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. 2021 Jun 6;21(1):118.
doi: 10.1186/s12874-021-01264-3.

Strategies for assessing the impact of loss to follow-up on estimates of neurodevelopmental impairment in a very preterm cohort at 2 years of age

Aurélie Piedvache  1 , Stef van Buuren  2   3 , Henrique Barros  4 , Ana Isabel Ribeiro  4 , Elizabeth Draper  5 , Jennifer Zeitlin  6   7 ; EPICE Research group
Collaborators, Affiliations

Strategies for assessing the impact of loss to follow-up on estimates of neurodevelopmental impairment in a very preterm cohort at 2 years of age

Aurélie Piedvache et al. BMC Med Res Methodol. .

Abstract

Background: Loss to follow-up is a major challenge for very preterm (VPT) cohorts; attrition is associated with social disadvantage and parents with impaired children may participate less in research. We investigated the impact of loss to follow-up on the estimated prevalence of neurodevelopmental impairment in a VPT cohort using different methodological approaches.

Methods: This study includes births < 32 weeks of gestational age (GA) from 4 regions in the UK and Portugal participating in a European birth cohort (N = 1737 survivors). Data on maternal characteristics, pregnancy complications, neonatal outcomes and neighborhood deprivation were collected at baseline. Neurodevelopment was assessed at 2 years of corrected age (CA) using standardized parent-report measures. We applied (1) multiple imputation (MI) and (2) inverse probability weighting (IPW) to estimate the impact of non-response on the prevalence of moderate to severe neurodevelopmental impairment and assessed violations of the missing at random (MAR) assumption using the delta method.

Results: 54.2% of children were followed-up. Follow-up was less likely when mothers were younger, multiparous, foreign-born, did not breastfeed and came from deprived areas. The prevalence of neurodevelopmental impairment was 18.4% (95% confidence interval (CI):15.9-21.1) and increased to 20.4% (95%CI: 17.3-23.4) and 20.0% (95%CI:16.9-23.1) for MI and IPW models, respectively. Simulating strong violations of MAR (children with impairments being 50% less likely to be followed-up) raised estimates to 23.6 (95%CI:20.1-27.1) CONCLUSIONS: In a VPT cohort with high loss to follow-up, correcting for attrition yielded modest increased estimates of neurodevelopmental impairment at 2 years CA; estimates were relatively robust to violations of the MAR assumption.

Keywords: Delta method; Inverse probability weighting; Loss to follow-up; Multiple imputation; Neurodevelopment; Preterm births.

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Conflict of interest statement

The authors declare that they have no competing interests

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