Objective Percutaneous coronary intervention (PCI) has seen substantial shifts in patient selection in recent years that have increased baseline patient mortality risk. It is unclear to what extent observed changes in mortality are attributable to background mortality risk or the indication and selection for PCI itself. PCI-attributable mortality can be estimated using relative survival, which adjusts observed mortality by that seen in a matched control population. We report relative survival ratios and compare these across different time periods.
Methods National Health Service PCI activity in England and Wales from 2007 to 2014 is considered using data from the British Cardiovascular Intervention Society PCI Registry. Background mortality is as reported in Office for National Statistics life tables. Relative survival ratios up to 1 year are estimated, matching on patient age, sex and procedure date. Estimates are stratified by indication for PCI, sex and procedure date.
Results 549 305 procedures were studied after exclusions for missing age, sex, indication and mortality status. Comparing from 2007 to 2008 to 2013–2014, differences in crude survival at 1 year were consistently lower in later years across all strata. For relative survival, these differences remained but were smaller, suggesting poorer survival in later years is partly due to demographic characteristics. Relative survival was higher in older patients.
Conclusions Changes in patient demographics account for some but not all of the crude survival changes seen during the study period. Relative survival is an under-used methodology in interventional settings like PCI and should be considered wherever survival is compared between populations with different demographic characteristics, such as between countries or time periods.
- coronary intervention
- quality in health care
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Patient consent for publication Not required.
Contributors WJH, MAM: conceived the study. WJH, GPM, MS, EK: participated in the design of the study. WJH: performed the statistical analysis and drafted the manuscript. WJH, GPM, MS, EK, NC, PL, MAM: interpreted the data and results, made important contributions and revisions to the work and read and approved the final manuscript.
Funding This work was supported by MRC grant number MR/K006665/1.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement Analysis scripts and a synthetic test dataset are available on GitHub: https://zenodo.org/badge/latestdoi/131696652
Collaborators British Cardiovascular Intervention Society; National Institute for Cardiovascular Outcomes Research
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