Even before the 2018 Declaration of Astana reaffirmed the global commitment to primary healthcare (PHC), many academics, nongovernmental organizations, and policymakers have promoted strong PHC as a crucial foundation of successful health systems, given increasing population demand for higher-quality services, rising health costs, and the emergence of non-communicable diseases (Bitton et al., 2017). However, many middle-income countries – as well as some high-income ones – today still face inadequate PHC. One of the reasons could be that quantifying the contribution of PHC to health outcomes poses many empirical challenges. PHC is often deeply embedded in larger health systems, and policymakers usually assign PHC interventions nonrandomly, creating selection bias and confounding factors for which it is difficult to control. Additionally, given the nature of preventive medical care, advances in PHC may take many years to become apparent, and the effect of PHC may increase over time. To overcome some of these challenges, recent papers have used natural experiments to quantify the effect of increasing the availability of PHC on mortality (Bhalotra et al., 2019, Bailey and Goodman-Bacon, 2015, Rocha and Soares, 2010). However, evidence on the effectiveness of large-scale, long-term PHC interventions on mortality remains scarce (Bitton et al., 2019, Hirschhorn et al., 2019, Coarasa et al., 2017, Kruk et al., 2010).

In this paper, we use the rollout of the Costa Rican PHC intervention of 1995 as a natural experiment to estimate the impact of PHC on mortality. The Costa Rican PHC intervention began in 1995, when the predominant healthcare provider in the country, namely, the publicly owned Costa Rican Social Security Fund (CCSS), gradually consolidated, improved, and expanded its PHC system. The intervention involved a staggered rollout of Health Areas (HAs), which are new primary care clinics that provide comprehensive, continuous, and coordinated primary care. The intervention’s main strategies included the consolidation of public health services, preventive care, and curative care at the primary care level, the geographic empanelment of Costa Ricans to specific HAs based on their place of residence, and the development of multidisciplinary healthcare teams. Currently, Costa Rica continues to invest in its PHC model without an estimation of the long-term effects of HAs on health. By 2019, the CCSS had created 106 HAs staffed by nearly 10,700 health professionals. HAs also represented a significant share of the total outpatient medical visits at the CCSS (around 75% of total outpatient visits) and a significant share of health expenditure (65% of total outpatient expenditure and almost 20% of the CCSS budget).

Our empirical strategy exploits the fact that HAs were rolled out across the country to different districts at different times, while also considering that some districts in Costa Rica had not received a HA by the end of our analysis. We test whether populations empaneled to an open HA experience reduced mortality relative to the level experienced before the HA opened and to populations without a HA. Since we are interested in estimating the dynamic effect of PHC over time, we employ an estimator that accounts for potential biases that may arise when treatment effects vary over time and do not require random treatment assignment (Sun and Abraham, 2021). Our outcome of interest is the age-adjusted mortality rate (AMR), which reflects changes in the likelihood of dying rather than changes in the population structure. We calculate the AMR using vital statistics from nationwide death records and population estimates from 1990 to 2011.

The main results show that HA opening is associated with a strong and persistent decline in the AMR. One year after HA opening, the AMR declines by 4% (14 fewer deaths per 100,000 people), and the effect increases over time, reaching a 13% reduction (49 fewer deaths per 100,000 people) nine years after HA opening. These results are robust to standard sensitivity tests, such as including and excluding various controls.

To examine where the effect of PHC on mortality is strongest, we further disaggregate by age group the relationship between HA opening and the AMR. We do so because HAs may have differential effects on different age groups as they emphasize different treatment protocols depending on the patient’s age, and because different age groups have different epidemiological profiles that may be more or less sensitive to primary care. We examine the effect on children, teens, adults, and older adults and find that mortality reductions are 1.7 times larger in people older than 65 years of age, as compared to the all-age AMR reduction nine years after opening a HA.

We then analyze the effects of different causes of death as certain conditions are more sensitive to primary care than others. We find stronger mortality reductions in cardiovascular, cancer, respiratory, and diabetes-related deaths, consistent with HAs showing decreased mortality from primary care-sensitive conditions such as chronic and noncommunicable diseases that can be easily diagnosed but require continuity of treatment. We also find no relationship between HA opening and mortality from car accidents, homicides, and suicides, consistent with HAs providing outpatient primary care and not inpatient, emergency room services.

In the last part of the paper, using two representative household surveys conducted before and after the intervention, we show that opening a HA increases the likelihood of receiving outpatient primary care and that this effect is strongest among older adults. In line with previous literature, we also find a decrease in emergency room visits after the PHC intervention; this effect was also strongest among older adults.

We conclude that this PHC intervention effectively decreases mortality mainly through an impact on the elderly and on deaths from noncommunicable diseases in Costa Rica. This study provides further evidence that PHC is an effective mechanism by which middle- and high-income countries with inadequate PHC can improve health outcomes and pursue universal health coverage.