Estimation of annual probabilities of changing disability levels in Australians with relapsing-remitting multiple sclerosis

Estimation of Transition Probabilities from a Large Cohort (> 6000) of Australians Living with Multiple Sclerosis (MS) for Changing Disability Severity Classifications, MS Phenotype, and Disease-Modifying Therapy Classifications

BACKGROUND

Multiple sclerosis (MS) is a chronic autoimmune/neurodegenerative disease associated with progressing disability affecting mostly women. We aim to estimate transition probabilities describing MS-related disability progression from no disability to severe disability. Transition probabilities are a vital input for health economics models. In MS, this is particularly relevant for pharmaceutical agency reimbursement decisions for disease-modifying therapies (DMTs).

METHODS

Data were obtained from Australian participants of the MSBase registry. We used a four-state continuous-time Markov model to describe how people with MS transition between disability milestones defined by the Expanded Disability Status Scale (scale 0-10): no disability (EDSS of 0.0), mild (EDSS of 1.0-3.5), moderate (EDSS of 4.0-6.0), and severe (EDSS of 6.5-9.5). Model covariates included sex, DMT usage, MS-phenotype, and disease duration, and analysis of covariate groups were also conducted. All data were recorded by the treating neurologist.

RESULTS

A total of N = 6369 participants (mean age 42.5 years, 75.00% female) with 38,837 person-years of follow-up and 54,570 clinical reviews were identified for the study. Annual transition probabilities included: remaining in the no, mild, moderate, and severe states (54.24%, 82.02%, 69.86%, 77.83% respectively) and transitioning from no to mild (42.31%), mild to moderate (11.38%), and moderate to severe (9.41%). Secondary-progressive MS was associated with a 150.9% increase in the hazard of disability progression versus relapsing-remitting MS.

CONCLUSIONS

People with MS have an approximately 45% probability of transitioning from the no disability state after one year, with people with progressive MS transitioning from this health state at a much higher rate. These transition probabilities will be applied in a publicly available health economics simulation model for Australia and similar populations, intended to support reimbursement of a plethora of existing and upcoming interventions including medications to reduce progression of MS.

Exploring the cost-effectiveness of EBV vaccination to prevent multiple sclerosis in an Australian setting

BACKGROUND

Increasing evidence suggests the potential of Epstein-Barr virus (EBV) vaccination in preventing multiple sclerosis (MS). We aimed to explore the cost-effectiveness of a hypothetical EBV vaccination to prevent MS in an Australian setting.

METHODS

A five-state Markov model was developed to simulate the incidence and subsequent progression of MS in a general Australian population. The model inputs were derived from published Australian sources. Hypothetical vaccination costs, efficacy and strategies were derived from literature. Total lifetime costs, quality-adjusted life years (QALYs) and incremental cost-effectiveness ratios (ICERs) were estimated for two hypothetical prevention strategies versus no prevention from the societal and health system payer perspectives. Costs and QALYs were discounted at 5% annually. One-way, two-way and probabilistic sensitivity analyses were performed.

RESULTS

From societal perspective, EBV vaccination targeted at aged 0 and aged 12 both dominated no prevention (ie, cost saving and increasing QALYs). However, vaccinating at age 12 was more cost-effective (total lifetime costs reduced by $A452/person, QALYs gained=0.007, ICER=-$A64 571/QALY gained) than vaccinating at age 0 (total lifetime costs reduced by $A40/person, QALYs gained=0.003, ICER=-$A13 333/QALY gained). The probabilities of being cost-effective under $A50 000/QALY gained threshold for vaccinating at ages 0 and 12 were 66% and 90%, respectively. From health system payer perspective, the EBV vaccination was cost-effective at age 12 only. Sensitivity analyses demonstrated the cost-effectiveness of EBV vaccination to prevent MS under a wide range of plausible scenarios.

CONCLUSIONS

MS prevention using future EBV vaccinations, particularly targeted at adolescence population, is highly likely to be cost-effective.

Multiple Sclerosis Progressive Courses: A Clinical Cohort Long-Term Disability Progression Study

OBJECTIVES

Improving the understanding of multiple sclerosis (MS) mechanism and disability progression over time is essential to assess the value of healthcare interventions. Poor or no data on disability progression are available for progressive courses. This study aims to fill this gap.

METHODS

An observational cohort study of patients with primary MS (PPMS) and secondary progressive MS (SPMS) was conducted on 2 Italian MS centers disease registries over an observational time of 34 years. Annual transition probabilities among Expanded Disability Status Scale (EDSS) states were estimated using continuous Markov models. A sensitivity analysis was performed in relation to clinical characteristic associated to disability progression.

RESULTS

The study cohort included 758 patients (274 PPMS and 434 SPMS) with a median follow-up of 8.2 years. Annual transition probability matrices of SPMS and PPMS reported different annual probabilities to move within EDSS levels. Excluding EDSS associated to relapse events or patient with relapses, the annual probability of staying stable in an EDSS level increased in both disease courses even not significantly.

CONCLUSIONS

This study provides estimates of annual disability progression as EDSS changes for PPMS and SPMS. These estimates could be a useful tool for healthcare decision makers and clinicians to properly assess impact of clinical interventions.

Long-term trajectories of employment status, workhours and disability support pension status, after a first episode of CNS demyelination

BACKGROUND

People with multiple sclerosis face significant employment-related challenges, with little known of the drivers of these outcomes.

OBJECTIVE

We examined prospective trajectories of employment-related outcomes up to 11 years following a first episode of central nervous system (CNS) demyelination (FCD).

METHODS

Participants were aged 18-59 years, at FCD, with at least two observations and were employed at study entry or anytime during follow-up (n = 207). Outcomes were employment status (full-time, part-time and unemployed), average workhours per week and disability support pension (DSP; receiving/not receiving). We used group-based trajectory modelling to identify groups with common trajectories. Factors associated with trajectory membership were explored using log-multinomial regression.

RESULTS

Distinct trajectories were identified for employment (4), workhours (4) and DSP (2). Compared with stable full-time, female sex was strongly associated with being in the stable part-time trajectory (risk ratio (RR): 5.35; 95% confidence interval (CI) = 2.56-11.20; p < 0.001). A greater level of disability at 5-year review (RR: 1.35; 95% CI = 1.19-1.53) and having more than two comorbidities at baseline (RR: 2.77; 95% CI = 1.37-5.64) were associated with being in early and late deteriorated employment trajectories, respectively. Compared with the increased part-time trajectory, every additional relapse during the 5 years post-FCD was associated with a 10% increased risk of being in the reduced part-time trajectory (RR = 1.10; 95%CI = 1.00-1.22). For every additional EDSS point at 5-year review, the risk of being in the DSP trajectory increased (RR = 1.21; 95% CI = 1.05-1.41).

CONCLUSION

These trajectories indicate substantial heterogeneity and the complex impact of MS on employment from its earliest timepoints. Understanding these trends could enable better targeting of interventions to facilitate workforce retention, particularly for females, those with a higher number of comorbidities, more frequent relapses and greater rate of disability accrual.

Measuring Hypertension Progression With Transition Probabilities: Estimates From the WHO SAGE Longitudinal Study

This paper assessed the transition probabilities between the stages of hypertension severity and the length of time an individual might spend at a particular disease state using the new American College of Cardiology/American Heart Association hypertension blood pressure guidelines. Data for this study were drawn from the Ghana WHO SAGE longitudinal study, with an analytical sample of 1884 across two waves. Using a multistate Markov model, we estimated a seven-year transition probability between normal/elevated blood pressure (systolic ≤ 129 mm Hg & diastolic <80 mm Hg), stage 1 (systolic 130-139 mm Hg & diastolic 80-89 mm Hg), and stage 2 (systolic ≥140mm Hg & diastolic≥90 mm Hg) hypertension and adjusted for the individual effects of anthropometric, lifestyle, and socio-demographic factors. At baseline, 22.5% had stage 1 hypertension and 52.2% had stage 2 hypertension. The estimated seven-year transition probability for the general population was 19.0% (95% CI: 16.4, 21.8) from normal/elevated blood pressure to stage 1 hypertension, 31.6% (95% CI: 27.6, 35.4%) from stage 1 hypertension to stage 2 hypertension, and 48.5% (45.6, 52.1%) for remaining at stage 2. Other factors such as being overweight, obese, female, aged 60+ years, urban residence, low education and high income were associated with an increased probability of remaining at stage 2 hypertension. However, consumption of recommended servings of fruits and vegetables per day was associated with a delay in the onset of stage 1 hypertension and a recovery to normal/elevated blood pressure. This is the first study to show estimated transition probabilities between the stages of hypertension severity across the lifespan in sub-Saharan Africa. The results are important for understanding progression through hypertension severity and can be used in simulating cost-effective models to evaluate policies and the burden of future healthcare.

Modelling the impact of multiple sclerosis on life expectancy, quality-adjusted life years and total lifetime costs: Evidence from Australia

Objectives:

To quantify life expectancy (LE), quality-adjusted life years (QALYs) and total lifetime societal costs for a hypothetical cohort of Australians with multiple sclerosis (MS).

Methods:

A 4-state Markov model simulated progression from no/mild to moderate and severe disability and death for a cohort of 35-year-old women over a lifetime horizon. Death risks were calculated from Australian life tables, adjusted by disability severity. State-dependent relapse probabilities and associated disutilities were considered. Probabilities of MS progression and relapse were estimated from AusLong and TasMSL MS epidemiological databases. Annual societal (direct and indirect) costs (2017 Australian dollars) and health-state utilities for each state were derived from the Australian MS Longitudinal Study. Costs were discounted at 5% annually.

Results:

Mean (95% confidence interval (CI)) LE from age 35 years was 42.7 (41.6–43.8) years. This was 7.5 years less than the general Australian population. Undiscounted QALYs were 28.2 (26.3–30.0), a loss of 13.1 QALYs versus the Australian population. Discounted lifetime costs were $942,754 ($347,856–$2,820,219).

Conclusion:

We have developed a health economics model of the progression of MS, calculating the impact of MS on LE, QALYs and lifetime costs in Australia. It will form the basis for future cost-effectiveness analyses of interventions for MS.