Evidence map›Paper›PMID 32830847›Full record

ArticleAmerican journal of epidemiology2021

Invited Commentary: Sibling-Comparison Designs, Are They Worth the Effort?

Thomas Frisell

Abstract readComment
In one paragraph

Article in American journal of epidemiology, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 47 papers, 1 of them a synthesis that pooled it.

0numbers the graph read from it
0cells of the map it votes in
47citing papers in PubMed, 1 pooled it
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

47 citing papers in PubMed, 1 synthesis or guideline pooled it.

  1. Pooled it
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  11. Prenatal ozone exposure and risk of intellectual disability.Journal of exposure science & environmental epidemiology · 2026
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4 · The record

Corrections and comments

5 · Who and what money

Authors and funding

1 author.

Thomas Frisell

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

In this issue of the Journal, von Ehrenstein et al. (Am J Epidemiol. 2021;190(5):728-737) add to the large and growing literature on the potentially causal association between prenatal exposure to maternal smoking and neuropsychiatric health. In addition to statewide, prospectively collected data, a particular strength was their ability to perform a sibling-comparison design, contrasting the rate of autism spectrum disorder in siblings discordantly exposed to maternal smoking. Unfortunately, the estimate from the sibling pairs could neither confirm nor refute the conclusions based on the full cohort. Interpretation was hampered by broad confidence limits, and even had power been higher, the authors acknowledge a range of potential biases that would have made it difficult to draw any firm conclusions from a similarity or difference in the sibling-pair estimate and estimate from the full cohort. Was the addition of the sibling comparison actually worth the effort? In this commentary, I will briefly summarize the benefits and limitations of this design, and, with some caveats, argue that its inclusion in the study by von Ehrenstein et al. was indeed a strength and not just an ornamentation.

Indexed as

Autism Spectrum DisorderSiblingsCaliforniaCohort StudiesFemaleHumansPregnancySmokingautism spectrum disordercausal inferencepregnancysibling designsmoking

Identifiers

PMID32830847
PMCPMC8096426

What OpenQuestion holds

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Registered trials

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.