Factors affecting sensitivity and specificity of head-turning sign in the studies.

We read with interest the comment by Williamson and Larner on our recent study titled "Attended With and Head-Turning Sign can be clinical markers of cognitive impairment in older adults" (Soysal et al., 2017). After the authors read the study, they re-examined their data according to the presence of Attended With (AW) and Head-Turning Sign (HTS), and compared their results with ours (Larner, 2014). Then, they found that while the sensitivity, specificity, positive predictive value, and negative predictive value of AW in detecting cognitive impairment were similar to ours, HTS had lower sensitivity (80.95% vs. 65.0%) and higher specificity (64.7% vs. 95.0%) than our results (Larner, 2014; Soysal et al., 2017). We think that some methodological and cultural differences may explain these discrepancies between the two.