PROMIS Physical Function 10-Item Short Form for Older Adults in an Emergency Setting

Functional status in older adults predicts hospital use and mortality, and offers insight into independence and quality of life. The Patient-Reported Outcome Measurement Information System (PROMIS) was developed to improve and standardize patient-reported outcomes measurements. The PROMIS Physical Function (PROMIS PF) 10-Item Short Form was not created specifically for older adults. By comparing PROMIS with the Katz Index of Activities of Daily Living (Katz), we evaluated PROMIS for measurement of physical function versus general function in an older adult population seen in the ED.

A prospective, convenience sample of ED patients 65 years and older (from January 1, 2015 to June 30, 2015) completed Katz and PROMIS PF. Both were compared for scoring distributions and conventional scoring thresholds for severity of impairment (eg, minimal, moderate, severe). We assessed convergence through Spearman correlations, equivalents of conventional thresholds and ranges of physical function, and item-response frequencies.

A total of 357 completed both function surveys. PROMIS PF and Katz have a modest positive correlation (r = .50, p < .01). Mean PROMIS PF scores within Katz scoring ranges for minimal (43, SD = 10), moderate (32, SD = 7), and severe (24, SD = 7) impairment fell within respective PROMIS PF scoring ranges (severe = 14-29, moderate = 30-39, mild = 40-45), indicating convergence. PROMIS identified impairment in 3× as many patients as did Katz, as PROMIS assesses vigorous physical function (eg, running, heavy lifting) not queried by Katz. However, PROMIS does not assess select activities of daily living (ADLs; eg, feeding, continence) important for assessment of function in older adults.

There is a modest correlation between PROMIS and Katz. PROMIS may better assess physical function than Katz, but is not an adequate replacement for assessment of general functional status in older adults.