Temporal Analysis of Patients Eligible for Randomized Controlled Trials in Total Hip Arthroplasty

There has been a shift in the demographics of patients undergoing elective lower extremity joint arthroplasties in recent years. This study aimed to assess whether research has kept pace with changing demographics through analyzing inclusion and exclusion criteria of randomized controlled trials (RCTs) relevant to total hip arthroplasties (THAs).

Cross-sectional analysis of RCTs studying primary THAs indexed on ClinicalTrials.gov was performed. Trial characteristics regarding inclusion and exclusion criteria of 706 studies initiated between 1994-2023 were analyzed. Sample size, type of intervention, year of study initiation, length of study, and inclusion/exclusion criteria were evaluated.

An increasing number of THA-based RCTs were initiated over the study period (1994-2004: 5.18 studies/y, 2021-2023: 36.7 studies/y). The majority of included RCTs had an upper age exclusion criterion (1994-2004: 65.9%, 2021-2023: 53.6%). Body mass index (BMI) restrictions have become more common than previously (1994-2004: 5.3%, 2021-2023: 29.1%); however, the range has expanded to include higher BMI limits. The most common exclusion criteria based upon health comorbidities included psychiatric health and cognitive impairment (36.4%), neurologic and neuromuscular dysfunction (32.6%), and systemic infections (31.4%).

Regarding elective primary THA, it is recognized that the age and BMI of patients have shifted substantially over recent decades. This study revealed that restrictions on participant age continue to be prevalent. Although the average BMI of patients undergoing elective THA is rising, BMI is increasingly being implemented as an exclusion criterion. Critical assessment of inclusion and exclusion criteria for all studies, especially RCTs, given their associated cost and potential impact, requires further attention in orthopaedics.