infarct, middle cerebral artery (MCA) infarct, and posterior cerebral artery (PCA) infarct on the basis of the clinical picture and radiological findings. The patients were prospectively observed for the development of infection or death. All patients were subjected to CT scan of the brain before being admitted to the wards. Magnetic resonance imaging (MRI) of the brain was done if the stroke localisation was in doubt. Recombinant tissue plasminogen activator (rtPA) was not used in any of the patients, as it is not a standard treatment at our institution. The relationship between baseline and clinical variables and DM were analysed with the chi[2] test and t test for categorical and continuous variables, respectively. The logistic multiple regression model was used for analysing the risk of developing infection, severe disability and death among diabetic patients. Odds ratios with 95% confidence interval (CI) were used to estimate the effects of each factor. All statistical analyses were performed with the SPSS 11.0 package, with statistical significance at 0.05 (2-sided). During the 8-month study period, 163 patients with ischaemic stroke were identified. There were 55 cases of intracerebral haemorrhage (not included in the analyses). Diabetes was present in 90 (55.2%) patients. The total case fatality rate was 11.7%. The characteristics of the study sample are reported in [Table-1]. DM was an independent risk factor for mortality, OR 4.88 (95%CI 1.25-19.1). However, there was no significant increase in the risk of infection, OR 2.1 (95%CI 0.8-5.4). Among the diabetic population, a multivariate analysis was done for the risk of mortality. The results are presented in [Table-2]. The mean admission random blood glucose level for diabetics who died was significantly higher than those who survived (18.71mmol/l vs. 13.95 mmol/l; P=0.001). The influence of the admission blood glucose on mortality is presented in [Table-2]. In this study the prevalence of DM amongst hospitalised patients with stroke was 55.2%, which is higher than that reported (13% and 36%) in other studies.[7],[8],[9] Although we are not certain about the reason for this difference, it could be related to differences in the selection of patients, the definition of diabetes used, methods of measuring glycaemia and the cohort size. There was no significant difference between the sexes regarding different types of stroke suggesting that diabetes has the same impact on the cerebral vessels in both sexes and all type of infarcts. As reported in previous studies, hypertension was significantly more common in diabetic patients.[9],[10] This strengthens the fact that diabetes and hypertension are closely related.[10] The key finding of our study was that DM independently predicted stroke mortality for all patients with ischaemic stroke. This was our main primary outcome, which supported our earlier hypothesis. Diabetic patients are generally prone to infection and are less immunocompetent, and usually have concurrent multiple end-organ damage that ultimately contributes to increased mortality. The detrimental effects of diabetes on the outcome of cerebrovascular disease are in keeping with previous reports that diabetics have poorer outcome after stroke and coronary artery disease than those without DM.[5],[11],[12] In comparison with non-diabetics, diabetics showed significantly higher admission blood glucose levels [Table-1]. Multivariate analysis demonstrated that blood sugar level at admission predicted mortality in these patients. Several large clinical studies have now demonstrated this and shown a two to six-fold increased risk of death extending across all clinical subtypes of stroke.[5],[13],[14] The study was also able to identify definite predictors of mortality in the diabetic group. MCA territory infarcts and poor GCS were independent risk factors in the multivariate analysis. Another key finding was that patients in the diabetic group had a longer length of stay. This will inevitably translate into higher overall cost. The longer length of stay might possibly be caused by the difficulties in controlling the blood glucose during the hospital stay. This might also be due to complications such as infection as diabetic patients are generally known to have a higher risk of developing infection. However, there was no significant difference in the incidence of infection between diabetics and non-diabetics in this study. A prospective study design and standardized observation by a single observer afforded strength to the study. The patients were not followed up after discharge. Deaths within a few days of discharge might have been missed. This could constitute a limitation of the study. Many studies have contrasting results on diabetes as a predictor of mortality in patients with stroke. Therefore, a systematic review of the subject would be the next step. However, the available data emanating from Asia is limited and pertains to local or institutional reports. As diabetes and hyperglycaemia are associated with an increased mortality rate, it would be interesting to know whether acute intervention with strict glycaemic control will reduce mortality associated with stroke. No large randomised studies have looked at this aspect and hence, future research should explore this direction.
Copyright 2003 - Journal of Postgraduate Medicine. Online full-text also available at http://www.jpgmonline.com/ The following images related to this document are available:Photo images[jp03086t2.jpg] [jp03086t1.jpg] |
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![[Table-1]](/showimage?jp/photo/jp03086t1.jpg){kind=link}
![[Table-2]](/showimage?jp/photo/jp03086t2.jpg){kind=link}