Personalized Reference Values for the Two-Minute Walk Test: An Analysis of Cross-Sectional Data From the National Institutes of Health Toolbox Study.
Andrew J Kittelson, Brian J Loyd
PMID 37037295WHAT IT FOUND
Two-minute walk results can be compared with similar age, sex, and height peers.
For very short or tall adults, the same distance may look more or less typical, so height can change interpretation.
Key findings
01Median two-minute walk distance decreased with age: in females from 582 feet at 18 years to 378 feet at 85 years, and in males from 713 feet at 18 years to 414 feet at 85 years.
02A peer-based method that matches age, sex, and height produced a narrower typical range than an age-based curve method, with average ranges of 149 feet and 158 feet, while broader ranges were similar at 369 feet and 374 feet.
03For a 63-inch person walking 546 feet, peer-based ranking was the 31st percentile versus the 12th percentile by age-based ranking; for a 74-inch person walking 400 feet, peer-based ranking was the 13th percentile versus the 32nd percentile by age-based ranking.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The reference values were developed and checked in the same 1,385-person sample, so they have not been tested in new patients or clinical settings. People who did not perform the two-minute walk test were recorded as walking zero feet, and the exact reasons for missing testing were not known. Missing zero values were much more common in older adults, especially those over 70 years. The study did not directly separate the effect of using a peer-based method from the effect of adjusting for height. The analysis excluded 61 participants with missing height data. The estimates may be less reliable at extreme percentiles, especially the 1st and 99th percentile. The study did not consider weight or body mass index, and it did not examine language, education, race or ethnicity, socioeconomic factors, or cultural background as possible influences on test performance. The paper did not test whether using these reference values changed care planning, goals, patient engagement, or health outcomes.
Declared interests
The authors reported no conflicts of interest. The publication types indicate NIH and non-U.S. government research support.
The easy way to misread this
Do not read these reference values as proof that personalized walking norms improve care. The study analyzed existing data from one sample and did not test whether using the age-based or peer-based values changed clinical decisions or health outcomes.