Non-inferiority Trial Design in Drug Development: A Primer for Cardiovascular Healthcare Professionals

Wearable Integrated Volitional Control Electrical Stimulation Device as Treatment for Paresis of the Upper Extremity in Early Subacute Stroke Patients: A Randomized Controlled Non-inferiority Trial

OBJECTIVE

To investigate the effect of a wearable integrated volitional control electrical stimulation (WIVES) device that has been developed as more compact and simpler to use in daily life compared with conventional integrated volitional control electrical stimulation (IVES) devices.

DESIGN

Randomized controlled non-inferiority trial.

SETTING

Convalescent rehabilitation ward.

PARTICIPANTS

Patients with paresis of the upper extremity (UE) after early subacute stroke (N=20).

INTERVENTIONS

Eligible patients were randomized to receive IVES treatment or WIVES treatment for 8 hours per day for 28 days in daily living, in addition to standard rehabilitation treatment. In both groups, the extensor digitorum communis on the affected side was the target muscle for stimulation.

MAIN OUTCOME MEASURE

Primary outcomes were assessed with Fugl-Meyer Assessment of the UE (FMA-UE) before and after treatment. Non-inferiority was determined with a specified margin of non-inferiority.

RESULTS

Twenty patients completed the trial (IVES group: n=10, WIVES group: n=10). FMA-UE improved in both groups. The mean change in FMA-UE was 4.7 for the IVES group and 6.0 for the WIVES group (P>.05, 95% confidence interval: -6.73 to 4.13). The mean difference between the groups was 1.3, and the upper 95% confidence interval did not exceed the non-inferiority margin.

CONCLUSION

The effectiveness of WIVES treatment is non-inferior to that of IVES treatment. As a portable device, IVES may facilitate the use of affected upper extremities in daily living and may help improve paresis of the UE.

Optimal Use of the Non-Inferiority Trial Design

Superiority trials are conducted to test the hypothesis that a treatment or strategy A is superior to (i.e., better than) treatment strategy B in reducing the impact of disease. However, A may be considerably safer, more convenient, or cheaper than B. These features may make A more attractive than B even if the burden of disease is reduced comparably by the two treatments, or even a bit worse by A over B. In this context, non-inferiority trials have become increasingly popular to test the hypothesis that a new treatment is not 'unacceptably worse' than an active comparator by more than a predefined non-inferiority margin. Non-inferiority trials have unique design features and methodology and require a different analysis than traditional superiority trials. The main aim of this overview is to analyze the role of non-inferiority trials in the development of new treatments, involving some scientific, statistical, and practical considerations. We elucidate some aspects of non-inferiority trials that contribute to the validity of the results. The unique design features and methodology of non-inferiority trials are summarized and key findings to consider when evaluating a non-inferiority trial are illustrated.