Clinical Presentation and Outcomes of Middle East Respiratory Syndrome in the Republic of Korea

Choi, Won Suk; Kang, Cheol-In; Kim, Yonjae; Choi, Jae-Phil; Joh, Joon Sung; Shin, Hyoung-Shik; Kim, Gayeon; Peck, Kyong Ran; Chung, Doo Ryeon; Kim, Hye Ok; Song, Sook Hee; Kim, Yang Ree; Sohn, Kyung Mok; Jung, Younghee; Bang, Ji Hwan; Kim, Nam Joong; Lee, Kkot Sil; Jeong, Hye Won; Rhee, Ji-Young; Kim, Eu Suk; Woo, Heungjeong; Oh, Won Sup; Huh, Kyungmin; Lee, Young Hyun; Song, Joon Young; Lee, Jacob; Lee, Chang-Seop; Kim, Baek-Nam; Choi, Young Hwa; Jeong, Su Jin; Lee, Jin-Soo; Yoon, Ji Hyun; Wi, Yu Mi; Joung, Mi Kyong; Park, Seong Yeon; Lee, Sun Hee; Jung, Sook-In; Kim, Shin-Woo; Lee, Jae Hoon; Lee, Hyuck; Ki, Hyun Kyun; Kim, Yeon-Sook

Our study has several limitations. First, clinical data were retrospectively collected through electronic medical records and chart review, although cases were enrolled prospectively by means of active surveillance of outbreaks. The present study was observational, and thus unknown risk factors and bias might have been unequally distributed between the two groups in the survival analysis. The possibility of limitations that preclude accurate comparisons should be kept in mind given the observational nature of this study. Clinical judgments regarding management of patients were made by attending physicians, not by researchers. Second, we have presented 4 months of clinical data after control of the outbreak, and thus the data might represent acute complications of MERS-CoV-infected patients. Only 36.2% of patients showed resolution of abnormal findings on chest radiologic evaluation, and there are concerns regarding chronic complications such as pulmonary fibrosis. Further follow-up prospective cohort studies are warranted in the future. Third, although this study was performed with a nationwide database, a relatively small number of patients with mechanical ventilation were included, with limited statistical power. The impact of ECMO and convalescent serum therapy on survival may not be fully adjusted for in the survival analysis. Finally, this study was conducted mainly at large referral centers in Korea, and our findings may not be generalizable to other institutions outside of Korea.