Minimal clinically important difference and minimal detectable change of the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) amongst patients with chronic musculoskeletal pain.
Niina Katajapuu, Ari Heinonen, Mikhail Saltychev
PMID 32718186WHAT IT FOUND
In patients with chronic musculoskeletal pain, a change in WHODAS 2.0 score must exceed 8.6 points to be real rather than measurement error.
This threshold is larger than the minimal clinically important difference of 3 to 5 points, meaning small score changes may not reflect true improvement.
Key findings
01The minimal detectable change for the WHODAS 2.0 in this population was 8.6 points.
02The minimal clinically important difference was estimated between 3.09 and 4.68 points.
03The minimal detectable change exceeded the minimal clinically important difference, suggesting small changes may be due to error.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
The study was cross-sectional, so it could not use an anchor-based method to validate the minimal clinically important difference. The estimates rely entirely on statistical distribution. Most patients had mild disability (mean score 13.1 out of 48). The results may not apply to patients with severe functional limitations. The minimal detectable percentage change was 66%, indicating a very high level of measurement error relative to the score. The study population was specific to chronic musculoskeletal pain in a Finnish hospital setting, limiting generalisability to other conditions or healthcare systems.
Declared interests
The paper does not state any funding sources or conflicts of interest.
The easy way to misread this
Do not assume that a small change in WHODAS 2.0 score indicates clinical improvement. A change of less than 8.6 points may be due to measurement error rather than a true change in the patient's functioning.