Stethee versus Littmann: A Randomised, Crossover, Non-Inferiority Trial (STELIT)

Introduction
Stethee™, a new wireless digital stethoscope, has not been evaluated alongside the conventional stethoscope. We therefore compared Stethee™ to Littmann® for the auscultation of heart sounds.

Methodology
In this randomised, open-label, two-period crossover, non-inferiority trial, non-specialist doctors with no more than 6 years of working experience post-house officer training, were randomly assigned (1:1) to Stethee™ first group or Littmann® first group to auscultate a set of 10 simulated heart sounds. Randomisation was stratified by type of centre. Doctors were also asked about their preference for stethoscopes in terms of audio clarity, ease of use, and diagnostic accuracy. The primary non-inferiority endpoint was the percentage of correctly identified heart sounds, with a non-inferiority margin of 10%. Differences were estimated using a generalised linear mixed effects model, adjusted for sequence and period effects. Secondary endpoints included the percentage of correctly identified cardiac diagnoses, and user preference.

Results
A total of 207 doctors were assessed for eligibility, of whom 105 were randomised and analysed. The percentage of correctly identified heart sounds was 31.1% for Stethee™ and 33.4% for Littmann® (difference 2.2%, 90% CI -0.7, 5.0). The proportion of correctly identified cardiac diagnoses was 24.8% for Stethee™ and 28.2% for Littmann® (difference 3.2%, 90% CI 0.7, 5.7). Most doctors rated Stethee™ as having better audio quality than Littmann® (83.8%), and would provide a more accurate diagnosis (84.8%), but felt that Stethee™ was less user-friendly than Littmann® (61.0%).

Discussion/Conclusion
Stethee™ is non-inferior to Littmann® in the identification of simulated heart sounds and cardiac diagnoses.