Reye Syndrome: Practice Essentials, Pathophysiology, Etiology

United States statistics

In the United States, national surveillance for Reye syndrome began in 1973. It is believed that before the 1970s, most of the cases that met the criteria for Reye syndrome were diagnosed as encephalitis or drug intoxication.

The peak annual incidence of 555 cases reported to the Centers for Disease Control and Prevention (CDC) was in 1979-1980. Between December 1, 1980, and November 30, 1997, 1207 cases of Reye syndrome in patients younger than 18 years were reported. [16] During that period, the incidence was 0.15-0.88 cases per 100,000 children per year and as high as 6 cases per 100,000 during regional outbreaks of influenza.

Cases of Reye syndrome declined in number after 1980, when the government began issuing warnings about the association between this syndrome and aspirin. Whereas an average of 100 cases per year were reported in 1985 and 1986, the maximum number of cases reported annually between 1987 and 1993 was 36, with a range of 0.03-0.06 cases per 100,000 per year. Since 1994, 2 or fewer cases have been reported every year. While Reye syndrome reporting to CDC is no longer mandated, many local/state health boards continue to require reporting.

The dramatic decrease in the frequency of Reye syndrome since the 1980s is largely attributable to reduced aspirin use in children, as well as to discoveries of and advances in the diagnosis of inborn errors of metabolism (IEMs) and identification of toxins and drugs capable of producing symptoms that mimic Reye syndrome. The decrease may also be partially attributable to overreporting of cases during the peak years that did not fully meet criteria and underreporting of cases in subsequent years by physicians who did not consider the diagnosis.

Seasonal occurrence initially peaked from December to April, which correlated with the peak occurrence of viral respiratory infections, particularly influenza. Since 1990, the seasonal variation has been less pronounced than was suggested by this initial observation.

International statistics

In the United Kingdom, 597 cases were reported between 1981 and 1996. After warnings of the association between Reye syndrome and aspirin were issued in 1986, the incidence of Reye syndrome decreased substantially, from a high of 0.63 per 100,000 children younger than 12 years in 1983-1984 to 0.11 cases per 100,000 in 1990-1991. Of the 597 cases, 155 were later reclassified, 76 of them as involving an IEM. Similar rates have been reported from other countries.

Age-, sex-, and race-related demographics

Based on US CDC surveillance statistics for 1980-1997 for patients younger than 18 years, 1207 cases were reported in the United States. [16] Incidence peaks between age 5 and 14 years (median, 6 years; mean, 7 years); 13.5% were younger than 1 year. Reye syndrome rarely occurs in newborns or in children older than 18 years. Reye syndrome is equally distributed between the sexes. The racial distribution of Reye syndrome is 93% White and 5% African American, with the remaining percentage Asian, American Indian, and Native Alaskan. Of those younger than 1 year, 67% were African American and 12% were White.