Health State Utilities and Disease Duration in Systemic Sclerosis: Is There an Association?

OBJECTIVE

Health state utility values (HSUV) are used as weightings to calculate quality-adjusted life years in economic evaluations. Evidence suggests that patients' perceptions of a new diagnosis for a chronic disease, while initially poor, may improve over time. The objective of this study was to examine the association between disease duration and direct HSUV scores in patients with systemic sclerosis (SSc).

METHODS

Our study included patients with SSc from a US SSc center. An interviewer administered direct HSUV techniques including the visual analog scale (VAS), time tradeoff (TTO), and standard gamble (SG). We calculated the Short Form 6D HSUV from the Medical Outcomes Study Short Form-36. Additional clinical and demographic variables were collected.

RESULTS

The mean age of the SSc sample (n = 223) was 51 years (SD 16) with the majority being women (84%). Median disease duration was 5 years (interquartile range 1.5-9). Mean (SD) HSUV scores were 0.67 (0.19) for the VAS, 0.76 (0.28) for the TTO, 0.84 (0.22) for the SG, and 0.65 (0.13) for the SF-6D. In patients with early disease (defined as ≤ 2 yrs, n = 78), the mean HSUV values were 0.64 (VAS), 0.70 (TTO), 0.80 (SG), and 0.63 (SF-6D) versus for those with a longer disease duration: 0.69, 0.79, 0.87, and 0.67, respectively. In multivariate analysis, the SG measure showed a significant and positive association with disease duration measured as a continuous variable and using a threshold of 2 years (p = 0.047 and p = 0.023, respectively).

CONCLUSION

Greater disease duration showed a positive association with a direct measure (SG) of utility elicitation after a period of 2 years.