A study to explore the reliability and precision of intra and inter-rater measures of ULNT1 on an asymptomatic population

Upper Limb Neurodynamic Test 1 (ULNT1) is commonly used within clinical practice. However, the existing evidence regarding its reliability is conflicting and raises methodological questions. Therefore, the aim of this study was to investigate how reliable and precise physiotherapists are at recording both intra and inter-rater measurements of ULNT1 on an asymptomatic population. Forty asymptomatic subjects, 29 females and 11 males (18-42 years, mean 23.35), were recruited into this intra (stability) and inter-rater (equivalence) reliability and precision study. ULNT1 was recorded twice using an electrogoniometer by two experienced physiotherapists using a standardised operational description in conditions replicating clinical practice. Reliability was analysed using the Intraclass Correlation Coefficient (ICC₂,₁), and precision using Standard Error of Measurement (SEM) and Smallest Detectable Difference (SDD). The findings demonstrated excellent intra-rater (ICC₂,₁ 0.98 Rater 1; ICC₂,₁) 0.96 Rater 2) and good inter-rater (ICC₂,₁ 0.80) reliability. Precision was acceptable for both intra-rater (SEM 2.59° Rater 1; SEM 0.97° Rater 2; SDD 7.16° Rater 1; SDD 2.68° Rater 2), and inter-rater (SEM 3.83°; SDD 10.58°) measurements. These findings demonstrate that physiotherapists can use ULNT1 reliably and with precision for intra and inter-rater measurements of asymptomatic subjects in conditions that replicate clinical practice. The reproduction of this study on a population of symptomatic subjects is now warranted.