Responsiveness of the Thai version ofthe Pain Anxiety Symptoms Scale-20 (PASS-20),the Patient-Reported Outcomes Measurement Information System Short Form-Anxiety 8a (PROMIS-ANX-8),and the Patient-Reported Outcomes Measurement Information System Short Form

Purpose: To evaluate the responsiveness, estimate minimal clinically important difference (MCID), and examine correlations between anxiety and depression measures of the Thai versions of the Patient-Reported Outcomes Measurement Information System Short Form v1.0 - Depression 8a (T-PROMIS-D-8a), Anxiety 8a (T-PROMIS-Anx8a), and Pain Anxiety Symptoms Scale-20 (PASS-20) measures in individuals with chronic low back pain (CLBP).Methods: The study sample comprised of 144 participants with CLBP. Responsiveness was evaluated by calculating the change scores, effect size (ES), standardized response mean (SRM), area under the curve (AUC), and correlations between the change scores and the Thai version of Global Perceived Effect (T-GPE). We also estimated MCIDs by computing half of the standard deviation (SD) and standard error of measurement (SEM) for each measure. Additionally, the correlations between anxiety measures (i.e., T-PROMIS-Anx8a and T-PASS-20) and depression measure (T-PROMIS-D-8a) was examined.Results: Responsiveness of all three measures was supported by statistically significant difference in the mean change scores between improved and unchanged groups, as well as by the estimated ESs and SRMs. All measures could distinguish between improved and not improved study participants (AUCs ranging from .70 to .72). The correlations of the T-GPE with the change scores on all measures were low in magnitude (Spearman’s r ranging .28 to .33). The estimated MCIDs for the T-PROMIS-D-8a, T-PROMIS-Anx8a, and T-PASS-20 were 4.30, 4.83, and 10.61, respectively. Both anxiety measures showed a correlation of .60, indicating moderate correlation with depression measure in current study.Conclusions: The T-PROMIS-D-8a, T-PROMIS-Anx8a, and T-PASS-20 measures were sensitive for detecting clinical changes over time in individuals with CLBP. The MCID values can be used as reference points for assessing meaningful improvements in the domains assessed by these scales in clinical and research practice.