Background: It is important to have an estimate of the incidence of acute disseminated encephalomyelitis (ADEM) because the incidence of ADEM is unknown and the outcomes undefined in China.
Objectives: This study attempts to describe ADEM incidence in large Chinese populations located in four geographically different and moderately distant areas of the same province.
Methods: A retrospective investigation was conducted with ADEM patients in Nanjing, Nantong, Yancheng and Xuzhou. The survey was carried out in regions that might have received patients meeting the case definition of ADEM provided by the International Pediatric MS Study Group from 2008 to 2011. A total of 125 hospitals were included and 412 patients were identified through the hospital information systems (HIS).
Results: The incidence of ADEM was 0.32/100,000/year. There are two peaks on the age-specific ADEM rates curve. One is 0.77/100,000/year among 0- to 9-year-olds, the other is 0.45/100,000/year in those aged 50-59 years. The incidence rate found for ADEM in males was 0.34/100,000/year, and in females was 0.29/100,000/year. The highest incidence rate was in Nanjing (0.40/100,000/year).
Conclusions: The average annual incidence of ADEM was 0.32/100,000/year. The peak age of onset was 50-59 years old and 0-9 years old. The incidence among males was insignificantly higher than that among females. There was no significant difference in incidence by seasonal variation.
Keywords: China; Epidemiology; acute disseminated encephalomyelitis; incidence.