Measured versus self-reported physical function in adult survivors of childhood cancer

Childhood cancer survivors (CCS) experience late effects that interfere with physical function. Limitations in physical function can affect CCS abilities to actively participate in daily activities. The purpose of this investigation was to evaluate the concordance between self-reported physical performance and clinically evaluated physical performance among adult CCS.

CCS 18 yr or older and 10 yr or older from diagnosis who are participants in the St. Jude Lifetime cohort study responded to the physical function section of the Medical Outcome Survey Short Form (SF-36). Measured physical performance was evaluated using the Physical Performance Test and the 6-Minute Walk Test.

Individuals (N = 1778, 50.8% female) with a median time since diagnosis of 24.9 yr (range = 10.9-48.2) and a median age of 32.4 yr (range = 19.1-48.2) completed testing. Limitations in physical performance were self-reported by 14.1% of participants. The accuracy of self-report physical performance was 0.87 when the SF-36 was compared with the 6-Minute Walk Test or the Physical Performance Test. Reporting inaccuracies most often involved reporting a physical performance limitation. Poor accuracy was associated with previous diagnosis of a bone or CNS tumor, lymphoma, older age, and large body size.

These results suggest that self-report, using the physical performance subscale of the SF-36, correctly identifies CCS who do not have physical performance limitations. In contrast, this same measure is less able to identify individuals who have performance limitations.