[Hospital mortality and length of stay: comparison between public and private hospitals in Ribeirão Preto, São Paulo State, Brazil].

Performance assessment in health services is essential. The comparison of performance indicators requires the use of risk adjustment strategies. The objective of this paper was to assess variations in clinical performance, measured by hospital mortality and length of stay, between private and public hospitals, while taking into account the hospital case mix. This study is located in the Ribeirão Preto region in São Paulo State, Brazil. From 1996 to 1998, 32,906 patients admitted with cardiovascular and respiratory diagnoses were studied. Variables used for risk adjustment of performance indicators were: sex, age, principal diagnosis, and severity measures based on co-morbidity. Clinical performance in public hospitals as measured by adjusted hospital mortality (OR = 0.41) was better than in private hospitals. Public and private hospitals were not statistically different concerning patients' length of stay. Although some conceptual and methodological problems persist, hospital mortality and other adjusted performance indicators should be considered as useful tools to identify health services' performance problems.