National Audit of Angioplasty Procedures - HQIP

All models have limitations and thesesorts of results must be interpretedwith caution. The results are not onlydependent on the risk model butalso on the accuracy of data entry; apatient’s risk factors, as well as theadverse outcomes must be recordedand captured correctly. In addition,when comparing a large numberof observations, statistical variationmay cause units to appear to beoutliers when their performance isactually satisfactory. Finally, althoughgrouping all units into a single plotmakes assessment easier, units thatunder report adverse outcomes willtend to cause the entire funnel to shiftto lower major adverse cardiac andcerebrovascular events (MACCE) values.This, potentially, incorrectly exposesunits with higher reported MACCE whoare performing well and are carefulto make sure all complications areaccurately reported.This funnel plot appears to show threeunits performing statistically less wellthan would have been predicted bythe risk model. Closer analysis of theindividual units was performed. In two,cumulative funnel plots demonstratedthat they were in fact performing asexpected. In the third mistakes indata entry were identified (incorrectreporting of complications that did notoccur).To attempt to avoid under reporting ofadverse outcomes we plan to use amortality only model, with the data linkedto Medical Research Information Service(MRIS) to validate outcomes.Mortality tracking has been used inthis audit to assess the outcomesof relatively homogenous groups ofpatients. For example, the validated 30day mortality of all patients treated byPPCI for STEMI is shown in the funnelplot figure 16. In this figure, each unitis represented by a point on the graphaccording to the total number of primaryPCI procedures performed against their30 day mortality. No unit has a mortalityabove the 3 significant difference (SD)line, suggesting that no unit’s outcomesare statistically significantly worse thanthe average.3025BETTER% mortality at 30 days2015103 SD2 SDMean55.7%00100 200 300 400 500 600 700 800 900 1000Number of PPCI proceduresFigure 16Independently validated 30 day mortality following primary PCIincludes shock and ventilation (England and Wales only)18