Psychometric properties of the SF-6Dv2 in an Iranian breast cancer population.

INTRODUCTION

The Short-Form Six-Dimension version 2 (SF-6Dv2) is the newest preference-based instrument for estimation of quality adjusted life-years (QALYs). The aim of this study is to evaluate the validity and reliability of the SF-6Dv2 in an Iranian breast cancer population.

METHODS

The SF-6Dv2 and FACT-B instruments were completed for 416 patients who were recruited from the largest academic center for cancer patients in Iran. The ceiling effects are computed as the proportion of participants reporting no problems in SF-6Dv2 index. Construct validity was evaluated using convergent validity, discriminant validity, and known-groups validity. Reliability was assessed using intra-class correlation coefficient (ICC) and Cohen's kappa value.

RESULTS

The ceiling effects of the SF-6Dv2 was 2.16%. Higher scores of all subscales of the FACT-B were associated with patients who reported no problems in each of the SF-6Dv2 dimensions. The correlation between SF-6Dv2 dimensions and FACT-B subscales varied from 0.109 between the role limitation of the SF-6Dv2 and the SWB subscale of the FACT-B to 0.665 between the pain dimension of SF-6Dv2 and the PWB of FACT-B. The lower mean score of SF-6Dv2 was associated with patients with older age, higher education level, more severe current treatment status, and more severe cancer stage status. ICC for the SF-6Dv2 index scores was 0.66, and Kappa values varied from 0.33 for mobility to 0.66 for mental health dimensions.

CONCLUSIONS

The validity and reliability of the SF-6Dv2 were satisfaction in a breast cancer population and it can be employed in clinical practice or research.