Participant attrition in a multi-regional population-based study in Africa: insights from the AWI-Gen study.
14 affiliations
- 1Division of Epidemiology and Biostatistics, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.
- 2Sydney Brenner Institute for Molecular Bioscience, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
- 3MRC/Wits Rural Public Health and Health Transitions Research Unit, School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
- 4SAMRC/Wits Ageing African Adult Research Unit, Department of Paediatrics, School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
- 5School of Human Development and Health, Southampton, UK.
- 6Department of Chemical Pathology, National Health Laboratory Service, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
- 7Navrongo Health Research Centre, Ghana Health Service, Navrongo, Ghana.
- 8Department of Biochemistry and Forensic Sciences, School of Chemical and Biochemical Sciences, C. K. Tedam University of Technology and Applied Sciences, Navrongo, Ghana.
- 9Department of Epidemiology, School of Public Health, C. K. Tedam University of Technology and Applied Sciences, Navrongo, Ghana.
- 10African Population and Health Research Center (APHRC), Nairobi, Kenya.
- 11DIMAMO Population Research Centre, University of Limpopo, Polokwane, South Africa.
- 12Clinical Research Unit of Nanoro, Institut de Recherche en Sciences de la Santè, CNRST, Nanoro, Burkina Faso.
- 13MRC Unit The Gambia at London School of Hygiene and Tropical Medicine, Banjul, The Gambia.
- 14Sydney Brenner Institute for Molecular Bioscience, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa. [email protected].
Abstract
Background
Attrition in longitudinal studies, defined as the loss of participants over time, may threaten the validity of study results. This study examined patterns, magnitude, and risk factors for attrition in the AWI-Gen cohort.Methods
The study included 12,032 participants from six African sites, with a median baseline age of 51 years (IQR: 45-57 years). Exploratory data analysis was conducted to examine attrition patterns and magnitude, and fixed-effects logistic regression models were used to identify significant factors associated with different causes of attrition (all-cause, non-death vs death, preventable vs non-preventable) while accounting for site-specific variation. Sensitivity analyses, including Bonferroni adjustments, imputation, and site-specific analyses, were used to assess model robustness. Model goodness-of-fit was evaluated, and adjusted odds ratios with 95% confidence intervals were reported, with a significance threshold of p < 0.05.Results
After five years, AWI-Gen experienced 40% attrition. Causes included being unreachable by cell phone (42.6%), refusal (26.0%), death (13.9%), relocation (10.5%), and being recorded as too ill to participate (3.9%), with variations across sites. Male sex and lower socioeconomic status were consistently associated with increased odds across attrition outcomes, while older age, tobacco use, hypertension, chronic kidney disease, and cardiovascular disease were additionally associated with death-related and non-preventable attrition.Conclusion
This study underscores the importance of reporting attrition causes for consistency in longitudinal research. Male participants, individuals of lower socioeconomic status, older adults, tobacco users, and those living with chronic conditions such as hypertension, chronic kidney disease, and cardiovascular disease were at increased risk of attrition. Tailored retention strategies, including enhanced participant tracing and communication, targeted engagement of men and socioeconomically disadvantaged groups, regular contact with older participants, and integration of follow-up activities with chronic disease management services, may improve participant retention and help preserve the validity of longitudinal research.
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BibTeX
@article{achilonu2026participant,
title = {{Participant attrition in a multi-regional population-based study in Africa: insights from the AWI-Gen study.}},
author = {Okechinyere Achilonu and Theophilus Mathema and Furahini Tluway and F Xavier Gómez-Olivé and Lisa K Micklesfield and Shane A Norris and Nigel J Crowther and Chodziwadziwa Whiteson Kabudula and Godfred Agongo and Engelbert A Nonterah and Kayode Adetunji and Siyanda Madala and Patrick O Ansah and Isaac Kisiangani and Shukri F Mohamed and Ananyo Choudhury and Cairo Bruce Ntimana and Reneilwe Given Mashaba and Hermann Sorgho and Palwende Romuald Boua and Michele Ramsay and as members of AWI-Gen and the H3Africa Consortium},
journal = {BMC public health},
year = {2026},
month = aug,
doi = {10.1186/s12889-026-28794-z},
url = {https://europepmc.org/article/MED/43009899},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Participant attrition in a multi-regional population-based study in Africa: insights from the AWI-Gen study.
AU - Okechinyere Achilonu
AU - Theophilus Mathema
AU - Furahini Tluway
AU - F Xavier Gómez-Olivé
AU - Lisa K Micklesfield
AU - Shane A Norris
AU - Nigel J Crowther
AU - Chodziwadziwa Whiteson Kabudula
AU - Godfred Agongo
AU - Engelbert A Nonterah
AU - Kayode Adetunji
AU - Siyanda Madala
AU - Patrick O Ansah
AU - Isaac Kisiangani
AU - Shukri F Mohamed
AU - Ananyo Choudhury
AU - Cairo Bruce Ntimana
AU - Reneilwe Given Mashaba
AU - Hermann Sorgho
AU - Palwende Romuald Boua
AU - Michele Ramsay
AU - as members of AWI-Gen and the H3Africa Consortium
PY - 2026
DA - 2026/08/03
JO - BMC public health
DO - 10.1186/s12889-026-28794-z
UR - https://europepmc.org/article/MED/43009899
AB - Background Attrition in longitudinal studies, defined as the loss of participants over time, may threaten the validity of study results. This study examined patterns, magnitude, and risk factors for attrition in the AWI-Gen cohort.Methods The study included 12,032 participants from six African sites, with a median baseline age of 51 years (IQR: 45-57 years). Exploratory data analysis was conducted to examine attrition patterns and magnitude, and fixed-effects logistic regression models were used to identify significant factors associated with different causes of attrition (all-cause, non-death vs death, preventable vs non-preventable) while accounting for site-specific variation. Sensitivity analyses, including Bonferroni adjustments, imputation, and site-specific analyses, were used to assess model robustness. Model goodness-of-fit was evaluated, and adjusted odds ratios with 95% confidence intervals were reported, with a significance threshold of p < 0.05.Results After five years, AWI-Gen experienced 40% attrition. Causes included being unreachable by cell phone (42.6%), refusal (26.0%), death (13.9%), relocation (10.5%), and being recorded as too ill to participate (3.9%), with variations across sites. Male sex and lower socioeconomic status were consistently associated with increased odds across attrition outcomes, while older age, tobacco use, hypertension, chronic kidney disease, and cardiovascular disease were additionally associated with death-related and non-preventable attrition.Conclusion This study underscores the importance of reporting attrition causes for consistency in longitudinal research. Male participants, individuals of lower socioeconomic status, older adults, tobacco users, and those living with chronic conditions such as hypertension, chronic kidney disease, and cardiovascular disease were at increased risk of attrition. Tailored retention strategies, including enhanced participant tracing and communication, targeted engagement of men and socioeconomically disadvantaged groups, regular contact with older participants, and integration of follow-up activities with chronic disease management services, may improve participant retention and help preserve the validity of longitudinal research.
SN - 1471-2458
ER -