A Systematic Approach to Evaluating Instrumental Variable Assumptions: Applied Example of Glucose-lowering Medications and Risk for Hospitalized Heart Failure in Older Adults.

One obstacle to adopting instrumental variable (IV) methods in pharmacoepidemiology is their reliance on strong, unverifiable assumptions. We can falsify IV assumptions by leveraging the causal structure, which can strengthen or refute their plausibility and increase the validity of effect estimates. We illustrate a systematic approach to evaluate calendar time IV assumptions in estimating the known effect of thiazolidinediones on hospitalized heart failure. Using cohort entry time before and after 09/2010, when the U.S. Food and Drug Administration issued a safety communication as a proposed IV, we estimated IV and propensity score-weighted 2-year risk differences (RDs) using Medicare data (2008-2014). We (i) performed inequality tests, (ii) identified the negative control IV/outcome using causal assumptions, (iii) estimated RDs after narrowing the calendar time range and excluding patients likely associated with unmeasured confounding, (iv) derived bounds for RDs, and (v) estimated the proportion of compliers and their characteristics. The findings revealed that IV assumptions were violated and RDs were extreme, but the assumptions became more plausible upon narrowing the calendar time range and restricting the cohort by excluding prevalent heart failure (the strongest measured predictor of outcome). Systematically evaluating IV assumptions could help detect bias in IV estimators and increase their validity.

Effectiveness and safety of empagliflozin: final results from the EMPRISE study.

AIMS/HYPOTHESIS: Limited evidence exists on the comparative safety and effectiveness of empagliflozin against alternative glucose-lowering medications in individuals with type 2 diabetes with the broad spectrum of cardiovascular risk. The EMPagliflozin compaRative effectIveness and SafEty (EMPRISE) cohort study was designed to monitor the safety and effectiveness of empagliflozin periodically for a period of 5 years with data collection from electronic healthcare databases. METHODS: We identified individuals ≥18 years old with type 2 diabetes who initiated empagliflozin or dipeptidyl peptidase-4 inhibitors (DPP-4i) from 2014 to 2019 using US Medicare and commercial claims databases. After 1:1 propensity score matching using 143 baseline characteristics, we identified four a priori-defined effectiveness outcomes: (1) myocardial infarction (MI) or stroke; (2) hospitalisation for heart failure (HHF); (3) major adverse cardiovascular events (MACE); and (4) cardiovascular mortality or HHF. Safety outcomes included lower-limb amputations, non-vertebral fractures, diabetic ketoacidosis (DKA), acute kidney injury (AKI), severe hypoglycaemia, retinopathy progression, and short-term kidney and bladder cancers. We estimated HRs and rate differences (RDs) per 1000 person-years, overall and stratified by age, sex, baseline atherosclerotic cardiovascular disease (ASCVD) and heart failure. RESULTS: We identified 115,116 matched pairs. Compared with DPP-4i, empagliflozin was associated with lower risks of MI/stroke (HR 0.88 [95% CI 0.81, 0.96]; RD -2.08 [95% CI (-3.26, -0.90]), HHF (HR 0.50 [0.44, 0.56]; RD -5.35 [-6.22, -4.49]), MACE (HR 0.73 [0.62, 0.86]; RD -6.37 [-8.98, -3.77]) and cardiovascular mortality/HHF (HR 0.57 [0.47, 0.69]; RD -10.36 [-12.63, -8.12]). Absolute benefits were larger in older individuals and in those with ASCVD/heart failure. Empagliflozin was associated with an increased risk of DKA (HR 1.78 [1.44, 2.19]; RD 1.59 [1.08, 2.09]); decreased risks of AKI (HR 0.62 [0.54, 0.72]; RD -2.39 [-3.08, -1.71]), hypoglycaemia (HR 0.75 [0.67, 0.84]; RD -2.46 [-3.32, -1.60]) and retinopathy progression (HR 0.78 [0.63, 0.96)]; RD -9.49 [-16.97, -2.10]); and similar risks of other safety events. CONCLUSIONS/INTERPRETATION: Empagliflozin relative to DPP-4i was associated with risk reductions of MI or stroke, HHF, MACE and the composite of cardiovascular mortality or HHF. Absolute risk reductions were larger in older individuals and in those who had history of ASCVD or heart failure. Regarding the safety outcomes, empagliflozin was associated with an increased risk of DKA and lower risks of AKI, hypoglycaemia and progression to proliferative retinopathy, with no difference in the short-term risks of lower-extremity amputation, non-vertebral fractures, kidney and renal pelvis cancer, and bladder cancer.

Cardiorenal effectiveness of empagliflozin vs. glucagon-like peptide-1 receptor agonists: final-year results from the EMPRISE study.

BACKGROUND: No randomized clinical trials have directly compared the cardiorenal effectiveness of empagliflozin and GLP-1RA agents with demonstrated cardioprotective effects in patients with a broad spectrum of cardiovascular risk. We reported the final-year results of the EMPRISE study, a monitoring program designed to evaluate the cardiorenal effectiveness of empagliflozin across broad patient subgroups. METHODS: We identified patients ≥ 18 years old with type 2 diabetes who initiated empagliflozin or GLP-1RA from 2014 to 2019 using US Medicare and commercial claims databases. After 1:1 propensity score matching using 143 baseline characteristics, we evaluated risks of outcomes including myocardial infarction (MI) or stroke, hospitalization for heart failure (HHF), major adverse cardiovascular events (MACE - MI, stroke, or cardiovascular mortality), a composite of HHF or cardiovascular mortality, and progression to end-stage kidney disease (ESKD) (in patients with chronic kidney disease stages 3-4). We estimated hazard ratios (HR) and rate differences (RD) per 1,000 person-years, overall and within subgroups of age, sex, baseline atherosclerotic cardiovascular disease (ASCVD), and heart failure (HF). RESULTS: We identified 141,541 matched pairs. Compared with GLP-1RA, empagliflozin was associated with similar risks of MI or stroke [HR: 0.99 (0.92, 1.07); RD: -0.23 (-1.25, 0.79)], and lower risks of HHF [HR: 0.50 (0.44, 0.56); RD: -2.28 (-2.98, -1.59)], MACE [HR: 0.90 (0.82, 0.99); RD: -2.54 (-4.76, -0.32)], cardiovascular mortality or HHF [HR: 0.77 (0.69, 0.86); RD: -4.11 (-5.95, -2.29)], and ESKD [0.75 (0.60, 0.94); RD: -6.77 (-11.97, -1.61)]. Absolute risk reductions were larger in older patients and in those with baseline ASCVD/HF. They did not differ by sex. CONCLUSIONS: The cardiovascular benefits of empagliflozin vs. cardioprotective GLP-1RA agents were larger in older patients and in patients with history of ASCVD or HF, while they did not differ by sex. In patients with advanced CKD, empagliflozin was associated with risk reductions of progression to ESKD.

Stratified analysis in comparative effectiveness studies that emulate randomized trials.

PURPOSE: For observational cohort studies that employ matching by propensity scores (PS), preliminary stratification by consequential predictors of outcome better emulates stratified randomization and potentially reduces variance and bias through relaxed dependence on modeling assumptions. We assessed the impact of pre-stratification in two real-life examples. For both, prior evidence from placebo-controlled randomized clinical trials (RCTs) suggested small or no risk reduction, but observational analysis suggested protection, presumably the result of confounding bias. STUDY DESIGN AND SETTING: The study populations consisted of Medicare beneficiaries (2014-18) with type 2 diabetes initiating either (i) empagliflozin versus dipeptidyl peptidase-4 inhibitors (DPP-4i) or (ii) empagliflozin versus glucagon-like peptide-1 receptor agonists (GLP-1RA). The outcome was myocardial infarction or stroke. We estimated hazard ratios (HR) and rate differences (RD) after controlling for 143 pre-exposure covariates via 1:1 PS matching after (1) PS estimation in the total cohort (total-cohort PS-matching) and (2) PS estimation separately by baseline cardiovascular disease (stratified PS matching). RESULTS: Stratified PS matching resulted in HRs that exceeded those from total-cohort PS-matching by 13% and 9%, respectively, for the comparisons of empagliflozin to DPP-4i and GLP-1RA. Against both comparators, HRs and RDs after stratified PS matching were closer to the null, with slightly higher variances (2%-3%) than those after total-cohort PS matching. CONCLUSION: Stratified PS matching produced effect estimates closer to the expected trial findings than total-cohort PS matching. The price paid in increased variance was minimal.

Risk of Severe Hypoglycemia With Newer Second-line Glucose-lowering Medications in Older Adults With Type 2 Diabetes Stratified by Known Indicators of Hypoglycemia Risk.

BACKGROUND: Severe hypoglycemia is associated with adverse clinical outcomes. We evaluated the risk of severe hypoglycemia in older adults initiating newer glucose-lowering medications overall and across strata of known indicators of high hypoglycemia risk. METHODS: We conducted a comparative-effectiveness cohort study of older adults aged >65 years with type 2 diabetes initiating sodium-glucose cotransporter 2 inhibitors (SGLT2i) versus dipeptidyl peptidase-4 inhibitors (DPP-4i) or SGLT2i versus glucagon-like peptide-1 receptor agonists (GLP-1RA) using Medicare claims (3/2013-12/2018) and Medicare-linked-electronic health records. We identified severe hypoglycemia requiring emergency or inpatient visits using validated algorithms. After 1:1 propensity score matching, we estimated hazard ratios (HR) and rate differences (RD) per 1,000 person-years. Analyses were stratified by baseline insulin, sulfonylurea, cardiovascular disease (CVD), chronic kidney disease (CKD), and frailty. RESULTS: Over a median follow-up of 7 (interquartile range: 4-16) months, SGLT2i was associated with a reduced risk of hypoglycemia versus DPP-4i (HR 0.75 [0.68, 0.83]; RD -3.21 [-4.29, -2.12]), and versus GLP-1RA (HR 0.90 [0.82, 0.98]; RD -1.33 [-2.44, -0.23]). RD for SGLT2i versus DPP-4i was larger in patients using baseline insulin than in those not, although HRs were similar. In patients using baseline sulfonylurea, the risk of hypoglycemia was lower in SGLT2i versus DPP-4i (HR 0.57 [0.49, 0.65], RD -6.80 [-8.43, -5.16]), while the association was near-null in those without baseline sulfonylurea. Results stratified by baseline CVD, CKD and frailty were similar to the overall cohort findings. Findings for the GLP-1RA comparison were similar. CONCLUSIONS: SGLT2i was associated with a lower hypoglycemia risk versus incretin-based medications, with larger associations in patients using baseline insulin or sulfonylurea.

Comparative Effectiveness of Empagliflozin vs Liraglutide or Sitagliptin in Older Adults With Diverse Patient Characteristics.

Importance: Limited evidence is available on the comparative effectiveness of empagliflozin vs alternative second-line glucose-lowering agents in patients with type 2 diabetes (T2D) receiving routine care who have a broad spectrum of cardiorenal risk. Objective: To evaluate the association of empagliflozin with cardiovascular outcomes relative to liraglutide and sitagliptin, stratified by age, sex, baseline atherosclerotic cardiovascular disease (ASCVD), heart failure (HF), and chronic kidney disease (CKD). Design, Setting, and Participants: This retrospective comparative effectiveness cohort study used deidentified Medicare claims data from August 1, 2014, to September 30, 2018, with follow-up from drug initiation until treatment changes, death, or gap in Medicare enrollment (>30 days). Data analysis was performed from October 1, 2021, to April 30, 2022. Medicare fee-for-service beneficiaries older than 65 years with T2D were included. A total of 45 788 patients (22 894 propensity score-matched pairs initiating treatment with either empagliflozin or liraglutide) were included in cohort 1, and 45 624 patients (22 812 propensity score-matched pairs initiating treatment with either empagliflozin or sitagliptin) were included in cohort 2. Exposures: Empagliflozin vs liraglutide (cohort 1) or empagliflozin vs sitagliptin (cohort 2). Main Outcomes and Measures: Primary outcomes were (1) modified major adverse cardiovascular events (MACEs), including a composite of myocardial infarction, stroke, and all-cause mortality, and (2) hospitalization for heart failure (HHF). Hazard ratios (HRs) and rate differences (RDs) per 1000 person-years were estimated, adjusting for 143 baseline covariates using 1:1 propensity score matching. Results: Among 45 788 patients in cohort 1, the mean (SD) age was 71.9 (5.1) years; 23 396 patients (51.1%) were female, 22 392 (48.9%) were male, and 38 049 (83.1%) were White. Among 45 624 patients in cohort 2, the mean (SD) age was 72.1 (5.1) years; 21 418 patients (46.9%) were female, 24 206 (53.1%) were male, and 37 814 (82.9%) were White. Relative to patients initiating liraglutide, those initiating empagliflozin had a similar risk of the modified MACE outcome (HR, 0.90; 95% CI, 0.79-1.03) and a reduced risk of HHF (HR, 0.66; 95% CI, 0.52-0.82). Across subgroups, empagliflozin was associated with a lower risk of the modified MACE outcome in patients with a history of ASCVD (HR, 0.83; 95% CI, 0.71-0.98) and HF (HR, 0.77; 95% CI, 0.60-1.00) compared with liraglutide, and potential heterogeneity in estimates was observed by sex (male: HR, 0.85 [95% CI, 0.71-1.01]; female: HR, 1.16 [95% CI, 0.94-1.42]; P = .02 for homogeneity). However, reductions in the risk of HHF were observed across most subgroups (eg, ASCVD: HR, 0.66 [95% CI, 0.51-0.85]; HF: HR, 0.66 [95% CI, 0.49-0.88]). Compared with sitagliptin, empagliflozin was associated with reduced risks of the modified MACE outcome (HR, 0.68; 95% CI, 0.60-0.77) and HHF (HR, 0.45; 95% CI, 0.36-0.56), which were consistent across all subgroups. Absolute benefits of empagliflozin vs sitagliptin were larger in patients with a history of ASCVD (modified MACE: RD, -17.6 [95% CI, -24.9 to -10.4]; HHF: RD, -16.7 [95% CI, -21.7 to -11.9]), HF (modified MACE: RD, -41.1 [95% CI, -59.9 to -22.6]; HHF: RD, -50.4 [95% CI, -67.5 to -33.9]), or CKD (modified MACE: RD, -26.7 [95% CI, -41.3 to -12.3]; HHF: RD, -31.9 [95% CI, -43.5 to -20.8]). Conclusions and Relevance: In this comparative effectiveness study of older adults, empagliflozin was associated with a lower risk of HHF (relative to both liraglutide and sitagliptin) and the modified MACE outcome (relative to sitagliptin), with larger absolute benefits in patients with established cardiorenal diseases. These findings suggest that older adults with T2D might benefit more from empagliflozin vs liraglutide or sitagliptin with respect to the risk of HHF; with respect to the risk of MACEs, empagliflozin might be preferable to liraglutide only in patients with cardiovascular disease history and to sitagliptin across all patient subgroups.

Evaluating Confounding Control in Estimations of Influenza Antiviral Effectiveness in Electronic Health Plan Data.

Observational studies of oseltamivir use and influenza complications could suffer from residual confounding. Using negative control risk periods and a negative control outcome, we examined confounding control in a health-insurance-claims-based study of oseltamivir and influenza complications (pneumonia, all-cause hospitalization, and dispensing of an antibiotic). Within the Food and Drug Administration's Sentinel System, we identified individuals aged ≥18 years who initiated oseltamivir use on the influenza diagnosis date versus those who did not, during 3 influenza seasons (2014-2017). We evaluated primary outcomes within the following 1-30 days (the primary risk period) and 61-90 days (the negative control period) and nonvertebral fractures (the negative control outcome) within days 1-30. We estimated propensity-score-matched risk ratios (RRs) per season. During the 2014-2015 influenza season, oseltamivir use was associated with a reduction in the risk of pneumonia (RR = 0.72, 95% confidence interval (CI): 0.70, 0.75) and all-cause hospitalization (RR = 0.54, 95% CI: 0.53, 0.55) in days 1-30. During days 61-90, estimates were near-null for pneumonia (RR = 1.04, 95% CI: 0.95, 1.15) and hospitalization (RR = 0.94, 95% CI: 0.91, 0.98) but slightly increased for antibiotic dispensing (RR = 1.14, 95% CI: 1.08, 1.21). The RR for fractures was near-null (RR = 1.09, 95% CI: 0.99, 1.20). Estimates for the 2016-2017 influenza season were comparable, while the 2015-2016 season had conflicting results. Our study suggests minimal residual confounding for specific outcomes, but results differed by season.

Cardiovascular Effectiveness of Sodium-Glucose Cotransporter 2 Inhibitors and Glucagon-Like Peptide-1 Receptor Agonists in Older Patients in Routine Clinical Care With or Without History of Atherosclerotic Cardiovascular Diseases or Heart Failure.

Background Randomized trials demonstrate the cardioprotective effects of sodium-glucose cotransporter 2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP-1RA). We evaluated their relative cardiovascular effectiveness in routine care populations with a broad spectrum of atherosclerotic cardiovascular diseases (CVDs) or heart failure (HF). Methods and Results We identified Medicare beneficiaries from 2013 to 2017, aged >65 years, initiating SGLT2i (n=24 747) or GLP-1RA (n=22 596) after a 1-year baseline. On the basis of diagnoses during baseline, we classified patients into: (1) no HF or CVD, (2) HF but no CVD, (3) no HF but CVD, and (4) both HF and CVD. We identified hospitalized HF and atherosclerotic CVD outcomes from drug initiation until treatment changes, death, or disenrollment. We estimated propensity score-weighted 2-year risk ratios (RRs) and risk differences, accounting for measured confounding, informative censoring, and competing risk. In patients with no CVD or HF, SGLT2i reduced the hospitalized HF risk compared with GLP-1RA (propensity score-weighted RR, 0.65; 95% CI, 0.43-0.96). The association was strongest in those who had HF but no CVD (RR, 0.48; 95% CI, 0.25-0.85). The combined myocardial infarction, stroke, and mortality outcome risk was slightly higher for SGLT2i compared with GLP-1RA in those without CVD or HF (RR, 1.31; 95% CI, 1.09-1.56). The association was favorable toward SGLT2i in subgroups with a history of HF. Conclusions SGLT2i reduced the cardiovascular risk versus GLP-1RA in patients with a history of HF but no CVD. Atherosclerotic CVD events were less frequent with GLP-1RA in those without prior CVD or HF.