Lacunar Strokes in Patients With Diabetes Mellitus: Risk Factors, Infarct Location, and Prognosis
The Secondary Prevention of Small Subcortical Strokes Study
Background and Purpose—Diabetes mellitus is an independent risk factor for lacunar strokes. Few data are available regarding patient features, infarct location, and recurrent vascular events for patients with diabetes mellitus with lacunar stroke.
Methods—We compared features at study entry and prognosis during 3.6 years of follow-up of patients with diabetes mellitus versus patients without diabetes mellitus with recent lacunar stroke participating in the Secondary Prevention of Small Subcortical Strokes (SPS3) randomized trial.
Results—Among the 3020 participants, the prevalence of diabetes mellitus was 37% with a mean duration of 11 years. Diabetes mellitus was independently associated with slightly younger age (63 versus 64 years; P<0.001), Hispanic ethnicity (36% versus 28%; P<0.0001), ischemic heart disease (11% versus 6%; P=0.002), and peripheral vascular disease (5% versus 2%; P<0.001). Patients with diabetes mellitus more frequently had intracranial stenosis ≥50% (P<0.001), infarcts involving the brain stem or cerebellum (P<0.001), and more extensive white matter abnormalities (P<0.001). Patients with diabetes mellitus were almost twice as likely to have a recurrent stroke (hazard ratio [HR], 1.8; 95% confidence interval [CI], 1.4–2.3), recurrent ischemic stroke (HR, 1.8; 95% CI, 1.4–2.4), disabling/fatal stroke (HR, 1.8; 95% CI, 1.2–2.9), myocardial infarction (HR, 1.7; 95% CI, 1.0–2.8), and death (HR, 2.1 95% CI, 1.6–2.8) compared with patients without diabetes mellitus.
Conclusions—Patients with diabetes mellitus with lacunar stroke have a distinctive clinical profile that includes double the prevalence of systemic and intracranial atherosclerosis, preferential involvement of the posterior circulation, and a poor prognosis for recurrent stroke and death.
Diabetes mellitus is an accepted independent risk factor for ischemic stroke, regardless of its mechanism. The prevalence of diabetes mellitus in patients with stroke is between 10% and 20% and has been increasing during the past 20 years, probably in response to rising rates of overweight and obesity in the general population.1–3
A hospital-based case–control study of patients presenting with a first-ever lacunar stroke showed that the risk of lacunar stroke was 2× higher in patients with diabetes mellitus compared with age and sex-matched controls.4 In another case–control study, diabetes mellitus was associated with an increased prevalence of lacunar strokes compared with other ischemic stroke subtypes.5
Little is known about the clinical implications of diabetes mellitus in patients with lacunar strokes because of cerebral small artery disease. We hypothesized that diabetes mellitus would be an independent risk factor for the severity of cerebral small artery disease in patients with lacunar strokes. Here, we characterize the differences between patients with and without diabetes mellitus in a large, well-defined cohort of patients with lacunar strokes attributed to cerebral small vessel disease participating in an international clinical trial. The anatomic distribution of infarcts, ethnic differences, prognosis regarding major vascular events, and mechanisms underlying recurrent strokes are analyzed.
We included 3020 participants of the Secondary Prevention of Small Subcortical Strokes (SPS3) trial performed in 8 countries between 2001 and 2011. The rationale, design, and main results of SPS3 have been reported elsewhere.6 In brief, patients ≥30 years old with a recent, MRI-defined small subcortical ischemic stroke were included if there was no ipsilateral carotid stenosis >50% or a major cardioembolic source requiring anticoagulation. Qualifying stroke had to demonstrate ≥1 of the following 4 specific MRI criteria: (1) diffusion-weighted imaging lesion ≤20 mm in size at largest dimension (including rostrocaudal extent); (2) well-delineated focal hyperintensity ≤20 mm in size at largest dimension (including rostrocaudal extent) on fluid attenuated inversion recovery (FLAIR) or T2 and clearly corresponding to the clinical syndrome; (3) multiple hypointense lesions of size 3 to 15 mm at largest dimension (including rostrocaudal extent) only in the cerebral hemispheres on FLAIR or T1 in patients whose qualifying event is clinically hemispheric. If qualifying event was clinically brain stem or cerebellar, this criterion alone was not sufficient for study entry; (4) well-delineated hypointense lesion ≤15 mm in size at largest dimension (including rostrocaudal extent) on FLAIR or T1 corresponding to the clinical syndrome. Patients with disabling strokes (modified Rankin scale ≥4) were excluded. Criteria for diabetes mellitus included ≥1 of a self-reported history of diabetes mellitus, prescribed antidiabetic medications, elevated glucose in medical records (>120 mg/dL), or diagnosis within 3 months of study entry.
White matter hyperintensities were evaluated visually on FLAIR images using the age-related white matter changes scale (range, 0–16) by readers unaware of clinical information.7 A priori, scores of 0 to 4 on the age-related white matter changes scale were defined as none-mild disease, 5 to 8 moderate, and 9+ severe. A neuroradiologist (C.B.) who was unaware of clinical data recorded the number of lacunar strokes and graded the severity of stenosis. The topography of lacunes was categorized as anterior circulation (basal ganglia, internal capsule, corona radiata), thalamic, and posterior circulation (brain stem and cerebellum). Recurrent ischemic strokes were classified according to Trial of Org 10 172 in Acute Stroke Treatment (TOAST) criteria; neuroimaging was available in 99% of the recurrent strokes.
We examined differences in participant features between patients with and without diabetes mellitus using 2-sample t tests and χ2 tests of association, as appropriate. Any factors found to differ between patients with and without diabetes mellitus in a univariate fashion were then included in a multivariable logistic regression model assessing associations with the likelihood of being diabetic at baseline. We then computed the rates of events for patients with and without diabetes mellitus and determined whether they differed using a Cox proportional hazards model. Initial models were run without adjustment; then factors found to be related to diabetes mellitus in the multivariable logistic regression model were included in Cox models to determine whether observed differences in rates of events were still significant after accounting for factors known to be related to diabetes mellitus. We further examined subtypes of stroke, and whether they differed in frequency by diabetes mellitus status, among those who experienced an ischemic stroke. Significance was assessed at an α level of 0.05 for all tests.
Of 3020 participants, 37% (n=1106) were classified as patients with diabetes mellitus, and in 71%, the hemoglobin A1c exceeded 7% at study entry. Of those patients with diagnosis of diabetes mellitus at study entry (91%), the mean estimated duration of diabetes mellitus was 11 years. There were no significant differences in sex (63% men) or prevalence of hypertension between both groups. Hypertension was highly prevalent both in patients with diabetes mellitus (92%) and in patients without diabetes mellitus (80%) with lacunar strokes (Table 1).
Diabetes mellitus was independently associated with younger age (63 versus 64 years; P<0.005), Hispanic ethnicity (36% versus 28%; P<0.0001), ischemic heart disease (P=0.002), and peripheral vascular disease (P<0.0004) compared with nondiabetics (Table 1). Measured blood pressure at study entry was higher in patients with and without diabetes mellitus (systolic 144 versus 142 mm Hg, respectively), despite the use of significantly more antihypertensive medications by patients with diabetes mellitus. (P<0.0001; Table 1). Current tobacco smoking was significantly less frequent among patients with diabetes mellitus (16%) versus patients without diabetes mellitus (23%; P=0.0009). The mean serum creatinine levels were not different, but average estimated glomerular filtration rates were slightly (2.1 mL/min), but significantly, higher among patients with diabetes mellitus versus patients without diabetes mellitus (P<0.0002; Table 1).
Brain imaging from 3004 patients (>99% of participants) was available for central review. The location of the qualifying lacunar infarct was more often in the brain stem or cerebellum (ie, posterior circulation) in patients with diabetes mellitus (32%) versus patients without diabetes mellitus (22%; P<0.0001), and intracranial arterial stenosis ≥50% was significantly more frequent (23% in patients with diabetes mellitus, 14% in patients without diabetes mellitus; P<0.0001; Table 2). The proportion of posterior circulation intracranial stenosis ≥50% was not significantly increased in patients with diabetes mellitus (P=0.50; Table I in the online-only Data Supplement). Patients with diabetes mellitus had more extensive white matter abnormalities on baseline imaging, but this was not significant after adjustment for other independent predictors (P=0.11; Table 1).
Major Vascular Events and Mortality During Follow-Up
During a mean follow-up of 3.6 years, recurrent ischemic stroke occurred in 11.4% of patients with diabetes mellitus versus 5.9% of patients without diabetes mellitus (P<0.0001). After adjustment for other predictors, the rates of recurrent stroke (hazard ratio [HR], 1.8; 95% confidence interval [CI], 1.4–2.3), recurrent ischemic stroke (HR, 1.8; 95% CI, 1.4–2.4), disabling/fatal recurrent stroke (HR, 1.8; 95% CI, 1.2–2.9), and myocardial infarction (HR, 1.7; 95% CI, 1.0–2.8) were almost 2× higher in patients with diabetes mellitus versus patients without diabetes mellitus (Table 3). All-cause mortality was twice as frequent in patients with diabetes mellitus (HR, 2.1; 95% CI, 1.6–2.8), as well as death because of vascular and uncertain causes (HR, 1.8; 95% CI, 1.1–3.0 and HR, 3.9; 95% CI, 2.1–7.0), versus patients without diabetes mellitus (Table 3). There were no significant differences in the risk of nonvascular death (HR, 1.6; 95% CI, 0.9–2.6) or major extracranial hemorrhages (HR, 0.88; 95% CI, 0.6–1.3) among patients with diabetes mellitus.
Pathogenetic Subtype of Recurrent Ischemic Strokes and Effect of Trial Interventions
Most recurrent ischemic strokes were lacunar and attributed to cerebral small artery disease, with no significant difference between patients with diabetes mellitus versus patients without diabetes mellitus (Table 4). The prescence/absence of anterior or posterior intracranial stenosis did not significantly increase the rate of recurent ischemic strokes in patients with diabetes mellitus (P value for interaction, 0.72; Table II in the online-only Data Supplement). The response to dual antiplatelet therapy versus aspirin alone and to lower versus higher target of systolic blood pressure on recurrent ischemic stroke did not differ between participants with diabetes mellitus versus participants without diabetes mellitus (Figure).
This is the first large study to describe in detail the specific risk factors and prognosis of patients with lacunar stroke according to the presence of diabetes mellitus. Patients with diabetes mellitus with lacunar strokes were slightly younger with nearly double the frequencies of intracranial arterial stenosis, ischemic heart disease, and peripheral vascular disease (ie, manifestations of systemic generalized atherosclerosis). Diabetes mellitus independently doubled the risks of recurrent stroke, recurrent lacunar stroke, myocardial infarction, and death. The association between worse clinical outcomes and diabetic status after stroke has been reported previously. Megherbi et al8 found that in a large European cohort, diabetic status was significantly associated with increased disability at 3 months after stroke. The excess risk of stroke in patients with diabetes mellitus and particularly in women was also observed in a recent systematic review and meta-analysis.9
Lacunar strokes tend to breed true, with recurrent strokes in patients with lacunar strokes are likely to be lacunar. Atherosclerosis at the ostium of the perforating arteries is one of the mechanisms that leads to lacunar infarcts. Although patients with diabetes mellitus in this cohort had significantly higher prevalence of intracranial stenosis, it is notable that the proportion of recurrent strokes that were classified as lacunar were similar for patients with diabetes mellitus and patients without diabetes mellitus, although the absolute rate of recurrent lacunar stroke was double among patients with diabetes mellitus.
The qualifying lacunar stroke significantly more frequently involved the posterior circulation in patients with diabetes mellitus versus patients without diabetes mellitus. This finding confirms other observational studies.10
Patients with diabetes mellitus were more likely to be Hispanics compared with other ethnic groups. This association, as well as the increased prevalence of intracranial atherosclerosis, in Hispanics has also been observed by others.11
It was previously reported that there were no significant differences in effects of the randomized interventions tested in the SPS3 trial (clopidogrel plus aspirin versus aspirin, higher versus lower systolic blood pressure targets) on all recurrent stroke between patients with diabetes mellitus versus patients without diabetes mellitus.12–14 Here, novel additional data are presented restricted to recurrent ischemic stroke (Figure). We hypothesized during the design of the trial that addition of clopidogrel might be particularly beneficial for prevention of recurrent ischemic stroke for relatively aspirin-resistant participants with diabetes mellitus, but there was no support for this construct in the SPS3 results (P for interaction by diabetic status, 0.98). It was additionally hypothesized that assignment to a lower target of systolic blood pressure would be particularly beneficial for prevention of recurrent stroke among patients with diabetes mellitus with lacunar stroke, but this was not confirmed (Figure).
Consequently, in the absence of differential effects of the randomized interventions according to the presence of diabetes mellitus, we hypothesize that intrinsic cerebral small artery disease remains the most likely cause for recurrent stroke in both patients with diabetes mellitus and patients without diabetes mellitus with lacunar stroke (Table 4).
Limitations include the absence of data about the control of diabetes mellitus during follow-up. We also acknowledge that the SPS3 inclusion and exclusion criteria may produce selection bias in ≥2 ways. First, participants in clinical trials are nearly always healthier than in population-based studies. Second, SPS3 excluded patients with lacunar stroke with occlusive extracranial atherosclerosis and major cardioembolic sources in an effort to include patients with relatively pure small vessel disease.
Patients with diabetes mellitus with lacunar strokes have distinctive risk factor profile and infarct location, have double the frequency of clinically manifest atherosclerosis, and carry a substantially worse prognosis compared with patients without diabetes mellitus. The predominant recurrent stroke subtype was lacunar. Although management implications specific to patients with diabetes mellitus did not emerge from the SPS3 trial, patients with diabetes mellitus with lacunar stroke represent a large high-risk subgroup of patients with cerebral small artery disease with distinctive clinical features that warrant further study.
Sources of Funding
The sponsor of the study, National Institute of Neurological Disorders and Stroke (U01 NS38529-04A1), participated in study design, data collection, data analysis, data interpretation, and writing of the report. The corresponding author had full access to all the data in the study and had final responsibility for the decision to submit for publication.
The online-only Data Supplement is available with this article at http://stroke.ahajournals.org/lookup/suppl/doi:10.1161/STROKEAHA.114.005018/-/DC1.
- Received February 20, 2014.
- Revision received June 11, 2014.
- Accepted June 16, 2014.
- © 2014 American Heart Association, Inc.
- 1.↵Centers for Disease Control and Prevention. National Diabetes Fact Sheet, 2011. Atlanta, GA: Centers for Disease Control and Prevention, US Department of Health and Human Services; 2011. http://www.cdc.gov/diabetes/pubs/pdf/ndfs_2011.Pdf. Accessed April 16, 2012.
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