What is driving 340B growth: utilization or price?

In 2023, the 340B Drug Pricing Program ("340B program") saw a 24% year-over-year growth, with the Health Resources and Services Administration (HRSA), the federal agency responsible for the program, announcing that 340B discounted purchases had reached $66 billion. Despite the program's growth, size, and impact, there is little published research on the factors causing 340B growth, with different stakeholders offering divergent explanations. Program advocates contend that manufacturer price increases are the primary driver of 340B growth, while program critics argue that 340B hospitals are driving utilization. This study used price-volume-mix decomposition to examine the relative importance of price vs utilization for 340B growth using a national sample of over 28 000 National Drug Code drugs. From 2018 to 2024, utilization accounted for an average of 79.6% of 340B growth based on list price, and close to 100% of growth based on 340B discount prices. Utilization also accounted for the majority of 340B growth for the top 10 drugs reported by HRSA and for the segment of drugs with price increases above inflation. These findings show that utilization increases, not manufacturer pricing decisions, are the main driver of 340B growth, a conclusion that may have significant public policy implications.