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November 2016 – Limited follow-up with incomplete retention is common among studies involving pediatric lymphoma patients in sub-Saharan Africa. This study examines the effects of retention and follow-up times on overall survival estimates.

Quantifying bias in survival estimates resulting from loss to follow-up among children with lymphoma in Malawi

Christopher C. Stanley, Kate D. Westmoreland, Salama Itimu, Ande Salima, Toon van der Gronde, Peter Wasswa, Idah Mtete, Mercy Butia, Nader K. El-Mallawany, Satish Gopal

Pediatric Blood & Cancer. 

Full text available at Wiley Online Library


Pediatric lymphoma is common in sub-Saharan Africa, where survival estimates are often based on limited follow-up with incomplete retention, introducing potential for bias. We compared follow-up and overall survival (OS) between passive and active tracing within a prospective cohort of children with lymphoma in Malawi. Median follow-up times were 4.4 months (interquartile range [IQR] 2.0-9.4) and 10.8 months (IQR 6.2-20.6) in passive and active follow-up, respectively. Twelve-month overall survival (OS) was 69% (95% confidence interval [CI] 54-80) in passive and 44% (95% CI 34-54) in active follow-up. Passive follow-up significantly overestimated the OS and underestimated the mortality. Efforts to improve retention in regional studies are needed.