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

Abstract

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.

Mature outcomes and prognostic indices in diffuse large B‐cell lymphoma in Malawi: a prospective cohort

“…This makes our study potentially more generalizable than others in SSA, which often describe only participants who survived long enough to receive chemotherapy or with excluded participants for other reasons (Mwanda et al , ; Bateganya et al , ; de Witt et al , ). We had no participants lost to follow‐up during the study period utilizing frequent, active mobile phone tracing by staff, limiting overestimation of survival which reliably results from loss to follow‐up in SSA (Stanley et al , ).…”

Risk factors and reasons for treatment abandonment among children with lymphoma in Malawi

“…Our study was nested within the prospective Kamuzu Central Hospital Lymphoma Study observational cohort in Lilongwe, Malawi, which has been previously described in detail [4, 5, 12]. These analyses focused on children less than 18 years of age with newly diagnosed lymphoma at our center, enrolled between June 2013 and March 2016.…”

“…Transport reimbursements were provided to families who attended clinic to encourage retention throughout care. We have also previously described successful use of cell phone tracing to ascertain vital status in nearly all children [4, 5, 12]. For this study focused on risk factors and reasons for defaulting from care, treatment abandonment during treatment was defined as failure to attend clinic within four weeks of a prescribed chemotherapy appointment [6].…”

Dissecting heterogeneous outcomes for paediatric Burkitt lymphoma in Malawi after anthracycline‐based treatment

“…Removing very sick children from analyses improves survival relative to descriptions of more unselected patient populations. Additionally, in sub-Saharan Africa, failure to appropriately account for loss to follow-up results in overestimated survival for human immunodeficiency virus (HIV), HIV-associated Kaposi sarcoma and paediatric lymphoma, as mortality is a major cause of loss to follow-up in these environments, where death often occurs at home and may be frequently unascertained without very active tracing (Stanley et al , 2016a). We believe these are important considerations in contextualizing otherwise important data presented by Molyneux and colleagues.…”