Faculty Bibliography

We present a new approach to population health, in which data-driven predictive models are learned for outcomes such as type 2 diabetes. Our approach enables risk assessment from readily available electronic claims data on large populations, without additional screening cost. Proposed model uncovers early and late-stage risk factors. Using administrative claims, pharmacy records, healthcare utilization, and laboratory results of 4.1 million individuals between 2005 and 2009, an initial set of 42,000 variables were derived that together describe the full health status and history of every individual. Machine learning was then used to methodically enhance predictive variable set and fit models predicting onset of type 2 diabetes in 2009-2011, 2010-2012, and 2011-2013. We compared the enhanced model with a parsimonious model consisting of known diabetes risk factors in a real-world environment, where missing values are common and prevalent. Furthermore, we analyzed novel and known risk factors emerging from the model at different age groups at different stages before the onset. Parsimonious model using 21 classic diabetes risk factors resulted in area under ROC curve (AUC) of 0.75 for diabetes prediction within a 2-year window following the baseline. The enhanced model increased the AUC to 0.80, with about 900 variables selected as predictive (p < 0.0001 for differences between AUCs). Similar improvements were observed for models predicting diabetes onset 1-3 years and 2-4 years after baseline. The enhanced model improved positive predictive value by at least 50% and identified novel surrogate risk factors for type 2 diabetes, such as chronic liver disease (odds ratio [OR] 3.71), high alanine aminotransferase (OR 2.26), esophageal reflux (OR 1.85), and history of acute bronchitis (OR 1.45). Liver risk factors emerge later in the process of diabetes development compared with obesity-related factors such as hypertension and high hemoglobin A1c. In conclusion, population-level risk prediction for type 2 diabetes using readily available administrative data is feasible and has better prediction performance than classical diabetes risk prediction algorithms on very large populations with missing data. The new model enables intervention allocation at national scale quickly and accurately and recovers potentially novel risk factors at different stages before the disease onset.

BACKGROUND: Hospital care on weekends has been associated with delays in care, reduced quality, and poor clinical outcomes. OBJECTIVE: The purpose of this study was to evaluate the impact of a weekend hospital intervention on processes of care and clinical outcomes. The multifaceted intervention included expanded weekend diagnostic services, improved weekend discharge processes, and increased physician and care management services on weekends. DESIGN AND PATIENTS: This was an interrupted time series observational study of adult non-obstetric patients hospitalized at a single academic medical center between January 2011 and January 2014. The study included 18 months prior to and 19 months following the implementation of the intervention. Data were analyzed using segmented regression analysis with adjustment for confounders. MAIN MEASURES: The primary outcome was average length of stay. Secondary outcomes included percent of patients discharged on weekends, 30-day readmission rate, and in-hospital mortality rate. KEY RESULTS: The study included 57,163 hospitalizations. Following implementation of the intervention, average length of stay decreased by 13 % (95 % CI 10-15 %) and continued to decrease by 1 % (95 % CI 1-2 %) per month as compared to the underlying time trend. The proportion of weekend discharges increased by 12 % (95 % CI 2-22 %) at the time of the intervention and continued to increase by 2 % (95 % CI 1-3 %) per month thereafter. The intervention had no impact on readmissions or mortality. During the post-implementation period, the hospital was evacuated and closed for 2 months due to damage from Hurricane Sandy, and a new hospital-wide electronic health record was introduced. The contributions of these events to our findings are not known. We observed a lower inpatient census and found differences in patient characteristics, including higher rates of Medicaid insurance and comorbidities, in the post-Hurricane Sandy period as compared to the pre-Sandy period. CONCLUSIONS: The intervention was associated with a reduction in length of stay and an increase in weekend discharges. Our longitudinal study also illuminated the challenges of evaluating the effectiveness of a large-scale intervention in a real-world hospital setting.

BACKGROUND: Randomized trials of percutaneous coronary intervention (PCI) versus coronary artery bypass graft (CABG) routinely exclude patients with chronic kidney disease (CKD). OBJECTIVES: This study evaluated outcomes of PCI versus CABG in patients with CKD. METHODS: Patients with CKD who underwent PCI using everolimus-eluting stents were propensity-score matched to patients who underwent isolated CABG for multivessel coronary disease in New York. The primary outcome was all-cause mortality. Secondary outcomes were myocardial infarction (MI), stroke, and repeat revascularization. RESULTS: Of 11,305 patients with CKD, 5,920 patients were propensity-score matched. In the short term, PCI was associated with a lower risk of death (hazard ratio [HR]: 0.55; 95% confidence interval [CI]: 0.35 to 0.87), stroke (HR: 0.22; 95% CI: 0.12 to 0.42), and repeat revascularization (HR: 0.48; 95% CI: 0.23 to 0.98) compared with CABG. In the longer term, PCI was associated with a similar risk of death (HR: 1.07; 95% CI: 0.92 to 1.24), higher risk of MI (HR: 1.76; 95% CI: 1.40 to 2.23), a lower risk of stroke (HR: 0.56; 95% CI: 0.41 to 0.76), and a higher risk of repeat revascularization (HR: 2.42; 95% CI: 2.05 to 2.85). In the subgroup with complete revascularization with PCI, the increased risk of MI was no longer statistically significant (HR: 1.18; 95% CI: 0.67 to 2.09). In the 243 matched pairs of patients with end-stage renal disease on hemodialysis, PCI was associated with significantly higher risk of death (HR: 2.02; 95% CI: 1.40 to 2.93) and repeat revascularization (HR: 2.44; 95% CI: 1.50 to 3.96) compared with CABG. CONCLUSIONS: In patients with CKD, CABG is associated with higher short-term risk of death, stroke, and repeat revascularization, whereas PCI with everolimus-eluting stents is associated with a higher long-term risk of repeat revascularization and perhaps MI, with no long-term mortality difference. In the subgroup on dialysis, the results favored CABG over PCI.

Background: Comorbid diabetes is common in heart failure and associated with increased hospitalization and mortality. Nonetheless, the optimal treatment strategy for diabetes in heart failure patients remains poorly characterized, particularly among low income and minority populations. The purpose of this study was to evaluate the association between glycemic control and outcomes among patients with heart failure and diabetes who were seen in a safety net health care system. Methods: We performed a retrospective cohort study of outpatients with heart failure and diabetes in the New York City Health and Hospitals Corporation, the largest municipal health care system in the United States. Subjects with diagnoses of heart failure and diabetes mellitus were included if they had an outpatient visit in 2007-2010 with an HbA1c performed in the prior 90 days. HbA1c and covariates, including demographics, comorbidities, vital signs, labs, and prior utilization, were obtained from the HHC data warehouse, which was linked to the New York State Inpatient Database and to New York State Vital Statistics to ascertain hospitalization and mortality events, respectively. Cox proportional hazard models were used to measure the association between HbA1c levels and outcomes of all-cause hospitalization, heart failure hospitalization, and mortality. Results: Of 4,723 patients with heart failure and diabetes, 42.6% were black, 30.5% were Hispanic/ Latino, 31.4% were Medicaid beneficiaries and 22.9% were uninsured. As compared to patients with an HbA1c of 8.0-8.9%, patients with an HbA1c of <6.5%, 6.5-6.9%, 7.0-7.9%, and >9.0% had an adjusted hazard ratio (aHR) (95% CI) for all-cause hospitalization of 1.03 (0.90-1.17), 1.05 (0.91-1.22), 1.03 (0.90-1.17), and 1.13 (1.00-1.28), respectively. An HbA1c>9.0% was also associated with an increased risk of heart failure hospitalization (aHR 1.33; 95% CI 1.11- 1.59) and a non-significant increased risk in mortality (aHR 1.20; 95% CI 0.99-1.45) when compared to HbA1c of 8.0-8.9%. Conclusions: Among a cohort of primarily minority and low income patients with heart failure and diabetes, an increased risk of hospitalization was observed only for an HbA1c greater than 9%

BACKGROUND: In patients with diabetes mellitus and multivessel disease, coronary artery bypass graft surgery and percutaneous coronary intervention are treatment options. However, there is paucity of data comparing coronary artery bypass graft surgery against newer generation stents. METHODS AND RESULTS: Patients included in the New York State registries who had diabetes mellitus and underwent isolated coronary artery bypass graft surgery or percutaneous coronary intervention with everolimus eluting stent (EES) for multivessel disease were included. Propensity score matching was used to assemble a cohort with similar baseline characteristics. The primary outcome was all-cause mortality. Secondary outcomes were myocardial infarction (MI), stroke, and repeat revascularization. Short-term (within 30 days) and long-term outcomes were evaluated. Among 16 089 patients with diabetes mellitus and multivessel disease, 8096 patients with similar propensity scores were included. At short-term, EES was associated with a lower risk of death (hazard ratio [HR] =0.58; 95% confidence interval [CI], 0.34-0.98; P=0.04) and stroke (HR=0.14; 95% CI, 0.06-0.30; P<0.0001) but higher risk of MI (HR=2.44; 95% CI, 1.13-5.31; P=0.02). At long-term, EES was associated with a similar risk of death (425 [10.50%] versus 414 [10.23%] events; HR=1.12; 95% CI, 0.96-1.30; P=0.16), a lower risk of stroke (118 [2.92%] versus 157 [3.88%] events; HR=0.76; 95% CI, 0.58-0.99; P=0.04) but a higher risk of MI (260 [6.42%] versus 166 [4.10%] events; HR=1.64; 95% CI, 1.32-2.04; P<0.0001) and repeat revascularization (889 [21.96%] versus 421 [10.40%] events; HR=2.42; 95% CI, 2.12-2.76; P<0.0001). The higher risk of MI was not seen in the subgroup of EES patients who underwent complete revascularization (HR=1.37; 95% CI, 0.76-2.47; P=0.30). CONCLUSIONS: In patients with diabetes mellitus and multivessel disease, EES was associated with lower upfront risk of death and stroke when compared with coronary artery bypass graft surgery. However, at long-term, EES was associated with similar risk of death, a higher risk of MI (in those with incomplete revascularization), and repeat revascularization but a lower risk of stroke.

Background Results of trials and registry studies have shown lower long-term mortality after coronary-artery bypass grafting (CABG) than after percutaneous coronary intervention (PCI) among patients with multivessel disease. These previous analyses did not evaluate PCI with second-generation drug-eluting stents. Methods In an observational registry study, we compared the outcomes in patients with multivessel disease who underwent CABG with the outcomes in those who underwent PCI with the use of everolimus-eluting stents. The primary outcome was all-cause mortality. Secondary outcomes were the rates of myocardial infarction, stroke, and repeat revascularization. Propensity-score matching was used to assemble a cohort of patients with similar baseline characteristics. Results Among 34,819 eligible patients, 9223 patients who underwent PCI with everolimus-eluting stents and 9223 who underwent CABG had similar propensity scores and were included in the analyses. At a mean follow-up of 2.9 years, PCI with everolimus-eluting stents, as compared with CABG, was associated with a similar risk of death (3.1% per year and 2.9% per year, respectively; hazard ratio, 1.04; 95% confidence interval [CI], 0.93 to 1.17; P=0.50), higher risks of myocardial infarction (1.9% per year vs. 1.1% per year; hazard ratio, 1.51; 95% CI, 1.29 to 1.77; P<0.001) and repeat revascularization (7.2% per year vs. 3.1% per year; hazard ratio, 2.35; 95% CI, 2.14 to 2.58; P<0.001), and a lower risk of stroke (0.7% per year vs. 1.0% per year; hazard ratio, 0.62; 95% CI, 0.50 to 0.76; P<0.001). The higher risk of myocardial infarction with PCI than with CABG was not significant among patients with complete revascularization but was significant among those with incomplete revascularization (P=0.02 for interaction). Conclusions In a contemporary clinical-practice registry study, the risk of death associated with PCI with everolimus-eluting stents was similar to that associated with CABG. PCI was associated with a higher risk of myocardial infarction (among patients with incomplete revascularization) and repeat revascularization but a lower risk of stroke. (Funded by Abbott Vascular.).