Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester,MN 55905, USA.
Ann Allergy Asthma Immunol. 2013 Jan;110(1):18-23. doi: 10.1016/j.anai.2012.10.010. Epub 2012 Nov 10.
Previous studies that assessed the role of birth weight in the risk of asthma have been limited because of selection bias and covariate imbalance.
To assess the association between birth weight and risk of asthma by applying a propensity score approach.
The study was designed as a retrospective cohort study based on a birth cohort of children born between January 1, 1976, and December 31, 1979, in Rochester, Minnesota. The propensity scores for birth weight were formulated using 16 covariates. We matched the propensity scores for children having low birth weight (<2,500 g) within a caliper of 0.2 SD of logit function of propensity scores. We calculated the cumulative incidence of asthma between low and normal birth weight groups using the Kaplan-Meier curve.
There were 3933 eligible children born between January 1, 1976, and December 31, 1979. Before matching, 13 of the 193 children (6.7%) born weighing 2,500 g developed asthma, whereas 201 of the 3,740 children (5.4%) born weighing 2,500 g and above developed asthma (P=.42). There were significant covariate imbalances between comparison groups. However, after propensity score matching, covariate imbalance was significantly reduced, and children born weighing less than 2,500 g had a similar risk to matched children born with normal birth weight (8.3% vs 7.3%, P=.75).
Birth weight is not associated with risk of asthma during the first 6 years of life. The propensity score may be a useful method for observational studies concerning asthma epidemiology.
先前评估出生体重在哮喘风险中的作用的研究受到选择偏差和协变量不平衡的限制。
通过应用倾向评分方法评估出生体重与哮喘风险之间的关联。
该研究设计为基于明尼苏达州罗切斯特市 1976 年 1 月 1 日至 1979 年 12 月 31 日出生的儿童队列的回顾性队列研究。使用 16 个协变量制定出生体重的倾向评分。我们在倾向评分的对数函数的 0.2 SD 卡尺内匹配低出生体重（<2500g）儿童的倾向评分。我们使用 Kaplan-Meier 曲线计算低出生体重组和正常出生体重组之间哮喘的累积发病率。
共有 3933 名符合条件的儿童于 1976 年 1 月 1 日至 1979 年 12 月 31 日出生。在匹配之前，193 名出生体重为 2500g 的儿童中有 13 名（6.7%）发展为哮喘，而 3740 名出生体重为 2500g 及以上的儿童中有 201 名（5.4%）发展为哮喘（P=.42）。比较组之间存在显著的协变量不平衡。然而，在进行倾向评分匹配后，协变量不平衡显著减少，出生体重低于 2500g 的儿童与匹配的正常出生体重儿童的风险相似（8.3%对 7.3%，P=.75）。
出生体重与 6 岁以下儿童哮喘风险无关。倾向评分可能是哮喘流行病学观察性研究的有用方法。
