Article

The Activity Measure for Post-Acute Care (AM-PAC) is a generic metric
of patient-reported functional status. The minimal clinically important
difference (MCID) in the AM-PAC score has not been determined. Objective: The
study objective was to determine the MCID for AM-PAC in people with low back
pain. Design: This was a retrospective cohort study. Methods: Anchor-based and
distribution-based methods were used to estimate the MCID.
The Modified Low Back
Pain Disability Questionnaire was used as the anchor. Adults who had a primary
ICD-9 code for low back pain in at least 1 outpatient physical therapist visit
during an episode of care and who completed both the AM-PAC and the Modified Low
Back Pain Disability Questionnaire in at least 2 visits during the care episode
were included. The MCID was calculated for the AM-PAC basic mobility version as
well its adapted version, which the Cleveland Clinic uses for patients 65 years
old or older. Results: A total of 1,271 participants were eligible for study. For
the AM-PAC basic mobility version, anchor-based methods yielded MCID estimates of
between 3.4 and 5.1, whereas distribution-based methods yielded estimates of 1.7
to 4.2. The minimal detectable change (MDC) for the AM-PAC basic mobility version
was 3.3. For the adapted AM-PAC basic mobility version, the MCID was estimated to
be between 2.9 and 4.0 via anchor-based methods and between 1.2 to 3.5 via
distribution-based methods.
The MDC for the adapted AM-PAC basic mobility version
was 3.5. Limitations: The estimated MCID was designed for people with low back
pain only. Conclusions: The MCID ranged from 3.3 to 5.1 for the AM-PAC basic
mobility version and 3.5 to 4 for the adapted version, with the MDC as the lower
limit. Changes in the AM-PAC for people with low back pain may be interpreted
using the estimated MCID. Future studies are needed to determine the AM-PAC MCID
for populations other than those with low back pain.

Langue : ANGLAIS