Objective: To determine whether the Activity Measure for Post-Acute Care® Basic Mobility Inpatient Short Form (Low Function) (6-clicks LF) has increased responsiveness for patients with lower levels of physical function compared to the Activity Measure for Post-Acute Care Basic Mobility Inpatient Short Form (6-clicks). Design: Retrospective cohort study using original scores and simulated scores for assessment of internal responsiveness of the 6-clicks LF compared to the 6-clicks. Simulated 6-clicks and 6-clicks LF scores were created as a hypothetical future AM-PAC® score. Results: We found a statistically significant difference between the 6-clicks and simulated 6-clicks, t=24.8, p \u3c 0.00 [two-tailed]. The effect size was large (d=1.2, r=0.51).There was a statistically significant difference between the 6-clicks LF and simulated 6-clicks LF, t=19.7, p \u3c 0.00 [two-tailed]. The effect size was medium (d=0.91, r=0.41). Finally, for patients with a 6-clicks score in the bottom five-percentile (n=27), we found a statistically significant difference between the 6-clicks and 6-clicks LF, t=11.9, p \u3c 0.00 [two-tailed]. Conclusion: Among patients scoring less than 15, the 6-clicks LF has greater internal responsiveness than the 6-clicks and thus demonstrates that the new low-level questions in the 6-clicks LF better quantify low-level patients’ functional level. Research using non-simulated data should be completed in the future to confirm these findings
