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.

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.

Using a cohort study of diabetes and peripheral artery disease to compare logistic regression and machine learning via random forest modeling.

BACKGROUND: This study illustrates the use of logistic regression and machine learning methods, specifically random forest models, in health services research by analyzing outcomes for a cohort of patients with concomitant peripheral artery disease and diabetes mellitus. METHODS: Cohort study using fee-for-service Medicare beneficiaries in 2015 who were newly diagnosed with peripheral artery disease and diabetes mellitus. Exposure variables include whether patients received preventive measures in the 6 months following their index date: HbA1c test, foot exam, or vascular imaging study. Outcomes include any reintervention, lower extremity amputation, and death. We fit both logistic regression models as well as random forest models. RESULTS: There were 88,898 fee-for-service Medicare beneficiaries diagnosed with peripheral artery disease and diabetes mellitus in our cohort. The rate of preventative treatments in the first six months following diagnosis were 52% (n = 45,971) with foot exams, 43% (n = 38,393) had vascular imaging, and 50% (n = 44,181) had an HbA1c test. The directionality of the influence for all covariates considered matched those results found with the random forest and logistic regression models. The most predictive covariate in each approach differs as determined by the t-statistics from logistic regression and variable importance (VI) in the random forest model. For amputation we see age 85 + (t = 53.17) urban-residing (VI = 83.42), and for death (t = 65.84, VI = 88.76) and reintervention (t = 34.40, VI = 81.22) both models indicate age is most predictive. CONCLUSIONS: The use of random forest models to analyze data and provide predictions for patients holds great potential in identifying modifiable patient-level and health-system factors and cohorts for increased surveillance and intervention to improve outcomes for patients. Random forests are incredibly high performing models with difficult interpretation most ideally suited for times when accurate prediction is most desirable and can be used in tandem with more common approaches to provide a more thorough analysis of observational data.

Validation of an indirect linkage algorithm to combine registry data with Medicare claims.

BACKGROUND: The linkage of registries to Medicare claims data can help extend follow-up for patients receiving medical devices. In the present study, we tested and validated an algorithm that does not require patient identifiers to link data from a national vascular registry and Medicare claims data. METHODS: We used data from the Vascular Quality Initiative (VQI), a registry capturing data from >600 centers for several different vascular procedures, and Medicare claims from 2003 to 2018. We restricted the study to patients aged ≥65 years who had fee-for-service entitlement at their procedure. We performed an indirect linkage to combine the VQI and Medicare data at the patient level using a sequential algorithm based on the patient's date of birth, sex, zip code, procedure date, and procedure facility. We compared the indirectly linked cohort against a reference standard of a cohort directly linked using Social Security numbers. We calculated the matching rate and accuracy overall and before and after October 2015 when the International Classification of Diseases, 10th revision (ICD-10) system was adopted in the United States. RESULTS: A total of 144,045 VQI-Medicare-linked patients were in the reference standard cohort. Using the indirect linking algorithm, we matched 133,966 of the 144,045 VQI patients to their Medicare claims with a matching rate of 93.0%. Of the 133,966 patients, 133,104 were correctly matched (matching accuracy, 99.4%). The matching rate was higher when the indirect linkage was implemented using the ICD-10 coded data than using the ICD-9 coded data (94.0% vs 92.2%). The accuracy of the indirect linkage remained high for all procedure modules after the ICD-10 coding change (overall, 99.4%; range, 99.0%-99.7%). CONCLUSIONS: In the present study, we successfully used indirect identifiers to link the VQI data to Medicare claims with >90% success and >99% accuracy. When direct linkage of the registry claims data using Social Security numbers is not possible because of availability or confidentiality, or both, our algorithm for indirect linkage provides a suitable alternative. The matching rate and accuracy will help ensure the accuracy of long-term follow-up and the completeness and representativeness of linked databases for relevant research and quality improvement initiatives.

Characterizing Reimbursements for Medicare Patients Receiving Endovascular Abdominal Aortic Aneurysm Repair at Vascular Quality Initiative Centers.

BACKGROUND: Endovascular aortic aneurysm repair (EVR) has a major financial impact on health care systems. We characterized reimbursement for index EVR hospitalizations among Medicare beneficiaries having surgery at Vascular Quality Initiative (VQI) centers. METHODS: We linked Medicare claims to VQI clinical registry data for patients undergoing EVR from 2003 to 2015. Analysis was limited to patients fully covered by fee-for-service Medicare parts A and B in the year of their operation and assigned a corresponding diagnosis-related group for EVR. The primary outcome was Medicare's reimbursement for inpatient hospital and professional services, adjusted to 2015 dollars. We performed descriptive analysis of reimbursement over time and univariate analysis to evaluate patient demographics, clinical characteristics, procedural variables, and postoperative events associated with reimbursement. This informed a multilevel regression model used to identify factors independently associated with EVR reimbursement and quantify VQI center-level variation in reimbursement. RESULTS: We studied 9,403 Medicare patients who underwent EVR at VQI centers during the study period. Reimbursements declined from $37,450 ± $9,350 (mean ± standard deviation) in 2003 to $27,723 ± $10,613 in 2015 (test for trend, P < 0.001). For patients experiencing a complication (n = 773; 8.2%), mean reimbursement for EVR was $44,858 ± $23,825 versus $28,857 ± $9,258 for those without complications (P < 0.001). Intestinal ischemia, new dialysis requirement, and respiratory compromise each doubled Medicare's average reimbursement for EVR. After adjusting for diagnosis-related group, several patient-level factors were independently associated with higher Medicare reimbursement; these included ruptured abdominal aortic aneurysm (+$2,372), additional day in length of stay (+$1,275), and being unfit for open repair (+$501). Controlling for patient-level factors, 4-fold variation in average reimbursement was seen across VQI centers. CONCLUSIONS: Reimbursement for EVR declined between 2003 and 2015. We identified preoperative clinical factors independently associated with reimbursement and quantified the impact of different postoperative complications on reimbursement. More work is needed to better understand the substantial variation observed in reimbursement at the center level.

A pilot study for long-term outcome assessment after aortic aneurysm repair using Vascular Quality Initiative data matched to Medicare claims.

OBJECTIVE: Accurate and complete long-term postoperative outcome data are critical to improving value in health care delivery. The Society for Vascular Surgery Vascular Quality Initiative (VQI) is an important tool to achieve this goal in vascular surgery. To improve on the capture of long-term outcomes after vascular surgery procedures for patients in the VQI, we sought to match VQI data to Medicare claims for comprehensive capture of major clinical outcomes in the first several years after vascular procedures. METHODS: Patient and procedure characteristics for abdominal aortic aneurysm procedures captured in the Society for Vascular Surgery VQI between January 1, 2002, and December 31, 2013, were matched to Medicare claims data using an indirect identifier methodology. Late outcomes captured in the VQI and in Medicare claims were compared. RESULTS: Matching procedures yielded 9895 endovascular aneurysm repair (EVAR) patients (82.4% of eligible VQI patients) and 3405 open aneurysm repair (OAR) patients (74.4% of eligible). Comparison of patients who did and did not match to a Medicare claim demonstrated similar patient and procedure characteristics. Evaluation of late outcomes revealed good patient-level agreement on mortality for both EVAR (κ, 0.64) and OAR (κ, 0.82). Postoperative reintervention rates demonstrated lower agreement for both EVAR (κ, 0.26) and OAR (κ, 0.16). CONCLUSIONS: This work demonstrates the feasibility of an algorithm using indirect identifiers to match VQI patients and procedures to Medicare claims data. The refinement of this strategy will focus on establishing and improving algorithms related to identifying and categorizing late events after EVAR and may serve as a mechanism to ensure that the best quality follow-up information is achieved within the VQI.