Stroke Rate in Diabetes Creeping Downward by Risk Manag...

Stroke Rate in Diabetes Creeping Downward by Risk Management

Stroke Rate in Diabetes Creeping Downward by Risk Management
August 31, 2008
MedPage Today

LULEA, Sweden, Aug. 21 -- Aggressive diabetes risk management here appears to have lessened the rate of stroke and mortality for the first time for these patients, researchers here found.

Initial stroke incidence slid 0.1% per year among diabetic men in Sweden and a significant 1.5% per year among diabetic women from 1985 to 2003, reported Aslak Rautio, M.D., of Umeå University here, and colleagues, online in Stroke: Journal of the American Heart Association.

Their findings from within a multinational stroke surveillance study also showed that case-fatality rates fell by 1.3% to 8.7% per year among diabetics and nondiabetics alike.

The results provide the first evidence that aggressive treatment of risk factors associated with diabetes is staring to pay off, commented Daniel T. Lackland, Dr.P.H., of the Medical University of South Carolina in Charleston and a spokesperson for the American Stroke Association, in an interview.
"We're beginning to see a more aggressive treatment of people with diabetes both for their blood pressure control as well as their glucose and lipid control," he said. "This is a more difficult patient to treat, but we're beginning to see a reward for this."

The Swedish findings are likely a harbinger of what's to come in the United States, Dr. Lackland said. Already, the upward trends in stroke risk for American diabetics are starting to plateau, he said. "They're ahead of us."

In the total U.S. population, the same benefits have yet to pan out in stroke rates likely because of the more diverse, higher-risk population compared with Sweden, Dr. Lackland said.

"If we were to look only at white populations with diabetes," he said, "I believe we would probably see similar results to what they saw in Sweden."

The researchers analyzed stroke event registries from two counties in northern Sweden done as part of the WHO Multinational Monitoring of Trends and Determinants in Cardiovascular Disease (MONICA) project.

For the population of half a million inhabitants in the two counties, 9,487 men and 5,895 women ages 35 through 74 years had a stroke registered in the database from 1985 through 2003. Diabetes was present in 22.8% of both men and women.

Overall stroke incidence declined during the study period for nondiabetic men and women from 358 and 204 per 100,000 to 284 and 183 per 100,000, respectively.

Although stroke incidence was five to nine times higher among diabetics, this group also saw a decrease in incidence from 1,961 per 100,000 among men and 1,921 per 100,000 among women in 1985 to 1,815 and 1,176 per 100,000, respectively, by 2003.

The disparity in stroke incidence by diabetes status stayed about the same between time periods among men but declined significantly among women.

These differences carried through for both first and recurrent stroke.

For first-ever stroke, the findings included:

Nondiabetic men had a significant decline of 0.8% per year (95% confidence interval 0.3 to 1.3).
Diabetic men had a nonsignificant 0.1% per year decline.
Nondiabetic women had no change in diabetes incidence.
Diabetic women had a significant yearly decrease in incidence of 1.5% (95% CI 0.3 to 2.7).

For recurrent stroke, only diabetic men failed to show a significant decrease in incidence. Again, diabetic women showed the greatest improvements with a 5.4% decline per year (95% CI 3.6 to 7.2) compared with 2.7% among nondiabetic women (95% CI 1.5 to 3.8).

Patients were also more likely to survive a stroke by 2003 compared with 1985 with improvements that were similar between diabetics and nondiabetics. Yearly change in case fatality rates were:

For nondiabetic men, -3.6% for first-ever strokes and -6.7% for recurrent stroke per year (both P<0.001).
For diabetic men, -4.1% for first-ever strokes and -4.1% for recurrent stroke per year (P=0.005).
For nondiabetic women, -4.6% for first strokes and -8.7% for recurrent strokes annually (both P<0.001).
For diabetic women, -1.3% for first-ever strokes (P=0.451) and -5.8% for recurrent strokes per year (P=0.017).

The combination of decreasing incidence and decreasing case-fatality led to a similar pattern in declining total stroke mortality.

"There is no apparent explanation for this gender difference," the researchers said. Although the age cutoff at 74 was one possibility, the authors added that there is "no reason to believe that the results differ among the eldest."

They also noted that the findings may have been limited by the considerable proportion of patients with stroke who may have had undiagnosed diabetes or impaired glucose tolerance.

The predominantly Caucasian population is also a challenge to generalizability, Dr. Lackland said. "We know that diabetes affects African Americans and other groups a little bit more than it does for Caucasians."

Based on the findings, the researchers concluded that both primary and secondary prevention of cardiovascular disease need to be intensified in the diabetic population. "Treatment of hypertension and hyperlipidemia are instrumental to this aim."

The study was supported by funds from county councils in the areas covered by the registries. One of the researchers reported support by a grant from the Swedish Medical Research Council and King Gustaf V and Queen Viktoria Foundations.

The researchers reported no conflicts of interest. Dr. Lackland reported no conflicts of interest.

Action Points

Explain to interested patients that diabetes increases the risk for stroke and cardiovascular events.

Note that the Swedish study was done in a predominantly white population, which suggests results would be different than in an ethnically diverse population such as in the United States.