“To whom do the results of this trial apply?”: External validity of a randomized controlled trial involving 130 patients scheduled for primary total hip replacement

Abstract

Background Although the randomized controlled trial (RCT) is regarded as the gold standard for evaluation of the effect of an intervention, its external validity has been questioned. RCTs cannot be expected to produce results that are directly relevant to all patients and all settings, but they should at least allow patients and clinicians to judge to whom trial results can reasonably be applied.We assessed the external validity of an RCT investigating the efficacy of a fast-track program after total hip replacement.Methods 130 patients were identified as potential participants.18 patients were excluded, 33 enrolled patients declined to participate, and 79 patients were enrolled and randomized. We studied the distribution of preoperative characteristics and postoperative clinical variables in these 3 groups.Results A significant difference was found in both preoperative characteristics and clinical outcome variables. The non-consenters were older, less healthy, and needed more help from the home care system. Furthermore, they were hospitalized longer and were more often transferred to a rehabilitation ward.Interpretation Our findings demonstrate the importance of patient inclusion criteria in RCTs. Moreover, they may account for the lack of reproducibility of RCT results in clinical practice dealing with fast-track programs.

Misconceptions about practicing evidence-based orthopedic surgery

“…While we may have some evidence to suggest what treatment to use in study patients, clinical expertise helps in making decisions regarding the generalizability of those results (Hannes et al 2005, Tonelli 2006). As pointed out clearly by Petersen et al in this issue of Acta Orthopaedica, results from an RCT apply only to the cohort of patients that consented (Petersen et al 2007). We are often uninformed about the patient characteristics of the "non-consenters".…”

Representativeness of the participants in the smoking Cessation in Pregnancy Incentives Trial (CPIT): a cross-sectional study

“…Current intervention protocols and clinical guidelines combine high-quality research from individual patient treatment [3] with clinical experience. Randomised controlled trials (RCTs) with reliable internal validity are considered the ‘gold standard’ [4] to inform decision-making for both individual patients and population health [5–7]. Guidelines to help clinicians make quick but accountable decisions should be guided by accurate and reliable research findings from RCTs [3] to minimise bias.…”

“…Guidelines to help clinicians make quick but accountable decisions should be guided by accurate and reliable research findings from RCTs [3] to minimise bias. However, trial findings must benefit the target group with similar therapeutic needs (external validity) [4]. Clinicians [8–10] have questioned the effectiveness and reliability of applying trial evidence to target populations outside a trial setting.…”

“…It is important, therefore, to compare trial participants with the target population with regard to demographic, clinical and other variables. Such comparison will help to uncover possible bias associated with nonrepresentative trial populations and allow a judgement to be made about the likely generalisability of trial results [4, 15]. Models of reasons for taking part and not taking part are important [16] to try to understand how better to run research projects that are representative and, therefore, produce results applicable to all groups in the target population.…”

The External Validity of Randomized Controlled Trials of Hypertension within China: from the Perspective of Sample Representation

“…However, external validity cannot be easily formalized [9] as the baseline clinical characteristics recorded often say very little about the real composition of the trial population. Easy to be quantified and reported abundantly, the sample representation is often used as an important indicator to assess external validity [16]; but, the lack of reference is frequently advocated as one of the obstacles to explore sample representation of RCTs. As few observational studies enrolled participants with stringent eligibility criteria, samples within observational studies were more likely representative, by which they could be candidate references for mirroring the real composition of patients in clinical practice.…”