Measuring quality of life of patients with axial spondyloarthritis for economic evaluation

Developing mapping algorithms to predict EQ-5D health utility values from Bath Ankylosing Spondylitis Disease Activity Index and Bath Ankylosing Spondylitis Functional Index among patients with Ankylosing Spondylitis

BACKGROUND

Preference-based measures of health-related quality of life (HRQoL), such as the EQ-5D or the SF-6D, are essential for health economic evaluation. However, they are rarely included in clinical trials of ankylosing spondylitis (AS). This study aims to develop mapping algorithms to predict EQ-5D-3L and EQ-5D-5L health utility scores from the Bath Ankylosing Disease Activity Index (BASDAI) and the Bath Ankylosing Spondylitis Functional Index (BASFI).

METHODS

Patients with AS were recruited from the largest tertiary hospital in Shandong province, China, between December 2019 and October 2020. Patients were selected by convenience sampling method according to the following criteria: (1) diagnosed with AS according to the New York criteria; (2) aged 18 years and above; and (3) without mental disorders; (4) able to understand the questionnaires; (5) without serious complications. There were 243 patients who completed the face-to-face questionnaire survey, and 5 cases with missing values in key variables were excluded. Ordinary least squares, censored least absolute deviations, Tobit, adjusted limited dependent variable mixture model and beta-mixture model (BM) in the direct approach and ordered logit and multinomial logit (Mlogit) model in the response approach were used to develop mapping algorithms. Mean absolute error, root mean square error, Spearman's correlation coefficient and concordance correlation coefficient were used to access predictive performance.

RESULTS

The 238 patients with AS had a mean age of 35.19 (SD = 9.59) years, and the majority (74.47%) were male. The observed EQ-5D-3L and EQ-5D-5L health utility values were 0.88 (SD = 0.12) and 0.74 (SD = 0.27), respectively. The EQ-5D-5L had higher conceptual overlap with the BASDAI and BASFI than the EQ-5D-3L did. The Mlogit was the best-performing model for the EQ-5D-3L, and the BM showed better performance in predicting EQ-5D-5L than other direct and indirect mapping models did.

CONCLUSION

This study demonstrates that the EQ-5D-5L, rather than EQ-5D-3L, should be selected as the target outcome measure of HRQoL in patients with AS in China, and the BM mapping algorithm could be used to predict EQ-5D-5L values from BASDAI and BASFI for health economic evaluation.

The cost-effectiveness of a bimekizumab versus IL-17A inhibitors treatment-pathway in patients with active axial spondyloarthritis in Scotland

OBJECTIVE

To estimate the cost-effectiveness of a treatment-pathway initiated with bimekizumab, a monoclonal IgG1 antibody that selectively inhibits interleukin (IL)-17F and IL-17A, in patients with axial spondyloarthritis (axSpA) compared with IL-17Ai's, ixekizumab, and secukinumab, from the NHS Scotland perspective.

METHODS

The axSpA treatment-pathway was modeled using a decision tree followed by a lifetime Markov model. The pathway included first- and second-line biologic disease-modifying antirheumatic drugs (bDMARD), followed by best supportive care (bDMARD, nonbiologic). Bimekizumab followed by any bDMARD ("BKZ") was compared with IL-17Ai's: secukinumab 150 mg followed by a blend ("SEC") of dose up-titration to secukinumab 300 mg and any bDMARD, or ixekizumab followed by any bDMARD ("IXE"). Transition to the next therapy was triggered by Bath Ankylosing Spondylitis Disease Activity Index-50% (BASDAI50) non-response or any-cause discontinuation. A published network meta-analysis provided efficacy data. EuroQoL-5-dimensions utilities were derived by mapping from Ankylosing Spondylitis Disease Activity Score. Costs included disease management (linked to functional limitations), biologics acquisition (list prices), administration and monitoring (NHS 2021/22). Discounting was 3.5%/year. Probabilistic results from patients with non-radiographic axSpA and ankylosing spondylitis were averaged to reflect the axSpA disease spectrum. Scenario and sensitivity analyses were performed.

RESULTS

The incremental cost-effectiveness ratio (ICER) of BKZ was £24,801/quality-adjusted life-year (QALY) vs. SEC (95% credible interval £24,163-£25,895). BKZ had similar costs (Δ -£385 [-£15,239-£14,468]) and QALYs (Δ 0.039 [-0.748-0.825]) to IXE, with £1,523 (£862-£2,222) net monetary benefit. Conclusions remained unchanged in most scenarios. Results' drivers included BASDAI50 response rate and disease management cost.

LIMITATIONS

Results were based on list prices. Data concerning up-titration to secukinumab 300 mg was scarce.

CONCLUSIONS

The bimekizumab treatment-pathway represents a cost-effective option across the axSpA disease spectrum in Scotland. Bimekizumab is cost-effective compared to a secukinumab-pathway that includes dose up-titration, and has similar costs and QALYs to an ixekizumab-pathway.

Burden of disease and impact on quality of life in chronic back pain - a comparative cross-sectional study of 150 axial spondyloarthritis and 150 orthopedic back pain patients

Objective

Chronic back pain (CBP) constitutes one of the most common complaints in primary care and a leading cause of disability worldwide. CBP may be of mechanical or inflammatory character and may lead to functional impairment and reduced quality of life. In this study, we aimed to assess and compare burden of disease, functional capacity, quality of life and depressive symptoms in axial spondyloarthritis (axSpA) patients with orthopedic chronic back pain patients (OBP). We further aimed to identify factors associated with quality of life.

Methods

Cross-sectional survey of a cohort of 300 CBP patients including 150 patients from a University Hospital Orthopedic Back Pain Outpatient Clinic with OBP and 150 patients with confirmed axSpA from a University Hospital Rheumatology Outpatient Clinic. Questionnaire-based assessment of pain character (Inflammatory Back Pain, MAIL-Scale), functional status (FFbH, BASFI), quality of life (WHOQOL-Bref) and depressive symptoms (Phq9) and retrospective medical chart analysis.

Results

Both, OBP and axSpA patients reported on average intermediate pain levels of mostly mixed pain character. Both groups demonstrated a reduced health-related quality of life and the presence of depressive symptoms. However, axSpA patients reported a significantly better subjective quality of life, more satisfaction with their health status and better functional capacity compared to OBP patients (all p < 0.001). In a multivariate regression model, depressive symptoms, mechanical back pain, pain level and age were negative predictors of subjective quality of life, whereas functional capacity was a positive predictor.

Conclusion

Chronic back pain was associated with a high morbidity and reduced quality of life regardless of pain character. We identified multiple factors associated with reduced quality of life. Awareness and addressing of these factors may help to overcome unmet needs and improve quality of life for these patients.