Summary
Objectives: To compare the quality of care regarding the use of elective percutaneous coronary
interventions (PCIs) in the inpatient and outpatient setting and to evaluate different
methods of confounder control in this context.
Methods: Based on data of three statutory health insurances including more than nine million
insurance members, a retrospective cohort study between 2005 and 2009 was conducted.
The occurrence of myocardial infarction, stroke, further coronary intervention and
death was ascertained following the first PCI in the study period, which was preceded
by a one-year period without a PCI. A Cox proportional hazard model was used to assess
the influence of the setting of the elective PCI on the risk for complications after
the PCI for each outcome separately. Age, sex, the number of diseases of the Elixhauser
comorbidity measure, past acute coronary syndrome, coronary artery disease, dyslipidemia,
past stroke, past coronary artery bypass surgery and the year of the PCI were included
as covariables. The analyses were repeated in a propensity score matched cohort as
well as in inverse probability of treatment weighted analyses.
Results: The cohort comprised 4,269 patients with an outpatient PCI and 26,044 patients with
an inpatient PCI. The majority of the analyses revealed no statistically significant
effect of the setting of the PCI on the risk of myocardial infarction, stroke and
further coronary interventions, whereas a reduced mortality risk was observed for
out-patient PCIs. Similar results were obtained in the propensity score analyses.
Conclusions: The analysis revealed that the adjusted risk for complications following an elective
PCI is similar between the inpatient and the outpatient setting. For mortality the
risk differed but this might be explained by residual or unmeasured confounding. The
different methods applied in this study revealed mostly similar results. Since our
study only covered one aspect of quality of care in the field of PCI and did not consider
drug treatment in hospital or in the outpatient setting, further studies are needed
which include these aspects.
Keywords
Percutaneous coronary intervention - quality of health care - outpatient and inpatient
care - methods for confounder control
