Intrarater and interrater reliability of sagittal head posture: a novel technique performed by a physiotherapist and a speech and language pathologist

Abstract

Introduction: Different professionals such as speech and language pathologists and voice scientists are involved in the evaluation of head and neck posture. Therefore, a reliable, time-efficient, and precise method of posture assessment is essential for use in clinical and research settings. Photogrammetry is one of the most commonly used methods to assess head and neck posture. The objectives of this study were to evaluate the intrarater reliability of the method with a large sample size and the interrater reliability by two different specialists (a physiotherapist and a speech and language pathologist).

Method: A total of three hundred four subjects (144 males and 160 females) aged between 18 and 28 years participated in the study. During the test session, a photograph was taken of the left-side profile of each subject in their ordinary and comfortable position. The head posture angle of each picture was calculated by two raters. The whole procedure was repeated in a retest session, 24 hours later. A total number of eight analyses were performed for each subject. The reliability was evaluated at several stages hierarchically and after confirming the reliability in each step, the next step was investigated. Paired t tests on the differences of scores obtained at all the aforementioned stages were used to ensure the absence of any systematic bias. To assess the reliability, intraclass correlation coefficients (ICCs) and the standard error of measurements (SEMs) were calculated.

Results: There was no significant difference between the mean values of the test and the retest angles at any stage of calculating the head posture angle in both pictures by both examiners (P > 0.05). The ICC and SEM values calculated for all stages were between 0.86-0.97 and 0.52-1.53, respectively.

Conclusion: Systematic bias has not occurred at any stage. The ICC and SEM values calculated have demonstrated that there were appropriate relative and absolute reliabilities in all stages. This method is suggested to be used simply in research and clinical areas by different specialists.

Keywords: Photogrammetry; Posture; Reliability.