Circadian pattern of ambulance use for children in a Japanese city.
OBJECTIVE
Many emergency events have a unique cyclic pattern. Understanding the patterns is important for anticipating the events and for providing appropriate medical services. This study aimed at verifying periodic fluctuation in ambulance use for children in Yokohama, Japan, and determining whether the periodic pattern differs between holidays and ordinary days.


METHODS
The study comprised a retrospective analysis of Yokohama city ambulance records covering transport of children aged 14 years or less between January 1994 and December 2001. A partial Fourier model was used to compare the pattern of ambulance use on holidays with that on ordinary days. The least squares method was used to determine coefficients of the partial Fourier series.


RESULTS
Twenty-four-hour periodicity was observed in the use of ambulances for children. Ambulance use per hour peaked in the evening and bottomed in the early morning. The patterns were nearly identical between holidays and ordinary days, although the frequencies of ambulance use differed significantly between holidays and ordinary days.


CONCLUSIONS
Ambulances are used for children more frequently from late afternoon to evening than in the morning.
Ohshige
Kenji
K
Department of Public Health, Yokohama City University Graduate School of Medicine, Yokohama, Japan. kenoh@med.yokohoma-cu.ac.jp
D000293:Adolescent; D000552:Ambulances / Q000706:statistics & numerical data*; D002648:Child; D002675:Child, Preschool; D019538:Health Care Surveys; D006693:Holidays / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007564:Japan; D010507:Periodicity; D012189:Retrospective Studies; D014600:Utilization Review