The Incidence, Risk Factors and Viral Etiologies of Influenza-Like Illness in a Community : A Prospective Cohort Study in a District in Seoul
지역사회 인플루엔자 유사질환 발생률, 위험요인 및 원인 바이러스: 서울시 한 지역의 전향적 코호트 연구
- 주제(키워드) influenza-like illness(ILI) , influenza , incidence , risk factors , respiratory viruses , cohort study , community study
- 발행기관 고려대학교 대학원
- 지도교수 천병철
- 발행년도 2015
- 학위수여년월 2015. 8
- 학위구분 박사
- 학과 대학원 보건학협동과정
- 세부전공 역학 및 의료정보학 전공
- 원문페이지 96 p
- 실제URI http://www.dcollection.net/handler/korea/000000060740
- 본문언어 영어
- 제출원본 000045851091
초록/요약
Objectives: This study was designed to prospectively observe a cohort of all age groups in a community in the Republic of Korea. The goals of the study were as follows: to determine the incidence and age-specific risk ratios (RR) of influenza and influenza-like illness (ILI), to determine age-stratified ILI risk factors for each of the non-adult (<20 years old) and adult (≥20 years old) groups, and to confirm the viral etiologies of ILI. Methods: A prospective cohort study was conducted from December 2012 to July 2014. The subjects included approximately 1,000 residents of Seongbuk-gu, Seoul, defined as those ≥6 months of age who were living in the community in residential houses with more than two family members. Baseline surveys and relevant data for influenza and ILI were collected. The study period was divided into two phases: Phase I lasted from January to October 2013 and Phase II lasted from November 2013 to July 2014. A total of 1,223 subjects participated in the study. The numbers of subjects participating in Phases I and II were 1,027 and 1,032, respectively, and some individuals were involved in both phases. The baseline studies investigated participants' demographic and household characteristics, lifestyle habits, preventive health behaviors, and underlying diseases. All subjects were evaluated every week to determine whether they had contracted ILI. Subjects with ILI were defined as individuals who showed fever or feverishness and cough or throat pain. When ILI was confirmed, a nasopharyngeal and nasal swab specimen was collected from the relevant subject and was tested by using real-time PCR assay for a panel of 14 respiratory viruses. All statistical analysis was based on the data from the Statistics Office and was weighted against the Seongbuk-gu ratios of gender and age per year. Poisson regression was performed for the RR calculation. Results: During Phase I, ILI incidence was 10.28 (cases/1,000person- week), and the incidence of influenza was 0.62 (cases/1,000person- week), or 6.03% of the ILI incidence. During Phase II, the incidence of ILI was 16.80 (cases/1,000person-week), and the incidence of influenza was 1.14 (cases/1,000person-week), or 6.79% of the ILI incidence. Compared to Phase I, Phase II showed higher incidences for both ILI and influenza. For the age-specific RRs, the group between the ages of 0 and 4 years was shown to be more at risk for ILI than the other age groups (p<0.001), and it was at a higher risk for influenza than those aged 20 and older (p<0.05). Among the ILI risk factors, exposure to non-direct smoking was found to be a risk factor for the non-adult group (p<0.001). For the adult group, risk factors were being female and married, living with more than five family members, being exposed to non-direct smoking, and pneumonia history. Such factors as an education level of middle school or above, heavy drinking (more than 5 drinks), handwashing for more than 10 seconds, and gargling for longer than 30 seconds were associated with lower ILI risks. Out of a total of 1,540 ILI specimens collected, 483 (31.36%) samples showed evidence of at least one of 14 respiratory viruses, and the co-infection rate was 8.49%. The most frequently detected viruses (in decreasing frequency) were hRv in 175 specimens (32.35%), hMPV in 71 (13.12%), influenza A in 67 (12.38%), influenza B in 40 (7.39%), hCoV-229E in 37 (6.84%), RSV B in 28 (5.18%), ADV in 27 (4.99%), hBoV in 26 (4.81%), hCoV-NL63 in 25 (4.62%), hCoV-OC43 in 23 (4.25%), PIV2 in 8 (1.48%), RSV A in 6 (1.11%), PIV3 in 6 (1.11%), and PIV1 in 2 (0.37%). The largest number of viruses was detected in samples from the 0-4 age group. When analyzed according to seasonality, the influenza virus and hCoV were more prevalent in winter, hRV and hMPV in spring, and hBoV in autumn. By contrast, hRV and hMPV were observed all year round. Conclusions: This study is of great significance, as it is the first Korean community-based prospective influenza cohort study to follow up with and observe all age groups and to be conducted for two consecutive terms. The results confirmed that those aged 0-4 years were the most at risk for ILI occurrence among all age groups, and they had the largest number of detected respiratory viruses. Furthermore, this study indicates that respiratory virus infections are seasonal. These findings will ultimately provide fundamental data required for future efforts to develop measures to prevent and deal with influenza-associated respiratory illness.
more목차
Abstract i
Ⅰ. Introduction 1
Ⅱ. Methodology 6
1. Cohort setting 6
2. Study population 6
3. Baseline survey 8
4. ILI incidence 9
5. Specimen collection and real-time PCR analysis 10
6. Statistical analysis 11
7. Ethics statement 16
Ⅲ. Results 17
1. General characteristics of study population 17
2. The incidence of ILI and influenza 19
3. Age-specific risk ratios of ILI and influenza 25
4. ILI risk factors for the non-adult group 26
5. ILI risk factors for the adult group 31
6. Viral etiologies of ILI 40
Ⅳ. Discussion 49
Ⅴ. Conclusions 64
References 66
Summary(Korean) 81
