Study Finds Incidence of Pediatric Strokes Higher Than Previously Thought

September 21, 2009

A new study from the University of California, San Francisco (UCSF), shows that the rate of strokes in infants and children is actually higher than previously thought, which may be due to inaccurate counts of diagnostic codes, typing errors, or the misreading of keywords on radiology reports.

A new study from the University of California, San Francisco (UCSF), shows that the rate of strokes in infants and children is actually higher than previously thought, which may be due to inaccurate counts of diagnostic codes, typing errors, or the misreading of keywords on radiology reports.

Heather J. Fullerton, MD, senior author of the study and associate professor of neurology at UCSF, and her research team set out to determine the actual number of pediatric stroke cases because they felt that the total count may have been underrepresented when determined with diagnostic codes alone. The team searched for strokes among children enrolled in the Kaiser Permanente managed care plan in northern California, using the International Classification of Diseases, 9th division (ICD-9) codes and keywords that suggested a stroke on radiology reports — CT scans, MRI, and angiograms. Searching with these criteria, the researchers confirmed 205 cases of ischemic stroke, or “an incidence rate of 2.4 strokes per 100,000 person-years.”

According to the researchers, this new figure is two to four times higher than previous research had shown, which estimated that between 0.54 and 1.2 per 100,000 US children suffered strokes each year. This original estimate was based only on ICD-9 searches, the researchers clarified.

The researchers utilized data from the Kaiser Permanente program from 1993 to 2003, which included the records of 2.3 million children from 0—19 years old. The team “compared the search methods on their ability to identify the charts of children who had experienced a stroke (the sensitivity of the measures),” which showed that the radiology search was “far more sensitive,” at a rate of 83%, than the ICD-9 code search, at a rate of 30%. Additionally, according to the researchers, there was an even wider discrepancy for strokes that occurred in infants around the time of childbirth, with “a sensitivity of 12 percent using ICD-9 codes for stroke, and 87 percent using radiology records.”

Fullerton said that parents should remember that strokes are still rare in children, despite the discrepancies that the research showed, adding that the “major lessons” from this study are geared toward researchers.

“Studies based on ICD-9 codes may vastly underestimate the incidence and cost of pediatric stroke,” Fullerton said. “Our findings suggest that the field needs more prospective studies; although more costly, prospective studies can capture more pediatric strokes by identifying them as they occur.”