Physical Functioning Scale of the Short-Form (SF) 36: Internal Consistency and Validity With Older Adults

Background and Purpose: There is a need to characterize the physical functioning of older adults. As the Physical Functioning Scale (PFS) of the 36-Item Short-Form Health Survey has not been utilized widely by therapists for this purpose, we sought to investigate its reliability and validity in this population. Methods: This study involved the secondary analysis of PFS, physical performance, and fall history data obtained from 19 men and 39 women, 65 to 94 years old. Results: Reliability (internal consistency) of the PFS was supported by a Cronbach alpha of .82 between its items. Known groups' validity was demonstrated by a significant difference in PFS scores of individuals with and individuals without a history of falls and by an area under the receiver operating characteristic curve of 0.850. Convergent validity was upheld by significant Pearson correlations between the PFS and single limb stance time (r = 0.42), Timed Up and Go test (r = -0.70) performance, and gait speed (r = 0.75). Conclusions: The simplicity and brevity of the PFS as well as its internal consistency and known groups and convergent validity provide support for its broader use by physical therapists among older community-dwelling adults.