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Cochrane Database of Systematic Reviews

Overall prognosis of preschool autism spectrum disorder diagnoses

Information

DOI:
https://doi.org/10.1002/14651858.CD012749.pub2Copy DOI
Database:
  1. Cochrane Database of Systematic Reviews
Version published:
  1. 28 September 2022see what's new
Type:
  1. Prognosis
Stage:
  1. Review
Cochrane Editorial Group:
  1. Cochrane Developmental, Psychosocial and Learning Problems Group

Copyright:
  1. Copyright © 2022 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

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Authors

  • Amanda Brignell

    Correspondence to: Department of Paediatrics, Monash University, Clayton, Australia

    [email protected]

    Speech and language, Murdoch Children's Research Institute, Parkville, Australia

    Department of Speech Pathology, Australian Catholic University, Fitzroy, Australia

    Developmental Paediatrics, Monash Children's Hospital, Clayton, Australia

  • Rachael C Harwood

    Community Child Health, Western Health, Melbourne, Australia

  • Tamara May

    Department of Paediatrics, Monash University, Clayton, Australia

  • Susan Woolfenden

    Community Child Health, Sydney Children's Hospital Network, Randwick, Australia

    School of Women's & Children's Health, UNSW Medicine, UNSW Sydney, Kensington, Australia

  • Alicia Montgomery

    Community Child Health, Sydney Children's Hospital Network, Randwick, Australia

  • Alfonso Iorio

    Department of Health Research Methods, Evidence and Impact (HEI), McMaster University, Hamilton, Canada

  • Katrina Williams

    Department of Paediatrics, Monash University, Clayton, Australia

    Developmental Paediatrics, Monash Children's Hospital, Clayton, Australia

    Department of Paediatrics, The University of Melbourne, Parkville, Australia

    Neurodisability and Rehabilitation, Murdoch Children's Research Institute, Melbourne, Australia

Contributions of authors

KW, SW and AB conceived the review.

KW, AB, SW designed the review.

AB and RH co‐ordinated the review.

AB, NA‐U, SW, AI, KW developed the protocol.

AB, RH, SW and KW screened search results at title, abstract level

AB, RH, SW, KW, and AM screened search results at full text level.

AB, RH, RB (acknowledgement), AM, SW and TM extracted data and rated risk of bias. KW resolved any conflicts.

AB, TM and RH analysed the data.

TM conducted the meta‐analyses, sensitivity and prognostic factor analyses.

AB, RH TM, KW and AI interpreted the data.

AB and TM graded the quality of the evidence using GRADE. KW and AI were consulted for their expertise when completing the GRADE assessments.

AB and RH wrote the review report, with KW and TM providing methodological, clinical and general advice.

All authors reviewed the final version.

AB is the guarantor for the review.

Sources of support

Internal sources

  • Monash University, Australia

    Salary support provided for AB, TM and KW

  • Murdoch Children's Research Institute (MCRI), Australia

    MCRI provided some salary support for AB

  • Sydney Children's Hospital Network, Australia

    Salary support provided for SW

  • National Health and Medical Research Council (NHMRC), Australia

    Susan Woolfenden is supported by an NHMRC Career Development Grant (GNT1158954)

  • University of New South Wales, Australia

    Salary support provided for SW

External sources

  • None, Australia

    We do not have any external sources of support to declare for this review.

Declarations of interest

AB works as a Speech Pathologist at Monash Children's Hospital, Clayton, Australia. She is also an Associate Editor for Cochrane Developmental, Psychosocial and Learning Problems (DPLP). AB was not involved in the editorial process for this review.

RH: is employed by Western Health as a Paediatric Registrar and works at multiple teaching hospitals in Victoria Australia, caring for children who have been diagnosed with autism spectrum disorder, including conducting diagnostic assessments for autism spectrum disorder as part of a multidisciplinary team.

TM works as a Psychologist in private practice in Victoria Australia.

AM is a Developmental and Community Paediatrician for the Sydney Local Health District and Developmental Paediatrics, Bondi, Sydney, Australia.

SW is the Director of Paediatrics at Sydney Local Health District, Sydney, Australia.

AI is a Hematology Consultant with Hamilton Health Sciences and Professor and Chair of the Department of Research Methods, Evidence, and Impact, McMaster University, Canada. AI is an Editor for Cochrane Cystic Fibrosis and Genetic Disorders and Cochrane Prognosis Methods.

KW is a Developmental Paediatrician for Monash Children's Hospital, Clayton, Australia, an Editor for Cochrane DPLP and a Convenor for Cochrane Child and Cochrane Prognosis. She was not involved in the editorial process for this review. KW declares a grant from the National Health and Medical Research Council for an autism prognosis study about predictors of autism outcome that will also publish diagnostic stability outcomes, and could be included in an update of this systematic review; paid to La Trobe University. The funder had no role in the design of this study or the methods, and will have no role in the data analysis and reporting.

Acknowledgements

We would like to thank the editorial team of Cochrane Developmental, Psychosocial and Learning Problems (DPLP) for their advice and support during the preparation of this review, particularly Margaret Anderson who contributed to the development of the search strategy and Joanne Duffield who also provided support through the process. We also wish to thank the editors, external referees and statistician who commented on earlier drafts. We would like to thank Natalia Albein Urios for her contribution to the published protocol, Ruth Braden for her assistance with data extraction and risk of bias ratings and Andrew Hayen for advice on the statistical analyses. We would also like to acknowledge Charissa Ying Zhen Chan and Francesca Lami for the translation of some articles that were not written in English.

The CRG Editorial Team are grateful to the following reviewers for their time and comments: Dr Farid Foroutan, Ted Rogers Centre for Heart Research, Toronto, Ontario, Canada; and Department of Health Research Methods, Evidence and Impact, McMaster University, Hamilton, Ontario, Canada; Dr Kristelle Hudry, Department of Psychology, Counselling and Therapy, School of Psychology and Public Health, La Trobe University, Australia; Nuala Livingstone, Cochrane Editorial and Methods Department, UK; and Zoe Thomas, Australia; as well as three reviewers who chose not to be publicly acknowledged. They are also grateful to Heather Maxwell for copyediting the review.

Cochrane DPLP supported the authors in the development of this prognosis review.

The following people conducted the editorial process for this article:

  • Sign‐off Editor (final editorial decision): Professor Geraldine Macdonald, Cochrane DPLP; University of Bristol, UK;

  • Managing Editor (selected peer reviewers, collated peer‐reviewer comments, provided editorial guidance to authors, edited the article): Dr Joanne Duffield, Cochrane DPLP; Queen's University Belfast, NI;

  • Deputy Managing Editor (conducted editorial policy checks, provided editorial guidance to authors, edited the article): Dr Sarah Davies, Cochrane DPLP; University of Bristol, UK;

  • Copy Editor (copy editing and production): Heather Maxwell;

  • Peer‐reviewers (provided comments): Dr Farid Foroutan, Ted Rogers Centre for Heart Research, Toronto, Ontario, Canada; and Department of Health Research Methods, Evidence and Impact, McMaster University, Hamilton, Ontario, Canada (methods review)a, Dr Kristelle Hudry, Department of Psychology, Counselling and Therapy, School of Psychology and Public Health, La Trobe University, Australia (clinical/content review), Dr Nuala Livingstone, Cochrane Editorial and Methods Department, UK (methods review)a; Zoe Thomas, Australia (consumer review), and Margaret Anderson, Cochrane DPLP; Queen's University Belfast, NI (search review). One additional peer reviewer provided clinical peer review, and two provided statistical peer reviewa,b, but chose not to be publicly acknowledged.

a*Dr Farid Foroutan is a member of Cochrane Metabolic and Endocrine Disorders Group and the Prognosis Methods Group, Dr Nuala Livingstone is a member of the Cochrane Editorial and Methods Department, as is one peer reviewer who chose to remain anonymous. All provided peer‐review comments on this article and approved it for copyediting and publication, but otherwise were not involved in the editorial process or decision making for this article.

bOne peer reviewer who chose to remain anonymous is a member of Cochrane DPLP, and provided peer‐review comments on this article, but was not otherwise involved in the editorial process or decision making for this article.

Version history

Published

Title

Stage

Authors

Version

2022 Sep 28

Overall prognosis of preschool autism spectrum disorder diagnoses

Review

Amanda Brignell, Rachael C Harwood, Tamara May, Susan Woolfenden, Alicia Montgomery, Alfonso Iorio, Katrina Williams

https://doi.org/10.1002/14651858.CD012749.pub2

2017 Aug 24

Overall prognosis of preschool autism spectrum disorder diagnoses

Protocol

Amanda Brignell, Natalia Albein‐Urios, Susan Woolfenden, Andrew Hayen, Alfonso Iorio, Katrina Williams

https://doi.org/10.1002/14651858.CD012749

Differences between protocol and review

Criteria for considering studies for this review

Types of outcome measures

We added an inclusion criterion to clarify the same diagnostic methods and tools needed to be used at both baseline and follow‐up. This was to ensure minimal impact of type of tool on diagnostic status.

We removed the wording "For studies that presented data using continuous measures (e.g. a score on a diagnostic scale), we analysed the data by computing a dichotomous variable" because a mean score on a tool did not allow us to determine change in diagnostic status. The primary outcome was proportion diagnosed with autism spectrum disorder, so it was not appropriate to use continuous measures for this outcome.

Data collection and analysis

We trialled the planned data collection forms and adapted these to ensure the most relevant information was collected (see Appendix 2 for adapted data collection form).

We added additional text on the criteria used to assign ratings and summaries. We added the following to the methods so the process for judging risk of bias was fully transparent.

"These items were then summarised into three domains (study participation, study attrition and outcome measurement) by combining the individual item ratings to provide a risk of bias rating for each summary domain. For study participation, we prioritised ratings for the 'participation in the study by all eligible' and 'study recruitment' criteria. Poor participation and retrospective studies were marked at high risk of bias. Those studies with good participation and prospective recruitment were marked at low risk of bias, which was then graded down to moderate risk of bias if they had one other high risk of bias criterion or three moderate risk of bias criteria across the remainder of the study participation domain criteria. In the study attrition domain, 'loss to follow‐up' criteria were prioritised for determining the domain rating. Those with no loss to follow‐up received a rating of low risk of bias for the study attrition domain rating, except in the case of retrospective studies, where the loss to follow‐up is determined by the selection of participants retrospectively, based on data availability. For the outcome measurement domain rating, we prioritised blinding of the study. If the study was unblinded, it was given a rating of high risk of bias for the domain rating. If the blinding was unclear and the remainder of the criteria were at low risk of bias, then the study was rated at moderate risk of bias; however, if blinding was unclear and there was at least one other criteria in the domain rated at moderate or high, then that study was rated at high risk of bias for the outcome measure domain. Lastly, we provided one overall risk of bias rating for each study. We rated studies to have an overall low risk of bias if all three summary domains were rated at low or moderate risk of bias. Those rated to be at overall high risk of bias were those where one or more summary domains were rated at high risk of bias."

We changed the wording of the term 'subgroup' (written in the protocol) to 'prognostic factor' throughout the manuscript. Prognostic factors modify overall prognosis rather than subgroups, so this term is preferred.

Unit of analysis issues

We stated in the protocol that "if studies had reported data for subgroups (e.g. autistic or autism spectrum disorder; male or female) we will calculate a composite mean score, if this is meaningful. We will do this by conducting a fixed‐effect meta‐analysis of within‐study groups, following the methods described by Borenstein 2009". Continuous mean scores provided for a whole group do not allow us to categorise the number of participants within the group who did and did not meet autism criteria on that measure using any type of analysis including a fixed‐effects meta‐analysis. Upon further consideration, we have removed the sentence on conducting a fixed‐effect meta‐analysis from the review, as we do not plan to use these methods in the future.

Dealing with missing data

We added the following text to the methods section of the review and followed these methods for the review.

"We only included studies when baseline and follow‐up data were provided, detailing the number of children diagnosed with autism spectrum disorder, and where the method of diagnosis was explicitly provided. For studies where we could not extract data on the primary outcome, we compared the characteristics of studies included and excluded from the meta‐analysis and reported any differences in study samples."

Reporting bias

It was not appropriate to complete funnel plots due to the nature of the data (ceiling effect of 100% made the analyses invalid). Therefore, we removed the following sections from the methods.

"If we are able to pool 10 or more studies, we will examine publication bias and other small study effects, using a funnel plot in Review Manager (RevMan), version 5 (Review Manager 2014). We will check for asymmetry at a 10% level. We will attempt to obtain the results of unpublished studies by contacting study authors. Where this is not possible, and the missing studies are thought to introduce significant bias, we will explore the impact of including such studies in the overall assessment of results using sensitivity analyses."

Data synthesis

We used Stata (StataCorp 2019) rather than Revman Web (RevMan Web 2020), to construct forest plots because Revman does not enable forest plots of proportion data.

We changed the minimum number of studies required for meta‐analysis from three to two since a meta‐analysis is possible with two studies. We wrote the following: "We conducted meta‐analyses since data were available from two or more sufficiently homogeneous studies".

We modified the wording of the GRADE assessment table (Appendix 4).

We decided not to collect information in a 'GRADE Evidence Profile' table (Schünemann 2013). We removed the 'GRADE Evidence Profile' table that had been included in the study protocol (Brignell 2017), as it was not required.

Keywords

MeSH

Medical Subject Headings Check Words

Adult; Child; Child, Preschool; Female; Humans; Infant; Male; Young Adult;

Study flow diagram.

Figures and Tables -
Figure 1

Study flow diagram.

Risk of bias ratings on the QUIPS tool (40 studies). Green is low risk of bias, orange is moderate risk of bias and red is high risk of bias.Summary risk of bias ratings for provided for each QUIPS domain (i.e.study participation, study attrition, outcome measurement). See Appendix 9 for a figure showing all criteria that were rated for each domain. Studies were rated to have an overall low risk of bias if all three summary domains were rated low or moderate risk of bias. Studies were rated to have an overall high risk of bias if all three summary domains were rated low or moderate risk of bias.

Figures and Tables -
Figure 2

Risk of bias ratings on the QUIPS tool (40 studies). Green is low risk of bias, orange is moderate risk of bias and red is high risk of bias.

Summary risk of bias ratings for provided for each QUIPS domain (i.e.study participation, study attrition, outcome measurement). See Appendix 9 for a figure showing all criteria that were rated for each domain. Studies were rated to have an overall low risk of bias if all three summary domains were rated low or moderate risk of bias. Studies were rated to have an overall high risk of bias if all three summary domains were rated low or moderate risk of bias.

Risk of bias graph: review authors' judgements about each risk of bias item for each included study presented as percentages across all included studies (41 studies).

Figures and Tables -
Figure 3

Risk of bias graph: review authors' judgements about each risk of bias item for each included study presented as percentages across all included studies (41 studies).

Risk of bias ratings for each included study for each of the 18 criteria. Red indicates high, orange indicates moderate, green indicates low and yellow indicates unclear risk of bias.

Figures and Tables -
Figure 4

Risk of bias ratings for each included study for each of the 18 criteria. Red indicates high, orange indicates moderate, green indicates low and yellow indicates unclear risk of bias.

Forest plot of proportion of children that retained their autism diagnosisFootnote
CI: confidence interval; ES: effect size; N: number in sample

Figures and Tables -
Figure 5

Forest plot of proportion of children that retained their autism diagnosis

Footnote
CI: confidence interval; ES: effect size; N: number in sample

Age at baseline: < 2 years; 2 to 3 years; 4 to 6 years; 7 to 12; years; 13 to 17 yearsFootnote
CI: confidence interval; ES: effect size; N: number in sample

Figures and Tables -
Figure 6

Age at baseline: < 2 years; 2 to 3 years; 4 to 6 years; 7 to 12; years; 13 to 17 years

Footnote
CI: confidence interval; ES: effect size; N: number in sample

Age at follow up: 2 to 3 years; 4 to 6 years; 7 to 12 years; 13 to 18 yearsFootnote
CI: confidence interval; ES: effect size; N: number in sample

Figures and Tables -
Figure 7

Age at follow up: 2 to 3 years; 4 to 6 years; 7 to 12 years; 13 to 18 years

Footnote
CI: confidence interval; ES: effect size; N: number in sample

Duration of follow‐up: short‐term (up to 2 years), medium‐term (2 to 5 years), and long‐term (6 to 17 years) follow‐upFootnote
CI: confidence interval; ES: effect size; N: number in sample

Figures and Tables -
Figure 8

Duration of follow‐up: short‐term (up to 2 years), medium‐term (2 to 5 years), and long‐term (6 to 17 years) follow‐up

Footnote
CI: confidence interval; ES: effect size; N: number in sample

Decade of publication: 1960 to 1969; 1970 to 1979; 1980 to 1989; 1990 to 1999; 2000 to 2009; 2010 to 2019Footnote
CI: confidence interval; ES: effect size; N: number in sample

Figures and Tables -
Figure 9

Decade of publication: 1960 to 1969; 1970 to 1979; 1980 to 1989; 1990 to 1999; 2000 to 2009; 2010 to 2019

Footnote
CI: confidence interval; ES: effect size; N: number in sample

Intelligence: mean IQ 70; mean IQ > 70; or more than 70% of the cohort has IQ 70Footnote
CI: confidence interval; ES: effect size; IQ: intelligence quotient; N: number in sample

Figures and Tables -
Figure 10

Intelligence: mean IQ 70; mean IQ > 70; or more than 70% of the cohort has IQ 70

Footnote
CI: confidence interval; ES: effect size; IQ: intelligence quotient; N: number in sample

Language: > 70% verbal; > 70% non‐verbal (i.e. use < 15 words); mean standardised language score < 70; mean standardised language score 70; or > 70% of the cohort has mean language score < 70Footnote
CI: confidence interval; ES: effect size; N: number in sample

Figures and Tables -
Figure 11

Language: > 70% verbal; > 70% non‐verbal (i.e. use < 15 words); mean standardised language score < 70; mean standardised language score 70; or > 70% of the cohort has mean language score < 70

Footnote
CI: confidence interval; ES: effect size; N: number in sample

Adaptive behaviour: mean standard score 70; mean standard score > 70; or > 70% of the cohort has mean standard score 70Footnote
CI: confidence interval; ES: effect size; N: number in sample

Figures and Tables -
Figure 12

Adaptive behaviour: mean standard score 70; mean standard score > 70; or > 70% of the cohort has mean standard score 70

Footnote
CI: confidence interval; ES: effect size; N: number in sample

Multidisciplinary team used for diagnosis, Yes or NoFootnote
CI: confidence interval; ES: effect size; N: number in sample

Figures and Tables -
Figure 13

Multidisciplinary team used for diagnosis, Yes or No

Footnote
CI: confidence interval; ES: effect size; N: number in sample

Funnel Plot of included studies

Figures and Tables -
Figure 14

Funnel Plot of included studies

Summary of findings 1. Summary of findings

Proportion of individuals who have a diagnosis of autism spectrum disorder at baseline and continue not meet diagnostic criteria at follow‐up one or more years later

Patient or population: children diagnosed with autism spectrum disorder

Settings: range of settings

Outcomes

Relative effect

(95% CI)

Number of participants

(studies)

Quality of the evidence
(GRADE)

Comments

Proportion with an autism spectrum disorder diagnosis at baseline and follow‐up

Follow‐up: > 12 months

0.92

(0.89 to 0.95)

11,105 (34 studies:

1 intervention trial with 1 arm;

1 RCTa;

2 non‐RCTsa;

30 TAU or in the community)

⊕⊕⊝⊝

Lowb,c

Limitations (ROB): seriousb

Inconsistency: seriousc

Indirectness: not serious

Imprecision: not serious

Publication/reporting bias: not serious

Effect size: N/A

Dose response gradient: N/A

Confirmatory evidence: N/A

See footnotes below.

Social communication at baseline and follow‐up (mean score)

Follow‐up: > 12 months

See comments

None of the included studies provided separate domain scores at baseline and follow‐up

Restricted and repetitive behaviours and interests at

baseline and follow‐up (mean score)

Follow‐up: > 12 months

See comments

None of the included studies provided separate domain scores at baseline and follow‐up

Defnitions of levels of evidence 

High: We are very confident that the true prognosis (probability of future events) lies close to that of the estimate

Moderate: We are moderately confident that the true prognosis (probability of future events) is likely to be close to the estimate, but there is a possibility that it is substantially different

Low: Our confidence in the estimate is limited: the true prognosis (probability of future events) may be substantially different from the estimate

Very low: We have very little confidence in the estimate: the true prognosis (probability of future events) is likely to be substantially different from the estimate

 

CI: Confidence intervals;N/A: Not applicable;RCT(s): Randomised controlled trial(s);ROB: Risk of bias; TAU: Treatment as usual.

aData were taken from the control arm of the study
bWe downgraded the quality of the evidence by one level for risk of bias due to high risk of bias across most studies: 85% of studies were rated moderate or high risk of bias in study participation, 68% were moderate or high risk of bias in study attrition and 88% were rated moderate or high risk of bias for outcome measurement. Only 5% of studies were rated low risk of bias across all three criteria.
cWe downgraded the quality of the evidence one level for inconsistency of results (large heterogeneity (I2 = 88.71%), P value (P < 0.01)). The forest plot showed significant variation between point estimates for studies and non‐overlapping confidence intervals across many studies. The least and most optimistic point estimates varied considerably (60% to 100%) and each of these estimates were likely to result in different conclusions about the stability of a diagnosis in autism spectrum disorder.

Figures and Tables -
Summary of findings 1. Summary of findings
Table 1. Changes to the classification systems over time

Year published

Classification system

Subgroups (as specified in the classification system)

1975

International Classification of Diseases, Ninth Revision, Clinical Modification (ICD‐9‐CM)

Autistic disorder

1980

Diagnostic and Statistical Manual of Mental Disorders, Third Edition (DSM‐III)

PDD: infantile autism, childhood onset PDD and atypical PDD

1987

Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised (DSM‐III‐R)

PDD: autistic disorder, PDD‐not otherwise specified (PDD‐NOS)

1994 to 2000

Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM‐IV)

Asperger’s disorder, autistic disorder, PDD‐NOS

1996

International Classification of Diseases, Tenth Revision (ICD‐10)

Childhood autism, Asperger's syndrome, atypical autism, pervasive developmental disorder (PDD) ‐ unspecified

2000 to 2013

Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM‐IV‐TR)

Asperger’s disorder, autistic disorder, PDD‐NOS

2013 to current

Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM‐5)

Autism spectrum disorder

2018

International Classification of Diseases, Eleventh Revision (ICD‐11)

Autism spectrum disorder

PDD‐NOS: pervasive developmental disorder

Figures and Tables -
Table 1. Changes to the classification systems over time
Table 2. Studies that had multiple publications

Primary publication

Additional publications from the same study

Anderson 2009a

Anderson 2007, Bedford 2016, Gotham 2012, Gotham 2011, Hus 2011, Lord 1995, Lord 2004, Lord 2012, Luyster 2007, Pickles 2014, Richler 2010, Thurm 2007

Baghdadli 2012

Baghdadli 2018, Baghdadli 2008, Baghdadli 2007, Darrou 2010, Pry 2011, Pry 2012

Bopp 2006

Bopp 2009; Smith 2007

Flanagan 2010

Flanagan 2012

Giserman‐Kiss 2020

Giserman‐Kiss 2018

Moss 2008

Magiati 2007, Magiati 2011a, Magiati 2011b

Qian 2018

Ke 2017, Li 2019

Rivard 2019

Mello 2018

Solomon 2014

Mahoney 2016

Solomon 2016

Solomon 2018, Waizbard‐Bartov 2021

Szatmari 2021

Baribeau 2020, Baribeau 2021, Courchesne 2021, Bennett 2014, Bennett 2015, Georgiades 2014, Georgiades 2021, Szatmari 2015

Venker 2014

Ellis‐Weismer 2015, Davidson 2017, Ray‐Subramanian 2012, Venker 2016

aMet inclusion criteria but unable to extract data for synthesis as children without a diagnosis of autism spectrum disorder were also included in the cohort. Authors were contacted but we were unable to obtain required data.

Figures and Tables -
Table 2. Studies that had multiple publications
Table 3. Characteristics of individual studies included in synthesis (n = 34)

Study

Diagnosis type

N at baseline (% male)

IQ

(mean standard score)a

Adaptive behavior

(mean standard score)a

Language (mean

standard score)a

Age at baseline (years)

Follow‐up duration (years)

Diagnostic tool used at baseline (multidisciplinary or not)

Proportion who met diagnostic criteria at follow‐up

Baghdadli 2012

ASD

152 (82)

< 70

< 70

NR

4.90

3.00

ICD‐10 & CARS (Y)

1.0

Benedetto 2021

ASD

147 (80)

NR

NR

NR

2.3

1

DSM‐5 and ADOS (Y)

0.73

Brian 2016

ASD

18 (72)

> 70

NR

> 70

3.15

6.36

DSM‐IV‐TR & ADOS (N)

0.94

Demb 1989

ASD

12 (75)

< 70

NR

NR

4.50

5.00

DSM‐III & DSM‐III R (N)

0.83

Eaves 2004

ASD

43 (80)

< 70

< 70

NR

2.75

2.25

DSM‐IV, CARS, MDT (Y)

0.93

Elmose 2014

ASD

23 (78)

NR

NR

NR

3.10

8.30

ICD‐10, ADOS (Y)

1.00

Flanagan 2010

ASD

67 (82)

NR

< 70

NR

3.59

1.38

CARS (N)

0.81

Freeman 2004

ASD

59 (81)

< 70

NR

NR

4.00

2.2

DSM IV, CARS (N)

0.97

Gillberg 1990

ASD

25 (68)

< 70

NR

NR

1.13

4.04

DSM‐III‐R (N)

0.92

Giserman‐Kiss 2020

ASD

60 (87)

<70

NR

<70

2.31

1.98

ADOS

0.883

Gonzalez 1993

ASD

30 (73)

< 70

NR

NR

4.50

1.00

DSM‐III, DSM‐III‐R, DSM‐IV and ICD 10 (N)

0.97

Hinnebusch 2017

ASD

219 (81)

Both

NR

< 70

2.13

2.16

DSM‐IV, ADOS, CARS (N)

0.83

Kim 2016

ASD

100 (84)

> 70

Both

NR

1.80

1.30

ADOS (Y)

0.93

Klintwall 2015

ASD

70 (89)

> 70

> 70

< 70

1.83

1.36

ADOS G, ADOS T (U)

0.93

Malhi 2011

ASD

77 (83)

< 70

NR

NR

2.48

1.65

CARS (Y)

0.95

Moore 2003

ASD

19 (80)

> 70

NR

< 70

2.83

1.59

ADI‐R (Y)

1.00

Moss 2008

ASD

35 (91)

< 70

< 70

< 70

3.5

7.00

ADI‐R (N)

0.80

Ozonoff 2015

ASD

79 (NR)

NR

NR

NR

2

1

ADI‐R, DSM IV, best clinical estimate (N)

0.82

Paul 2008

ASD

37 (NR)

> 70

> 70

< 70

1.82

1.09

ADOS (Y)

1.00

Qian 2018

ASD

37 (86)

<70

NR

NR

2.57

2

DSM IV TR; CARS ADI‐R (N)

1.00

Robain 2020

ASD

60 (100)

>70

NR

NR

3

1

DSM 5 ADOS (N)

1.00

Santocchi 2012

ASD

98 (NR)

NR

NR

NR

3.25

1.75

ADOS, CARS

0.86

Sheinkopf 1998

ASD

11 (NR)

< 70

NR

NR

2.94

1.51

DSM‐III (Y)

1.00

Soke 2011

AD

28 (79)

< 70

NR

NR

2.75

2.08

ADI‐R (Y)

0.89

Solomon 2014

ASD

55 (84)

< 70

NR

NR

4.21

1.00

ADOS (U)

0.78

Solomon 2016

ASD

102 (80)

> 70

Both

Both

2.86

2.76

ADOS (N)

0.95

Spjut Jansson 2016

ASD

71 (79)

Both

Both

NR

3.03

2.00

ADOS, DISCO, ADI‐R (Y)

0.93

Sullivan 2010

ASD

75 (83)

< 70

< 70

NR

3.94

2.18

CARS (N)

0.53

Takeda 2007

ASD

126 (81)

< 70

NR

NR

2.62

2.90

ICD‐10, CARS (N)

1.00

Venker 2014

ASD

129 (87)

> 70

> 70

Both

2.80

5.85

DSM‐IV, ADOS (Y)

1.00

Wu 2016

ASD

8564 (83)

NR

NR

NR

3.67

1.43

DSM‐IV‐TR file record review (N)

0.91

Zappella 1990

AD

15 (87)

> 70

Both

NR

4.50

1.83

DSM‐III (N)

0.60

Zappella 2010

ASD

534 (84)

NR

NR

NR

5.00

2.67

DSM‐IV‐TR (U)

0.93

Zwaigenbaum 2015

ASD

23 (69)

NR

> 70

NR

1.50

1.50

DSM‐IV‐TR (N)

0.83

aMean score (IQ, adaptive behaviour or language) for the cohort is < 70 or more than 70% are less than 70. If cohort evenly spread this is signified 'both'.

AD: autistic disorder; ADI: Autism Diagnostic Interview;ADOS: Autism Diagnostic Observation Schedule; ASD: autism spectrum disorder; CARS: Childhood Autism Rating Scale; DISCO: Diagnostic Interview for Social and Communication Disorders; DSM: Diagnostic Statistical Manual of Mental Disorders; ICD: International Classification of Diseases; IQ: intelligence quotient; N: no; NR: not reported; PDD‐NOS: pervasive developmental disorder‐ not otherwise specified; U: unclear; Y: yes.

Figures and Tables -
Table 3. Characteristics of individual studies included in synthesis (n = 34)
Table 4. Prognostic factor analyses (eight comparisons), with effect sizes and confidence intervals

Domain

Relative effect (95% CIs)

No. of participants (studies)

I2

Age at baseline

0 to 2 years

0.94 (0.88 to 0.98)

251 (5 studies)

52.64%, P = 0.08

2 to 3 years

0.92 (0.88 to 0.95)

9989 (22 studies)

90.17%, P < 0.01

4 to 5 years

0.91 (0.76 to 0.99)

152 (5 studies)

90.48%, P < 0.01

5 to 6 years

0.93 (0.90 to 0.95)

534 (1 study)

Age at follow‐up

< 4 years

0.89 (0.79 to 0.96)

443 (6 studies)

86.80%, P < 0.01

4 to 6 years

0.92 (0.88 to 0.95)

9794 (21 studies)

87.88%, P < 0.01

7 to 12 years

0.96 (0.89 to 1.00)

868 (7 studies)

88.18%, P < 0.01

Duration of follow‐up

1 to 2 years

0.91 (0.88 to 0.94)

10,745 (27 studies)

87.86%, P < 0.01

2 to 5 years

0.99 (0.92 to 1.00)

293 (4 studies)

78.16%, P < 0.01

6 to 17 years

0.92 (0.77 to 1.00)

67 (3 studies)

Decade of publication

1980 to 1989

0.83 (0.55 to 0.95)

12 (1 studies)

1990 to 1999

0.91 (0.74 to 1.00)

82 (4 studies)

73.16% P = 0.01

2000 to 2009

0.98 (0.93 to 1.00)

479 (7 studies)

80.57% P < 0.01

2010 to 2019

0.90 (0.87 to 0.93)

10,273 (19 studies)

86.84% P < 0.01

2020 to 2029

0.90 (0.68 to 1.00)

259 (3 studies)

Intelligencea

< 70

0.93 (0.85 to 0.98)

793 (15 studies)

90.88%, P < 0.01

> 70

0.97 (0.92 to 1.00)

502 (9 studies)

77.54%, P < 0.01

Both < 70 and > 70

0.86 (0.81, 0.89)

289 (2 studies)

Languagea

< 70

0.92 (0.84 to 0.98)

382 (6 studies)

79.65%, P < 0.01

> 70

0.94 (0.74 to 0.99)

18 (1 study)

Both

0.98 (0.96 to 1.00)

205 (2 studies)

Adaptive behavioura

< 70

0.85 (0.60 to 0.99)

300 (5 studies)

96.33%, P < 0.01

> 70

0.97 (0.8 to 1.00)

233 (4 studies)

83.28%, P < 0.01

Both

0.91 (0.82, 0.97)

283 (4 studies)

73.88%, P = 0.01

Multidisciplinary assessment

Yes

0.97 (0.91 to 1.00)

767 (13 studies)

87.97%, P < 0.01

No

0.88 (0.83 to 0.93)

9468 (16 studies)

89.46%, P < 0.01

aMean score (IQ, adaptive behaviour or language) for the cohort is < 70 or more than 70% are less than 70. If cohort was evenly spread this is signified 'both'.

CI: confidence interval;I2: a statistic that describes the percentage of variation across studies; No.: number.

Figures and Tables -
Table 4. Prognostic factor analyses (eight comparisons), with effect sizes and confidence intervals