The study evaluated adherence to the rule six to nine months after it was implemented. Researchers collected data on whether hospitals had posted all five required price types (gross charges, discounted prices, payer-specific negotiated prices and minimum and maximum negotiated prices) in a machine-readable file and also a separate accessible display or price estimator for at least 300 shoppable items. The final rule requires that both conditions be met.

Across 5,239 hospitals:

• 729 (14 percent) had an adherent machine-readable file but no shoppable display
• 1,542 (29.4 percent) had an adherent shoppable display but no machine-readable file
• 300 (5.7 percent) had both
• 2,668 hospitals (51 percent) had neither an adherent machine-readable file nor a shoppable display.

Among other findings:

• The difference in the proportion of adherent vs non-adherent facilities that were in unconcentrated and highly or very highly concentrated markets was significant.
• Total gross revenue had no significant association with final rule adherence. However, being in the first (lowest) quartile of revenue per patient-day was associated with greater rates of adherence than was being in other quartiles.
• Being in a moderately, highly or very highly concentrated market was associated with worse adherence.
• Urban location was associated with better adherence to the final rule compared to rural location.
• Hospital size, emergency service capabilities and hospital ownership were not associated with adherence.

"Adherence to the final rule price transparency mandate six to nine months after its effective date was low," the study concluded. "Acute-care hospitals with lesser revenue per patient-day, within unconcentrated health care markets and in urban areas were more likely to be transparent. Greater scrutiny of hospitals without these characteristics may be needed to ensure hospital price transparency.

Also: Lack of price transparency still keeping many from seeking health care

"Because multiple factors affect revenue per patient-day, including patient acuity, operational expenses and provision of specialty care, refining which financial determinants are associated with adherence is needed. Longer-term trends in hospital adherence and whether changes in penalties beginning in 2022 may lead to greater adherence remain to be elucidated."