Impact of Foot Infection on Infrainguinal Bypass Outcomes in Patients With Limb-Threatening Ischemia (original) (raw)

2016, Journal of Vascular Surgery

demographic variables, comorbidities, and outcomes, including 30-day mortality, reoperation, bleeding, wound infection, myocardial infarction (MI), and stroke, were analyzed. For variables with different definitions between VQI and NSQIP-PT, a standardized definition was created to permit comparison across databases. Differences in categoric variables were tested using the Pearson c 2 test, binary variables with two-sample tests of proportions, and in continuous variables using the Wilcoxon rank-sum test. Measures of central tendency are presented as medians with interquartile range. To account for any baseline differences that may be due to regional variability relative to national averages rather than a true difference between the data sets, VQI records were propensity-matched 1:1 with NSQIP-PT records. Creating these matched cohorts allows a comparison of outcomes between databases that in theory adjusts for any case-mix differences. Propensity scores were derived from a model that included all demographic and comorbidity variables that were significantly different between the two data sets in unadjusted analyses. Standardized bias was used as the metric for adequate balance. Differences in outcomes were tested as previously described. Statistical significance for all tests was set at a ¼ .05. Results: Sample. The VQI database contained 1358 records from 2011 to 2015. The NSQIP-PT database contained 5613 records, of which 340 could not be matched to the general NSQIP PUFs, giving a total of 5273 complete NSQIP records, including cases from 2011 to 2013. Intradatabase reliability. Several outcomes are captured twice in NSQIP records, once as part of the procedure-targeted module and once in the general PUF. Standardized definitions were used to evaluate the patient-level correlation between NSQIP-PT and NSQIP outcomes in wound infection, composite MI and stroke, and bleeding. Agreement was 92% (k ¼ 0.56) for wound infection, 99% (k ¼ 0.85) for any postoperative MI or stroke, and 83% for postoperative bleeding (k ¼ 0.52). Patient populations. Patients in VQI are younger than in NSQIP (65 [15] vs 68 [16] years; P < .001), and have a slightly higher BMI (27.6 [8.3] vs 27.0 [7.5] kg/m 2 ; P ¼ .003). VQI also had a higher proportion of recent smokers (46% vs 41%; P ¼ .001) and patients with CHF (16% vs 3.1%, P < .001) and COPD (29% vs 13%; P < .001). VQI patients were also less likely to be on dialysis (3.9% vs 6.1%; P ¼ .003) or on preoperative aspirin (62% vs 79%; P < .001) or statin therapy (63% vs 68%; P < .001). Rates of diabetes were similar across databases (47% vs 45%, P ¼ .1). Prior ipsilateral percutaneous interventions/stents were recorded in 23% and 22% of VQI and NSQIP patients, respectively (P ¼ .6), but VQI patients were much less likely to have had a prior ipsilateral bypass (15% vs 28%, P < .001). Emergency cases accounted for 4.6% and 5.6% of VQI and NSQIP cases respectively (P ¼ .1). Outcomes. Overall 30-dday mortality was equivalent between VQI and NSQIP (2.0% vs 1.8%; P ¼ .6; Table), as was composite MI/stroke (3.9% vs 3.2%; P ¼ .2). Major amputation, return to the OR, and wound infection rates were higher in NSQIP relative to VQI (3.3% vs 1.6%, P ¼ .002; 16% vs 12%, P < .001; and 13% vs 1.4%, P < .001, respectively). Bleeding rates, however, were higher in VQI (37% vs 17%; P < .001). Total and postprocedure length of stay were both equivalent between VQI and NSQIP (6 [8] vs 6 [7], P ¼ .7; and 4 [5] vs 5 [4], P ¼ .2). Propensity-matched analysis. The propensity-matching model generated 1266 pairs of records that were well matched on all included covariates (20% standardized bias or less). The C statistic of the matching model was 0.77 before matching, and appropriately decreased to 0.56 in the matched sample. Similar to the unmatched cohorts, there was no statistically significant difference between VQI and NSQIP outcomes in 30-day mortality (1.9% vs 1.6%; P ¼ .5), or composite MI/stroke rates (3.9% vs 3.0%; P ¼ .2). In the matched cohort, the difference in major amputation rates between VQI and NSQIP is no longer significant (1.4% vs 2.4%, P ¼ .1). Rates of wound infection and return to OR remain significantly higher in NSQIP (13% vs 1.2%, P < .001; 15% vs 11%, P ¼ .008, respectively), whereas bleeding rates remain higher in VQI (36% vs 15%, P < .001). Conclusions: This is the first study to compare overall population and outcome differences between the VQI and NSQIP-PT registries. We find