Abstract
Objective:
Physician-oriented outcomes, such as patency and amputation-free survival (AFS), have traditionally been markers of success after lower extremity revascularization. Previous studies have defined clinical success based on a composite of patient-centered outcomes and have shown this outcome to be achieved in less than 50% of patients, far lower than standard physician-oriented outcomes. The purpose of this study is to evaluate clinical success after lower extremity bypass (LEB) or peripheral vascular intervention (PVI) for tissue loss in diabetic patients treated in a multidisciplinary setting to better understand what factors are associated with success from a patient’s perspective.
Methods:
All patients presenting to our multidisciplinary diabetic limb preservation service from July 2012 to January 2020 were enrolled in a prospective database. Patients who underwent either LEB or PVI for ulcer or gangrene were included in the analysis. Clinical success was defined as the composite outcome of secondary patency to the point of wound healing, limb salvage for 1 year, maintenance of ambulatory status for 1 year, and survival for 6 months. Secondary outcomes included 1-year wound healing, patency, and AFS.
Results:
A total of 134 revascularizations were performed in 131 patients, including 91 (68%) PVI and 43 (32%) LEB. Patients were more frequently male (64%) and black (61%), and 16% were dialysis-dependent. All patients had tissue loss (53% ulcer, 47% gangrene). There were 5 (3.7%) wound, ischemia, and foot infection stage 1, 6 (6.0%) stage 2, 29 (22%) stage 3, and 92 (69%) stage 4 limbs at the time of revascularization. Overall, 76.9% of patients preserved secondary patency to the point of wound healing, 92.5% had limb salvage for 1 year, 90.3% had maintenance of ambulatory status for 1 year, and 96.3% survived for 6 months. The clinical success composite outcome was achieved in 71.6% of patients and was not statistically different between those undergoing PVI vs LEB (69.2% vs 76.7%, P = .37). Secondary patency, limb salvage, and AFS at 1 year were 80.8% ± 3.6%, 91.8% ± 2.3%, and 83.3% ± 3.1%, respectively. Wound healing at 1 year was 84.3% ± 3.4%. The only covariate associated with clinical failure on multivariable analysis was increased age (odds ratio, 0.95; 95% confidence interval, 0.91-0.99; P = .008).
Conclusions:
Among diabetic patients presenting with tissue loss, the composite outcome of patient-centered clinical success is lower than traditional physician-centered outcomes after lower extremity revascularization, mostly due to low rates of secondary patency to the point of wound healing. In the current study, clinical failure was only associated with older age and was no different after PVI compared with LEB.
Keywords: Peripheral arterial disease, Limb preservation, Diabetic foot wound, Multidisciplinary
Chronic limb-threatening ischemia is a complex spectrum of disease, and its management must weigh patient risk, limb severity, and anatomic complexity.1 Multiple trials have attempted to guide decisionmaking by comparing endovascular and open options using outcomes such as patency rates and limb salvage.2–4 The Society for Vascular Surgery Lower Extremity Threatened Limb Classification System was designed to categorize limbs based on the presence and severity of wound(s), ischemia, and foot infection (WIfI).5 The WIfI schema has proven helpful in predicting outcomes after revascularization, with higher stage associated with poor wound healing and higher amputation rates.6–8 We have previously shown the WIfI stage to be independently associated with wound healing in our multidisciplinary diabetic limb preservation service, with increasing WIfI stage being the strongest predictor of delayed wound healing on multivariable analysis.9,10
Although patency and limb salvage are important measures of revascularization success for both physicians and patients, other factors may also be of concern to patients, such as the ability to return to their baseline preoperative functional and ambulatory status and perform their activities of daily living. These patient-centered metrics are less frequently evaluated in the literature. Recently, Khan et al11 proposed including ambulatory status as a component within the WIfI classification as an additional factor to consider during preoperative decision-making. Postoperative ambulation as an outcome of revascularization has been associated with preoperative functional status, WIfI stage, and patient age and comorbidities.12 Taylor et al13 had previously described a new patient-centered outcome measure of clinical success and defined this as a composite of secondary patency to the point of wound healing, limb salvage to 1 year, maintenance of ambulatory status to 1 year, and survival to 6 months. Their rates of clinical success were much lower than traditional metrics for success at 41%, with no significant difference between patients undergoing open vs endovascular intervention.14 This was driven by poor patency to the point of wound healing, suggesting that more durable revascularizations and aggressive wound healing modalities may lead to improved patient-centered clinical success. Our objective was to evaluate clinical success using this metric after lower extremity bypass (LEB) or peripheral vascular intervention (PVI) for tissue loss in patients treated by our multidisciplinary diabetic limb preservation service.
METHODS
Population.
All inpatients and outpatients enrolled in our multidisciplinary diabetic limb preservation service since July 2012 were followed in a prospectively maintained database. This service has previously been described.9 Our integrated service consists of vascular surgery, surgical podiatry, and endocrinology, with involvement of a prosthetist, wound care nurse, and infectious diseases, orthopedic foot and ankle surgery, and plastic surgery as needed. As part of our paradigm, patients with nonhealing wounds and an absolute toe pressure of ≤60 mm Hg undergo a diagnostic angiogram and either simultaneous endovascular recanalization or subsequent LEB.15 For this analysis, we included all patients from July 2012 through January 2020 who had an ulcer or gangrene and subsequently underwent first-time PVI or LEB. Only the initial intervention on each limb was included, with a second limb only being included if the intervention occurred greater than 1 year after the first intervention. The Johns Hopkins Hospital institutional review board approved this study. All patients signed informed consent for longitudinal data collection and analysis.
Variables.
Our prospective database records demographic and socioeconomic information for each patient and is maintained longitudinally. All patients have diabetes. Other comorbid conditions are recorded in a binary fashion per patient report and electronic medical record review. The WIfI stage5 just before revascularization was used for this analysis. We defined level of disease as either femoropopliteal segment, tibial or distal, or multilevel, which includes both femoropopliteal and tibial disease, as per our prior analyses.16
We defined clinical success using the previously established definition from Taylor et al,13 where success is achieved if the patient maintains a composite of: (1) secondary patency to the point of wound healing, (2) limb preservation at 1 year, (3) preservation of ambulatory status at 1 year, and (4) survival to 6 months. Intervention or graft patency was followed with serial duplex ultrasonography starting at 6 weeks postoperatively, and every 3 months thereafter for the first year. Wound healing was defined as complete epithelialization for 6 weeks with sustained functional and anatomic continuity.17,18 Limb salvage was defined as avoiding a below-knee or above-knee amputation on the side of the intervention. Preoperative ambulatory status was determined from patient report of their ambulation before development of the wound, with patients categorized as fully ambulatory, in-house ambulation, transfer only, or fully bedridden. None of the patients in this analysis were fully bedridden preoperatively. Ambulatory status was then recorded at subsequent clinic visits through patient report and direct observation. A change in ambulatory status was defined as per the studies from Taylor et al13,14 as “a permanent postoperative change in ambulatory classification, despite full recover from operation.” Survival was established from a combination of clinical follow-up, electronic medical record review, and Social Security Death Index queries.
Statistical analysis.
Categorical variables were presented as number (percentage) and continuous variables as mean (± standard deviation). We performed bivariate analyses comparing patient clinical characteristics among those who underwent PVI vs LEB using the Pearson χ2 test for categorical variables and Student’s t-test for continuous variables, where appropriate. Kaplan-Meier curve analyses estimated traditional markers of success, including survival, amputation-free survival, limb salvage, wound healing, and primary and secondary patency and were presented as estimate ± standard error. The log-rank test compared 1-year outcomes for PVI vs LEB. We assessed each component of clinical success, as defined above, with a binary outcome, with the overall measure of clinical success only achieved if all four individual measures were met. If a patient died before 6 months and therefore did not have 1-year follow-up data for the other components, that patient was considered a clinical failure. Patients who lived greater than 6 months but less than 1 year were included only if they failed one of the other three patient-centered components. Patients who lived great than 6 months but less than 1 year and did not fail any of the other three patient-centered components were excluded if they did not have 1-year follow-up. In addition, we performed a subanalysis in which the outcome of clinical success used 1 year for all time points, including survival. Stepwise logistic regression was then performed to assess the associations between patient characteristics and the binary primary outcome of clinical success, removing variables one at a time until all remaining variables had P < .01, with the repair type (PVI vs LEB) forced into the model. For the multivariable analyses, clustering was performed by the patient. Preoperative in-house ambulation and transfer only were grouped together as impaired ambulation for the multivariable analysis. All tests were two-sided, and we considered a P value of less than .05 statistically significant. Statistical analysis was conducted using STATA version 14 (StataCorp LP, College Station, Tex).
RESULTS
We identified 131 patients who underwent 134 interventions for ulcer or gangrene during the study period, of which 91 (68%) were PVI and 43 (32%) LEB. The median follow-up time was 21.5 months (interquartile range, 10.3-43.4 months). Demographics and comorbid patient conditions are displayed in Table I. All patients had diabetes, with 8.4% of patients having type I diabetes mellitus. There were no differences in baseline demographics or comorbidities by procedure type. LEB procedures were more often performed urgently (58% vs 34% of limbs, P = .008) and for gangrene as opposed to ulceration (65% vs 39% of limbs, P = .004; Table II). Although not statistically significant, LEB tended to have higher WIfI stages and more multilevel diseases compared to PVI. There were no differences in preoperative ambulation by procedure type.
Table I.
Baseline characteristics of patients presenting with diabetic foot wounds
| Characteristic | Overall (N = 131) | PVI (N = 89) | LEB (N = 42) | P value |
|---|---|---|---|---|
| Age, years | 65.0 (11.1) | 65.9 (11.0) | 63.1 (11.3) | .91 |
| Male sex | 84 (64.1%) | 58 (65.2%) | 26 (61.9%) | .72 |
| Race | .11 | |||
| White | 44 (33.6%) | 35 (39.3%) | 9 (21.4%) | |
| Black | 80 (61.1%) | 49 (55.1%) | 31 (73.8%) | |
| Other | 7 (5.3%) | 5 (5.6%) | 2 (4.8%) | |
| Body mass index | 29.8 (7.1) | 29.6 (6.8) | 30.3 (7.6) | .29 |
| Type of diabetes | .75 | |||
| DM-I | 11 (8.4%) | 7 (7.9%) | 4 (9.5%) | |
| DM-II | 120 (91.6%) | 82 (92.1%) | 38 (90.5%) | |
| Comorbidities | ||||
| Hypertension | 121 (92.4%) | 81 (91.0%) | 40 (95.2%) | .40 |
| Dyslipidemia | 96 (73.3%) | 65 (73.0%) | 31 (73.8%) | .93 |
| Coronary artery disease | 57 (43.5%) | 38 (42.7%) | 19 (45.2%) | .78 |
| Congestive heart failure | 25 (19.1%) | 19 (21.4%) | 6 (14.3%) | .34 |
| Chronic kidney disease | 26 (19.9%) | 17 (19.1%) | 9 (21.4%) | .76 |
| Dialysis | 21 (16.0%) | 17 (19.1%) | 4 (9.5%) | .16 |
| Kidney transplant | 15 (11.5%) | 8 (9.0%) | 7 (16.7%) | .20 |
| COPD | 5 (3.8%) | 3 (3.4%) | 2 (4.8%) | .70 |
| Smoking status | .04 | |||
| Current | 27 (20.6%) | 13 (14.6%) | 14 (33.3%) | |
| Former | 49 (37.4%) | 35 (39.3%) | 14 (33.3%) | |
| Never | 55 (42.0%) | 41 (46.1%) | 14 (33.3%) | |
| Preoperative functional status | .72 | |||
| Independent | 106 (80.9%) | 72 (80.9%) | 34 (81.0%) | |
| Partially or fully dependent | 25 (19.1%) | 17 (19.1%) | 8 (19.1%) |
COPD, Chronic obstructive pulmonary disease; DM, diabetes mellitus; LEB, lower extremity bypass; PVI, peripheral vascular intervention.
Data are presented as n (%) or mean (standard deviation).
Table II.
Baseline limb and wound characteristics
| Characteristic | Overall (N = 134) | PVI (N = 91) | LEB (N = 43) | P value |
|---|---|---|---|---|
| Procedure urgency | .008 | |||
| Nonurgent | 78 (58.2) | 60 (65.9) | 18 (41.9) | |
| Urgent | 56 (41.8) | 31 (34.1) | 25 (58.1) | |
| Tissue loss | .004 | |||
| Ulcer | 71 (53.0) | 56 (61.5) | 15 (34.9) | |
| Gangrene | 63 (47.0) | 35 (38.5) | 28 (65.1) | |
| WIfI clinical stage | .055 | |||
| 1 | 5 (3.7) | 5 (5.5) | 0 (0) | |
| 2 | 8 (6.0) | 7 (7.7) | 1 (2.3) | |
| 3 | 29 (21.6) | 23 (25.3) | 6 (14.0) | |
| 4 | 92 (68.7) | 56 (61.5) | 36 (83.7) | |
| Level of disease | .17 | |||
| Femoropopliteal | 9 (6.7) | 7 (7.7) | 2 (4.7) | |
| Tibial | 44 (32.8) | 34 (37.4) | 10 (23.3) | |
| Multilevel | 79 (59.0) | 48 (52.8) | 31 (72.1) | |
| Prior vascular intervention | 18 (13.4) | 8 (8.8) | 10 (23.3) | .02 |
| Preoperative ambulation | .62 | |||
| Fully ambulatory | 96 (71.6) | 67 (73.6) | 29 (67.4) | |
| In-house ambulation | 22 (16.4) | 13 (14.3) | 9 (20.9) | |
| Transfer only | 16 (11.9) | 11 (12.1) | 5 (11.6) | |
| Bedridden | 0 (0) | 0 (0) | 0 (0) |
LEB, Lower extremity bypass; PVI, peripheral vascular intervention; WIfI, wound, ischemia, and foot infection.
Data are presented as n (%)
Traditional markers of revascularization success were high, with overall 1-year survival 91.1% ± 2.4%, amputation-free survival 83.3% ± 3.1%, limb salvage 91.8% ± 2.3%, and wound healing 84.3% ± 3.4% (Table III). Primary and secondary patency were 57.5% ± 4.5% and 80.8% ± 3.6% at 1 year, respectively. There were no differences in outcomes between patients who underwent LEB vs PVI (all P > .05).
Table III.
Traditional measures of success after lower extremity revascularization for tissue loss among patients with diabetes
| One-year outcomes | Overall (N = 134) | PVI (N = 91) | LEB (N = 43) | P value |
|---|---|---|---|---|
| Survival | 91.1 ± 2.4 | 91.9 ± 2.8 | 89.5 ± 4.5 | .60 |
| Amputation-free survival | 83.3 ± 3.1 | 84.0 ± 3.7 | 81.7 ± 5.5 | .62 |
| Limb salvage | 91.8 ± 2.3 | 91.8 ± 2.8 | 92.0 ± 3.9 | .89 |
| Primary patency | 57.5 ± 4.5 | 55.9 ± 5.5 | 60.9 ± 7.7 | .79 |
| Secondary patency | 80.8 ± 3.6 | 78.5 ± 4.6 | 85.5 ± 5.6 | .43 |
| Wound healing | 84.3 ± 3.4 | 84.4 ± 4.2 | 84.9 ± 5.5 | .60 |
LEB, Lower extremity bypass; PVI, peripheral vascular intervention.
Data are presented as estimate ± standard error (%).
The composite outcome of clinical success was achieved in 71.6% of patients, including 76.7% who underwent LEB and 69.2% who underwent PVI (P = .37; Table IV). Although overall limb salvage at 1 year, maintenance of ambulatory status at 1 year, and survival at 6 months were all at least 90%, intervention patency to the point of wound healing was lower at 76.9%. Those patients undergoing LEB more often maintained their ambulatory status at 1 year (97.7% vs 86.8%, P = .047); no other markers of success were different between interventions. In a subanalysis using survival to 1 year in the composite outcome, the rates of clinical success were still no different between interventions (72.1% LEB vs 68.1% PVI, P = .77; Supplementary Table, online only).
Table IV.
Patient-centered measures of clinical success after lower extremity revascularization for tissue loss among patients with diabetes
| Outcome parameter | Overall (N = 134) | PVI (N = 91) | LEB (N = 43) | P value |
|---|---|---|---|---|
| Intervention patency to wound healing | 103 (76.9) | 67 (73.6) | 36 (83.7) | .20 |
| Limb preservation for 1 year | 124 (92.5) | 84 (92.3) | 40 (93.0) | .88 |
| Maintenance of ambulatory status for 1 year | 121 (90.3) | 79 (86.8) | 42 (97.7) | .047 |
| Survival for 6 months | 129 (96.3) | 88 (96.7) | 41 (95.4) | .70 |
| Composite outcome | 96 (71.6) | 63 (69.2) | 33 (76.7) | .37 |
LEB, Lower extremity bypass; PVI, peripheral vascular intervention.
Data are presented as n (%)
Factors associated with clinical success on bivariate analysis are displayed in Table V. Patients who achieved clinical success were younger (63 vs 70 years, P = .003), more likely to be fully ambulatory at baseline (78% vs 55%, P = .008), and more likely to be functionally independent (77% vs 56%, P = .03). Urgent procedures were less often associated with clinical success (62% vs 78%, P = .047). Level of disease had no significant association with clinical success (femoropopliteal: 78%, multilevel: 76%, tibial: 64%, P = .43). There were no differences in mean hemoglobin A1c between patients with and without clinical success (8.42 vs 7.77, P = .21). Smoking status, presence of gangrene vs ulceration, WIfI stage on presentation, and type of intervention (LEB vs PVI) were not associated with clinical success. On multivariable analysis, only increased age was significantly associated with lower success (odds ratio [OR], 0.94; 95% confidence interval [CI], 0.90-0.99; P = .008). There were nonsignificant negative associations between clinical success and dialysis dependence (OR, 0.35; CI, 0.12-1.03; P = .06), impaired ambulation (OR, 0.41; CI, 0.17-1.00; P = .05), and urgent procedures (OR, 0.45; CI, 0.19-1.10; P = .08; Table VI). Type of intervention was not associated with clinical success after adjustment (LEB vs PVI: OR, 1.67; CI, 0.62-4.48; P = .31).
Table V.
Rates of clinical success by the presence or absence of covariates after lower extremity revascularization for tissue loss among patients with diabetes
| Characteristics | Clinical success | P value |
|---|---|---|
| Age, years | .003 | |
| Mean (SD) for successes | 63.3 (10.1) | |
| Mean (SD) for failures | 69.7 (12.5) | |
| Sex | .52 | |
| Male | 60 (71.4) | |
| Female | 36 (76.6) | |
| Race | .19 | |
| White | 28 (63.6) | |
| Black | 62 (77.5) | |
| Other | 6 (85.7) | |
| Body mass index, kg/m2 | .41 | |
| Mean (SD) for successes | 30.1 (6.8) | |
| Mean (SD) for failures | 29.0 (7.8) | |
| Diabetes | .14 | |
| Type I | 6 (54.5) | |
| Type II | 90 (75.0) | |
| Mean HbA1c | .21 | |
| Mean (SD) for successes | 8.42 (0.30) | |
| Mean (SD) for failures | 7.77 (0.35) | |
| Hypertension | .62 | |
| Yes | 88 (72.7) | |
| No | 8 (80.0) | |
| Dyslipidemia | .29 | |
| Yes | 68 (70.8) | |
| No | 28 (80.0) | |
| Coronary artery disease | .93 | |
| Yes | 42 (73.7) | |
| No | 54 (73.0) | |
| Congestive heart failure | .87 | |
| Yes | 18 (72.0) | |
| No | 78 (73.6) | |
| Chronic kidney disease | .98 | |
| Yes | 19 (73.1) | |
| No | 77 (73.3) | |
| Dialysis | .07 | |
| Yes | 12 (57.1) | |
| No | 84 (76.4) | |
| Kidney transplant | .54 | |
| Yes | 10 (66.7) | |
| No | 86 (74.1) | |
| COPD | .09 | |
| Yes | 2 (40.0) | |
| No | 94 (74.6) | |
| Smoking status | .29 | |
| Current | 23 (85.2) | |
| Former | 34 (69.4) | |
| Never | 39 (70.9) | |
| Preoperative fully ambulatory status | .008 | |
| Yes | 75 (78.1) | |
| No | 21 (55.3) | |
| Functional status | .03 | |
| Independent | 82 (77.4) | |
| Partially dependent | 14 (56.0) | |
| Procedure urgency | .047 | |
| Nonurgent | 61 (78.2) | |
| Urgent | 35 (62.5) | |
| Tissue loss | .47 | |
| Ulcer | 49 (69.0) | |
| Gangrene | 47 (74.6) | |
| WIfI stage on presentation | .62 | |
| 1 | 3 (60.0) | |
| 2 | 7 (87.5) | |
| 3 | 22 (75.9) | |
| 4 | 64 (69.6) | |
| Level of disease | .43 | |
| Femoropopliteal | 7 (77.8) | |
| Tibial | 28 (63.6) | |
| Multilevel | 60 (75.9) | |
| Prior vascular intervention | .61 | |
| Yes | 12 (66.7) | |
| No | 84 (72.4) | |
| Intervention | .37 | |
| PVI | 63 (69.2) | |
| LEB | 33 (76.7) |
COPD, Chronic obstructive pulmonary disease; LEB, lower extremity bypass; PVI, peripheral vascular intervention; SD, standard deviation; WIfI, wound, ischemia, and foot infection.
Data are presented as n (%) unless otherwise specified
Table VI.
Multivariable analysis to evaluate covariates associated with clinical success after lower extremity revascularization for tissue loss among patients with diabetes
| Outcome | Multivariable model | |
|---|---|---|
| OR for success (95% CI) | P value | |
| Age, per year | 0.95 (0.91-0.99) | .008 |
| Fully ambulatory | 2.44 (1.00-6.02) | .05 |
| Dialysis | 0.35 (0.12-1.03) | .06 |
| Urgent procedure | 0.45 (0.19-1.10) | .08 |
| LEB (vs PVI) | 1.67 (0.62-4.48) | .31 |
CI, Confidence interval; LEB, lower extremity bypass; OR, odds ratio; PVI, peripheral vascular intervention.
DISCUSSION
We sought to understand the rate of patient-centered clinical success after lower extremity revascularization, previously defined by Taylor et al13,14 as secondary patency to the point of wound healing, limb salvage and maintenance of ambulatory status at 1 year, and survival to 6 months. Among patients with diabetes presenting to our multidisciplinary limb preservation service with tissue loss, clinical success was achieved in 72% of patients after LEB or PVI. This rate was lower than traditional markers of revascularization success in our cohort, including 84% wound healing, 92% limb preservation, and 91% survival at 1 year. We found no differences in the rates of patient-centered clinical success or traditional markers of success after open vs endovascular intervention; however, open bypass was associated with higher rates of maintaining ambulatory status as compared with endovascular intervention. Younger age was the only statistically significant predictor of clinical success on multivariable analysis.
The clinical success of 72% in this study was lower than traditional physician-centric markers of success but higher than in the previous report from Taylor et al14 of 677 patients undergoing open bypass and endovascular therapy, with a composite clinical success of 41%. In both our series and theirs, the most discriminatory component was intervention patency to wound healing, which was 77% in the current cohort and 44% in theirs. Complete and timely wound healing therefore offers the most potential for improvement to maximize successful patient-centered outcomes in the future. Despite higher rates of gangrene and WIfI stage 4 limbs in our patients undergoing LEB compared with those undergoing PVI, our rates of wound healing and clinical success were similar between groups. We attribute this to our multidisciplinary approach to limb preservation, which has been shown to accelerate wound healing and decrease rates of major amputations.19–21 Furthermore, the majority of our patients undergo operative podiatric intervention, and this is not infrequently supplemented by orthopedic or plastic surgery interventions to maximize wound coverage and healing potential. Although we do not have our own institutional non-multidisciplinary comparison group, we hypothesize that the higher rates of clinical success we found compared with Taylor et al could be partially attributable to our aggressive multidisciplinary approach to diabetic foot wounds.
Two of the other components of clinical success, limb preservation at 1 year and survival to 6 months, are considered more traditional markers of revascularization success. These markers were higher than the other components of clinical success in our series, with 1-year limb salvage and survival of 92% and 91% on Kaplan-Meier analyses. Darling et al6 similarly identified an 88% rate of limb preservation at 1 year in their series of 1336 first-time lower extremity revascularizations for chronic limb-threatening ischemia. Our 1-year survival rates are also comparable to the 90% after endovascular intervention in the IN.PACT DEEP trial4 and the 84% 1-year survival after open revascularization in the PREVENT III trial.3
The final component of clinical success was the maintenance of one’s ambulatory status for at least 1 year. Although this is the least studied of the components, ambulatory status is an important patient-centered outcome that may be underappreciated in its significance to patients. In our cohort, 90% of patients were able to maintain their ambulatory status at 1 year after revascularization. Interestingly, this was the only component of clinical success with a difference in outcome by intervention type; only one of 43 patients undergoing open intervention had a worsening in his or her ambulation postoperatively, whereas 12 of 91 undergoing endovascular intervention progressed to worse function. The majority of these 12 patients were near the end of their life and were selectively offered endovascular intervention as a minimally invasive attempt at limb preservation; however, the limitations of their comorbidities in conjunction with the offloading needed for their wounds resulted in them not regaining ambulatory status by 1 year. Maintenance of ambulatory status postoperatively is an important patient-centered outcome and should be a goal when considering treatment strategies.
Finally, we sought to identify independent predictors of clinical success and found only older age to be negatively associated with clinical success. Advanced age is, of course, associated with worse survival but also predicts higher rates of amputation and impaired ambulatory status.12,22 Age also likely serves as a marker of patient frailty, which has been associated with worse limb preservation outcomes.23–25 When Taylor et al evaluated clinical success, they found diabetes, impaired preoperative ambulation, end-stage renal disease, gangrene, and prior vascular intervention to all be associated with failure by at least one metric. In our cohort, all patients had diabetes; however, we did not find a difference in mean hemoglobin A1c between those with clinical success or failure. A previous meta-analysis used a threshold of 8% to difference between adequate and insufficient glycemic control,26 and the mean in this analysis was 8.2%, so our average A1c may not have been high enough to notice a difference in outcomes. Impaired preoperative ambulation, end-stage renal disease, gangrene, and prior vascular intervention were all found to be associated with clinical success but only on unadjusted analyses. The presence of end-stage renal disease should be considered in predicting the likelihood of success with revascularization for chronic limb-threatening ischemia in patients with diabetes, as this can frequently be associated with impaired microcirculatory function and distal perfusion.27 Dialysis dependence predicts worse survival but also worse limb-related outcomes in prior series, and in our cohort, there is an association between dialysis dependence and clinical failure although this was not statistically significant on multivariable analysis.13,22
We also found a nonsignificant correlation between procedure urgency and impaired preoperative ambulation and eventual clinical failure. Procedure urgency likely serves as a marker for disease severity on presentation, which may not be fully captured by the other categorical severity variables including WIfI score, which has also been shown to be associated with outcomes in chronic limb-threatening ischemia.6,7,9,10 Preoperative poor functional or ambulatory status has portended worse outcomes in patients with chronic limb-threatening ischemia,14,28,29 and we found that both pre-operative independent functional status and unassisted ambulation were associated with clinical success, but only before adjusting for other comorbidities. These comorbidities may account for much of the impaired baseline function and serve to explain the worse outcomes, at least in our series.
This study should be interpreted within the confines of the study design. This was a single institution series and may be underpowered to detect differences in clinical success, or components of clinical success, by intervention type. This study also reflects a single institutional experience with an endovascular-first approach to revascularization for limb preservation; therefore, there is an inherent selection bias in the intervention type. In addition, ambulatory status, in particular, can vary with time and may be impacted by factors unable to be controlled for in this analysis. However, our analyses are strengthened by highly granular clinical and anatomic data with good longitudinal follow-up.
CONCLUSIONS
Clinical success, defined by intervention patency to wound healing, limb salvage and maintenance of ambulatory status at 1 year, and survival to 6 months, is lower than traditional markers of revascularization success such as survival and limb preservation. Wound healing and ambulatory status impact patients’ quality of life and, when accounting for these measures, clinical success is lower than we would traditionally believe based on physician-centered outcomes. Patient-centered outcomes should continue to be studied to aid in informed communication and clinical decision-making for patients with diabetes and chronic limb-threatening ischemia.
Supplementary Material
ARTICLE HIGHLIGHTS.
Type of Research: Retrospective single-institution cohort study
Key Findings: Among 134 revascularizations for tissue loss among patients with diabetes in our multidisciplinary limb preservation service, clinical success, that is, intervention patency to wound healing, maintenance of ambulatory status and limb preservation at 1 year, and survival to 6 months, was 72%, with no differences by intervention type. On adjusted analyses, the only covariate associated with higher success was younger age.
Take Home Message: This study found lower rates of patient-centered clinical success compared with traditional physician-centered outcomes after lower extremity revascularization for tissue loss among diabetic patients.
Footnotes
Presented virtually at the Thirty-fourth Annual Meeting of the Eastern Vascular Society, October 2020.
Additional material for this article may be found online at www.jvascsurg.org.
Author conflict of interest: none.
The editors and reviewers of this article have no relevant financial relationships to disclose per the JVS policy that requires reviewers to decline review of any manuscript for which they may have a conflict of interest.
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