Measles-related Hospitalizations and Complications in Japan, 2007-2008

Objective In the present study we aim to describe the clinical features and related complications of severe measles requiring hospitalization in Japan in 2007 and 2008. Methods We extracted the records of patients diagnosed with measles between July and December in 2007 and 2008 from the Diagnosis Procedure Combination (DPC) inpatient database and the verified age distribution of patients with measles requiring hospitalization and the rate of measles-related complications. We also examined the rate of measles patients who were pregnant or had malignancies. Results We identified 1,037 inpatients in 377 hospitals; 879 in 2007 and 158 in 2008. Overall, 554 (53.4%) were male. Patient age distribution showed two peaks; <= 4 years (21%) and 15-29 years (45%). Ninety (8.7%) patients had pneumonia, 22 (2.1%) had encephalitis, 7 (0.7%) had intestinal complications, 7 (0.7%) had conjunctivitis, 6 (0.6%) had meningitis, and 4 (0.4%) had otitis media. Patients aged <= 14 years were significantly more likely to have pneumonia (16.4%; p<0.001). The rate of encephalitis was relatively low in patients aged <= 14 years (0.9%) compared with those aged 15-29 years (3.0%) and those aged >= 30 years (2.0%); the difference was not statistically significant (p=0.141). Of 31 pregnant women, 10 had spontaneous abortion or stillbirth. Twenty-eight patients had malignancies. Conclusion The present study adds important information to our knowledge of the clinical features of severe measles. Follow-up monitoring of the trends of this distressing disease using the DPC database will be essential.