Studies find stroke strikes poor on Mondays in Finland and fewer deaths from bleeding strokes in Sweden

Ischemic stroke takes a holiday on Sunday but returns with a vengeance on Monday, particularly in the elderly who are poor and less educated, according to a Finnish study.  A Swedish study found that deaths from subarachnoid hemorrhage are declining in men and women – but for different reasons.

The studies use data from two centers involved in the World Health Organizations’ MONICA project and are published in today’s rapid access issue of Stroke: Journal of the American Heart Association.  MONICA is the acronym for MONItonitoring Trends and Determinants in CArdiovascular Disease Project.  There are 32 MONICA collaborating centers in 21 countries; nine of them have stroke registries.

In the Finnish study, researchers investigated the relationship between the weekday variations in ischemic stroke and socioeconomic status.  Ischemic strokes are caused by blood clots that block blood flow in the brain or arteries leading to the brain. 

Researchers reviewed data from FINMONICA, a stroke registry of people age 25 to 99 that includes data from 12,801 ischemic strokes that occurred from 1982 to 1992.  Researchers focused on first strokes among people age 25-74.

Among their findings:

• Overall, the fewest ischemic strokes occurred on Sunday.  The highest number of events occurred on Mondays -- 10 percent above the weekly average among men and 8.3 percent above the weekly average among women.
• However, among the elderly, education and wealth appeared to protect against Monday strokes, said lead author Dimitrije Jakovljeviã, M.D., a neurosurgeon and doctoral candidate at the National Public Health Institute of Finland, Department of Epidemiology and Health Promotion.
• Among men aged 60 to 74, incidence of ischemic stroke increased 29.2 percent from Sunday to Monday.
• Among elderly men in the low-income group, incidence of ischemic stroke peaked at 17.9 percent above the weekly average on Monday.  Strokes reached 14.4 percent above the weekly average in the middle-income group on Monday. 
• Among the elderly poor, the Sunday incidence was 13.9 percent lower than the weekly average, and the incidence stroke rate was 15.7 percent lower on Sunday among people with basic education.
• In the middle-income group, the most significant increase in strokes occurred on Thursday, when the stroke rate shot up by 20.7 percent over the weekly average.

Researchers say the higher incidence of stroke among the poor and less educated is of substantial public health interest, but they are still unclear on the cause of the increase.  They note that if the registry had included lifestyle information, that information could have helped determine if weekend drinking and smoking habits were factors in the increased Monday strokes.

However, “our findings are somewhat surprising because we would expect elderly people’s lifestyle during the weekend to be more stable than in the working population,” he said.

The Swedish study is the first analysis of time trends in subarachnoid hemorrhage (SAH) data from northern Sweden.  A subarachnoid hemorrhage occurs when a blood vessel on the brain's surface ruptures and bleeds into the space between the brain and the skull (but not into the brain itself).  SAH can affect all ages, and more than a third of people who experience SAH die early after onset, said senior author Birgitta Stegmayr, Ph.D., associate professor, Department of Public Health and Clinical Medicine at Umeå University in Umeå, Sweden.

Researchers reviewed data from its population-based MONICA registry of 984 SAHs that occurred among people age 25 to 74 in northern Sweden between 1985 and 2000.  The registry includes all SAHs (in-hospital and out of hospital).  For a three-year period (1997-1999) SAHs in people 75 and older were also included in the registry.

The 16-year study found that deaths from SAH declined steadily in both men and women, but for different reasons.  While men had a lower death rate because the risk of being afflicted with SAH declined steadily during the study period, women had no decline in incidence but “women were more likely to survive SAH,” Stegmayr said.

The bottom line, Stegmayr said, is “that we will need to do more studies to determine why the SAH incidence rate declines in men, but not in women and why women are more likely to survive an SAH.”

During the study, the SAH incidence in all ages was 13.3 per 100,000 population in men and 24.4 per 100,000 in women.  In people under age 75, the 28-day case fatality rate for all years was 36.5 percent for men and 35 percent in women.  Overall, the annual decline in SAH mortality was about 3.87 percent in men and 3.97 percent in women,” Stegmayr said.

Jakovljeviãs co-authors are Cinzia Sarti, M.D., Ph.D.; Veikko Salomaa, M.D., Ph.D.; Jorma Torppa, MSc; Jaakko Tuomilehto, M.D., Ph.D.; Juhani Sivenius, M.D., Ph.D.; and Pirjo Immonen-Räihä, M.D., Ph.D.      Stegmayr’s co-authors are Marie Eriksson, M.Sc.; and Kjell Asplund, M.D., Ph.D.

Editor’s note: For more info on stroke, visit the American Stroke Association Web site:strokeassociation.org.