Reliability and validity of SF-12v2 among adults with self-reported cancer

Background: The SF-12v2 has been validated in general population and other conditions but the evidence is limited in Americans with cancer. Objective: To assess reliability and validity of SF-12v2 among adults with self-reported cancer using the Medical Expenditure Panel Survey (MEPS). Methods: Self-reported cancer participants (SCPs) were identified from 2003 MEPS. SF-12v2 was administered as part of self-administered questionnaires. Physical (PCS12) and mental (MCS12) component scores of SF-12v2 were evaluated for reliability (internal consistency, test-retest) and validity (convergent, discriminant, predictive, concurrent). Results: 420 SCPs were identified with average age of 59.3 years (SE = 0.9). 10.7% had multiple cancers (> 1) and 52% had at least one other chronic condition (OCC). Average PCS12 and MCS12 were 45.09 (SE = 0.5) and 50.75 (SE = 0.5). PCS12 and MCS12 demonstrated high internal consistency (alpha(PCS12) = 0.89; alpha(MCS12) = 0.88), acceptable test-retest reliability (ICCPCS12 = 0.82; ICCMCS12 = 0.73), strongly correlated with most of the expected EQ-5D domains (r = 0.51-0.71), and demonstrated strong convergent validity on perceived health (r = 0.61) and perceived mental health (r = 0.52). PCS12 and MCS12 were able to discriminate between groups with and without physical/cognitive limitations. Only PCS12 was negatively correlated with number of OCCs. Conclusion: The SF-12v2 is a reliable and valid instrument to quantify health-related quality of life among adults with self-reported cancer.