Identifying a Heterogeneous Effect of Atrial Fibrillation Screening in Older Adults: A Secondary Analysis of the VITAL-AF Trial.

Background: One-time screening trials for atrial fibrillation (AF) have produced mixed results; however, it is unclear if there is a subset of individuals for whom screening would be effective. Identifying such a subgroup would support targeted screening. Methods: We conducted a secondary analysis of VITAL-AF, a randomized trial of one-time, single-lead ECG screening during primary care visits. We tested two approaches to identify heterogeneous screening effects. First, we developed an effect-based model for heterogeneous screening effects using a potential outcomes framework. Specifically, we predicted the likelihood of AF diagnosis under both screening and usual care conditions using LASSO, a penalized regression method. The difference between these probabilities was the predicted screening effect. Second, we used the CHARGE-AF score, a validated AF risk model, to test for a heterogeneous screening effect. We used interaction testing to determine if observed AF diagnosis rates in the screening and control groups differed when stratified by decile of the predicted screening effect and predicted AF risk. Results: Baseline characteristics were similar between the screening (n=15187) and usual care (n=15078) groups (mean age 74 years, 59% female). On average, screening did not significantly increase the AF diagnosis rate (2.55 vs. 2.30 per 100 person-years, rate difference 0.24, 95%CI -0.18 to 0.67). In the effect-based analysis, in the highest decile of predicted screening efficacy (n=3026), AF diagnosis rates were higher in the screening group (6.5 vs. 3.06 per 100 person-years, rate difference 3.45, 95%CI 1.62 to 5.28, interaction p-value 0.003). In this group, the mean age was 84 years, 68% were female, and 55% had vascular disease. The risk-based analysis did not identify a subgroup where screening was more effective. Predicted screening effectiveness and predicted baseline AF risk were poorly correlated and demonstrated a U-shaped relationship (Spearman coefficient 0.13). Conclusions: In a secondary analysis of the VITAL-AF trial, we identified a small subgroup where one-time screening was associated with increased AF diagnoses using an effect-based approach. In this study, predicted AF risk was a poor proxy for predicted screening efficacy. These data caution against the assumption that high AF risk is necessarily correlated with high screening efficacy.

The Impact of Organizational Boundaries on Healthcare Coordination and Utilization.

We measure organizational concentration-the distribution of a patient's healthcare across organizations-to examine how firm boundaries affect healthcare efficiency. First, when patients move to regions where outpatient visits are typically concentrated within a small set of firms, their healthcare utilization falls. Second, for patients whose PCPs exit the market, switching to a PCP with 1 standard deviation higher organizational concentration reduces utilization by 21%. This finding is robust to controlling for the spread of healthcare across providers. Increases in organizational concentration predict improvements in diabetes care and are not associated with greater use of emergency department or inpatient care.

Association of Hospital Adoption of Probiotics With Outcomes Among Neonates With Very Low Birth Weight.

Importance: For neonates with very low birth weight (VLBW), randomized clinical trials (RCTs) indicate that probiotic treatment decreases the risk of necrotizing enterocolitis (NEC), with smaller decreases in the risk of sepsis and death. There is little evidence on the rate of probiotic adoption in US neonatal intensive care units (NICUs) and whether the benefits seen in trials have materialized in practice. Objective: To estimate changes in probiotic use among neonates with VLBW and to test whether neonates with VLBW treated at NICUs adopting routine probiotic use experience better outcomes compared with neonates treated at nonadopting NICUs. Design, Setting, and Participants: This cohort study used Vermont Oxford Network data on neonates with VLBW in US NICUs from January 1, 2012, to December 31, 2019. Data were analyzed from January 2022 through February 2023. Exposure: Probiotics adoption vs nonadoption. Adopting NICUs were defined as those that currently or previously treated at least 20% of neonates with VLBW with probiotics. Main Outcomes: The primary outcomes were rates of NEC, in-hospital mortality, and sepsis, defined as bacterial or fungal infection occurring after day 3 from birth. A difference-in-differences analysis compared changes in VLBW infant outcomes between adopting and nonadopting NICUs before and after hospital-level adoption of probiotics. Additional analyses used the proportion of neonates treated with probiotics in each neonate's birth NICU and year. Results: The analysis included 307 905 neonates with VLBW (mean [SD] gestational age, 28.4 [2.9] weeks; 50.0% male) at 807 US hospitals. The rate of probiotic treatment of neonates with VLBW rose from 1572 of 38 296 neonates (4.1%) in 2012 to 4788 of 37 910 (12.6%) in 2019. Only 123 of 745 NICUs (16.5%) adopted probiotics by 2019, with 4591 of 6017 neonates with VLBW (76.3%) receiving probiotics in 2019 at adopting NICUs. Incidence of NEC declined by 18% at adopting NICUs (odds ratio [OR], 0.82; 95% CI, 0.70-0.95; P = .10) compared with nonadopting NICUs. Probiotic adoption was not associated with a significant reduction in sepsis (OR, 1.11; 95% CI, 0.98-1.25; P = .09) or mortality (OR, 0.93; 95% CI, 0.80-1.08; P = .33). Conclusion and Relevance: In this cohort study, adoption of routine use of probiotics increased slowly in US NICUs and was associated with lower NEC risk but not with sepsis or mortality among neonates with VLBW. The findings for probiotic adoption and NEC, sepsis, and mortality were smaller than would have been predicted by the totality of RCT evidence but are consistent with a meta-analysis restricted to studies at low risk of bias.

Drug Diffusion Through Peer Networks: The Influence of Industry Payments.

Pharmaceutical companies market to physicians through individual detailing accompanied by monetary or in-kind transfers. Large compensation payments to a small number of physicians account for most of this promotional spending. Studying US promotional payments and prescriptions for anticoagulant drugs, we investigate how peer influence broadens the payments' reach. Following a compensation payment, prescriptions for the marketed drug increase by both the paid physician and the paid physician's peers. Payments increase prescriptions to both recommended and contraindicated patients. Over three years, marketed anticoagulant prescriptions rose 23 percent due to payments, with peer spillovers contributing a quarter of the increase.

Team Relationships and Performance: Evidence from Healthcare Referral Networks.

We examine the teams that emerge when a primary care physician (PCP) refers patients to specialists. When PCPs concentrate their specialist referrals-for instance, by sending their cardiology patients to fewer distinct cardiologists-repeat interactions between PCPs and specialists are encouraged. Repeated interactions provide more opportunities and incentives to develop productive team relationships. Using data from the Massachusetts All Payer Claims Database, we construct a new measure of PCP team referral concentration and document that it varies widely across PCPs, even among PCPs in the same organization. Chronically ill patients treated by PCPs with a one standard deviation higher team referral concentration have 4% lower health care utilization on average, with no discernible reduction in quality. We corroborate this finding using a national sample of Medicare claims and show that it holds under various identification strategies that account for observed and unobserved patient and physician characteristics. The results suggest that repeated PCP-specialist interactions improve team performance.

THE LOCAL INFLUENCE OF PIONEER INVESTIGATORS ON TECHNOLOGY ADOPTION: EVIDENCE FROM NEW CANCER DRUGS.

Local opinion leaders may play a key role in easing information frictions associated with technology adoption. This paper analyzes the influence of physician investigators who lead clinical trials for new cancer drugs. By comparing diffusion patterns across 21 new cancer drugs, we separate correlated regional demand for new technology from information spillovers. Patients in the lead investigator's region are initially 36% more likely to receive the new drug, but utilization converges within four years. We also find that superstar physician authors, measured by trial role or citation history, have broader influence than less prominent authors.

Trends and Variation in the Utilization and Diagnostic Yield of Chest Imaging for Medicare Patients With Suspected Pulmonary Embolism in the Emergency Department.

OBJECTIVE: The purpose of this study is to assess trends and variation in chest CT utilization in the emergency department (ED) and its diagnostic yield for suspected pulmonary embolism (PE) among a national sample of Medicare beneficiaries. The relationship between hospital and provider characteristics is also discussed. MATERIALS AND METHODS: We conducted an observational analysis of Medicare beneficiaries evaluated in the ED for suspected PE from 2000 to 2009. Standard Medicare analytic files representing a 20% sample of fee-for-service beneficiaries were linked to the American Hospital Association Annual Survey of Hospitals, American Medical Association Physician Masterfile, Medicare Physician Identification and Eligibility Registry, and Dartmouth Atlas Project to calculate geographic- and physician-level chest CT utilization (i.e., the proportion of ED visits involving chest CT examination for suspected PE) and diagnostic yield (i.e., the proportion of chest CT examinations with a positive PE diagnosis). RESULTS: Of 2.5 million ED visits, 2.5% (n = 164,274) included chest CT for suspected PE; 6.2% visits (n = 10,121) resulted in positive findings for PE. Between 2000 and 2009, chest CT utilization increased fivefold. Geographic variation in CT utilization (median, 2.38%; interquartile range [IQR], 1.91-2.92%) and diagnostic yield (median, 6.31%; IQR, 5.11-7.66%) was observed between 306 hospital referral regions. Physician use of imaging was explained by greater experience (lower utilization and higher yield) and emergency medicine board certification (lower utilization and equivalent yield). CONCLUSION: CT utilization in the ED for suspected PE has steadily risen, whereas diagnostic yields have declined over time. Wide variation in practice is observed at the physician and geographic levels and is explained by several physician and hospital characteristics. Taken together, our findings suggest a substantial inefficiency of chest CT use and substantial opportunities for improvement.

The Determinants of Productivity in Medical Testing: Intensity and Allocation of Care.

A large body of research has investigated whether physicians overuse care. There is less evidence on whether, for a fixed level of spending, doctors allocate resources to patients with the highest expected returns. We assess both sources of inefficiency exploiting variation in rates of negative imaging tests for pulmonary embolism. We document enormous across-doctor heterogeneity in testing conditional on patient population, which explains the negative relationship between physicians' testing rates and test yields. Furthermore, doctors do not target testing to the highest risk patients, reducing test yields by one third. Our calibration suggests misallocation is more costly than overuse.

The Determinants of Productivity in Medical Testing: Intensity and Allocation of Care.

A large body of research has investigated whether physicians overuse care. There is less evidence on whether, for a fixed level of spending, doctors allocate resources to patients with the highest expected returns. We assess both sources of inefficiency, exploiting variation in rates of negative imaging tests for pulmonary embolism. We document enormous across-doctor heterogeneity in testing conditional on patient population, which explains the negative relationship between physicians' testing rates and test yields. Furthermore, doctors do not target testing to the highest risk patients, reducing test yields by one-third. Our calibration suggests misallocation is more costly than overuse.

Research funding. Big names or big ideas: do peer-review panels select the best science proposals?

This paper examines the success of peer-review panels in predicting the future quality of proposed research. We construct new data to track publication, citation, and patenting outcomes associated with more than 130,000 research project (R01) grants funded by the U.S. National Institutes of Health from 1980 to 2008. We find that better peer-review scores are consistently associated with better research outcomes and that this relationship persists even when we include detailed controls for an investigator's publication history, grant history, institutional affiliations, career stage, and degree types. A one-standard deviation worse peer-review score among awarded grants is associated with 15% fewer citations, 7% fewer publications, 19% fewer high-impact publications, and 14% fewer follow-on patents.

The effects of health information technology on the costs and quality of medical care.

Information technology has been linked to productivity growth in a wide variety of sectors, and health information technology (HIT) is a leading example of an innovation with the potential to transform industry-wide productivity. This paper analyzes the impact of health information technology (HIT) on the quality and intensity of medical care. Using Medicare claims data from 1998 to 2005, I estimate the effects of early investment in HIT by exploiting variation in hospitals' adoption statuses over time, analyzing 2.5 million inpatient admissions across 3900 hospitals. HIT is associated with a 1.3% increase in billed charges (p-value: 5.6%), and there is no evidence of cost savings even five years after adoption. Additionally, HIT adoption appears to have little impact on the quality of care, measured by patient mortality, adverse drug events, and readmission rates.