Evidence map›Paper›PMID 30867896›Full record

SynthesisMolecular autism2019

Selection bias on intellectual ability in autism research: a cross-sectional review and meta-analysis.

Ginny Russell, William Mandy, Daisy Elliott, Rhianna White, Tom Pittwood, Tamsin Ford

Open access · goldAbstract readMeta-AnalysisSystematic Review
PubMed Full text at PMC Publisher
In one paragraph

Synthesis in Molecular autism, 2019. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 153 papers, 11 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
153citing papers in PubMed, 11 pooled it
19.6field-weighted citation impact, top 1% of its field
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

153 citing papers in PubMed, 11 syntheses or guidelines pooled it, 351 citations in OpenAlex.

  1. Pooled it
  2. A systematic review of ecological momentary assessment in autism research.Autism : the international journal of research and practice · 2025
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  9. Loneliness in autistic adults: A systematic review.Autism : the international journal of research and practice · 2022
    Pooled it
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  12. Trial
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  15. Randomized Study of Survey Recruitment Strategies for Parents of Autistic Children.Journal of pediatric health care : official publication of National Association of Pediatric Nurse Associates & Practitioners
    Trial
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  18. Navigating Mixed-Neurotype Dialogue: Environmental and Affective Influences on Autistic Speakers.Autism : the international journal of research and practice · 2026
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  20. Article

93 more citing papers are in PubMed but not listed here.

4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

6 authors at 2 institutions in 1 country.

Ginny Russell1College House, University of Exeter Medical School, University of Exeter, Exeter, EX1 2LU UK.
William Mandy2UCL Research Department of Clinical, Educational and Health Psychology, Gower Street, London, WC1E 6BT UK.
Daisy Elliott3College of Social Science and International Studies, Byrne House, University of Exeter, Exeter, EX4 4PJ UK.
Rhianna White3College of Social Science and International Studies, Byrne House, University of Exeter, Exeter, EX4 4PJ UK.
Tom Pittwood4Brain in Hand, Innovations Centre, University of Exeter, Exeter, EX4 4QJ UK.
Tamsin Ford1College House, University of Exeter Medical School, University of Exeter, Exeter, EX1 2LU UK.
University of Exeter · GBUniversity College London · GB

Funding

Medical Research Council G108/625Wellcome TrustWellcome Trust 108676/Z/1 SFZ
6 · The paper itself

Abstract

Background: Current global estimates suggest the proportion of the population with autism spectrum disorder (ASD) who have intellectual disability (ID) is approximately 50%. Our objective was to ascertain the existence of selection bias due to under-inclusion of populations with ID across all fields of autism research. A sub-goal was to evaluate inconsistencies in reporting of findings. Methods: This review covers all original research published in 2016 in autism-specific journals with an impact factor greater than 3. Across 301 included studies, 100,245 participants had ASD. A random effects meta-analysis was used to estimate the proportion of participants without ID. Selection bias was defined as where more than 75% of participants did not have ID. Results: Meta-analysis estimated 94% of all participants identified as being on the autism spectrum in the studies reviewed did not have ID (95% CI 0.91-0.97). Eight out of ten studies demonstrated selection bias against participants with ID. The reporting of participant characteristics was generally poor: information about participants' intellectual ability was absent in 38% of studies ( Conclusions: We found selection bias against ID throughout all fields of autism research. We recommend transparent reporting about ID and strategies for inclusion for this much marginalised group.

Indexed as

Patient SelectionAutism Spectrum DisorderBiomedical ResearchHumansIntellectual DisabilitySelection BiasAutismAutism spectrum disorderIntellectual disabilityNosologySelection bias

Identifiers

PMID30867896
PMCPMC6397505
OpenAlexW2927010782

What OpenQuestion holds

Textmetadata
LicenceCC BY
Read underepoch 390

Registered trials

None linked

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.