Outcome ascertainment and follow-up strategies in large-scale population-based prospective cohort studies in resource-limited settings
1
Nuffield Department of Population Health, University of Oxford, Oxford, United Kingdom
Popul. Med. 2026;8(Supplement Supplement 1):A3735
ABSTRACT
BACKGROUND:
Reliable ascertainment of cause-specific outcomes in large-scale, population-based prospective studies is essential for valid aetiological inference. However, in many low-income and middle-income countries (LMICs), limited digital health records and incomplete routine data systems necessitate active follow-up and alternative approaches for capturing fatal and non-fatal outcomes. We aimed to map follow-up strategies and methods used to ascertain fatal and non-fatal outcomes in large LMIC cohorts.
METHODS:
We conducted a scoping review following Joanna Briggs Institute methodology and PRISMA-ScR guidance. Medline, Embase, and Global Health were searched from inception to March 2025. Eligible studies were population-based prospective cohorts in LMICs, published from 2000 onwards, enrolling ≥5,000 adults with ≥12 months follow-up, and reporting incident fatal and/or non-fatal outcomes for at least one major chronic disease domain. We extracted and summarised data on follow-up procedures, retention strategies, and outcome ascertainment.
RESULTS:
Thirty-eight cohorts were included, spanning South Asia (12), East Asia (5), the Middle East (10), Latin America (5), sub-Saharan Africa (1), and multi-country settings (5); 13 enrolled ≥50,000 participants. Active follow-up predominated: 28/38 (73.7%) used active follow-up alone, while 10/38 (26.3%) combined active and passive methods. For non-fatal outcomes, 18/38 (47.4%) relied solely on self-report, and 14/38 (36.8%) used clinician adjudication; only 4/38 (11.1%) reported pre-specified adjudication forms and case definitions for all incident events. For fatal outcomes, 11/38 (26.3%) were linked to death registries, and 19/38 (50.0%) used verbal autopsy; among these, physician certification was most common, with automated algorithms used in five cohorts.
CONCLUSIONS:
Large LMIC cohorts rely primarily on active follow-up but use heterogeneous and often poorly reported methods for outcome ascertainment. Improved standardisation and transparent reporting of case definitions, adjudication processes, and validation, tailored to resource-limited contexts, are needed to enhance the validity, comparability, and policy relevance of evidence generated from large-scale cohort studies.
Reliable ascertainment of cause-specific outcomes in large-scale, population-based prospective studies is essential for valid aetiological inference. However, in many low-income and middle-income countries (LMICs), limited digital health records and incomplete routine data systems necessitate active follow-up and alternative approaches for capturing fatal and non-fatal outcomes. We aimed to map follow-up strategies and methods used to ascertain fatal and non-fatal outcomes in large LMIC cohorts.
METHODS:
We conducted a scoping review following Joanna Briggs Institute methodology and PRISMA-ScR guidance. Medline, Embase, and Global Health were searched from inception to March 2025. Eligible studies were population-based prospective cohorts in LMICs, published from 2000 onwards, enrolling ≥5,000 adults with ≥12 months follow-up, and reporting incident fatal and/or non-fatal outcomes for at least one major chronic disease domain. We extracted and summarised data on follow-up procedures, retention strategies, and outcome ascertainment.
RESULTS:
Thirty-eight cohorts were included, spanning South Asia (12), East Asia (5), the Middle East (10), Latin America (5), sub-Saharan Africa (1), and multi-country settings (5); 13 enrolled ≥50,000 participants. Active follow-up predominated: 28/38 (73.7%) used active follow-up alone, while 10/38 (26.3%) combined active and passive methods. For non-fatal outcomes, 18/38 (47.4%) relied solely on self-report, and 14/38 (36.8%) used clinician adjudication; only 4/38 (11.1%) reported pre-specified adjudication forms and case definitions for all incident events. For fatal outcomes, 11/38 (26.3%) were linked to death registries, and 19/38 (50.0%) used verbal autopsy; among these, physician certification was most common, with automated algorithms used in five cohorts.
CONCLUSIONS:
Large LMIC cohorts rely primarily on active follow-up but use heterogeneous and often poorly reported methods for outcome ascertainment. Improved standardisation and transparent reporting of case definitions, adjudication processes, and validation, tailored to resource-limited contexts, are needed to enhance the validity, comparability, and policy relevance of evidence generated from large-scale cohort studies.
| eISSN: | 2654-1459 |
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