Validity and reliability of the block method for measuring thoracic hyperkyphosis

This study aimed to investigate the concurrent validity of the block method as compared with the gold standard (Cobb's method). An additional aim was to examine the intra- and inter-rater reliability of expert and novice assessors using the block method.

In a cross-sectional study, we enrolled 62 participants with hyperkyphosis aged ≥10 years, with hyperkyphosis defined as one or more blocks. The participants were stratified by age (<60 years and ≥60 years). To determine concurrent validity, and kyphosis was assessed in all the participants using the block method and Cobb's method. Finally, 15 participants were included in a reliability study. To determine intra- and inter-rater reliability, each participant was assessed twice, 7 days apart, by one expert and one novice using the block method.

The concurrent validity of the block method and gold standard method showed moderate correlation (r = 0.53, P < .001). However, after stratifying the participants by age (<60 years and ≥60 years), there was small to moderate correlation (r = 0.42, P = .006, and r = 0.64, P = .002, respectively). The intra- and inter-rater reliability of the expert and novice assessors was excellent (ICC_3,1 = 0.82-0.97, P < .001).

The findings showed small correlation in those <60 and moderate correlation in those ≥60 years, and reported excellent reliability. The block method can be used by novices with strong reliability. This method is a practical technique for early screening hyperkyphosis in the elderly.