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

BackgroundDuring Nigerias largest recorded diphtheria outbreak, hospital capacity in Kano State was rapidly overwhelmed. Medecins Sans Frontieres introduced home-based care (HBC) for patients with mild disease to prioritise facility-based care for severe cases. We assessed whether HBC was non-inferior to facility-based treatment in terms of mortality, sequelae, and household transmission. MethodsWe conducted a retrospective matched cohort study. Mild diphtheria cases treated between January 2023 and May 2024 were matched 1:1 by treatment modality (HBC or diphtheria treatment centre [DTC]) on sex, age group, vaccination status, and residence. Conditional logistic regression estimated the association between treatment modality and mortality, with robustness assessed through propensity score weighting, sensitivity analyses, and E-value computation. FindingsOf 990 sampled patients, 678 (367 HBC, 311 DTC) were enrolled (68{middle dot}5%). After adjustment, treatment modality was not independently associated with mortality (HBC vs. DTC: aOR 0{middle dot}40, 95% CI 0{middle dot}13-1{middle dot}30), with similar estimates across sensitivity analyses (E-value 4{middle dot}40). Clinical complications were the strongest predictor of death (aOR 23{middle dot}1, 95% CI 1{middle dot}73-307). Vaccination was protective (aOR 0{middle dot}28, 95% CI 0{middle dot}08- 0{middle dot}94) and treatment delay of four or more days increased mortality (aOR 4{middle dot}15, 95% CI 1{middle dot}23-14{middle dot}0). HBC was not associated with increased household transmission or long-term sequelae. InterpretationVaccination and early treatment, rather than care setting, were the main determinants of survival. When supported by clinical triage and structured follow-up, decentralised care can be used to manage mild cases during diphtheria epidemics in settings with constrained hospital capacity. FundingMedecins Sans Frontieres, West and Central Africa. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSWe searched PubMed and Google Scholar for articles published between January 1, 2000, and February 28, 2026, using combinations of the terms "diphtheria", "outbreak", "home-based care", "outpatient", "ambulatory", "community care", and "decentralised care". We found no published studies evaluating any form of decentralised or home-based clinical management for diphtheria. The existing literature on diphtheria case management is confined to facility-based settings: outbreak reports from multiple affected countries describe hospital-based treatment with diphtheria antitoxin (DAT) and antibiotics, and a systematic review pooled epidemiological and clinical data from historical outbreaks. Decentralised care models have been evaluated for other epidemic-prone diseases, including a measles epidemic in the Democratic Republic of the Congo (DRC) where decentralised management reduced mortality among children, and Ebola virus disease outbreaks in DRC where decentralised treatment centres were piloted to improve geographic access, though with limited outcome data. No study has assessed whether patients with diphtheria can be safely managed outside hospital settings. Added value of this studyNo prior evaluation of home-based care for diphtheria has been published. Using a retrospective matched cohort design with 678 patients during the largest diphtheria outbreak in Africa in decades, we found no evidence that home-based care increased mortality, long-term complications, or household transmission compared with facility-based care, and acceptability was high among patients in both groups. The study also provides one of the largest datasets on household transmission of diphtheria in an urban epidemic setting, finding no evidence that home-based care increased secondary transmission, and showing that vaccination status of the index case was the main factor influencing spread within the household. Implications of all the available evidenceProvided that triage is reliable, antibiotics are started promptly, and a functioning referral pathway exists, mild diphtheria can be managed safely at home during large epidemics. This approach preserves limited hospital and DAT resources for patients with moderate or severe disease, shortens treatment delays, and is acceptable to patients. Given ongoing outbreaks across West and Central Africa and persistent DAT supply constraints, decentralised care warrants inclusion in epidemic preparedness.