Table 2 Inclusion and exclusion criteria according to PICOS guidelines

Population

Inclusion: Studies conducted in LMICs. The list of eligible countries is provided in Additional file 2, following the World Bank classification of countries by income groups.

Exclusion: Studies conducted in high-income countries.

Intervention

Inclusion: Relevant measures of health financing fragmentation (e.g., risk pools, benefits packages, premiums, payment mechanisms to providers, and funding organizations in the health system).

Exclusion: Measures not related to health systems fragmentation or concerning fragmentation in healthcare provision (e.g., fragmentation of care index, a metric of dispersion of medical visits across different providers).

Comparison

Inclusion: Any relevant measure of financing fragmentation in alternative settings (i.e., intervention and control groups) or at alternative time points (e.g., before and after an intervention implementation).

Exclusion: Studies with no comparator and a single data point

Outcomes

Inclusion: The primary outcomes will be health system-related goals such as health outcomes (e.g., mortality, morbidity, patient-reported outcome measures) and indicators of access, services utilization, equity, and financial risk protection. Additional outcomes will include intermediate health system objectives (e.g., indicators of efficiency and quality).

Exclusion: Outcomes not related to health systems’ goals.

Study

Inclusion: Eligible designs are experimental (e.g., randomized controlled trials), quasi-experimental (e.g., interrupted time series, pretest-posttest, regression discontinuity, difference-in-difference, and propensity score matching analyses), or observational studies (e.g., cross-sectional studies, case-control, cohort studies). Included studies will be restricted to articles and working papers published in English, Portuguese, or Spanish and with free access to the full text. There are no date restrictions.

Exclusion: Non-empirical, qualitative, or descriptive studies (e.g., editorials, experts’ opinions, meeting reports, news items, case series, case reports, case studies, interview-based studies).