aard Allergy, Asthma & Respiratory Disease Allergy Asthma Respir Dis 2288-0402 2288-0410 The Korean Academy of Pediatric Allergy and Respiratory Disease; The Korean Academy of Asthma 10.4168/aard.2019.7.2.78 aard-7-78 Original Article Seasonal patterns and etiologies of croup in children during the period 2010–2015: A multicenter retrospective study LeeYong Ju 1 KimHyo-Bin 2 KimBong-Seong 3 KimChang-Keun 2 KimCheol Hong 4 KimHyung Young 5 KimSangyoung 6 KimYunsun 6 ParkChorong 6 SeoJu-Hee 7 SolIn Suk 8 SungMyongsoon 9 SongMin Seob 10 SongDae Jin 11 AhnYoung Min 12 LeeJu Suk JangYoon Young 18 ChungEun Hee 19 ChungHai Lee 18 ChoiSung-Min 20 ChoiYun Jung 21 22 HanMan Yong 23 YangHyeon-Jong 6 24 ShimJung Yeon 25 KimJin-Tack 26 OhHea Lin 13 YuJinho 14 LeeKyung Suk 15 LeeEun 16 JangGwang Cheon 17 Department of Pediatrics, Hallym University Kangnam Sacred Heart Hospital, Seoul Korea Department of Pediatrics, Asthma and Allergy Center, Inje University Sanggye Paik Hospital, Seoul Korea Department of Pediatrics, Gangneung Asan Hospital, University of Ulsan College of Medicine, Gangneung Department of Pediatrics, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon Department of Pediatrics, Pusan National University Yangsan Hospital, Yangsan SCH Biomedical Informatics Research Unit, Soonchunhyang University Seoul Hospital, Seoul Korea Department of Pediatrics, Dankook University Hospital, Cheonan Department of Pediatrics, Yonsei University Severance Hospital, Seoul Korea Department of Pediatrics, Soonchunhyang University Gumi Hospital, Gumi Department of Pediatrics, Inje University Haeundae Paik Hospital, Busan Department of Pediatrics, Korea University Guro Hospital, Seoul Korea Department of Pediatrics, Eulji University Eulji General Hospital, Seoul Korea Department of Pediatrics, Korea Cancer Center Hospital, Seoul Korea Department of Pediatrics, Asan Medical Center, University of Ulsan College of Medicine, Seoul Korea Department of Pediatrics, Hanyang University Guri Hospital, Guri Department of Pediatrics, Chonnam National University Hospital, Gwangju Department of Pediatrics, National Health Insurance Service, Ilsan Hospital, Ilsan Department of Pediatrics, Daegu Catholic University Medical Center, Daegu Department of Pediatrics, Chungnam National University Hospital, Daejeon Department of Pediatrics, Dongguk University Gyungju Hospital, Gyungju Department of Pediatrics, Sowha Children's Hospital, Seoul Korea Department of Pediatrics, Seoul National University Children Hospital, Seoul Korea Department of Pediatrics, CHA University CHA Bundang Medical Center, Seongnam Department of Pediatrics, Soonchunhyang University Seoul Hospital, Seoul Korea Division of Pediatric Allergy & Pulmonology, Department of Pediatrics, Sungkyunkwan University School of Medicine, Kangbuk Samsung Hospital, Seoul Korea Department of Pediatric Allergy & Pneumology, Catholic University Uijeongbu St. Mary's Hospital, Uijeongbu, Korea Correspondence to: Hyeon-Jong Yang https://orcid.org/0000-0002-7287-4300 Department of Pediatrics, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, 59 Daesagwan-ro, Yongsan-gu, Seoul 04401, Korea Tel: +82-2-709-9390, Fax: +82-2-709-9083, E-mail: pedyang@schmc.ac.kr Co-correspondence to: Jung Yeon Shim https://orcid.org/0000-0001-9367-2233 Division of Pediatric Allergy & Pulmonology, Department of Pediatrics, Kangbuk Samsung Hospital, Sungkyunkwan University of Medicine, 29 Saemunan-ro, Jongno-gu, Seoul 31116, Korea Tel: +82-2-2001-2484, Fax: +82-2-2001-2199, E-mail: jy7.shim@samsung.com

*These authors contributed equally to this study as co-first authors.

This research was supported by a grant from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HI16C2300).

 04 2019 12 04 2019 7 2 78 85 11102018 04012019 14012019 Copyright © 2019 The Korean Academy of Pediatric Allergy and Respiratory Disease; The Korean Academy of Asthma, Allergy and Clinical Immunology 2019 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Purpose

Croup is known to have epidemics in seasonal and biennial trends, and to be strongly associated with epidemics of para-influenza virus. However, seasonal and annual epidemics of croup have not been clearly reported in Korea. This study aimed to examine the seasonal/annual patterns and etiologies of childhood croup in Korea during a consecutive 6-year period.

 Methods

Pediatric croup data were collected from 23 centers in Korea from 1 January 2010 to 31 December 2015. Electronic medical records, including multiplex reverse transcription polymerase chain reaction (RT-PCR) results, demographics and clinical information were cross-sectionally reviewed and analyzed.

 Results

Overall, 2,598 childhood croup patients requiring hospitalization were identified during the study period. Among them, a

 Conclusion

It is concluded that croup hospitalization has a biennial pattern in even-numbered years. PIV may be the most common cause of childhood croup; however, croup epidemics could be attributed to other viruses.

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Pathogens detected in hospitalized children with croup between 2010 and 2015. A total of 927 children with croup were hospitalized between 1 January 2010 through 31 December 2015. Among them, most prevalent age group was <2 years old (n=584, 63.0%). Most commonly detected pathogen was parainfluenza virus under the age of 4 years. MP, Mycoplasma pneumoniae; AdV, adenovirus; RV, human rhinovirus; Flu, influenza virus; PIV, parainfluenza virus; HMPV, human metapneumovirus; RSV, respiratory syncytial virus; BoV, bocavirus; CoV, coronavirus.

Numbers of hospitalized children with croup and pathogen-detected croup between 1 January 2010 through 31 December 2015, according to month and year. A total of 2,598 hospitalized children with croup were identified. Among them respiratory pathogens were detected in 927 children.

Distribution of pathogen-detected croup between 1 January 2010 and 31 December 2015, according to month and year. (A) Pathogens detected in hospitalized children with croup. (B) Distribution of PIV, and PIV subtypes. (C) Distribution of CoV and CoV subtypes. AdV, adenovirus; HRV, human rhinovirus; Flu, influenza virus; PIV, parainfluenza virus; HMPV, human metapneumovirus; RSV, respiratory syncytial virus; BoV, bocavirus; HCoV, human coronavirus.

Characteristics among 927 hospitalized childhood croup from 1 January 2010 to 31 December 2015

Variable Value
Age (mo), median (IQR) 19 (11–31)
Age group (yr)  
<2 584 (63.0)
2–4 266 (28.7)
5–9 62 (6.7)
10–17 15 (1.6)
Male sex 570 (61.5)
Season at hospitalization  
Spring (March–May) 264 (28.5)
Summer (June–August) 253 (27.3)
Autumn (September–November) 247 (26.6)
Winter (December–February) 163 (17.6)
Hospitalization-related information  
Length of stay (hr), mean±SD 126.7±92.1
Intensive care unit admission 1 (0.1)
Oxygen supply 84 (9.1)
Use of corticosteroids 166 (17.9)
Oral prednisolone 44 (4.8)
Methylprednisolone 42 (4.5)
Dexamethasone 121 (13.1)

Values are presented number (%) unless otherwise indicated. IQR, interquartile range; SD, standard deviation.

Respiratory pathogens and laboratory findings among 927 hospitalized childhood croup from 1 January 2010 to 31 December 2015

Variable Value
Identified-pathogen 721 (77.8)
Single 521 (56.2)
Adenovirus 14 (2.7)
Human rhinovirus 65 (12.5)
Influenza virus 34 (6.5)
Parainfluenza virus 207 (39.7)
Human metapneumovirus 24 (4.61)
Respiratory syncytial virus 78 (15.0)
Bocavirus 6 (1.2)
Coronovirus 38 (7.3)
Mycoplama pneumoniae 55 (10.6)
Multiple 200 (21.6)
No identification 206 (22.2)
Laboratory findings  
WBC (×103/μL) 11.3±4.8
Neutrophil (%) 48.7±19.5
Lymphocyte (%) 38.9±17.6
Eosinophil (%) 1.4±2.1
Platelet count (×103/μL) 294.5±104.8
AST (U/L) 40.6±33.3
ALT (U/L) 22.5±45.9
LDH (U/L) 361.8±45.9
CRP (mg/dL) 3.2±6.9
ESR (mm/hr) 18.2±16.7

Values are presented as number (%) or mean±standard deviation.

Multiple, multiple pathogens with coinfection; WBC, white blood cell; AST, aspartate aminotransferase; ALT, alanine aminotransferase; LDH, lactate dehydrogenase; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate.

Comparison of clinical characteristics and laboratory findings among hospitalized children with croup due to single adenovirus, influenza virus, parainfluenza virus, respiratory syncytial virus, corona virus, and Mycoplasma pneumoniae infection

Variable 1. AdV (n=14) 2. Flu (n=34) 3. PIV (n=207) 4. RSV (n=78) 5. CoV (n=24) 6. MP (n=27) P-value Post hoc test
Age (mo), median (IQR) 24.5 (23.0) 26.0 (32.0) 17.0 (16.0) 16.0 (11.0) 13.0 (12.0) 66.0 (51.0) <0.01 5≤4=3≤1=2≤6
Male sex, n (%) 8 (57.1) 22 (64.7) 126 (60.9) 52 (66.7) 24 (63.2) 27 (49.1) 0.46  
LOS (hr), median (IQR) 120.0 (72.0) 120.0 (48.0) 96.0 (48.0) 120.0 (48.0) 96.0 (24.0) 144.0 (96.0) <0.01 3=5=4≤1=2≤6
ICU admission, n (%) 0 (0) 0 (0) 1 (0.5) 0 (0) 0 (0) 0 (0)    
Oxygen supply, n (%) 0 (0) 3 (8.8) 19 (9.2) 6 (7.7) 6 (15.8) 1 (1.8) 0.19  
Use of steroids, no. (%) 5 (35.7) 6 (17.7) 41 (19.8) 9 (11.5) 11 (29.0) 18 (32.7) 0.03  
Laboratory findings                
WBC (×103/μL), median (IQR) 10.47 (5.65) 8.77 (4.04) 9.80 (5.42) 10.97 (4.68) 12.99 (7.24) 7.89 (3.39) <0.01 6≤2≤3≤1≤4≤5
Neutrophil 48.5 (14.0) 58.0 (36.1) 46.0 (30.2) 45.5 (25.6) 49.8 (18.1) 56.6 (21.7) 0.12 4=3≤1=5≤6=2
Lymphocyte 32.7 (17.9) 32.0 (31.2) 40.7 (28.1) 40.3 (23.8) 36.3 (17.5) 30.4 (18.3) 0.03 6≤2=1=5=4≤3
Eosinophil 0.5 (1.4) 0.4 (0.8) 0.3 (0.8) 0.5 (1.4) 0.35 (1.3) 1.8 (3.0) <0.01 3=5=1=2=4<6
Platelet (×103/μL), median (IQR) 297.0 (81.0) 228.5 (60.0) 249.0 (104.0) 300.0 (108.5) 298.0 (90.0) 273.0 (118.0) <0.01 2=3≤6=1≤5=4
CRP (mg/dL), median (IQR) 2.05 (3.0) 0.83 (2.27) 0.96 (2.47) 1.08 (2.56) 1.06 (1.45) 1.50 (4.20) 0.37  
ESR (mm/hr), median (IQR) 33.0 (31.0) 7.0 (13.0) 10.0 (15.0) 11.0 (15.5) 7.0 (8.0) 26.0 (30.0) <0.01 2=5=3=4<6=1
AST (U/L), median (IQR) 30.0 (10.0) 39.5 (17.0) 37.0 (12.0) 39.0 (13.0) 37.0 (10.0) 31.0 (8.0) <0.01 1=6≤5=3=4=2
ALT (U/L), median (IQR) 15.5 (8.0) 15.0 (9.0) 16.0 (8.0) 17.0 (9.0) 19.5 (8.0) 12.0 (6.0) <0.01 6≤2=1=3=4=5
LDH (U/L), median (IQR) 270.0 (81.0) 286.0 (170.0) 327.0 (88.0) 324.0 (151.0) 516.0 (246.0) 436.0 (218.5) 0.24  

IQR, interquartile range; LOS, length of stay; AdV, adenovirus; Flu, influenza virus; PIV, parainfluenza virus; RSV, respiratory syncytial virus; CoV coronavirus; MP, Mycoplasma pneumoniae; ICU, intensive care unit; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; AST, aspartate aminotransferase; ALT, alanine aminotransferase; LDH, lactate dehydrogenase.