Effectiveness of clinician-directed default nudges on reducing overuse of tests and treatments in healthcare: a systematic review of randomised controlled trials.

Objective: To evaluate the effectiveness of clinician-directed default nudges for reducing overuse of tests and treatments.

Design: A systematic review was conducted to synthesise evidence from randomised controlled trials examining the effect of clinician-directed default nudges on overuse of tests or treatments, measured as a proportion of encounters or patients. Four databases and three clinical trial registries were searched up to 13 January 2025. Two reviewers screened, extracted data, assessed risk of bias and certainty of evidence using Cochrane guidance. Because there was high clinical heterogeneity, we used the Synthesis Without Meta-analysis guidelines for our overall analysis. A secondary exploratory meta-analysis was performed on a subgroup of default nudge interventions targeting opioid prescriptions.

Results: We included six trials (five cluster randomised trials and one patient randomised trial, n=767 to 21 331). Trials targeted overuse of opioids, antibiotics, high-risk medicines for older patients and imaging during palliative radiotherapy. Lowering default quantities of opioids may cause reductions in opioid overuse, but on one occasion increased overuse. It is unclear if opt-out defaults reduce antibiotic overuse in patients with sepsis eligible for de-escalation or if lowering default doses reduce overuse of high-risk medications in older patients. Reducing the default frequency of imaging probably causes large reductions in unnecessary imaging in people receiving palliative radiotherapy. A subgroup meta-analysis was only possible on one type of default for opioids. A 10-tablet default may reduce overuse of large packs of opioids (risk difference=-14.3%, 95% CI -51.4% to +22.9%, 3 trials, 18 186 encounters, very low certainty evidence).

Conclusions: Clinician-directed default nudges had inconsistent effects on overuse of healthcare, with limited and mostly low certainty evidence. High-quality trials are essential to determine whether default nudges reduce overuse or improve patient outcomes.

Prospero registration number: 42024516423.