Yet another study has shown that people who are treated for stroke over a weekend tend to fare worse than those who are treated during the week, but the reasons remain unclear.

Canadian researchers found that people who checked into the hospital on the weekend tended to have more severe strokes than those who came in during the week, presumably because those with minor stroke symptoms chose to wait until Monday or Tuesday.

However, when they used statistical tools to eliminate the influence of stroke severity on the findings, they found that the association remained - people who came to the hospital on the weekend were 12 percent more likely to die within 7 days than those who arrived during the week, regardless of the severity of their condition.

“It’s not because of severity differences that there’s a difference in outcome,” Dr. Mat Reeves, stroke epidemiologist at Michigan State University in East Lansing, who was not involved in the study, told Reuters Health.

So what’s the explanation? There may be unintentional differences in quality of care between the week and weekend, study author Dr. Moira Kapral at Toronto General Hospital suggested. She and her team actually found some signs of improved care over the weekend - such as a higher use of clot-busting drugs - but there may be additional differences they couldn’t measure, she said. “For example, hospitals may have fewer staff working on weekends, or less experienced staff,” she said.

“It’s difficult to quantify how much nursing care is available at any given time,” Reeves agreed.

Previous research has shown a “weekend effect” for patients admitted to the hospital for heart attack, a blood clot in a lung, a ruptured abdominal artery, and strokes of all kinds. The data have been somewhat inconsistent with stroke, however - for instance, a study earlier this year found no difference in the odds of survival between weekend and weekday strokes, and, like this current study, weekend patients were more likely to receive clot-busting therapy.

The variation between studies may simply stem from differences in hospitals and data analysis, and the fact that the overall effect is relatively small, Reeves explained. The participating patients may also differ from one group to another, Kapral added.

In general, “I am impressed as to how many good, large studies across multiple countries show a small but consistent weekend effect for stroke,” Reeves noted.

In the current study, Kapral and her colleagues reviewed data collected from 20,657 people who were admitted for stroke at 11 centers in Ontario between 2003 and 2008.

Reporting in the journal Neurology, they found that 8 percent of those who arrived on the weekend died within 7 days, versus only 7 percent who came in during the week.

Regardless of the reason why weekend patients fare worse, this trend should never encourage people to delay treatment if they suspect they are experiencing a stroke, Kapral and Reeves cautioned.

“The worst thing a patient could do is wait until Monday,” Kapral noted in an e-mail. “There are many stroke treatments that need to be given immediately to be effective, and people are far more likely to have complications if they stay at home than if they go to the hospital.”

Symptoms of a stroke can be subtle and can include sudden numbness or weakness of the face or a limb, sudden confusion, trouble speaking or walking, or a sudden headache.

Stroke is the third leading cause of death in the United States, after heart disease and cancer.

SOURCE:  Neurology, November 2, 2010.