Background
Primary health care (PHC) is an essential part of Universal Health Coverage (UHC) and key to achieving the Sustainable Development Goals (SDGs), but a lack of robust evidence, including on disaggregated effects, in low and middle-income countries (LMICs) is limiting prioritisation of PHC in national and international health agendas. The Brazilian Family Health Strategy (the Estratégia de Saúde da Família (ESF)) is an important setting for understanding disaggregated effects of primary care given that it is a highly replicable PHC model that has been rapidly expanded in recent years and excellent data systems exist to facilitate evaluation.

Objective
To generate evidence on the differential impact of the ESF across geographical and population sub-groups.

Methods
1. Fixed-effects longitudinal regression of 1,622 municipalities is employed examining the association between ESF coverage and amenable mortality by the strength of municipal governance. 2. Fixed-effects longitudinal regression of 1,622 municipalities is employed examining differential associations between ESF coverage and ambulatory care-sensitive conditions (ACSC) across racial groups. 3. Survival analysis is undertaken on 601,208 adults (aged 18-74) from a disadvantaged urban population in Rio de Janeiro and the overall and disaggregate effects of ESF registration on mortality are examined.

Results
Expansion and coverage with the ESF was associated with reductions in mortality in all three analyses: 1. Amenable mortality declined on average 1.7% a year whilst expanding municipal ESF coverage from 0 to 100% was associated with 6.8% reduction in amenable mortality. Examining differences by strength of municipal governance revealed ESF expansion was associated with greater reductions in amenable mortality in the municipalities with the highest governance scores. 2. ACSC mortality decreased annually by 3.4% for the black/pardo study population and by 2.9% in the white population. There were different effects of expanding ESF between racial groups with a 100% increase in municipal ESF coverage associated with a 15.4% reduction in ACSC mortality in the black/pardo population and a 6.8% reduction in the white population. 3. Adults in Rio de Janeiro who were registered with ESF teams had an 18% reduction in the risk of mortality from ACSCs.

Conclusions
This thesis demonstrates that, whilst many other factors have contributed to better health in Brazil over recent decades, primary care has played a role in reducing mortality especially in disadvantaged populations. Policy-makers should pay greater attention to the role primary care has in global development agendas for UHC and the SDGs.