SLR - June 2010 - Joshua Worley

Clinical success using patient-oriented outcome measures after lower extremity bypass and endovascular intervention for ischemic tissue loss

Taylor, S., York. J., Cull, D., Kalbaugh, C., Cass, A., Langan, E. Clinical success using patient-oriented outcome measures after lower extremity bypass and endovascular intervention for ischemic tissue loss. Journal of Vascular Surgery. (2009) 50: 534-541 

Scientific Literature Reviews

Reviewed by:  Joshua Worley, DPM
Residency Program: Florida Hospital East Orlando

Podiatric Relevance:
Understanding that not all patients with critical limb ischemia are candidates for vascular intervention, and the patient variables that influence the success of vascular intervention, is paramount in our role as limb salvage experts.  

A retrospective study of 677 consecutive patients who underwent technically successful unilateral revascularization for ischemic tissue loss were analyzed for successful outcome using four clinical endpoints: (1) interventional or graft patency to the point of wound healing, (2) limb salvage for 1 year, (3) maintenance of ambulatory status for 1 year, and (4) survival for 6 months.  Of the 677 procedures, 316 were endovascular intervention and 361 were open bypasses.  Type of intervention performed was at the discretion of the attending physician.  Only patients who achieved all four of the criteria were considered to have had a successful outcome.   The influence of a series of patient factors and comorbidities on clinical success was analyzed using bivariate and multivariate logistic regression analysis.  Factors analyzed included age, gender, ethnicity, history of cigarette smoking, the presence or history of multiple co-morbidities, independent living status, preoperative ambulatory status, level of atherosclerotic disease, presentation (ischemic vs. gangrene) and type of intervention.  Also, comorbidities found to be statistically significant in bivariate analysis were studied using logistic regression analysis to determine independent predictors of failure.  Probability of failure (%) was calculated for each predictor and for combinations of predictors. 

 The results based on clinical endpoints were the following: intervention or graft patency to wound healing 295/677 (43.6%), limb salvage for 1 year 512/677 (75.6%), maintenance of ambulatory status for 1 year 572/677 (84.5), survival for 6 month 573/677 (84.6%).  When all four parameters were combined, clinical success was achieved in 277/677 (40.9%) of patients.  The most influential element was patency to the point of wound healing (43.6% overall success).  The independent predictors of adverse outcomes that were the most statistically significant using  bivariate analysis was presence of diabetes mellitus, presence of endstage renal disease, diagnosis of dementia, history of prior vascular surgery, independent living status, impaired ambulatory status at presentation, presence of infrainguinal disease requiring bypass, and patients treated with endovascular intervention.  Statistically significant patient predictors of failure after revascularization included impaired ambulatory status at presentation, presence of diabetes, presence of end stage renal disease, presence of gangrene, and history of prior vascular intervention.  The presence of hyperlipidemia was an independent predictor of success.  The type of treatement (endovascuar vs open) did not predict successful outcome.  The probability of failure increased significantly when associated with each independent predictor.  If no independent predictors of failure were present at the time of revascularization, the probability of failure was 35.4%.  If a patient presented with all 8  independent predictors of adverse outcomes, then the probability of failure was 92.8%.  

The determination of a successful outcome after lower extremity revascularization has historically been based on physician oriented end points such as graft patency and limb salvage.  This study and ones like it demonstrate that patient oriented endpoints such as the four described in the study can better measure treatment effectiveness. Understanding the patient's risk factors and there contribution to successful outcome with vascular intervention is a critical tool necessary when predictors significantly favor palliative or primary amputation.  

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