Derivation and Validation of ICD-10 Codes for Identifying Incident Stroke.

Importance: Claims data with International Statistical Classification of Diseases, Tenth Revision (ICD-10) codes are routinely used in clinical research. However, the use of ICD-10 codes to define incident stroke has not been validated against expert-adjudicated outcomes in the US population. Objective: To develop and validate the accuracy of an ICD-10 code list to detect incident stroke events using Medicare inpatient fee-for-service claims data. Design, Setting, and Participants: This cohort study used data from 2 prospective population-based cohort studies, the Atherosclerosis Risk in Communities (ARIC) study and the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, and included participants aged 65 years or older without prior stroke who had linked Medicare claims data. Stroke events in the ARIC and REGARDS studies were identified via active surveillance and adjudicated by expert review. Medicare-linked ARIC data (2016-2018) were used to develop a list of ICD-10 codes for incident stroke detection. The list was validated using Medicare-linked REGARDS data (2016-2019). Data were analyzed from September 1, 2022, through September 30, 2023. Exposures: Stroke events detected in Medicare claims vs expert-adjudicated stroke events in the ARIC and REGARDS studies. Main Outcomes and Measures: The main outcomes were sensitivity and specificity of incident stroke detection using ICD-10 codes. Results: In the ARIC study, there were 110 adjudicated incident stroke events among 5194 participants (mean [SD] age, 80.1 [5.3] years) over a median follow-up of 3.0 (range, 0.003-3.0) years. Most ARIC participants were women (3160 [60.8%]); 993 (19.1%) were Black and 4180 (80.5%) were White. Using the primary diagnosis code on a Medicare billing claim, the ICD-10 code list had a sensitivity of 81.8% (95% CI, 73.3%-88.5%) and a specificity of 99.1% (95% CI, 98.8%-99.3%) to detect incident stroke. Using any diagnosis code on a Medicare billing claim, the sensitivity was 94.5% (95% CI, 88.5%-98.0%) and the specificity was 98.4% (95% CI, 98.0%-98.8%). In the REGARDS study, there were 140 adjudicated incident strokes among 6359 participants (mean [SD] age, 75.8 [7.0] years) over a median follow-up of 4.0 (range, 0-4.0) years. More than half of the REGARDS participants were women (3351 [52.7%]); 1774 (27.9%) were Black and 4585 (72.1%) were White. For the primary diagnosis code, the ICD-10 code list had a sensitivity of 70.7% (95% CI, 63.2%-78.3%) and a specificity of 99.1% (95% CI, 98.9%-99.4%). For any diagnosis code, the ICD-10 code list had a sensitivity of 77.9% (95% CI, 71.0%-84.7%) and a specificity of 98.9% (95% CI, 98.6%-99.2%). Conclusions and Relevance: These findings suggest that ICD-10 codes could be used to identify incident stroke events in Medicare claims with moderate sensitivity and high specificity.

Guideline-Directed Medical Therapy and Long-Term Mortality and Amputation Outcomes in Patients Undergoing Peripheral Vascular Interventions.

BACKGROUND: Lack of guideline-directed medical therapy (GDMT) in patients undergoing peripheral vascular interventions (PVIs) may increase mortality and amputation risk. OBJECTIVES: The authors sought to study the association between GDMT and mortality/amputation and to examine GDMT variability among providers and health systems. METHODS: We performed an observational study using patients in the Vascular Quality Initiative registry undergoing PVI between 2017 and 2018. Two-year all-cause mortality and major amputation data were derived from Medicare claims data. Compliance with GDMT was defined as receiving a statin, antiplatelet therapy, and angiotensin-converting enzyme inhibitor/angiotensin receptor blocker if hypertensive. Propensity 1:1 matching was applied for GDMT vs no GDMT and survival analyses were performed to compare outcomes between groups. RESULTS: Of 15,891 patients undergoing PVIs, 48.8% received GDMT and 6,120 patients in each group were matched. Median follow-up was 9.6 (IQR: 4.5-16.2) months for mortality and 8.4 (IQR: 3.5-15.4) for amputation. Mean age was 72.0 ± 9.9 years. Mortality risk was higher among patients who did not receive GDMT versus those on GDMT (31.2% vs 24.5%; HR: 1.37, 95% CI: 1.25-1.50; P < 0.001), as well as, risk of amputation (16.0% vs 13.2%; HR: 1.20; 95% CI: 1.08-1.35; P < 0.001). GDMT rates across sites and providers ranging from 0% to 100%, with lower performance translating into higher risk. CONCLUSIONS: Almost one-half of the patients receiving PVI in this national quality registry were not on GDMT, and this was associated with increased risk of mortality and major amputation. Quality improvement efforts in vascular care should focus on GDMT in patients undergoing PVI.

Non-guideline-compliant endovascular abdominal aortic aneurysm repair in women is associated with increased mortality and reintervention compared with men.

OBJECTIVE: Sex-based disparities in surgical outcomes have emerged as an important focus in contemporary healthcare delivery. Likewise, the appropriate usage of endovascular abdominal aortic aneurysm repair (EVAR) in the United States remains a subject of ongoing controversy, with a significant number of U.S. EVARs failing to adhere to the Society for Vascular Surgery (SVS) clinical practice guideline (CPG) diameter thresholds. The purpose of the present study was to determine the effect of sex among patients undergoing EVAR that was not compliant with the SVS CPGs. METHODS: All elective EVAR procedures for abdominal aortic aneurysms without a concomitant iliac aneurysm (≥3.0 cm) in the SVS Vascular Quality Initiative were analyzed (2015-2019; n = 25,112). SVS CPG noncompliant repairs were defined as a size of <5.5 cm for men and <5.0 cm for women. The primary endpoint was 30-day mortality. The secondary endpoints were all-cause mortality, complications, and reintervention. Logistic regression was performed to control for surgeon- and patient-level factors. Freedom from the endpoints was determined using the Kaplan-Meier method. RESULTS: Noncompliant EVAR was performed in 9675 patients (38.5%). Although men were significantly more likely to undergo such procedures (90% vs 10%; odds ratio [OR], 3.1; 95% confidence interval [CI], 2.9-3.4; P < .0001), the 30-day mortality was greater for the women than the men (1.8% vs 0.5%; P = .0003). Women also experienced significantly higher rates of multiple complications, including postoperative myocardial infarction (1% vs 0.3%; P = .006), respiratory failure (1.4% vs 0.6%; P = .01), intestinal ischemia (0.7% vs 0.2%; P = .003), access vessel hematoma (3% vs 1.2%; P = .0006), and iliac access vessel injury (2.4% vs 0.8%; P < .0001). Additionally, women experienced increased overall 1-year reintervention rates (11.5% vs 5.8%; P < .0001). In the adjusted analysis, 30-day mortality and any in-hospital complication risk remained significantly greater for the women (30-day death: OR, 3.1; 95% CI, 1.6-5.8; P = .0005; in-hospital complication: OR, 1.9; 95% CI, 1.4-2.6; P < .0001). Women also experienced increased reintervention rates over time compared with men (OR, 1.5; 95% CI, 1.1-2.2; P = .02). CONCLUSIONS: Although men were more likely to undergo non-CPG compliant EVAR, women experienced increased short-term morbidity and 30-day mortality and higher rates of reintervention when undergoing non-CPG compliant EVAR. These unanticipated findings necessitate increased scrutiny of current U.S. sex-based EVAR practice and should caution against the use of non-CPG compliant EVAR for women.

Summarizing causal differences in survival curves in the presence of unmeasured confounding.

Proportional hazard Cox regression models are frequently used to analyze the impact of different factors on time-to-event outcomes. Most practitioners are familiar with and interpret research results in terms of hazard ratios. Direct differences in survival curves are, however, easier to understand for the general population of users and to visualize graphically. Analyzing the difference among the survival curves for the population at risk allows easy interpretation of the impact of a therapy over the follow-up. When the available information is obtained from observational studies, the observed results are potentially subject to a plethora of measured and unmeasured confounders. Although there are procedures to adjust survival curves for measured covariates, the case of unmeasured confounders has not yet been considered in the literature. In this article we provide a semi-parametric procedure for adjusting survival curves for measured and unmeasured confounders. The method augments our novel instrumental variable estimation method for survival time data in the presence of unmeasured confounding with a procedure for mapping estimates onto the survival probability and the expected survival time scales.

Significant regional variation exists in morbidity and mortality after repair of abdominal aortic aneurysm.

OBJECTIVE: Limited data exist comparing perioperative morbidity and mortality after open and endovascular abdominal aortic aneurysm (AAA) repair (EVAR) among regions of the United States. This study evaluated the regional variation in mortality and perioperative outcomes after repair of AAAs. METHODS: The Vascular Quality Initiative (VQI) was used to identify patients undergoing open AAA repair and EVAR between 2009 and 2014. Ruptured and intact aneurysms were evaluated separately, and the analysis of intact aneurysms was limited to infrarenal AAAs. All 16 regions of the VQI were deidentified, and those with <100 open repairs were combined to eliminate the effect of low-volume regions. Regional variation was evaluated using χ2 and Fisher exact tests. Regional rates were compared against current quality benchmarks. RESULTS: Perioperative outcomes from 14 regions were compared. After open repair of intact aneurysms, no significant variation was seen in 30-day or in-hospital mortality; however, multiple regions exceeded the Society for Vascular Surgery benchmark for in-hospital mortality after open repair of intact aneurysms of <5% (range, 0%-7%; P = .55). After EVAR, all regions met the Society for Vascular Surgery benchmark of <3% (range, 0%-1%; P = .75). Significant variation in in-hospital mortality existed after open (14%-63%; P = .03) and endovascular (3%-32%; P = .03) repair of ruptured aneurysms across the VQI regional groups. After repair of intact aneurysms, wide variation was seen in prolonged length of stay (>7 days for open repair: 32%-53%, P = .54; >2 days for EVAR: 16-43%, P < .01), transfusion (open: 10%-35%, P < .01; EVAR: 7%-18%, P < .01), use of vasopressors (open: 19%-37%, P < .01; EVAR: 3%-7%, P < .01), and postoperative myocardial infarction (open: 0%-13%, P < .01; EVAR: 0%-3%, P < .01). After open repair, worsening renal function (6%-18%; P = .04) and respiratory complications (6%-20%; P = .20) were variable across regions. The frequency of endoleak at completion of EVAR also had considerable variation (15%-38%; P < .01). CONCLUSIONS: Despite limited variation, multiple regions do not meet current benchmarks for in-hospital mortality after open AAA repair for intact aneurysms. Significant regional variation exists in perioperative outcomes and length of stay, and mortality is widely variable after repair for rupture. These data identify important areas for quality improvement initiatives and clinical practice guidelines.

The natural history of type II endoleaks after endovascular aneurysm repair for ruptured abdominal aortic aneurysm.

OBJECTIVE: The natural history of type II endoleak (T2EL) after endovascular aneurysm repair (EVAR) for ruptured abdominal aortic aneurysm (rAAA) remains elusive; as such, treatment guidelines are ill defined. The purpose of this study was to better delineate the natural history of T2EL after EVAR for rAAA in an effort to determine the need for reintervention and optimal surveillance. METHODS: A retrospective record review was conducted of all patients undergoing EVAR for rAAA in two large tertiary care academic vascular centers. Patient demographics, comorbidities, anatomic variables, and operative details were analyzed. Primary outcomes included the presence of T2EL, reintervention, delayed rupture, and aneurysm-related death. RESULTS: EVAR was used to treat rAAA in 56 patients between 2000 and 2013. Mean follow-up of this cohort was 634 days. Completion arteriogram demonstrated T2ELs in 12 patients (21%), and an additional four T2ELs (7%) were found by postoperative computed tomography angiogram that were not identified on the completion angiogram. Body mass index was the only statistically significant variable associated with the development of T2EL (P = .03). Preoperative warfarin use, aortic thrombus burden, and device type did not correlate with T2EL development. Iliolumbar vessels supplied 75% (n = 12) of T2ELs. Of the 14 patients with T2ELs who underwent serial imaging postoperatively, six (43%) sealed spontaneously. Five patients (36%) underwent reintervention for T2EL by way of coil embolization-four in which treatment was initiated by attending preference. One patient was treated for ongoing anemia in the immediate postoperative period. There was no sac expansion, delayed rupture, or graft explantation. CONCLUSIONS: T2ELs after EVAR for rAAA are common and appear to be associated with a benign natural history if left untreated. Although many will spontaneously seal early in the postoperative period, those that remain patent do not appear to increase the risk for sac expansion or delayed rupture or affect patient survival. As such, a conservative approach to treatment of T2ELs in rAAA may be warranted.

Regional variation exists in patient selection and treatment of abdominal aortic aneurysms.

OBJECTIVE: Significant regional variation in surgical rates has been identified following multiple surgical procedures. However, limited data have examined the regional variability in patient selection and treatment of abdominal aortic aneurysms (AAAs). This study aimed to evaluate regional variation in patient selection, perioperative management, and operative approach for the repair of AAAs. METHODS: All patients undergoing open repair or endovascular aneurysm repair (EVAR) of an AAA in the Vascular Quality Initiative from 2009 to 2014 were identified. All regional groups were deidentified, and those with fewer than 100 open repairs were combined into a single region. RESULTS: We identified 17,269 elective repairs (EVAR, 13,759; open, 3510) and 1462 ruptured AAAs (EVAR, 749; open, 713). There was significant regional variation in the use of EVAR for elective repair (range, 66%-88%; P < .01) and ruptured AAA repair (40%-80%; P < .01). The median diameter for elective repair was similar among regions (EVAR, 5.4 cm; open, 5.7 cm). There was wide variation in the treatment of small aneurysms in male patients (<5.5 cm) for EVAR (34%-49%; P < .01) and open repair (17%-38%; P < .01) and variation in the treatment of small aneurysms in female patients (<5 cm) for EVAR (14%-32%; P < .01) but not significant for open repair (6%-24%). For elective cases, preoperative aspirin (EVAR, 50%-75% [P < .01]; open, 49%-78% [P < .01]) and statin use (EVAR, 61%-75% [P < .01]; open, 56%-80% [P < .01]) varied widely. Among elective cardiac patients, preoperative management varied significantly, including beta-blocker use (EVAR, 66%-78% [P < .01]; open, 69%-88% [P = .01]) and the frequency of stress tests (EVAR, 33%-64% [P < .01]; open, 31%-73% [P < .01]). Among open repairs for aneurysms extending at or beyond the juxtarenal segment, there was wide variation in the use of retroperitoneal exposures (7%-70%; P < .01) and adjunctive renal protective measures (cold renal perfusion, 2%-43% [P < .01]; mannitol, 47%-92% [P < .01]). CONCLUSIONS: Significant regional variation exists in patient selection, perioperative management, and operative approach for the repair of AAA. Definitive evidence is lacking in many aspects of operative care, including the use of the retroperitoneal approach and renal protective strategies. However, this variation emphasizes the importance of research to determine best practice in the areas of greatest variation. Furthermore, where current clinical process measures exist and data are clear, such as the use of statin and antiplatelet agents, the high degree of variation should serve as an impetus for regional quality improvement projects.