# Sample Size of Trials Investigating the Impact of Point‐of‐Care Ultrasound‐Guided Strategies on Patient Outcomes: A Systematic Review

## TL;DR

This paper reviews how sample sizes in trials using point-of-care ultrasound are often too small to detect meaningful effects, leading to underpowered studies.

## Contribution

The study introduces a systematic analysis of sample size assumptions in POCUS-guided trials and highlights their underpowered nature.

## Key findings

- Most POCUS-guided trials have median sample sizes of 206 participants, often below what is needed for adequate power.
- Only 68% of trials reported sample size justifications, and 41% failed to meet recruitment targets.
- Sample size requirements depend heavily on the proportion of cases where POCUS changes management.

## Abstract

Point‐of‐care ultrasound (POCUS) is increasingly utilized for bedside diagnosis and management in diverse clinical contexts. However, the design of randomized controlled trials (RCTs) evaluating the impact of POCUS‐guided strategies on clinical outcomes presents significant challenges. This study aims to explore the assumptions underlying sample size estimation in POCUS‐guided trials and assess the adequacy of sample sizes in published trials through a systematic review. We performed a sample size analysis considering varying rates of POCUS‐induced management changes and plausible effect sizes on binary and continuous patient‐centered outcomes. Additionally, a systematic review of PubMed was conducted to identify RCTs comparing POCUS‐guided management to usual care, extracting data on planned and actual sample sizes and justifications for sample size decisions. Sample size estimations revealed a substantial dependence on the proportion of participants experiencing management changes due to POCUS findings. For example, achieving adequate power in a trial with a moderate effect size requires over 1000 participants if POCUS alters management in 50% of cases. Our review included 25 RCTs, with a median sample size of 206 participants (interquartile range 122–250). Only 68% of trials reported sample size justifications, and 41% failed to meet planned recruitment targets, primarily due to recruitment challenges and other logistical barriers. Most trials investigating POCUS‐guided strategies are underpowered, underscoring the need for realistic sample size estimations that consider the rate of POCUS‐induced management changes and anticipated effect sizes. Future trials should incorporate pilot phases and innovative designs to optimize feasibility and power.