Clinical Implications of Low Body Mass Index on Endovascular Lower Extremity Revascularization

The epidemic of obesity and associated cardiovascular morbidity continues to grow, attracting public attention and healthcare resources. However, the impact of being underweight has not received sufficient attention and continues to be overshadowed by obesity, especially in patients with peripheral arterial disease (PAD). This study assesses the characteristics and outcomes of underweight patients with low body mass index (BMI ≤ 18.5) compared to patients with normal BMI undergoing peripheral vascular interventions (PVI). A retrospective analysis of patients undergoing PVI due to PAD registered in the VQI database was performed. Patients were categorized into underweight (BMI ≤ 18.5) and normal weight (BMI = 18.5-30.0). Patients in both groups were matched 3:1 for baseline demographic characteristics, comorbidities, and indications. Perioperative and long-term outcomes were compared. Kaplan-Meier analysis was done for long-term outcomes. A total of 276,863 patients underwent PVI, of whom 10,448 (4%) were underweight, 176,752 (64%) had normal weight, and 89,663 (32%) were obese. Underweight patients were more likely to be older, female, and smokers, with multiple comorbidities such as chronic obstructive pulmonary disease, diabetes, hypertension, and congestive heart failure (P < .01), and were more likely to present with critical limb ischemia (P < .01). After propensity matching, there were 23,989 normal-weight patients and 8002 underweight patients. There were no significant differences in matched characteristics (Table). Patients with a low BMI were more likely to undergo emergency procedures (20% vs 19%; P < .01) and to have a more advanced Inter-Society Consensus for the Management of Peripheral Arterial Disease score (P = .02). Underweight patients had significantly higher pulmonary complications (1.2%; P < .01), mortality at 30 days (3%; P < .01), and longer hospital length of stay (mean, 5.6 days) compared to patients with normal weight. As for long-term outcomes, the 3-year rate of amputation-free survival differed significantly among the two groups and was significantly lower in underweight patients (33% vs 46%; P < .001) (Figure). Even though underweight patients constitute a relatively small proportion of patients undergoing PVI for PAD, their revascularization outcomes are disproportionately worse than those with normal weight. Increased scrutiny and optimization of nutrition and other factors contributing to low weight should be addressed prior to PVI.TableBaseline characteristicsCharacteristicUnderweight (n = 8002)Normal weight (n = 23,989)SMDP valueaAge, years71 (63-81)72 (64-81)0.10.25Female sex69,828 (39)13,811 (58)0.03.22Race0.07.08 White5855 (73)17,825 (74) African American1528 (19)4456 (18) Other1708 (7.1)619 (7.7)Hypertension6641 (83)20,109 (84)0.10.08Diabetes5682 (71)16,977 (71)0.02.69Smoking6337 (79)18,987 (79)0.01.94Chronic obstructive pulmonary disease2932 (37)8785 (37)0.02.98Coronary artery disease2065 (26)5955 (25)0.01.08Congestive heart failure1461 (18)4218 (18)0.01.17Kidney function634 (8)1772 (7)<.01 GFR ≥ 902215 (29)4771 (20) GFR ≥ 60 < 902578 (34)8850 (38) GFR ≥ 30 < 601830 (24)7014 (30) GFR ≥ 15 < 30187 (2.5)733 (3) GFR < 1530 (0.4)114 (0.5)Dialysis634 (8.4)1772 (7.6).2Prior lower extremity revascularization4236 (52.9)12,614 (52.6)0.04.59History of amputation1436 (18)3961 (17)0.06<.01Ambulation<.01 Independent4704 (60)15,607 (66) Assisted ambulation2312 (29)6124 (26) Nonambulatory890 (11)1970 (8)Aspirin5256 (66)16,567 (69)<.01P2Y123183 (40)10,129 (42)<.01Statin4935 (62)16,090 (67)<.01Anticoagulation1388 (17)4470 (18.6)<.01Procedural characteristics Indication0.04.14Chronic limb-threatening ischemia5299 (66)16,104 (67)Claudication2703 (34)7885 (33) Urgency0.07<.01Nonemergent6399 (80)19,490 (81)Emergent1603 (20)4499 (19) Treated arteries1.6 ± 0.81.6 ± 0.8.58 Fluoroscopy time, minutes18.2 ± 1618.9 ± 22<.01 Failed closure49 (5)101 (3)<.01 Protamine2068 (27)5398 (23)<.01 Treatment artery<.01Aortoiliac1385 (23)3418 (19)Femoropopliteal2441 (41)8091 (45)Tibial597 (10)1871 (11)Multilevel1534 (26)4463 (25) Inter-Society Consensus for the Management of Peripheral Arterial Disease II.02A48 (29)206 (40)B28 (17)77 (15)C39 (23)111 (22)D54 (32)116 (23) Treatment type<.01Stenting2811 (47)8339 (47)Balloon angioplasty2255 (38)6370 (36)Atherectomy592 (10)2137 (12)Atherectomy and stenting302 (5)1005 (6)Periprocedural outcomes Postprocedural complicationsCardiac82 (1.5)267 (1.7).05Myocardial infarction19 (0.3)92 (0.6).06Pulmonary65 (1.2)127 (0.8)<.01Renal46 (1.0)133 (0.8).9 Surgical length of stay, days5.6 (32)4.2 (28)<.01 30-Day mortality140 (3)205 (1.0)<.01Long-term outcomesUnderweight (n = 5017)Normal weight (n = 15,476) Reintervention611 (20)1984 (18).05 Patency<.01Occluded294 (12)881 (9) Major amputation363 (11)811 (7)<.01 Major adverse limb events882 (27)2606 (23)<.01GFR, Glomerular filtration rate; SMD, Standardized mean difference for variables used in propensity matching.Values are number (%), median (interquartile range), or mean ± standard deviation.Boldface entries indicate statistical significance for P < .05 and for SMD >0.1.aPearson's χ2 test, Fisher's exact test, or Wilcoxon rank-sum test. 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