Indiana University, USA
Indiana University, USA.
Autism. 2016 Jul;20(5):517-27. doi: 10.1177/1362361315592378. Epub 2015 Jun 29.
Two-phase designs in epidemiological studies of autism prevalence introduce methodological complications that can severely limit the precision of resulting estimates. If the assumptions used to derive the prevalence estimate are invalid or if the uncertainty surrounding these assumptions is not properly accounted for in the statistical inference procedure, then the point estimate may be inaccurate and the confidence interval may not be a true reflection of the precision of the estimate. We examine these potential pitfalls in the context of a recent high-profile finding by Kim et al. (2011, Prevalence of autism spectrum disorders in a total population sample. American Journal of Psychiatry 168: 904-912), who estimated that autism spectrum disorder affects 2.64% of children in a South Korean community. We reconstructed the study's methodology and used Monte Carlo simulations to analyze whether their point estimate and 95% confidence interval (1.91%, 3.37%) were reasonable, given what was known about their screening instrument and sample. We find the original point estimate to be highly assumption-dependent, and after accounting for sources of uncertainty unaccounted for in the original article, we demonstrate that a more reasonable confidence interval would be approximately twice as large as originally reported. We argue that future studies should give serious consideration to the additional sources of uncertainty introduced by a two-phase design, which may easily outstrip any expected gains in efficiency.
在自闭症患病率的流行病学研究中采用两阶段设计会引入一些方法学上的复杂性，这些复杂性可能会严重限制最终估计的准确性。如果用于推导出患病率估计值的假设是无效的，或者在统计推断过程中没有正确考虑这些假设的不确定性，那么点估计值可能不准确，置信区间可能无法真实反映估计值的精度。我们将在 Kim 等人最近发表的一项备受瞩目的研究结果的背景下探讨这些潜在的陷阱（Kim 等人，2011 年，自闭症谱系障碍在总人口样本中的流行率。美国精神病学杂志 168：904-912），他们估计自闭症谱系障碍在韩国社区的儿童中影响 2.64%。我们重建了研究的方法，并使用蒙特卡罗模拟来分析他们的点估计值和 95%置信区间（1.91%，3.37%）是否合理，考虑到他们的筛选工具和样本的已知情况。我们发现原始的点估计值高度依赖于假设，并且在考虑了原始文章中未考虑的不确定性来源之后，我们证明一个更合理的置信区间将比最初报告的大约大两倍。我们认为，未来的研究应该认真考虑两阶段设计引入的额外不确定性来源，这些不确定性来源可能很容易超过任何预期的效率增益。
