Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA.
Department of Pediatrics, University of Maryland School of Medicine, Baltimore, Maryland, USA.
Clin Infect Dis. 2023 Apr 19;76(76 Suppl 1):S5-S11. doi: 10.1093/cid/ciac968.
Diarrheal diseases remain a health threat to children in low- and middle-income countries. The Vaccine Impact on Diarrhea in Africa (VIDA) study was a 36-month, prospective, matched case-control study designed to estimate the etiology, incidence, and adverse clinical consequences of moderate-to-severe diarrhea (MSD) in children aged 0-59 months. VIDA was conducted following rotavirus vaccine introduction at 3 censused sites in sub-Saharan Africa that participated in the Global Enteric Multicenter Study (GEMS) ∼10 years earlier. We describe the study design and statistical methods of VIDA and where they differ from GEMS.
We aimed to enroll 8-9 MSD cases every 2 weeks from sentinel health centers in 3 age strata (0-11, 12-23, 24-59 months) and 1 to 3 controls matched by age, sex, date of case enrollment, and village. Clinical, epidemiological, and anthropometric data were collected at enrollment and ∼60 days later. A stool specimen collected at enrollment was analyzed by both conventional methods and quantitative PCR for enteric pathogens. For the matched case-control study, we estimated the population-based, pathogen-specific attributable fraction (AF) and attributable incidence adjusted for age, site, and other pathogens, and identified episodes attributable to a specific pathogen for additional analyses. A prospective cohort study nested within the original matched case-control study allowed assessment of (1) the association between potential risk factors and outcomes other than MSD status and (2) the impact of MSD on linear growth.
GEMS and VIDA together comprise the largest and most comprehensive assessment of MSD conducted to date in sub-Saharan Africa populations at highest risk for morbidity and mortality from diarrhea. The statistical methods used in VIDA have endeavored to maximize the use of available data to produce more robust estimates of the pathogen-specific disease burden that might be prevented by effective interventions.
腹泻病仍然是低收入和中等收入国家儿童的健康威胁。疫苗对非洲腹泻病的影响（VIDA）研究是一项为期 36 个月的前瞻性病例对照研究，旨在估计 0-59 个月儿童中度至重度腹泻（MSD）的病因、发病率和不良临床后果。VIDA 在非洲撒哈拉以南地区的 3 个普查点进行，这些点在大约 10 年前参加了全球肠道多中心研究（GEMS），当时已经引入了轮状病毒疫苗。我们描述了 VIDA 的研究设计和统计方法，以及它们与 GEMS 的不同之处。
我们的目标是从 3 个年龄组（0-11、12-23 和 24-59 个月）的哨点卫生中心每 2 周招募 8-9 例 MSD 病例，并根据年龄、性别、病例登记日期和村庄与 1-3 例匹配对照。在登记时和大约 60 天后收集临床、流行病学和人体测量数据。在登记时采集的粪便标本同时采用常规方法和定量 PCR 分析肠道病原体。对于匹配的病例对照研究，我们估计了人群特异的归因分数（AF）和调整了年龄、地点和其他病原体的归因发病率，并确定了特定病原体引起的病例。一个嵌套在原始匹配病例对照研究中的前瞻性队列研究允许评估（1）除 MSD 状态外，潜在危险因素与结局之间的关系，以及（2）MSD 对线性生长的影响。
GEMS 和 VIDA 共同构成了迄今为止在腹泻病发病率和死亡率最高的撒哈拉以南非洲人群中对 MSD 进行的最大和最全面的评估。VIDA 中使用的统计方法努力最大限度地利用现有数据，以产生更稳健的病原体特异性疾病负担估计，这些估计可能通过有效的干预措施得到预防。
