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The time has come for living systematic reviews in autism research

While the inclusion of more recent estimates can听improve accuracy and utility of systematic听reviews, there is a key challenge: how can evidence influence policy if it cannot be updated in real time?

Autism prevalence estimates have been used for decades听to inform policy and practice in research and service听delivery. In our recent systematic review update (Zeidan听et al., 2022), we found a large increase in the number of听estimates available relative to the first systematic review听we conducted in 2012 (Elsabbagh et al., 2012). The听increase was most notable in world regions which were听largely unrepresented in the past.

In their Letter to the Editor, Roman-Urrestarazu听et al. (2021) argued that a missing study from our review,听led to inaccurate estimates for the European region. We听caution against interpreting prevalence estimates as 鈥済round听truth鈥 but rather as useful snapshots in time of who听is being counted or not counted as having autism. In our听systematic review, we comprehensibly examined methodological听features such as definitions of autism, study听design attributes, data sources, and sampling procedures that substantially impact prevalence estimates.

Roman-Urrestarazu et al. (2021) is indeed a unique听study because it went beyond estimating prevalence to听examining key social determinants modifying prevalence听in a large population of school-age children. However,听when our search was last updated in November 2021, the听publication from Roman-Urrestarazu et al. (2021)听despite being in the database, had not yet been indexed, and was therefore not captured by our literature search.

While the inclusion of more recent estimates can听indeed improve accuracy and utility of systematic听reviews, there is a key challenge: how can evidence effectively听influence policy if it cannot be comprehensively听updated in real time? Traditional systematic reviews like听the one we conducted are time-consuming, costly, and听their results necessarily lag behind. The proliferation of听epidemiological literature all over the world amplifies the听challenge of maintaining prevalence estimates up to date.

To illustrate this point, we reran our search on March听16, 2022. Not surprisingly the updated search identified听Roman-Urrestarazu et al. (2021) embedded within a听large number of 267 articles published in this area only in听the last few months (Supporting Information, Figure S1). We went further and screened these articles to check if they contained new epidemiological estimates. Indeed, we identified not one but eight new estimates in different world regions. As expected, our global estimates remain largely similar with the addition of the new estimates but regional estimates were more susceptible to change only听in those regions where fewer estimates are available (Table 1).

Summary of autism prevalence estimates across world regions from 2012 to 2022 (updated search on March 16, 2022).
Open file to view table:听PDF icon The time has come for living systematic reviews in autism research

We believe that the utility of systematic reviews lies in the transparency of the search and availability of all the data extracted (Supporting Information, Tables S1 and S2). As we did here, researchers and knowledge users can reuse the extracted data to perform updates, more targeted analyses such as regional ones, and new analyses such as economic estimates.

Another solution is on the horizon. A new review format has been developed (Elliott et al., 2014) and implemented in a number of journals (Rahal et al., 2016) leading to a Cochrane guidance (Cochrane Community, 2019). A 鈥渓iving systematic review鈥 is one that is updated continually to include new evidence. Key to its success is commitment to monthly updates of the search, inclusion, and interpretation of new evidence. The time has come for living reviews in autism research.

Letter to the editor on May 15, 2022.听


Data availability statement
The data that supports the findings of this study are听available in the supplementary material of this article
Mayada Elsabbagh1
Afiqah Yusuf1
Jinan Zeidan1
Julie Scorah1
Eric Fombonne2
Maureen S. Durkin3
Shekhar Saxena4
Andy Shih5
1Montreal Neurological Institute-Hospital, Faculty of Medicine & Health Sciences, 平特五不中, Montreal, Canada
2Department of Psychiatry, Oregon Health and Science University, Portland, Oregon, USA
3Population Health Sciences, Department of Pediatrics, Waisman Center, University of Wisconsin-Madison,听Madison, Wisconsin, USA
4Department of Global Health and Population, Harvard T H Chan School of Public Health, Boston,听Massachusetts, USA
5Science, Autism Speaks, New York City, New York, USA
Correspondence
Mayada Elsabbagh, Montreal Neurological听Institute-Hospital, Faculty of Medicine & Health听Sciences, 平特五不中, 3775 Rue University,听Room C18, Montreal, Quebec H3A 2B4, Canada.
Email: mayada.elsabbagh [at] mcgill.ca
ORCID
Mayada Elsabbagh
Andy Shih
References
Cochrane Community. 2019. Guidance for the production and publication听of Cochrane living systematic reviews: Cochrane reviews in听living mode - version December 2019.听
Elliott, J. H., Turner, T., Clavisi, O., Thomas, J., Higgins, J. P. T.,听Mavergames, C., & Gruen, R. L. (2014). Living systematic听reviews: An emerging opportunity to narrow the evidence-practice听gap. PLoS Medicine, 11(2), e1001603.听
Elsabbagh, M., Divan, G., Koh, Y.-J., Kim, Y. S., Kauchali, S.,听Marc铆n, C., Montiel-Nava, C., Patel, V., Paula, C. S., Wang, C.,听Yasamy, M. T., & Fombonne, E. (2012). Global prevalence of听autism and other pervasive developmental disorders. Autism听Research, 5(3), 160鈥179.
Rahal, A. K., Badgett, R. G., & Hoffman, R. M. (2016). Screening coverage听needed to reduce mortality from prostate cancer: A living听systematic review. PLoS One, 11(4), e0153417.
Roman-Urrestarazu, A., van Kessel, R., Allison, C., Matthews, F. E.,听Brayne, C., & Baron-Cohen, S. (2021). Association of听Race/ethnicity and social disadvantage with autism prevalence in听7 million school children in England. JAMA Pediatrics, 175(6),听e210054.
Supporting information
Additional supporting information may be found in the听online version of the article at the .
Cite this article
Elsabbagh, M., Yusuf, A., Zeidan, J., Scorah, J., Fombonne, E., Durkin, M.S., Saxena, S. and Shih, A. (2022), The time has come for living systematic reviews in autism research. Autism Research, 15: 1187-1188.听

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