Health Plan Switching and Health Care Utilization: A Randomized Clinical Trial.

Importance: While the Patient Protection and Affordable Care Act (ACA) helped make health insurance premiums more affordable with premium tax credits, ACA marketplace enrollees continue to face barriers to care. Objective: To investigate the effect of informational emails on plan switching and health care utilization. Design, Setting, and Participants: This randomized clinical trial was conducted during the 2021 special enrollment period in California's Affordable Care Act marketplace among households that reported receiving unemployment insurance and were enrolled in non-silver-tier plans. The trial targeted 42 470 households that became temporarily eligible for cost-sharing reduction (CSR) silver plans that covered 94% of medical costs (CSR silver 94 plans) as a result of the 2021 American Rescue Plan Act. Intervention: Households were randomized to either a no-email control group or to a treatment group receiving 2 informational emails encouraging households to switch to CSR plans. Main Outcomes and Measures: The primary outcome was the switch rate to a CSR silver plan by July 31, 2021. Secondary outcomes include various measures of health care utilization in the second half of 2021 (July 1, 2021, to December 31, 2021). Health care utilization was measured by rates of practitioner visits, emergency department visits, hospitalizations, and prescription fills. Results: Of the 42 470 households (head of household mean [SD], age, 41.4 [13.3] years; 51.7% male), 10 650 (25.1%) were in the control group and 31 820 (74.9%) were in the treatment group. The emails led to a statistically significant 3.1-percentage point (95% CI, 2.6-3.6 percentage points) increase in CSR silver 94 enrollment (a 74.8% relative increase) by July 31, 2021, and a 1.3-percentage point (95% CI, 0.2-2.4 percentage points) increase (a 2.3% relative increase) in practitioner visits by December 31, 2021. The emails had no detectable effect on prescription fills, emergency department visits, or hospitalizations. Conclusions and Relevance: The results of this randomized clinical trial provide experimental evidence that, with access to more affordable health care, individuals are more likely to visit practitioners. Trial Registration: ClinicalTrials.gov Identifier: NCT05891418.