INTRODUCTION: Ageing populations and the increasing prevalence of multimorbidity are a challenge for healthcare delivery and health system design. Integrated care has been discussed as a solution to address these challenges. In Portugal, Local Health Units (LHU) promote vertical integration of healthcare, with one of the expected effects being a decrease of readmission rates in individuals with chronic conditions. Readmissions are frequently studied for its negative impacts on individuals, carers, and providers, with excessive unplanned readmission rates among hospitals being a sign of frail integrated care. Thus, we assume as the main aim of this study to assess the impact of vertical integration on the readmission of individuals with chronic conditions.
METHODS: A database including administrative data from 1 679 634 inpatient episodes from years 2002-14 was considered. We identified readmissions with the hospital-wide all-cause unplanned readmission measure methodology of Centers for Medicare and Medicaid Services. The considered outcome was 30-day hospital-wide all-cause unplanned readmissions (1: readmitted), and risk-standardized readmission ratio. Chronic conditions were identified from all diagnoses coded with International Classification of Diseases – 9th version – Clinical Modification codes (1: chronic). In order to assess the impact of LHU on the readmission of individuals with chronic conditions, we compared 30-day readmissions before and after the creation of each LHU. We used difference-in- differences technique to address our main aim. In addition, to understand the associations between individuals’ risk factors and time to readmission, we developed a Cox regression model for LHU and control group.
RESULTS: Difference-in-differences results suggest that vertical integration promoted a decrease on risk-standardized readmission ratio in four LHU, but significant only in LHU 1. In addition, when analysed the individual risk of readmission we observed that it was reduced for four LHU, but only significantly for LHU 3 and LHU 5. A sensitivity analysis was performed for annual evolution of odds ratio of risk of readmission, and initial results were considered stable for most years. Cox regression results suggest that for LHU and control hospitals, female individuals were less at risk of readmission than men, the risk increased with increasing age and number of comorbidities. At LHU, we observed a decreased risk of readmission with increasing number of chronic conditions.