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Mortality among children with Kawasaki disease in Japan
Y Nakamura1, H Yanagawa, T Kawasaki
1Department of Public Health, Jichi Medical School, Tochigi, Japan.
Insights
Boys with Kawasaki disease (KD) in Japan have double the mortality rate of healthy boys, with most deaths occurring within two months of diagnosis. KD mortality in girls appears similar to healthy girls.
Area of Science:
- Pediatrics
- Epidemiology
- Cardiovascular Research
Background:
- Kawasaki disease (KD) is a pediatric illness primarily affecting children under five.
- Uncertainty exists regarding the elevated mortality risk in KD patients compared to the general population.
Purpose of the Study:
- To investigate the mortality rate of patients diagnosed with Kawasaki disease in Japan.
- To compare the observed death rate in KD patients against age-matched healthy individuals.
Main Methods:
- A cohort study was conducted from July 1982 to December 1988, involving 53 treatment centers in Japan.
- Data were collected on 4676 patients with new-onset Kawasaki disease, excluding recurrent cases or those presenting after 14 days.
- Patient follow-up extended to December 31, 1989, with mortality compared against Japanese vital statistics.
Main Results:
- Of 4676 eligible patients, 13 deaths were recorded. The observed to expected death ratio was 1.71 overall (95% CI, 0.91-2.92).
- Boys exhibited a higher observed to expected death ratio (2.04; 95% CI, 0.98-3.76) compared to girls (1.11; 95% CI, 0.23-3.23).
- During the acute phase (first two months), mortality ratios were significantly elevated (overall 9.86, boys 13.33), decreasing to below 1 after this period.
Conclusions:
- Boys with Kawasaki disease in Japan face a twofold increased mortality risk compared to healthy peers.
- The majority of deaths in boys with KD occur within the initial two months post-diagnosis.
- While the study suggests similar mortality for girls with KD, the small sample size warrants cautious interpretation.
Background And Methods:
It is not certain whether patients with Kawasaki disease have a higher death rate than the age-matched healthy population. We therefore undertook a study to investigate this question. Between July 1982 and December 1988, 53 collaborating treatment centers collected data on all patients who had an unequivocal new diagnosis of Kawasaki disease; patients who had recurrent disease or whose first visit to the treatment center occurred more than 14 days after the onset of symptoms were excluded. Patients were followed from the time of the first visit to the treatment center until December 31, 1989, or until death, whichever occurred first. The expected number of deaths was calculated from Japanese vital-statistics data and compared with the number observed.
Results:
Of 4676 patients who met the eligibility criteria, 4608 (98.5 percent) were followed through either the end of the study or the date of death. Thirteen patients (10 boys and 3 girls) died during the study period. The number of deaths expected was 7.61 (ratio of observed to expected deaths, 1.71; 95 percent confidence interval, 0.91 to 2.92). The ratio was 2.04 (95 percent confidence interval, 0.98 to 3.76) for boys and 1.11 (95 percent confidence interval, 0.23 to 3.23) for girls. During the acute phase of the disease (the first two months after onset), the ratios of observed to expected deaths were higher: 9.86 overall (95 percent confidence interval, 3.95 to 20.31), 13.33 for boys (95 percent confidence interval, 4.89 to 29.07), and 3.85 for girls (95 percent confidence interval, 0.10 to 21.42). After the acute phase, however, both sexes had ratios of observed to expected deaths that were lower than 1, and the difference from the control population was not statistically significant.
Conclusions:
The mortality rate among boys with Kawasaki disease in Japan is twice that among healthy boys of the same age, and most deaths occur within two months of diagnosis. The mortality rate among girls with the disease appears similar to that among healthy girls, although the numbers are very small.