Outcomes of home-based versus facility-based care for mild diphtheria during a large epidemic in Kano State, Nigeria: A retrospective matched cohort study.

BACKGROUND: During Nigeria's largest recorded diphtheria epidemic (first notified on 1 December 2022; more than 40,000 confirmed cases by January 2026), hospital capacity in Kano State was overwhelmed. Médecins Sans Frontières (MSF) introduced home-based care (HBC) for patients with mild disease; we asked whether mortality, long-term sequelae, and household transmission differed between HBC and care in a diphtheria treatment centre (DTC).

METHODS AND FINDINGS: We conducted a retrospective matched cohort study using MSF registry data and household interviews to compare mortality, long-term sequelae, and household transmission between patients with mild diphtheria treated under HBC or in a DTC. The primary outcomes were mortality, long-term sequelae, and household transmission. Mild diphtheria cases notified between January 2023 and January 2024 were exactly matched by treatment modality (HBC or DTC) on sex, age group, vaccination status, and ward of residence, and interviewed between September and October 2024, a median of 421 days after notification. Conditional logistic regression, adjusted for age, vaccination status, and treatment delay, was used to estimate the association between treatment modality and mortality, with robustness checked with propensity score weighting and sensitivity analyses. Of the 986 originally sampled patients, 491 (49.8%) were interviewed; with 178 replacements (substitute patients of similar age, sex, vaccination status, and area, interviewed when an originally selected patient could not be), 669 patients (362 HBC, 307 DTC) were analysed. After adjustment, mortality was lower with HBC than DTC care, but the interval included 1 (odds ratio [OR] 0.36, 95% confidence interval [CI] [0.12,1.07]; p = 0.066); treatment delay was associated with increased mortality (OR 1.29 per day, 95% CI [1.00,1.67]; p = 0.048). Adding calendar time gave a similar estimate (OR 0.35, 95% CI [0.08,1.57]; p = 0.170). Vaccination was associated with lower odds of death (OR 0.32, 95% CI [0.10,0.98]; p = 0.047). HBC was not associated with increased household transmission or long-term sequelae. Residual confounding by disease severity, the small number of deaths (24), and replacement patients limit these findings.

CONCLUSIONS: Vaccination and early treatment were associated with survival; care setting was not clearly associated. When supported by clinical triage and structured follow-up, decentralised care may be an option to manage mild cases during diphtheria epidemics in settings with constrained hospital capacity.

Copyright: © 2026 Polonsky et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.