Avoidable hospitalizations and access to primary care: comparisons among Italians, resident immigrants and undocumented immigrants in administrative hospital discharge records.

Background: Immigrants face multiple barriers in accessing healthcare; however, empirical assessment of access presents serious methodological issues, and evidence on undocumented immigrants is scant and based mainly on non-representative samples. We examine avoidable hospitalization (AH) as an indicator of poor access to primary care (PC) in Italy, where a universal healthcare system guarantees access but fails to assign general practitioners to undocumented immigrants. Methods: Using anonymized national hospital discharge records in 2019, undocumented immigrants were identified through an administrative financing code. Potential effects of poor access to PC were measured by focusing on the incidence of AH, differentiated among chronic, acute and vaccine-preventable conditions, comparing Italian citizens, documented (foreign nationals with residence permits) and undocumented immigrants. We estimated odd ratios (ORs) through logistic regression models, controlling for individual and contextual confounders. Findings: Compared with Italians, undocumented and documented immigrants adjusted odd ratios (OR) for the risk of AH were 1·422 (95% CI 1·322-1·528) and 1·243 (95% CI 1·201-1·287), respectively. Documented immigrants showed ORs not significantly greater than 1 for AH due to chronic diseases compared with Italians, while undocumented immigrants registered higher adjusted OR for all AH categories - chronic (OR 1·187; 95% CI 1·064-1·325), acute (OR 1·645; 95% CI 1·500-1·803) and vaccine-preventable (OR 2·170; 95% CI 1·285-3·664). Interpretation: Documented and undocumented immigrants face considerably higher risk of AH compared to Italians. Considering the burden of AHs, access to PC (including preventive and ambulatory care) should be provided to undocumented immigrants, and additional barriers to care for all immigrants should be further explored. Funding: None.