Association between tissue loss type and amputation risk among Medicare patients with concomitant diabetes and peripheral arterial disease.

OBJECTIVE: Prior studies have described risk factors associated with amputation in patients with concomitant diabetes and peripheral arterial disease(DM/PAD). However, the association between the severity and extent of tissue loss type and amputation risk remains less well-described. We aimed to quantify the role of different tissue loss types in amputation risk among patients with DM/PAD, in the context of demographic, preventive, and socioeconomic factors. METHODS: Applying ICD-9 and ICD-10 codes to Medicare claims data(2007-2019), we identified all patients with continuous fee-for-service Medicare coverage diagnosed with DM/PAD. Eight tissue loss categories were established using ICD-9 and ICD-10 diagnosis codes, ranging from lymphadenitis(least severe) to gangrene(most severe). We created a Cox proportional hazards model to quantify associations between tissue loss type and one- and five-year amputation risk, adjusting for age, race/ethnicity, sex, rurality, income, comorbidities, and preventive factors. Regional variation in DM/PAD rates and risk-adjusted amputation rates was examined at the hospital referral region(HRR) level. RESULTS: We identified 12,257,174 patients with DM/PAD(48% male, 76% White, 10% prior myocardial infarction, 30% chronic kidney disease). While 2.2 million patients(18%) had some form of tissue loss, 10.0 million patients(82%) did not. The one-year crude amputation rate(major and minor) was 6.4% in patients with tissue loss, and 0.4% in patients without tissue loss. Among patients with tissue loss, one-year any amputation rate varied from 0.89% for patients with lymphadenitis to 26% for patients with gangrene. One-year amputation risk varied from two-fold for patients with lymphadenitis(aHR 1.96, 95%CI 1.43-2.69) to 29-fold for patients with gangrene(aHR 28.7, 95%CI 28.1-29.3), compared to patients without tissue loss. No other demographic variable including age, sex, race, or region incurred a hazard ratio for one- or five-year amputation risk higher than the least severe tissue loss category. Results were similar across minor and major amputation, and one- and five-year amputation outcomes. At a regional level, higher DM/PAD rates were inversely correlated with risk-adjusted five-year amputation rates(R2=0.43). CONCLUSION: Among 12 million patients with DM/PAD, the most significant predictor of amputation was presence and extent of tissue loss, with an association greater in effect size than any other factor studied. Tissue loss could be used in awareness campaigns as a simple marker of high-risk patients. Patients with any type of tissue loss require expedited wound care, revascularization as appropriate, and infection management to avoid amputation. Establishing systems of care to provide these interventions in regions with high amputation rates may prove beneficial for these populations.

A Retrospective Analysis of Surgical Acuity & Procedure Volume Before & During the COVID-19 Pandemic.

INTRODUCTION: In March 2020, the American College of Surgeons recommended postponing elective procedures amid the COVID-19 pandemic. We used Medicare claims to analyze changes in surgical and interventional procedure volumes from 2016 to 2021. METHODS: We studied 37 common surgical and interventional procedures using 5% Medicare claims files from January 1, 2016, through December 31, 2021. Procedures were classified according to American College of Surgeons guidelines as low, intermediate, or high acuity, and counts were analyzed per calendar year quarter (Q1-Q4), with stratification by sex and race/ethnicity. RESULTS: We observed 1,840,577 procedures and identified two periods of marked decline. In Q2 2020, overall procedure counts decreased by 32.2%, with larger declines in low (41.1%) and intermediate (30.8%) acuity procedures. High acuity procedures declined the least (18.2%). Overall volumes increased afterward but never returned to baseline. Another marked decline occurred in Q4 2021, with all acuity levels having declined to a similar extent (40.1%, 44.2%, and 46.9% for low, intermediate, and high acuity, respectively). High and intermediate acuity procedures declined more in Q4 2021 than Q2 2020 (P = 0.002). Similar patterns were observed across sex and race/ethnicity strata. CONCLUSIONS: Two major procedural volume declines occurred between 2020 and 2022 during the COVID-19 pandemic in the United States. High acuity (life or limb threatening) procedures were least affected in the first decline (Q2 2020) but not spared in second decline (Q4 2021). Future efforts should prioritize preserving high-acuity access during times of stress.

Inter-Rater Reliability for the Amputation Endpoint in the National Vascular Quality Initiative.

BACKGROUND: National quality reporting efforts after revascularization for peripheral artery disease (PAD) are ongoing. Validation of endpoints are necessary in national quality registries. OBJECTIVES: This study sought to examine the interrater reliability for the endpoint of major amputation at 1 year in the Vascular Quality Initiative (VQI) registry and the Medicare-linked Vascular Quality Initiative registry (VQI-VISION) against electronic health record (EHR) review. METHODS: Surgical or endovascular revascularization procedures between January 1, 2010, and December 31, 2017, in the VQI registry and VQI-VISION for 2 academic health systems were queried. Major amputation data were abstracted by trained data collectors for the VQI and derived from Current Procedural Terminology codes for VQI-VISION. Cases underwent protocolized adjudication for the endpoint of major amputation by EHR review. Paired tests were used to evaluate the sensitivity and specificity. Spearman's ρ and Cohen's κ were used to evaluate interrater reliability. RESULTS: Amputation endpoints for 1,936 revascularizations were examined. Compared with major amputation data in EHR review, the sensitivity for the VQI registry was 35.9% and the specificity was 99.4% (ρ = 0.53; κ = 0.48). For VQI-VISION, sensitivity was 67.7% and specificity was 98.9% (ρ = 0.75; κ = 0.74). For any amputation in VQI data, sensitivity was 35.3% and specificity was 99.3% (ρ = 0.53; κ = 0.46), and for VQI-VISION, they were 71.6% and 97.7%, respectively (ρ = 0.75; κ = 0.74). CONCLUSIONS: Almost two-thirds of the amputations in the VQI registry and one-third of amputations in VQI-VISION were missing at 1 year compared against adjudicated EHR review. In preparing for national reporting systems for major amputation tracking, data collection system reform is needed.

Trends of Concomitant Diabetes and Peripheral Artery Disease and Lower Extremity Amputation in US Medicare Patients, 2007 to 2019.

BACKGROUND: Previous studies demonstrate geographic and racial/ethnic variation in diagnosis and complications of diabetes and peripheral artery disease (PAD). However, recent trends for patients diagnosed with both PAD and diabetes are lacking. We assessed the period prevalence of concurrent diabetes and PAD across the United States from 2007 to 2019 and regional and racial/ethnic variation in amputations among Medicare patients. METHODS: Using Medicare claims from 2007 to 2019, we identified patients with both diabetes and PAD. We calculated period prevalence of concomitant diabetes and PAD and incident cases of diabetes and PAD for every year. Patients were followed to identify amputations, and results were stratified by race/ethnicity and hospital referral region. RESULTS: 9 410 785 patients with diabetes and PAD were identified (mean age, 72.8 [SD, 10.94] years; 58.6% women, 74.7% White, 13.2% Black, 7.3% Hispanic, 2.8% Asian/API, and 0.6% Native American). Period prevalence of diabetes and PAD was 23 per 1000 beneficiaries. We observed a 33% relative decrease in annual new diagnoses throughout the study. All racial/ethnic groups experienced a similar decline in new diagnoses. Black and Hispanic patients had on average a 50% greater rate of disease compared with White patients. One- and 5-year amputation rates remained stable at ≈1.5% and 3%, respectively. Native American, Black, and Hispanic patients were at greater risk of amputation compared with White patients at 1- and 5-year time points (5-year rate ratio range, 1.22-3.17). Across US regions, we observed differential amputation rates, with an inverse relationship between the prevalence of concomitant diabetes and PAD and overall amputation rates. CONCLUSIONS: Significant regional and racial/ethnic variation exists in the incidence of concomitant diabetes and PAD among Medicare patients. Black patients in areas with the lowest rates of PAD and diabetes are at disproportionally higher risk for amputation. Furthermore, areas with higher prevalence of PAD and diabetes have the lowest rates of amputation.

Deriving International Classification of Diseases, 9th and 10th revision, codes for identifying and following up patients with diabetic lower extremity ulcers.

Objective: Administrative claims data offer a rich data source for clinical research. However, its application to the study of diabetic lower extremity ulceration is lacking. Our objective was to create a widely applicable framework by which investigators might derive and refine the International Classification of Diseases, 9th and 10th revision (ICD-9 and ICD-10, respectively) codes for use in identifying diabetic, lower extremity ulceration. Methods: We created a seven-step process to derive and refine the ICD-9 and ICD-10 coding lists to identify diabetic lower extremity ulcers. This process begins by defining the research question and the initial identification of a list of ICD-9 and ICD-10 codes to define the exposures or outcomes of interest. These codes are then applied to claims data, and the rates of clinical events are examined for consistency with prior research and changes across the ICD-9 to ICD-10 transition. The ICD-9 and ICD-10 codes are then cross referenced with each other to further refine the lists. Results: Using this method, we started with 8 ICD-9 and 43 ICD-10 codes used to identify lower extremity ulcers in patients with known diabetes and peripheral arterial disease and examined the association of ulceration with lower extremity amputation. After refinement, we had 45 ICD-9 codes and 304 ICD-10 codes. We then grouped the codes into eight clinical exposure groups and examined the rates of amputation as a rudimentary test of validity. We found that the rate of lower extremity amputation correlated with the severity of lower extremity ulceration. Conclusions: We identified 45 ICD-9 and 304 ICD-10 ulcer codes, which identified patients at risk of amputation from diabetes and peripheral artery disease. Although further validation at the medical record level is required, these codes can be used for claims-based risk stratification for long-term outcomes assessment in the treatment of patients at risk of limb loss.