Healthcare Utilization Unchanged in the Control Arm of a Randomized Clinical Trial.

Background: In low-income settings, clinical trial participation may influence participant behavior, including among control groups. Increased access to care and heightened health awareness during trial enrollment could lead to altered behaviors, a phenomenon known as the Hawthorne effect, which may obscure true intervention impacts; however, this effect remains poorly studied in low-income environments.

Aim: To conduct a secondary exploratory analysis of healthcare utilization among control participants of a randomized clinical trial (RCT).

Methods: We retrospectively analyzed electronic medical records from the control arm (n = 26) of an RCT involving low-income Hispanic adults with type 2 diabetes receiving care at a community clinic. Before randomization to a 12-month diabetes education intervention or usual care (control), participants underwent on-site measurements of HbA1c, blood pressure, and weight. Healthcare utilization among control participants was compared during the year before and throughout the study, including all types of exposures: provider visits and other services (eg, orders).

Results: Total healthcare utilization was similar between the pre-period (11.9 exposures/year) and the study-period (11.4 exposures/year; P = .93), with no significant changes across visit types. There were no significant differences in fitted mean monthly visits between the pre- and study-periods (P = .93), nor over time (P = .89).

Conclusions: This exploratory study found no evidence of a Hawthorne effect on healthcare utilization among control participants. While this may suggest consistent healthcare behaviors, it may also highlight an important public health concern: individuals in low-income settings may lack the resources to translate increased awareness into health-related action. Larger studies are needed to further elucidate behavioral patterns in low-income populations.