Objectives
We aimed to review the extent to which analysis of randomized controlled trials (RCTs) of device interventions includes methods to handle compliance to the study intervention as described in the protocol.

Study Design and Setting
We conducted a systematic review of the statistical methods used to handle compliance to a device intervention when estimating the effect of the device compared to another intervention in RCTs. We searched Embase, MEDLINE, PsychInfo, and the Cochrane Central Register of Controlled Trials. We sought to evaluate what methods were used and how using these methods impacted the estimate of the effect size.

Results
One hundred fifty eight RCTs were identified for inclusion, of which only 21 (13%) described using a method to account for compliance to the device intervention, consisting of alternative analysis populations such as per-protocol, modified intention-to-treat, or as-treated, alongside a primary intention-to-treat analysis. No causal inference methods were used. Fourteen (9%) studies included compliance as a factor in the analysis and investigated its effect on outcomes.

Conclusion
Although some studies consider methods to handle compliance, causal inference methods have not been well adopted in the analysis of device trials. An increased awareness of the applications of statistical methods to adjust for compliance is needed.