A growing area of research in epidemiology is the identification of health-related sibling spillover effects, or the effect of one individual's exposure on their sibling's outcome. The health and health care of family members may be inextricably confounded by unobserved factors, rendering identification of spillover effects within families particularly challenging. We demonstrate a gain-score regression method for identifying exposure-to-outcome spillover effects within sibling pairs in a linear fixed effects framework. The method can identify the exposure-to-outcome spillover effect if only one sibling's exposure affects the other's outcome; and it identifies the difference between the spillover effects if both siblings' exposures affect the others' outcomes. The method fails in the presence of outcome-to-exposure spillover and outcome-to-outcome spillover. Analytic results and Monte Carlo simulations demonstrate the method and its limitations. To exercise this method, we estimate the spillover effect of a child's preterm birth on an older sibling's literacy skills, measured by the Phonological Awarenesses Literacy Screening-Kindergarten test. We analyze 20,010 sibling pairs from a population-wide, Wisconsin-based (United States) birth cohort. Without covariate adjustment, we estimate that preterm birth modestly decreases an older sibling's test score (-2.11 points; 95% confidence interval: -3.82, -0.40 points). In conclusion, gain-scores are a promising strategy for identifying exposure-to-outcome spillovers in sibling pairs while controlling for sibling-invariant unobserved confounding in linear settings.
翻译:流行病学研究的一个日益增长的领域是确定与健康有关的血浆溢出效应,或一个人暴露给他人的血浆溢出效应的影响;家庭成员的健康和保健可能受到未观察因素的密不可分的混淆,使得家庭内外溢效应的识别特别具有挑战性。我们展示了一种增分回归法,用以在线性固定效应框架内确定双胞胎中暴露于结果外溢效应。如果只有一人暴露给他人的血浆溢出效应影响对方的结果,该方法可以确定接触至结果溢出效应;如果两个兄弟姐妹的接触影响他人的结果,则该方法的溢出效应之间会存在不可分化的混杂杂杂杂杂杂杂杂因素,使得家庭内外溢出效应的确定特别具有挑战性。我们用这种方法来评估儿童出生前期出生的溢出效应,根据感认知性认知-不成熟的血浆递增结果进行测量;我们用20年期的血浆估算了生育前的血浆递减值;我们用20年期的血浆测试来测定了生育前的血浆。