Modeling rheumatoid arthritis using different techniques - a review of model construction and results

Research trends in contemporary health economics: a scientometric analysis on collective content of specialty journals

INTRODUCTION

Health economics is a thriving sub-discipline of economics. Applied health economics research is considered essential in the health care sector and is used extensively by public policy makers. For scholars, it is important to understand the history and status of health economics-when it emerged, the rate of research output, trending topics, and its temporal evolution-to ensure clarity and direction when formulating research questions.

METHODS

Nearly 13,000 articles were analysed, which were found in the collective publications of the ten most specialised health economic journals. We explored this literature using patterns of term co-occurrence and document co-citation.

RESULTS

The research output in this field is growing exponentially. Five main research divisions were identified: (i) macroeconomic evaluation, (ii) microeconomic evaluation, (iii) measurement and valuation of outcomes, (iv) monitoring mechanisms (evaluation), and (v) guidance and appraisal. Document co-citation analysis revealed eighteen major research streams and identified variation in the magnitude of activities in each of the streams. A recent emergence of research activities in health economics was seen in the Medicaid Expansion stream. Established research streams that continue to show high levels of activity include Child Health, Health-related Quality of Life (HRQoL) and Cost-effectiveness. Conversely, Patient Preference, Health Care Expenditure and Economic Evaluation are now past their peak of activity in specialised health economic journals. Analysis also identified several streams that emerged in the past but are no longer active.

CONCLUSIONS

Health economics is a growing field, yet there is minimal evidence of creation of new research trends. Over the past 10 years, the average rate of annual increase in internationally collaborated publications is almost double that of domestic collaborations (8.4% vs 4.9%), but most of the top scholarly collaborations remain between six countries only.

Health and economic impact associated with rheumatoid arthritis discharges: a cost analysis of a two-year cohort in Mexico

BACKGROUND

Rheumatoid arthritis is a highly prevalent disease. Patients undergo various medical and pharmacological treatments, which have an economic impact on hospitals. The aim of this study was to estimate the direct economic costs of Mexican Social Security Institute (IMSS) resources used to provide healthcare to adult patients with rheumatoid arthritis in 2016-2017.

METHODS

Data of patients aged > 18 years with Rheumatoid Arthritis (RA) were obtained from databases and public information sources to estimate the use of IMSS resources for the target population. Total costs were estimated by means of the macro-costing method, employing the diagnosis-related group (DRG). Each DRG of the IMSS was constructed with one of the diagnoses and the respective combination of clinical characteristics included in the ICD-9. This study was conducted from the national perspective of IMSS, the largest healthcare service administrator in the country. As such, it can be considered representative of the broader healthcare landscape in Mexico.

RESULTS

The total cost per year of furnishing inpatient care to RA patients was found to be $170,099,794 MXN ($9,096,245.67 USD) for 2016 and $167,039,481 MXN ($8,932,592.57 USD) for 2017, implying an enormous economic impact on the government budget for Mexican public health services.

CONCLUSIONS

Our results demonstrate that the direct costs of musculoskeletal and cardiovascular surgery represented the highest costs of RA in-hospital care at IMSS (the largest health institution in Mexico) in 2016 and 2017. Further studies are needed that include the cost of drugs and other indirect costs in addition to our results to get the most accurate approximation of the cost of living with RA.

Tofacitinib in the Treatment of Moderate-to-Severe Rheumatoid Arthritis in China: A Cost-Effectiveness Analysis Based on a Mapping Algorithm Derived from a Chinese Population

INTRODUCTION

To estimate the cost-effectiveness of tofacitinib for patients with moderate-to-severe rheumatoid arthritis (RA) who failed conventional synthetic disease-modifying antirheumatic drugs from the Chinese healthcare system perspective.

METHODS

An individual patient simulation model was used to estimate the lifetime cost and effectiveness. The comparator sequence commenced with etanercept, followed by rituximab-tocilizumab- non-biologic therapy. The intervention sequences were assumed to add tofacitinib to different positions in the comparator sequence. Quality-of-life estimates were generated by mapping Health Assessment Questionnaire scores to utility with the algorithm derived from a Chinese population. Scenario analyses, univariable and probabilistic sensitivity analyses were performed to evaluate the model uncertainty.

RESULTS

Compared with the comparator sequence, patients receiving tofacitinib as the first-, second-, third- and fourth-line treatment gained additional 0.49, 0.59, 0.44 and 0.53 QALYs, respectively, and the use of tofacitinib as the first- and second-line treatment was less costly, whereas the use of tofacitinib as the third- and fourth-line treatment cost an additional $234,998 and $381,116, respectively. This produced an incremental cost-effectiveness ratio of $333.73 and $9669.34/QALY, respectively.

CONCLUSION

Tofacitinib is estimated to be dominant in both the first- and second-line settings and to be highly cost-effective in both the third- and fourth-line settings.

A System Dynamics Simulation Applied to Healthcare: A Systematic Review

In recent years, there has been significant interest in developing system dynamics simulation models to analyze complex healthcare problems. However, there is a lack of studies seeking to summarize the available papers in healthcare and present evidence on the effectiveness of system dynamics simulation in this area. The present paper draws on a systematic selection of published literature from 2000 to 2019, in order to form a comprehensive view of current applications of system dynamics methodology that address complex healthcare issues. The results indicate that the application of system dynamics has attracted significant attention from healthcare researchers since 2013. To date, articles on system dynamics have focused on a variety of healthcare topics. The most popular research areas among the reviewed papers included the topics of patient flow, obesity, workforce demand, and HIV/AIDS. Finally, the quality of the included papers was assessed based on a proposed ranking system, and ways to improve the system dynamics models' quality were discussed.

Addressing Challenges of Economic Evaluation in Precision Medicine Using Dynamic Simulation Modeling

OBJECTIVES

The objective of this article is to describe the unique challenges and present potential solutions and approaches for economic evaluations of precision medicine (PM) interventions using simulation modeling methods.

METHODS

Given the large and growing number of PM interventions and applications, methods are needed for economic evaluation of PM that can handle the complexity of cascading decisions and patient-specific heterogeneity reflected in the myriad testing and treatment pathways. Traditional approaches (eg, Markov models) have limitations, and other modeling techniques may be required to overcome these challenges. Dynamic simulation models, such as discrete event simulation and agent-based models, are used to design and develop mathematical representations of complex systems and intervention scenarios to evaluate the consequence of interventions over time from a systems perspective.

RESULTS

Some of the methodological challenges of modeling PM can be addressed using dynamic simulation models. For example, issues regarding companion diagnostics, combining and sequencing of tests, and diagnostic performance of tests can be addressed by capturing patient-specific pathways in the context of care delivery. Issues regarding patient heterogeneity can be addressed by using patient-level simulation models.

CONCLUSION

The economic evaluation of PM interventions poses unique methodological challenges that might require new solutions. Simulation models are well suited for economic evaluation in PM because they enable patient-level analyses and can capture the dynamics of interventions in complex systems specific to the context of healthcare service delivery.

Systematic Literature Review of Economic Evaluations of Biological Treatment Sequences for Patients with Moderate to Severe Rheumatoid Arthritis Previously Treated with Disease-Modifying Anti-rheumatic Drugs

OBJECTIVE

This systematic literature review (SLR) had two objectives: to analyse published economic evaluations of biological disease-modifying anti-rheumatic drugs (bDMARDs) for patients with moderate to severe rheumatoid arthritis (RA) previously treated with DMARDs and to assess the quality of those that included sequences of treatments.

METHODS

We performed an SLR on PubMed, Central, Cochrane, and French databases from January 2000 to December 2018. The search focused on cost-effectiveness/utility/benefit analyses. We extracted data on treatment sequences, outcomes (e.g. quality-adjusted life year) and choices of economic evaluation methods (e.g. model type, type of analysis, and method of utility estimation). We analysed the improvement of methods by comparing two sub-periods (2000-2009 and 2010-2018). The quality of reporting and the quality of the methods were assessed using the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) and a set of eight key aspects for a reference case for economic evaluation of bDMARDs based on the Outcome Measures in Rheumatology (OMERACT) and Drummond checklists. Data extraction and study assessment were performed independently by two health economists.

RESULTS

From the 824 records identified in the initial search, 51 publications were selected. Of these, 31 included sequences. Individual models such as discrete-event simulations were used in over two-fifths (22/51, 43%) of the selected studies. Few studies (7/51, 14%) used utility scores based on generic instruments (e.g. EQ-5D). Estimation of hospitalization costs was described in only approximately one-third of studies (19/51). Loss of quality of life (QoL) related to adverse events such as tuberculosis and pneumonia was included in one-tenth (5/51, 10%) of the studies. It was difficult to compare the results of the economic evaluations (i.e. incremental cost-effectiveness ratios) due to the high heterogeneity of studies in terms of disease stage, data sources, inputs, and methods of health outcome assessment used. For identified studies including sequences, the CHEERS assessment of reporting quality showed insufficient reporting of uncertainty analyses and utility weights in more than a third of the studies (11/31, 35%; 9/25, 36%). An in-depth assessment of the quality of the studies revealed that only seven, mostly conducted during the sub-period 2010-2018, addressed the majority of methodological quality assessment issues such as the simulation of patient sequence pathways, the use of systematic reviews and meta-analyses of comparative effectiveness, the choice of treatment sequence, and rules for switching.

CONCLUSION

Our SLR identified a lack of high-quality evaluations assessing bDMARD sequences, although some improvements were made in the reporting and modelling of patients' pathways in studies published after 2010. In order to improve economic evaluations of RA, clear health technology assessment guidance on RA health-related QoL instruments must be provided, and data including long-term disease progression must be made available.

A modeling framework for the economic evaluation of baricitinib in moderate-to-severe rheumatoid arthritis

Objectives: The approval in more than 50 countries of baricitinib, an oral Janus Kinase inhibitor for the treatment of Rheumatoid Arthritis (RA), warrants a framework for corresponding economic evaluations. To develop a comprehensive economic model assessing the cost-effectiveness of baricitinib for the treatment of moderately-to-severely active RA patients in comparison to other relevant treatments, considering the natural history of the disease, real world treatment patterns, and clinical evidence from the baricitinib trials.Methods: A systematic literature review of previously developed models in RA was conducted to inform the model structure, key modeling assumptions and data inputs. Consultations with rheumatologists were undertaken to validate the modeling approach and underlying assumptions.Results: A discrete event simulation model was developed to international best practices with flexibility to assess the cost-effectiveness of baricitinib over a lifetime in a variety of markets. The model incorporates treatment sequencing to adequately reflect treatment pathways in clinical practice. Outcomes assessed include cost and quality-adjusted life years, allowing for a full incremental analysis of cost-effectiveness of competing treatments and treatment sequences.Conclusion: The economic model developed provides a robust framework for future analyses assessing the cost-effectiveness of baricitinib for the treatment of RA in specific country settings.

Quantitative Predictive Modelling Approaches to Understanding Rheumatoid Arthritis: A Brief Review

Rheumatoid arthritis is a chronic autoimmune disease that is a major public health challenge. The disease is characterised by inflammation of synovial joints and cartilage erosion, which lead to chronic pain, poor life quality and, in some cases, mortality. Understanding the biological mechanisms behind the progression of the disease, as well as developing new methods for quantitative predictions of disease progression in the presence/absence of various therapies is important for the success of therapeutic approaches. The aim of this study is to review various quantitative predictive modelling approaches for understanding rheumatoid arthritis. To this end, we start by briefly discussing the biology of this disease and some current treatment approaches, as well as emphasising some of the open problems in the field. Then, we review various mathematical mechanistic models derived to address some of these open problems. We discuss models that investigate the biological mechanisms behind the progression of the disease, as well as pharmacokinetic and pharmacodynamic models for various drug therapies. Furthermore, we highlight models aimed at optimising the costs of the treatments while taking into consideration the evolution of the disease and potential complications.

Conceptual model for the health technology assessment of current and novel interventions in rheumatoid arthritis

The objective of this study was to evaluate current approaches to economic modeling in rheumatoid arthritis (RA) and propose a new conceptual model for evaluation of the cost-effectiveness of RA interventions. We followed recommendations from the International Society of Pharmacoeconomics and Outcomes Research-Society of Medical Decision Making (ISPOR-SMDM) Modeling Good Research Practices Task Force-2. The process involved scoping the decision problem by a working group and drafting a preliminary cost-effectiveness model framework. A systematic literature review (SLR) of existing decision-analytic models was performed and analysis of an RA registry was conducted to inform the structure of the draft conceptual model. Finally, an expert panel was convened to seek input on the draft conceptual model. The proposed conceptual model consists of three separate modules: 1) patient characteristic module, 2) treatment module, and 3) outcome module. Consistent with the scope, the conceptual model proposed six changes to current economic models in RA. These changes proposed are to: 1) use composite measures of disease activity to evaluate treatment response as well as disease progression (at least two measures should be considered, one as the base case and one as a sensitivity analysis); 2) conduct utility mapping based on disease activity measures; 3) incorporate subgroups based on guideline-recommended prognostic factors; 4) integrate realistic treatment patterns based on clinical practice/registry datasets; 5) assimilate outcomes that are not joint related (extra-articular outcomes); and 6) assess mortality based on disease activity. We proposed a conceptual model that incorporates the current understanding of clinical and real-world evidence in RA, as well as of existing modeling assumptions. The proposed model framework was reviewed with experts and could serve as a foundation for developing future cost-effectiveness models in RA.

Clinical and demographic factors associated with change and maintenance of disease severity in a large registry of patients with rheumatoid arthritis

Background

We examined models to predict disease activity transitions from moderate to low or severe and associated factors in patients with rheumatoid arthritis (RA).

Methods

Data from RA patients enrolled in the Corrona registry (October 2001 to August 2014) were analyzed. Clinical Disease Activity Index (CDAI) definitions were used for low (≤10), moderate (>10 and ≤22), and severe (>22) disease activity states. A Markov model for repeated measures allowing for covariate dependence was used to model transitions between three (low, moderate, severe) states and estimate population transition probabilities. Mean sojourn times were calculated to compare length of time in particular states. Logistic regression models were used to examine impacts of covariates (time between visits, chronological year, disease duration, age) on disease states.

Results

Data from 29,853 patients (251,375 visits) and a sub-cohort of 9812 patients (46,534 visits) with regular visits (every 3–9 months) were analyzed. The probability of moving from moderate to low or severe disease by next visit was 47% and 18%, respectively. Patients stayed in moderate disease for mean 4.25 months (95% confidence interval: 4.18–4.32). Transition probabilities showed 20% of patients with low disease activity moved to moderate or severe disease within 6 months; >35% of patients with moderate disease remained in moderate disease after 6 months. Results were similar for the regular-visit sub-cohort. Significant interactions with prior disease state were seen with chronological year and disease duration.

Conclusion

A substantial proportion of patients remain in moderate disease, emphasizing the need for treat-to-target strategies for RA patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1289-x) contains supplementary material, which is available to authorized users.

A Systematic Review of Health Economics Simulation Models of Chronic Obstructive Pulmonary Disease

BACKGROUND

Many decision-analytic models with varying structures have been developed to inform resource allocation in chronic obstructive pulmonary disease (COPD).

OBJECTIVES

To review COPD models for their adherence to the best practice modeling recommendations and their assumptions regarding important aspects of the natural history of COPD.

METHODS

A systematic search of English articles reporting on the development or application of a decision-analytic model in COPD was performed in MEDLINE, Embase, and citations within reviewed articles. Studies were summarized and evaluated on the basis of their adherence to the Consolidated Health Economic Evaluation Reporting Standards. They were also evaluated for the underlying assumptions about disease progression, heterogeneity, comorbidity, and treatment effects.

RESULTS

Forty-nine models of COPD were included. Decision trees and Markov models were the most popular techniques (43 studies). Quality of reporting and adherence to the guidelines were generally high, especially in more recent publications. Disease progression was modeled through clinical staging in most studies. Although most studies (n = 43) had incorporated some aspects of COPD heterogeneity, only 8 reported the results across subgroups. Only 2 evaluations explicitly considered the impact of comorbidities. Treatment effect had been mostly modeled (20) as both reduction in exacerbation rate and improvement in lung function.

CONCLUSIONS

Many COPD models have been developed, generally with similar structural elements. COPD is highly heterogeneous, and comorbid conditions play an important role in its burden. These important aspects, however, have not been adequately addressed in most of the published models.