The US hospital standardised mortality ratio: Retrospective database study of Massachusetts hospitals

SummaryObjectivesTo present a case-mix adjustment model that can be used to calculate Massachusetts hospital standardised mortality ratios and can be further adapted for other state-wide data-sets.DesignWe used binary logistic regression models to predict the probability of death and to calculate the hospital standardised mortality ratios. Independent variables were patient sociodemographic characteristics (such as age, gender) and healthcare details (such as admission source). Statistical performance was evaluated using c statistics, Brier score and the Hosmer–Lemeshow test.SettingMassachusetts hospitals providing care to patients over financial years 2005/6 to 2007/8.Patients1,073,122 patients admitted to Massachusetts hospitals corresponding to 36 hospital standardised mortality ratio diagnosis groups that account for 80% of in-hospital deaths nationally.Main outcome measuresAdjusted in-hospital mortality rates and hospital standardised mortality ratios.ResultsThe significant factors determining in-hos...