Abstract
Background
Randomized, controlled trials (RCTs) are generally accepted as the “gold standard” for the provision of the most unbiased measures of the efficacy of interventions but are often criticized for the lack of external validity. We assessed the external validity of a RCT examining the efficacy of local infiltration analgesia (LIA) compared with continuous epidural infusion after total knee arthroplasty (TKA)
Methods
During a one-year period, all patients consecutively admitted for elective, unilateral, primary TKA were identified as potential participants. All underwent eligibility screening to determine who were eligible for participation in a randomized controlled trial. We investigated the distribution of preoperative characteristics and postoperative variables among excluded patients, non-consenters, and enrolled and randomized participants.
Results
In all 157 patients were identified as potential participants. Only 49 patients (31%) were enrolled and randomized. A significant difference was found in both preoperative characteristics and clinical outcome variables. Non-participants were less healthy and needed more help from the home care service than did participants. Furthermore, they were hospitalized longer.
Interpretation
Our findings demonstrate the importance of reporting the results of RCTs in a way that allows clinicians to judge to whom the results can reasonably be applied.
