Worst-case future scenarios of patients with rheumatoid arthritis: a cross-sectional study.

OBJECTIVE: The time trade-off is a health-related quality of life instrument that measures valuations for health states (utilities) by asking patients to value their health state anchored on a scale between death (0) and perfect health (1). Dying earlier is not perceived as a realistic worst-case consequence of the disease by RA patients. Of the previous focus groups study on RA patients, five worst-case future scenarios emerged. The aim of this study was to examine which potential worst-case scenario was the most appropriate for RA patients to use in utility calculation. METHODS: In a cross-sectional study of 74 consecutive RA patients visiting the rheumatology outpatient clinic, participants were presented with descriptions of the five worst-case future scenarios. In pairwise comparisons, patients had to choose the scenario that would be the worst to experience. The worst-case future scenario was defined by the scenario that was chosen by a significantly greater proportion of participants than could be expected based on chance (20%). Therefore, analysis based on a single fraction ( ) was used and 95% CI was calculated. RESULTS: The scenario being dependent on others was chosen most often as the worst to experience [by 35% of participants (95% CI 24%, 46%)] and significantly more often than could be expected based on chance ( = 0.35, z = 6.45, P = 0.00). CONCLUSION: The scenario being dependent on others is likely to be the most appropriate worst-case future scenario for RA patients. Using an alternative anchor could improve the validity and responsiveness of the time trade-off in RA patients.

Construct validity of the interview time trade-off and computer time trade-off in patients with rheumatoid arthritis: a cross-sectional observational pilot study.

BACKGROUND: The Time Trade-Off (TTO) is a widely used instrument for valuing preference-based health-related quality of life (HRQoL). The TTO reveals preferences for own current health ('utilities') on a scale anchored between death (0) and perfect health (1). Limited information on the external validity of the TTO is available. Aim of this pilot study was to examine the construct validity of both an interview TTO and a computer-based TTO in patients with rheumatoid arthritis (RA). METHODS: Thirty patients visiting the outpatient rheumatology clinic participated. Construct validity was assessed by measuring convergent and discriminative validity. Convergent validity was assessed by calculating Spearman's correlations between the utilities obtained from the TTOs and pain, general health (rating scales), health-related quality of life (SF-36 and SF-6D) and functional status (HAQ-DI). Discriminative power of both TTO measures was determined by comparing median utilities between worse and better health outcomes. RESULTS: Correlations of both TTO measures with HRQoL, general health, pain and functional status were poor (absolute values ranging from .05 to .26). Both TTOs appeared to have no discriminative value among groups of RA patients who had a worse or better health status defined by six health outcome measures. About one-third of respondents were zero-traders on each of the TTO measures. After excluding zero-traders from analysis, the correlations improved considerably. CONCLUSIONS: Both the interview TTO and computer TTO showed poor construct validity in RA patients when using measures of HRQol, general health, pain and functional status as reference measures. Possibly, the validity of the TTO improves when using an anchor that is more realistic to RA patients than the anchor 'death'.

Future expectations and worst-case future scenarios of patients with rheumatoid arthritis: a focus group study.

OBJECTIVE: Over the past 15 years, developments in the treatment of rheumatoid arthritis (RA) have resulted in better clinical outcomes. The aim of the present study was to explore how patients think their RA will influence their lives in the future, and which of these future expectations would be the worst for them to experience. METHODS: A focus group study was performed in 16 RA patients. Three groups were heterogeneously composed, based on age group (18-40, 40-65, 65-80), gender and having a paid job or not. Patients were asked about the expected future impact of RA and worst-case future scenarios. Transcripts were coded by three researchers under the main components of the International Classification of Functioning, Disability and Health. The codes were discussed until agreement was reached about all codes. RESULTS: Dependency on others, increasing dependency on medication, inability to walk, activity limitations and worsening fatigue were mentioned as worst-case future scenarios. Further concerns were raised about the acceptance of RA and possible disappearance of physicians' expertise. Nevertheless, hope and positive feelings were expressed toward continuous medication improvements. CONCLUSION: The present study provided insight into RA patients' future expectations and worst-case future scenarios. The results may be of help in the development of support interventions to put concerns and worst-case future scenarios into a realistic perspective. Furthermore, insight into patients' worst-case future scenarios could be used to improve the validity and responsiveness of the Time Trade-Off, an instrument to measure preference-based health-related quality of life.

Comparative responsiveness of the EuroQol-5D and Short Form 6D to improvement in patients with rheumatoid arthritis treated with tumor necrosis factor blockers: results of the Dutch Rheumatoid Arthritis Monitoring registry.

OBJECTIVE: For cost-utility analyses of health technologies, utilities are commonly measured with the EuroQol-5D (EQ-5D) or the Short Form 6D (SF-6D). Although most studies in rheumatoid arthritis (RA) found the SF-6D to be more responsive than the EQ-5D, evidence is not convincing. The aim of this study was to compare the responsiveness of the EQ-5D and SF-6D to improvement in RA patients treated with tumor necrosis factor (TNF) blockers. METHODS: Data from 278 RA patients included in the Dutch Rheumatoid Arthritis Monitoring registry were used. Internal responsiveness over 1 year was evaluated by using standardized response means (SRMs). External responsiveness was evaluated by using receiver operating characteristic curves based on perceived health change (self-reported health transition item Short Form 36) and change in disease activity (European League Against Rheumatism response criteria based on the Disease Activity Score in 28 joints). RESULTS: The scores of the EQ-5D and SF-6D changed moderately over 1 year (SRMs 0.50 and 0.67, respectively). The SF-6D was significantly more responsive to treatment than the EQ-5D. The EQ-5D and SF-6D were moderately able to correctly classify patients according to health transition (areas under the curve [AUCs] 0.67 and 0.72, respectively) and change in disease activity (AUCs 0.71 and 0.65, respectively). CONCLUSION: The EQ-5D and SF-6D were only moderately responsive to improvement in RA patients treated with TNF blockers. Overall, the SF-6D was more responsive than the EQ-5D.

A computer Time Trade-Off: a feasible and reliable alternative for the interview Time Trade-Off in rheumatoid arthritis.

OBJECTIVES: The Time Trade-Off (TTO) is an instrument used for valuing health-related quality of life. This study evaluated the test-retest reliability of a computer TTO in rheumatoid arthritis (RA), and compared the computer with the interview TTO regarding feasibility and agreement. METHODS: In study 1 using a cross-over design, thirty patients completed both TTOs. In study 2, twenty-nine other patients completed the computer TTO twice to examine test-retest reliability. Feasibility was measured by assessing actual and perceived time duration and general experience of the patient. Agreement between utility scores of both TTOs was measured by Bland-Altman analysis. RESULTS: Both TTOs were feasible. The computer TTO showed high test-retest reliability (ICC = 0.88). Bland-Altman analysis showed a small mean difference (0.06, SD = 0.14, effect size=0.30) between both TTOs. Limits of agreement were wide (-0.22 to 0.34). Differences between interview and computer TTO utilities did not vary over the range of scores. CONCLUSIONS: The computer TTO was feasible and reliable, but did not provide similar results as the interview TTO. However, no systematic biases in the differences were found over the range of scores.