A Comparison of Markov and Discrete-Time Microsimulation Approaches: Simulating the Avoidance of Alcohol-Attributable Harmful Events from Reduction of Alcohol Consumption Through Treatment of Alcohol Dependence

Applying dynamic systems theory and complexity theory methods in psychotherapy research: A systematic literature review

OBJECTIVE

Dynamic systems theory and complexity theory (DST/CT) is a framework explaining how complex systems change and adapt over time. In psychotherapy, DST/CT can be used to understand how a person's mental and emotional state changes during therapy incorporating higher levels of complexity. This study aimed to systematically review the variability of DST/CT methods applied in psychotherapy research.

METHODS

A primary studies search was conducted in the EBSCO and Web of Knowledge databases, extracting information about the analyzed DST/CT phenomena, employed mathematical methods to investigate these phenomena, descriptions of specified dynamic models, psychotherapy phenomena, and other information regarding studies with empirical data (e.g., measurement granularity).

RESULTS

After screening 38,216 abstracts and 4,194 full texts, N = 41 studies published from 1990 to 2021 were identified. The employed methods typically included measures of dynamic complexity or chaoticity. Computational and simulation studies most often employed first-order ordinary differential equations and typically focused on describing the time evolution of client-therapist dyadic influences. Eligible studies with empirical data were usually based on case studies and focused on data with high time intensity of within-session dynamics.

CONCLUSION

This review provides a descriptive synthesis of the current state of the proliferation of DST/CT methods in the psychotherapy research field.

A review of simulation models for the long-term management of type 2 diabetes in low-and-middle income countries

INTRODUCTION

The burden of type 2 diabetes is steadily increasing in low-and-middle-income countries, thereby posing a major threat from both a treatment, and funding standpoint. Although simulation modelling is generally relied upon for evaluating long-term costs and consequences associated with diabetes interventions, no recent article has reviewed the characteristics and capabilities of available models used in low-and-middle-income countries. We review the use of computer simulation modelling for the management of type 2 diabetes in low-and-middle-income countries.

METHODS

A search for studies reporting computer simulation models of the natural history of individuals with type 2 diabetes and/or decision models to evaluate the impact of treatment strategies on these populations was conducted in PubMed. Data were extracted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and assessed using modelling checklists. Publications before the year 2000, from high-income countries, studies involving animals and analyses that did not use mathematical simulations were excluded. The full text of eligible articles was sourced and information about the intervention and population being modelled, type of modelling approach and the model structure was extracted.

RESULTS

Of the 79 articles suitable for full text review, 44 studies met the inclusion criteria. All were cost-effectiveness/utility studies with the majority being from the East Asia and Pacific region (n = 29). Of the included studies, 34 (77.3%) evaluated the cost-effectiveness of pharmacological interventions and approximately 75% of all included studies used HbA1c as one of the treatment effects of the intervention. 32 (73%) of the publications were microsimulation models, and 29 (66%) were state-transition models. Most of the studies utilised annual cycles (n = 29, 71%), and accounted for costs and outcomes over 20 years or more (n = 38, 86.4%).

CONCLUSIONS

While the use of simulation modelling in the management of type 2 diabetes has been steadily increasing in low-and-middle-income countries, there is an urgent need to invest in evaluating therapeutic and policy interventions related to type 2 diabetes in low-and-middle-income countries through simulation modelling, especially with local research data. Moreover, it is important to improve transparency and credibility in the reporting of input data underlying model-based economic analyses, and studies.

Cost-effectiveness of Recurrent Dupuytren Contracture Treatment

IMPORTANCE

Owing to its tendency to recur, Dupuytren contracture often requires multiple treatments, which places additional economic burden on health care. The likelihood of contracture recurrence varies not only with treatment but also with disease characteristics, such as contracture severity and location, but prior cost-effectiveness analyses of Dupuytren contracture treatments have not considered these patient-specific disease characteristics.

OBJECTIVE

To identify the most cost-effective treatment regimen for patients with recurrent Dupuytren contracture.

DESIGN, SETTING, AND PARTICIPANTS

This economic evaluation was conducted with state-transition microsimulation modeling using data from published studies and Medicare. A simulated cohort of 10 000 individuals with Dupuytren contracture was created. Patients could transition yearly between the following health states: symptom-free, symptomatic, and death. Available treatments were collagenase clostridium histolyticum injection, percutaneous needle aponeurotomy (PNA), and limited fasciectomy (LF); individuals randomly chose any treatment when symptomatic. Patients were limited to 3 rounds of treatment for a contracture affecting 1 joint, totaling 27 unique combinations. If the contracture recurred after 3 treatments, patients lived with the disease for the remainder of life.

EXPOSURES

PNA, collagenase clostridium histolyticum injection, or LF.

MAIN OUTCOMES AND MEASURES

Quality-adjusted life-years (QALYs), total costs (in US dollars), and incremental cost-effectiveness ratios (ICERs). A willingness-to-pay threshold of $100 000 per quality-adjusted life-year was used to assess cost-effectiveness.

RESULTS

For the base case scenario of a patient aged 60 years with recurrent, low-severity metacarpophalangeal (MCP) joint contracture, repeated PNA treatment was the only cost-effective treatment (2 PNA treatments followed by LF vs 3 PNA treatments, ICER [Monte Carlo SE]: $212 647/QALY [$36 000/QALY]). For recurrent high-severity MCP joint contractures, treatment regimens composed of PNA and LF were cost-effective (ICER [Monte Carlo SE], $93 932/QALY [$16 500/QALY]). LF was cost-effective for high-severity MCP joint contracture (ICER [Monte Carlo SE], $98 624/QALY [$26 233/QALY]). For recurrent proximal interphalangeal (PIP) joint contractures, PNA was the only cost-effective treatment, regardless of severity (eg, 2 PNA treatments followed by LF vs 3 PNA treatments for low-severity PIP joint contracture, ICER [Monte Carlo SE]: $263 726/QALY [$29 000/QALY]). Any combination with collagenase clostridium histolyticum injection compared with 3 PNA treatments had an ICER greater than $100 000 per QALY. Probabilistic sensitivity analysis estimated a 44%, 15%, 41%, and 52% chance of a regimen consisting of only PNA being cost-effective in low-severity MCP, high-severity MCP, low-severity PIP, and high-severity PIP joint contractures, respectively.

CONCLUSIONS AND RELEVANCE

The results of this study suggest that LF is a cost-effective intervention for recurrent high-severity MCP joint contractures. For recurrent low-severity MCP joint contractures and PIP joint contractures of all severity levels, PNA was the only cost-effective intervention. Collagenase clostridium histolyticum injections were not a cost-effective intervention for recurrent Dupuytren contracture and should not be preferred over PNA or LF.