Publications

The noniterative conditional expectation (NICE) parametric g-formula can be used to estimate the causal effect of sustained treatment strategies. In addition to identifiability conditions, the validity of the NICE parametric g-formula generally requires the correct specification of models for time-varying outcomes, treatments, and confounders at each follow-up time point. An informal approach for evaluating model specification is to compare the observed distributions of the outcome, treatments, and confounders with their parametric g-formula estimates under the "natural course." In the presence of loss to follow-up, however, the observed and natural-course risks can differ even if the identifiability conditions of the parametric g-formula hold and there is no model misspecification. Here, we describe 2 approaches for evaluating model specification when using the parametric g-formula in the presence of censoring: 1) comparing factual risks estimated by the g-formula with nonparametric Kaplan-Meier estimates and 2) comparing natural-course risks estimated by inverse probability weighting with those estimated by the g-formula. We also describe how to correctly compute natural-course estimates of time-varying covariate means when using a computationally efficient g-formula algorithm. We evaluate the proposed methods via simulation and implement them to estimate the effects of dietary interventions in 2 cohort studies.

BACKGROUND: Female sex is frequently cited as a risk factor for anthracycline cardiotoxicity based on pediatric data, but the role of sex in the development of cardiotoxicity has not been clearly established in adults.

OBJECTIVES: To assess the effect of female sex on the development of incident heart failure (HF) in adult patients treated with anthracyclines.

METHODS: This was a retrospective cohort study of 1525 adult patients with no prior history of HF or cardiomyopathy who were treated with anthracyclines between 1992 and 2019. The primary outcome was new HF within 5 years of the first dose of anthracyclines. The effect of sex was assessed using Cox proportional hazards and competing risk models.

RESULTS: Over a median (IQR) follow-up of 1.02 (0.30-3.01) years, 4.78% of patients developed HF (44 men and 29 women). Female sex was not associated with the primary outcome in a multivariable Cox proportional hazards model (HR 0.87; 95% CI 0.53-1.43; P = 0.58). Similar results were observed in a multivariable model accounting for the competing risk of death (HR 0.94; 95% CI 0.39-2.25; P = 0.88). Age, coronary artery disease and hematopoietic stem cell transplant were associated with the primary outcome in a multivariable Cox proportional hazards model. Age and body mass index were associated with the primary outcome in a multivariable competing risk model.

CONCLUSIONS: In this large, single-center, retrospective cohort study, female sex was not associated with incident HF in adult patients treated with anthracyclines.

CONDENSED ABSTRACT: Female sex is frequently cited as a risk factor for anthracycline cardiotoxicity based on pediatric data, but the role of sex in the development of cardiotoxicity has not been clearly established in adults. In this retrospective cohort study, we assessed the effect of female sex on the development of incident heart failure in adult patients treated with anthracyclines. Using Cox proportional hazards and competing risk regression models, we found that there was no association between female sex and heart failure after treatment with anthracyclines.

BACKGROUND AND AIMS: Declines in cardiovascular mortality have stagnated in the United States since 2011. There is growing concern that these patterns reflect worsening cardiovascular health in younger adults. However, little is known about how the burden of acute cardiovascular hospitalizations and mortality have changed in this population. Changes in cardiovascular hospitalizations and mortality among adults aged 25-64 years were evaluated, overall and by community-level income.

METHODS: Using the National Inpatient Sample, age-standardized annual hospitalization and inhospital mortality rates for acute myocardial infarction (AMI), heart failure, and ischemic stroke were determined among adults aged 25-64 years. Quasi-Poisson and quasi-binominal regression models were fitted to compare outcomes between individuals residing in low- and higher-income communities.

RESULTS: Between 2008 and 2019, age-standardized hospitalization rates for AMI increased among younger adults from 155.0 (95% CI 154.6, 155.4) per 100,000 to 160.7 (160.3, 161.1) per 100,000 (absolute change +5.7 [5.0, 6.3], p<0.001). Heart failure hospitalizations also increased (165.3 [164.8, 165.7] to 225.3 [224.8, 225.8], absolute change +60.0 (59.3, 60.6), p<0.001), as ischemic stroke hospitalizations (76.3 [76.1, 76.7] to 108.1 [107.8, 108.5], absolute change +31.7 (31.2, 32.2), p<0.001). Across all conditions, hospitalizations rates were significantly higher among younger adults residing in low-income compared with higher-income communities, and disparities did not narrow between groups. In-hospital mortality decreased for all conditions over the study period.

CONCLUSIONS: There was an alarming increase in cardiovascular hospitalizations among younger adults in the US from 2008 to 2019, and disparities between those residing in low- and higher-income communities did not narrow.

The EVOLVE Short DAPT study demonstrated the safety of truncated dual antiplatelet therapy (DAPT) in patients with a high bleeding risk (HBR) treated with SYNERGY stent(s) (Boston Scientific Company, Marlborough, Massachusetts). In this population, bleeding and ischemic risk prediction may further inform DAPT decisions. This post hoc analysis of the EVOLVE Short DAPT study identified predictors of ischemic and bleeding events up to 15 months using Cox proportional hazard models. The predicted probabilities of bleeding were calculated using the Breslow method. Of 2,009 enrolled patients, 96.9% of the patients met at least 1 HBR criteria. At 15 months, the cumulative incidences of bleeding and ischemic events were 6.3% and 6.0%, respectively. The risk of bleeding was increased in patients who received oral anticoagulants (hazard ratio [HR] 2.24, 95% confidence interval [CI] 1.50 to 3.36, p <0.001) or had peripheral vascular disease (HR 1.61, 95% CI 1.01 to 2.56, p = 0.045). The risk of ischemic events was increased in patients with diabetes (HR 1.86, 95% CI 1.24 to 2.78, p <0.01) or congestive heart failure (HR 2.06, 95% CI 1.39 to 3.04, p <0.001). Renal insufficiency/failure was associated with both endpoints. There was a strong positive correlation between the predicted probability of ischemic and bleeding events (R = 0.77, p <0.001). In 617 patients with a predicted bleeding risk <4%, ischemic events predominated, and the ischemic and bleeding rates were higher in patients with a predicted bleeding risk ≥4%. Within an HBR cohort, specific characteristics identify patients at a higher risk for ischemic and separately, bleeding events. Increased bleeding risk is tied to increased ischemic risk. In conclusion, standardized risk models are needed to inform DAPT decisions in patients with a higher risk. Clinical Trial Registration: NCT02605447.

The EVOLVE Short DAPT study demonstrated the safety of truncated dual antiplatelet therapy (DAPT) in patients with a high bleeding risk (HBR) treated with SYNERGY stent(s) (Boston Scientific Company, Marlborough, Massachusetts). In this population, bleeding and ischemic risk prediction may further inform DAPT decisions. This post hoc analysis of the EVOLVE Short DAPT study identified predictors of ischemic and bleeding events up to 15 months using Cox proportional hazard models. The predicted probabilities of bleeding were calculated using the Breslow method. Of 2,009 enrolled patients, 96.9% of the patients met at least 1 HBR criteria. At 15 months, the cumulative incidences of bleeding and ischemic events were 6.3% and 6.0%, respectively. The risk of bleeding was increased in patients who received oral anticoagulants (hazard ratio [HR] 2.24, 95% confidence interval [CI] 1.50 to 3.36, p <0.001) or had peripheral vascular disease (HR 1.61, 95% CI 1.01 to 2.56, p = 0.045). The risk of ischemic events was increased in patients with diabetes (HR 1.86, 95% CI 1.24 to 2.78, p <0.01) or congestive heart failure (HR 2.06, 95% CI 1.39 to 3.04, p <0.001). Renal insufficiency/failure was associated with both endpoints. There was a strong positive correlation between the predicted probability of ischemic and bleeding events (R = 0.77, p <0.001). In 617 patients with a predicted bleeding risk <4%, ischemic events predominated, and the ischemic and bleeding rates were higher in patients with a predicted bleeding risk ≥4%. Within an HBR cohort, specific characteristics identify patients at a higher risk for ischemic and separately, bleeding events. Increased bleeding risk is tied to increased ischemic risk. In conclusion, standardized risk models are needed to inform DAPT decisions in patients with a higher risk. Clinical Trial Registration: NCT02605447.

BACKGROUND: Left atrial appendage occlusion (LAAO) is an approved alternative for stroke prevention in atrial fibrillation for patients with an "appropriate rationale" to avoid long-term oral anticoagulation (OAC). Many patients undergoing LAAO are at high risk of bleeding.

OBJECTIVES: This study sought to investigate whether dual antiplatelet therapy (DAPT) is a safe alternative to OAC (direct oral anticoagulation [DOAC] or warfarin) with aspirin after LAAO.

METHODS: Using National Cardiovascular Data Registry LAAO registry data, patients undergoing Watchman FLX (Boston Scientific) implantation (August 5, 2020-September 30, 2021) were included in 1:1 propensity-matched analyses comparing discharge medication regimens (DAPT, DOAC/aspirin, or warfarin/aspirin). A composite endpoint (death, stroke, major bleeding, and systemic embolism), its components, and device-related thrombus between discharge and 45 days were evaluated.

RESULTS: In 49,968 patients implanted with the Watchman FLX during the study period, the mean age was 77 years, and 40% were women. Postimplant DOAC/aspirin was prescribed in 24,497 patients, warfarin/aspirin in 3,913, and DAPT in 4,155. DAPT patients had more comorbid conditions than patients receiving OAC/aspirin. After propensity score matching, the 45-day composite endpoint rates were similar among the groups (DAPT = 3.44% vs DOAC/aspirin: 4.06%; P = 0.13 and DAPT = 3.23% vs warfarin/aspirin: 3.08%; P = 0.75). Death, stroke, and device-related thrombus were also similar; major bleeding was slightly increased in DOAC/aspirin patients (DAPT = 2.48% vs DOAC/aspirin = 3.25%; P = 0.04 and DAPT = 2.25% vs warfarin/aspirin = 2.22%; P = 0.93).

CONCLUSIONS: In a large registry, DAPT had a similar safety profile compared with current Food and Drug Administration-approved postimplant drug regimens of OAC with aspirin following LAAO with the Watchman FLX. Shared decision making for nonpharmacologic stroke prevention should include a discussion of postprocedure medical therapy options.

BACKGROUND/AIMS: When the randomized clusters in a cluster randomized trial are selected based on characteristics that influence treatment effectiveness, results from the trial may not be directly applicable to the target population. We used data from two large nursing home-based pragmatic cluster randomized trials to compare nursing home and resident characteristics in randomized facilities to eligible non-randomized and ineligible facilities.

METHODS: We linked data from the high-dose influenza vaccine trial and the Music & Memory Pragmatic TRIal for Nursing Home Residents with ALzheimer's Disease (METRICaL) to nursing home assessments and Medicare fee-for-service claims. The target population for the high-dose trial comprised Medicare-certified nursing homes; the target population for the METRICaL trial comprised nursing homes in one of four US-based nursing home chains. We used standardized mean differences to compare facility and individual characteristics across the three groups and logistic regression to model the probability of nursing home trial participation.

RESULTS: In the high-dose trial, 4476 (29%) of the 15,502 nursing homes in the target population were eligible for the trial, of which 818 (18%) were randomized. Of the 1,361,122 residents, 91,179 (6.7%) were residents of randomized facilities, 463,703 (34.0%) of eligible non-randomized facilities, and 806,205 (59.3%) of ineligible facilities. In the METRICaL trial, 160 (59%) of the 270 nursing homes in the target population were eligible for the trial, of which 80 (50%) were randomized. Of the 20,262 residents, 973 (34.4%) were residents of randomized facilities, 7431 (36.7%) of eligible non-randomized facilities, and 5858 (28.9%) of ineligible facilities. In the high-dose trial, randomized facilities differed from eligible non-randomized and ineligible facilities by the number of beds (132.5 vs 145.9 and 91.9, respectively), for-profit status (91.8% vs 66.8% and 68.8%), belonging to a nursing home chain (85.8% vs 49.9% and 54.7%), and presence of a special care unit (19.8% vs 25.9% and 14.4%). In the METRICaL trial randomized facilities differed from eligible non-randomized and ineligible facilities by the number of beds (103.7 vs 110.5 and 67.0), resource-poor status (4.6% vs 10.0% and 18.8%), and presence of a special care unit (26.3% vs 33.8% and 10.9%). In both trials, the characteristics of residents in randomized facilities were similar across the three groups.

CONCLUSION: In both trials, facility-level characteristics of randomized nursing homes differed considerably from those of eligible non-randomized and ineligible facilities, while there was little difference in resident-level characteristics across the three groups. Investigators should assess the characteristics of clusters that participate in cluster randomized trials, not just the individuals within the clusters, when examining the applicability of trial results beyond participating clusters.