Antiplatelet therapy and statins improve vascular surgery patient survival by 26% at five years

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The use of antiplatelet therapy and statins has increased over time; however, many patients remain medically undertreated around their vascular surgical procedures. An analysis of the Vascular Quality Initiative (VQI) including data for over 50,000 patients shows that optimal medical therapy improves survival by 26% at five years.

Patients undergoing vascular surgical procedures have a high rate of coronary artery and cerebrovascular disease, such that 75% of these patients ultimately die of cardiovascular causes. Antiplatelet and statin medications have shown to reduce cardiovascular events.

Randall De Martino, Mayo Clinic, Rochester, USA, who presented the analysis results on behalf of the VQI at the Society for Vascular Surgery Annual Meeting (5–7 June, Boston, USA), said: “Because of their beneficial effects, multiple societal guidelines recommend antiplatelet and statin use for patients with coronary artery, symptomatic peripheral arterial and cerebrovascular diseases. However, many patients remain medically undertreated and are not administered these medications at an opportune time such as surrounding vascular surgical procedures.”

The purpose of the study presented by De Martino was to evaluate antiplatelet and statin use across the VQI and identify the factors associated with improved medical management, such as the duration of participation in the VQI, as well as patient and procedural characteristics.

The investigators analysed all patients undergoing procedures within the VQI from 2005 to 2013 including carotid endarterectomy and stenting, open and endovascular aneurysm repair, peripheral vascular intervention, as well as supra and infrainguinal bypass procedures. The analysis was limited to the first time and elective procedure for each patient. The primary outcome was the use of medical management defined as the use of antiplatelet and statin medications, both preoperatively and prescribed at discharge. The secondary outcome was five-year mortality.

The study excluded patients undergoing urgent and emergent procedures, and patients (<1%) who had missing preoperative data on medications, leaving nearly 53, 000 patients available for perioperative analysis. For the survival analysis, patients who suffered in-hospital post-operative mortality, or who had missing discharge medication data were also excluded, leaving 50,108 patients (94%) of all eligible patients to provide five-year survival analysis.

Of the patient population studied, 37% underwent carotid interventions, 17% aneurysm repair, 16% bypass and 30% peripheral procedures.

De Martino explained that from 2005 to 2009 the use of optimal medical management increased from 55% to 68%—and that this was driven primarily by the Vascular Study Group of New England QI initiative to improve statin use. From 2009 to 2013 a large number of new centres entered the VQI; however, over the same time interval, optimal medical management within VQI dropped from nearly 70% to 59%. “It appeared that centres that joined over this time interval had reduced rates of medical management similar to those seen by centres in 2005 and 2006, deluding the overall rate of optimal medical management in the total of VQI cohort,” he said. “To investigate this we looked at medical management as a function of the length of the participation within the VQI. This analysis confirmed that longer participation was associated with improved medical management particularly after the third year.”

Furthermore, the rise in optimal medical management was not driven by any one procedure collected within VQI. But rather all procedures slowly increased rates of optimal medical management as a function of participation time within VQI.

By multivariable analyses, optimal medical management was less likely in older patients, those with chronic end-stage diseases as well as racial and ethnic minorities. As expected, patients with risk factors for vascular disease were more likely to be on optimal medical management. When analysed by procedure type, patients undergoing all non-carotid procedures were less frequently treated with optimal medical management. However, prolonged participation in VQI of at least three years was associated with improved medical management after controlling for other risk factors.

“Importantly, optimal medical management is associated with improved survival. Patients who were discharged on both antiplatelet and statin medications had five-year survival of 81%, and those discharged on neither medication had a survival of 55%—this represents an absolute survival benefit of 26% at five years,” De Martino noted. He added: “As expected the predictors of worse survival included increasing age, male gender, functional capacity, and advanced heart and renal diseases.”

De Martino told delegates that the findings were limited by the fact that these were observational data, therefore causation could not be proven. However, he said, “the multivariable model provides strong evidence for our conclusions”. In addition, he stated that “although medical adherence was not tracked year on year, we know that 85% of those discharged on these agents remained on them at one-year follow-up”.

“Importantly, optimal medical management improved survival. Patients who were discharged on both antiplatelet and statin medications had five-year survival of 81%, and those discharged on neither medication had a survival of 55%—this represents an absolute survival benefit of 26% at five years,” De Martino noted. He added: “As expected the predictors of worse survival included increasing age, male gender, functional capacity, and advanced heart and renal diseases. However, predictors of improved survival were VQI participation of over three years as well as discharge on optimal medical management of antiplatelet and statins, and these factors were independent.”

De Martino told delegates that the findings were limited by the fact that these were observational data, therefore causation could not be proven. However, he said, “the multivariable model provides strong evidence for our conclusions”. In addition, he stated that “although medical adherence was not tracked year on year, we know that 85% of those discharged on these agents remained on them at one-year follow-up”.

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