Space-time clustering at birth and at diagnosis of type 1 diabetes mellitus in relation to early clinical manifestation.
OBJECTIVE
To investigate whether space-time clustering at diagnosis of type 1 diabetes mellitus (DM1) is related to clinical manifestations and to see whether there is a time-space clustering at birth of children who later develop DM1.


METHODS
Using the method by Knox, clustering was analysed in all 1,144 children diagnosed between 1977 and 1994 in south-east Sweden.


RESULTS
The strongest significance was obtained for the cut-off value of 5 km and 7 months (p<0.01). Using this cut-off, children with a short duration of symptoms before diagnosis had the same degree of clustering as children with a longer duration. Children diagnosed during autumn and winter tended to have a higher degree of clustering than children diagnosed during spring and summer. We found no significant clustering regarding birthplace and birth month.


CONCLUSIONS
This study is consistent with the existence of space-time clustering at diagnosis. The most plausible explanation is that infections elicit several cases of DM1 in children in whom the disease process has already begun.
Samuelsson
Ulf
U
Division of Pediatrics, Department of Molecular and Clinical Medicine, Faculty of Health Sciences, Linköping University, Sweden. ulf.samuelsson@lio.se
Carstensen
John
J
D000293:Adolescent; D001327:Autoimmune Diseases / Q000150:complications / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D012621:Seasons; D013029:Space-Time Clustering; D013548:Sweden / Q000453:epidemiology