Consequences of using SF-12 and RAND-12 when examining levels of well-being and psychological distress

Objective: To explore the consequences of using the Short-Form Health Survey ( SF-12) and the RAND-12 Health Status Inventory ( RAND-12) for estimation of associations between its component scores and the levels of well-being and psychological distress. Methods: Data from a rural community mental health survey of 5641 participants were analysed. Physical and mental health component scores of the SF-12 and RAND-12 were compared between participants with different rating on the Satisfaction with Life Scale and the Kessler-10. Descriptive graphical methods were utilized to explore the relationship between SF-12 and RAND-12 components scores against well-being and psychological distress. Proportional odds model was utilized to estimate the quantitative relationship between component scores of the SF-12 and RAND-12 against categories of well-being and psychological distress. Results: Both SF-12 and RAND- 12 component scores were generally positively associated with well-being and negatively associated with psychological distress. Median scores were similar despite scoring techniques used. However, distribution of scores differed whereby the RAND- 12 yielded wider spread of scores in measures of well-being and psychological distressed when compared to the SF-12. A larger proportion of participants was classified as having moderate and severe disability under the RAND- 12 compared to the SF-12. Conclusion: It is recommended that users of the SF-12 and the RAND- 12 are aware of the implications of utilizing either of the scoring techniques. Scoring techniques used should ideally be based on the theoretical basis of the study with consideration of the target population. Researchers may wish to use the SF-12 if distinct uncorrelated physical and mental constructs are required and for studies on clinical populations. In contrast, RAND12 should be used if correlated physical and mental constructs are required and if the study is on community or general populations.