Chang, Jessica

Background: Recent literature has found rapid uptake of short-acting filgrastim biosimilars but slower uptake of other biosimilars, such as infliximab, in both Medicare and privately insured enrollees. Objectives: To describe patient, provider, and health plan characteristics associated with a switch to biosimilar among existing infliximab patients. Research Design: We constructed a retrospective panel dataset of patients undergoing active infliximab treatments and the choice of infliximab drug for each infusion. We used mixed logit regression controlling for patient, provider, and health plan characteristics as well as time-fixed effects. Subjects: Medicare Advantage and privately insured enrollees with evidence of active infliximab treatments between 2016 and 2020 (n=357,430). Measures: Our primary outcome of interest was to switch from infliximab originator to one of the infliximab biosimilars. Exposure variables of interest variables such as out-of-pocket, site of care, and in-network deductible. Results: Our study found nominally low switching among existing infliximab originator users (3.4%). We found that patients who previously received 1 infliximab originator infusion were 63.7% more likely to switch to biosimilar compared with patients who previously received administration of 20 infliximab originators. We found that biosimilar’s placement as health’s plan preferred drug was attributed to higher likelihood of biosimilar use (odds ratio: 1.666; P -value=0.001). We did not observe any statistically significant effect among out-of-pocket amount or deductible with respect to switch to infliximab biosimilar. Conclusions: To encourage uptake and switch to biosimilar, policymakers should consider targeted policies that include leveraging health plan tools such as placement of biosimilar as preferred drug and aim to educate patients on the clinical equivalence between infliximab biosimilar and originator.

ImportancePrevious studies have found that hospitals participating in the 340B Drug Pricing Program have higher Medicare Part B spending and expansion into affluent neighborhoods. Less is known about the association of 340B participation with spending by commercial insurance, where reimbursements are higher than Medicare.ObjectiveTo use the Affordable Care Act expansion of eligibility for the 340B Drug Pricing Program to study the association between participation and spending on outpatient-administered oncological drugs for commercially insured patients.Design, Setting, and ParticipantsThis cohort study included a balanced panel hospital cohort containing new and never 340B program participants between 2007 and 2019; more recent data were not included to avoid the effect of disruptions in care due to the COVID-19 pandemic. Descriptive analyses documented spending trends for patients receiving common outpatient-administered biologics used in cancer treatments (bevacizumab, filgrastim, pegfilgrastim, rituximab, and trastuzumab) at 340B (treated) and non-340B (control) hospitals. A difference-in-differences model assessed changes in episode drug spending. Analyses were conducted between December 2021 and June 2022.ExposureNew 340B program participation between 2010 and 2016.Main Outcome and MeasuresTotal drug episode spending, with control variables including total billed units, drug, calendar-year fixed effects, and hospital fixed effects.ResultsOf 95 127 included episodes (56 917 [59.8%] episodes in female patients) across 478 hospitals, patients seen in 340B and non-340B hospitals were similar in sex and drug used, and 340B hospital patients were older than non-340B patients (median [IQR] age for all patients, 61 [51-71] years). New 340B participating hospitals were more likely to be small (<50 beds) and more likely to be in rural settings. In the difference-in-differences analysis, total episode drug spending increased by $4074.69 (95% CI, $1592.84-$6556.70; P = .001) in the year following start of 340B program participation relative to nonparticipants. Heterogeneous group time effects were seen, with earlier participants less likely to have increased episode spending.Conclusions and RelevanceIn this cohort study, new 340B participation was associated with statistically significant higher oncological drug episode spending compared with nonparticipants after changes in 340B inclusion rules in 2010. These findings raise questions about unintended consequences of the 340B program on drug spending from the commercially insured population.

Aim: Missing data, particularly missing variables, can create serious analytic challenges in observational comparative effectiveness research studies. Statistical linkage of datasets is a potential method for incorporating missing variables. Prior studies have focused upon the bias introduced by imperfect linkage. Methods: This analysis uses a case study of hepatitis C patients to estimate the net effect of statistical linkage on bias, also accounting for the potential reduction in missing variable bias. Results: The results show that statistical linkage can reduce bias while also enabling parameter estimates to be obtained for the formerly missing variables. Conclusion: The usefulness of statistical linkage will vary depending upon the strength of the correlations of the missing variables with the treatment variable, as well as the outcome variable of interest.