Reliability and Validity of Measurement of Infrasternal Angle by Radiographic Methods

Reliability and Validity of Measurement of Infrasternal Angle by Radiographic Methods

Background The infrasternal angle is typically measured using goniometric or photographic methods. Because chest anterior–posterior radiographic images cannot be used to identify the xiphoid process, no study has evaluated the validity of infrasternal angle measurement. Purpose The purpose of this study was to determine reliability and validity of measurement of infrasternal angle by radiographic method. Study design Intra- and inter-tester repeated measures. Methods Infrasternal angles were measured in 25 healthy students using goniometric and radiographic method. To check the xiphoid process in radiographs, the examiner set the marker at the xiphoid process. Radiographs were taken by one X-ray technician for each subject using a radiographic apparatus. Repeated radiographs measurements were made in two test sessions conducted on different days by two testers to assess inter-rater and intra-rater reliability. The reliability of the infrasternal angle measurement was using intraclass correlation coefficients (ICCs: 3,1). The correlation between measurements taken by the radiograph and goniometric methods was calculated to test the validity of the radiographic method. The alpha level was set at 0.05. Results The intra- and inter-rater reliability of infrastenral angle measurements taken by the radiographic method were excellent (ICC=0.991 and 0.993, respectively). Radiographic measurement of the infrasternal angle was highly correlated with goniometric measurement (r= 0.85). Conclusions We suggest that the radiographic method is a highly reliable and valid tool for infrasternal angle measurement.