Developing survey weights to ensure representativeness in a national, matched cohort study: results from the Children and young people with Long Covid (CLoCk) study.

Abstract

Background: Findings from studies assessing Long Covid in children and young people (CYP) need to be viewed in light of their methodological limitations. For example, if non-response and/or attrition over time systematically differ by sub-groups of CYP, findings could be biased and generalisation limited. The present study aimed to (i) construct survey weights for the Children and young people with Long Covid (CLoCk) study, and (ii) apply them to published CLoCk findings showing the prevalence of shortness of breath and tiredness increased over time from baseline to 12-months post-baseline in both SARS-CoV-2 Positive and Negative CYP. Methods: Logistic regression was used to compute the probability of (i) Responding given envisioned to take part, (ii) Responding timely given responded, and (iii) (Re)infection given timely response. Response, timely response and (re)infection weights were generated as the reciprocal of the corresponding probability, with an overall ‘envisioned population’ survey weight derived as the product of these weights. Survey weights were trimmed, and an interactive tool developed to re-calibrate target population survey weights to the general population using data from the 2021 UK Census. Results: Flexible survey weights for the CLoCk study were successfully developed. In the illustrative example re-weighted results (when accounting for selection in response, attrition, and (re)infection) were consistent with published findings. Conclusions: Flexible survey weights to address potential bias and selection issues were created for and used in the CLoCk study. Previously reported prospective findings from CLoCk are generalisable to the wider population of CYP in England. This study highlights the importance of considering selection into a sample and attrition over time when considering generalisability of findings.

Loneliness Trajectories, Associated Factors and Subsequent Health in Children and Young People During the COVID-19 Pandemic: A National Matched Cohort Study

“…We have recently developed flexible survey weights to address potential bias and selection issues in the CLoCk study and have demonstrated that previously reported prospective findings from CLoCk (based on a sample similar to those presented in the current manuscript) are generalizable to the wider population of CYP in England. 55 , 56 Third, all relevant measures (eg loneliness, health outcomes etc.) were self-reported which is subject to biases and measurement errors.…”

Post-Covid-19 condition (Long Covid) in children and young people 12 months after infection or reinfection with the Omicron variant: a prospective observational study

“…Second, we do not have any information on additional infections since April 2022 when all community testing for SARS-CoV-2 was stopped. Additionally, although respondents in the main CLoCk study are broadly representative of the target population 23 , only 7.3% of those approached for this smaller Omicron sub-study participated at all time points. However, respondents to the Omicron sub-study are broadly similar to the target population, albeit with some differences (e.g., by region).…”

“…Equally, they could be less invested in being involved in a study than young people still experiencing symptoms. Overall, the participants in the main CLoCk study are largely representative of the target population 23 .…”

“People don’t have the answers”: A qualitative exploration of the experiences of young people with Long COVID

“…Topic guides were informed by the CLoCk PPIE group to ensure questions were relevant to young people living with Long COVID. Participants were also recruited from the wider CLoCk study ( Stephenson et al, 2021 ), which initial analysis indicates is broadly representative of the population of young people in England ( Rojas et al, 2023 ).…”