Box 1.

Definitions of key concepts and variables

Health episode	Defined as an illness or injury reported during the weekly interview, which may last, and be reported, for several consecutive weeks. Health episodes are symptoms as described by respondents, without verification of medical records
Provider type	Provider choice was classified in four categories: (0) No provider (1) Informal providers: patent and proprietary medicine vendors (PPMVs), chemists, drug peddlers and traditional healers (2) Non-upgraded facilities: healthcare facilities in the area not linked to the KSHI, as well as private doctors, nurses, community-health extension workers, paramedics and pharmacists not linked to a health facility (3) Upgraded facilities: three health facilities linked to the KSHI, both enrolees and non-enrolees could access care at these facilities
Insurance status	Insurance status (insured/uninsured) at the time of a health episode was based on weekly administrative data available through the KSHI and Hygeia Ltd
Health episode category	We categorized the symptoms using the Global Burden of Disease classification to: (1) communicable diseases [renamed from its original definition ‘communicable, maternal, neonatal, and nutritional diseases’ (University of Washington, 2019), to reflect the exclusion of preventive services and therefore the low number of maternal, neonatal, and nutritional diseases] (2) non-communicable diseases (3) injuries Note: The symptom ‘headache’ was classified as non-communicable disease, except for the cases when headache was reported together with a communicable disease symptom, such as ‘fever/malaria’
Health episode severity	The ability to perform daily activities at the time of a health episode was used as a proxy for health episode severity: Less severe: able to perform daily activities More severe: unable to perform daily activities for one or more days
Seasonality	Dry season: health episodes onset between November and April Wet season: health episode onset between May and October
Household location	Rural: households located in the rural clusters. The distance to the upgraded facility was between 5 and 15 km Urban: households located in the urban clusters. The distance to the upgraded facility was within 5 km
Household wealth	Categorized as ‘low’, ‘medium’ and ‘high’, corresponding to the first, second and third terciles of the wealth index generated using principle component analysis on household size, type of housing, and household assets recorded at baseline
Out-of-pocket health expenditure	Continuous variables including payments made by the individual per consultation and excluding health insurance premium, transportation costs and medical expenses reimbursed by the insurance