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Original research
Determinants of loss to follow-up in the Canadian Longitudinal Study on Aging: a retrospective cohort study
  1. Doaa Farid1,
  2. Patricia Li2,3,
  3. Kaberi Dasgupta3,4,
  4. Elham Rahme3,5
  1. 1 Department of Family Medicine, McGill University Faculty of Medicine and Health Sciences, Montreal, Québec, Canada
  2. 2 Department of Pediatrics, McGill University Faculty of Medicine and Health Sciences, Montreal, Québec, Canada
  3. 3 Centre for Outcomes Research and Evaluation, McGill University Health Centre, Montreal, Québec, Canada
  4. 4 Department of Medicine, Divisions of Internal Medicine, Clinical Epidemiology, and Endocrinology and Metabolism, McGill University, Montreal, Québec, Canada
  5. 5 Department of Medicine and Health Sciences, Division of Clinical Epidemiology, McGill University, Montreal, Québec, Canada
  1. Correspondence to Dr Elham Rahme, Department of Medicine and Health Sciences, Division of Clinical Epidemiology, McGill University, Montreal, Canada; elham.rahme{at}mcgill.ca

Abstract

Background Systematic loss to follow-up (LFU) creates selection bias and hinders generalisability in longitudinal cohort studies. Little is known about LFU risks in underserved populations including immigrants, those with depressive symptoms and language minorities. We used the Canadian Longitudinal Study on Aging (baseline 2012–2015 and 3-year follow-up 2015–2018) comprehensive and tracking cohorts to examine the association of language with LFU and its effect modification by immigrant status and depressive symptoms among participants from Quebec and those from outside Quebec.

Methods Language was English-speaking, French-speaking and Bilingual according to the language participants’ reported being able to converse in. Language minorities were French-speakers outside Quebec and English-speakers inside Quebec. LFU was withdrawal or not providing follow-up data. Logistic regression models assessed the associations of interest.

Results Our cohort included 49 179 individuals (mean age 63.0, SD 10.4 years; 51.4% female). Overall, 7808 (15.9%) were immigrants and 7902 (16.1%) had depressive symptoms. Language was 4672 (9.5%) French-speaking, 33 532 (68.2%) English-speaking and 10 976 (22.3%) Bilingual. Immigration ≤20 years (OR 1.84, 95% CI 1.34 to 2.53) or arrival at age >22 years (1.32, 95% CI 1.10 to 1.58) and depressive symptoms (1.23, 95% CI 1.13 to 1.46) had higher LFU risks. Bilingual (vs French-speaking) had lower LFU risk outside (0.45, 95% CI 0.24 to 0.86) and inside Quebec (0.78, 95% CI 0.63 to 0.98). LFU risk was higher in French-speakers (vs English-speakers) outside (2.33, 95% CI 1.19 to 4.55), but not inside Quebec. Female, higher income, higher education and low nutritional risk had lower LFU risks.

Conclusion Speaking only French (vs Bilingual), having depressive symptoms and immigrant status increased LFU risks, with the latter not modifying the language effect.

  • depression
  • longitudinal studies
  • aging
  • health inequalities

Data availability statement

Data are available on reasonable request. CLSA data can be requested through https://www.clsa-elcv.ca/data-access.

https://doi.org/10.1136/jech-2022-219307

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    Data availability statement

    Data are available on reasonable request. CLSA data can be requested through https://www.clsa-elcv.ca/data-access.

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    Footnotes

    • Contributors DF conceived the idea, performed the analyses, interpreted the results and wrote the first draft of the manuscript. ER conceived the idea, acquired the data, supervised the analyses, interpreted the findings and edited the manuscript. KD and PL provided content expertise and thoughtful comments throughout the process and edited the manuscript. All authors read and approved the final draft of the manuscript. ER is responsible for the overall content as the guarantor.

    • Funding Funding was received from the McGill University’s Institute for Health and Social Policy under the HCALM-Network.

    • Competing interests None declared.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.