Epidemiology of mumps, mumps complications, and mumps orchitis in Korea using the National Health Insurance Service database

PURPOSE: To analyze the presentation of mumps and mumps orchitis using the National Health Insurance Service Database (NHISD). MATERIALS AND METHODS: Using information from the NHISD representing all cases of mumps in Korea, data regarding mumps orchitis were analyzed. The International Classification of Diseases, Tenth Revision, and Clinical Modification codes were used for diagnosis. The incidence estimates of the number of mumps cases were analyzed using the Statistical Analysis System (SAS) software. RESULTS: Based on the NHISD, 199,186 people were diagnosed with mumps, and males accounted for 62.3% cases. Teen males accounted for 69,870 cases, the largest number of patients diagnosed with mumps. The annual incidence of mumps increased every year (poisson regression, hazard ratio [HR] 1.026, 95% confidence interval [CI] 1.024–1.027; p<0.025). The risk of mumps was lower in females than that in males (poisson regression, HR 0.594, 95% CI 0.589–0.599; p<0.001). Of the 199,186 patients diagnosed with mumps, 3,872 patients (1.9%) had related complications. Among the mumps complications, the most diagnosed complication was mumps orchitis, which was seen in 41.8% of the males. Mumps orchitis cases accounted for less than 1.5% of the patients with mumps in minors under the age of 20 years and was somewhat higher in 2009 and 2013–2015. CONCLUSIONS: Among the complications related to mumps, meningitis was most common in females, while orchitis was dominant in males. Mumps orchitis also shows periodic outbreaks but is particularly prevalent in adults, which suggests the potential need for additional vaccination against mumps.