Decision analysis for small, asymptomatic intracranial arteriovenous malformations

Markov models for clinical decision-making in radiation oncology: A systematic review

The intrinsic stochasticity of patients' response to treatment is a major consideration for clinical decision-making in radiation therapy. Markov models are powerful tools to capture this stochasticity and render effective treatment decisions. This paper provides an overview of the Markov models for clinical decision analysis in radiation oncology. A comprehensive literature search was conducted within MEDLINE using PubMed, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Only studies published from 2000 to 2023 were considered. Selected publications were summarized in two categories: (i) studies that compare two (or more) fixed treatment policies using Monte Carlo simulation and (ii) studies that seek an optimal treatment policy through Markov Decision Processes (MDPs). Relevant to the scope of this study, 61 publications were selected for detailed review. The majority of these publications (n = 56) focused on comparative analysis of two or more fixed treatment policies using Monte Carlo simulation. Classifications based on cancer site, utility measures and the type of sensitivity analysis are presented. Five publications considered MDPs with the aim of computing an optimal treatment policy; a detailed statement of the analysis and results is provided for each work. As an extension of Markov model-based simulation analysis, MDP offers a flexible framework to identify an optimal treatment policy among a possibly large set of treatment policies. However, the applications of MDPs to oncological decision-making have been understudied, and the full capacity of this framework to render complex optimal treatment decisions warrants further consideration.

Cost-Effectiveness Analysis of Percutaneous Sclerotherapy for Venous Malformations

PURPOSE

To assess cost-effectiveness of sclerotherapy for venous malformations (VMs) to improve patient quality of life (QOL).

MATERIALS AND METHODS

This prospective study enrolled 28 patients with symptomatic VMs who underwent sclerotherapy. EuroQol-5 Dimension (EQ-5D) and Short-Form 36 (SF-36) Health Survey were used to measure health-related QOL. Questionnaires were collected before and 1, 3, 6, and 12 months after sclerotherapy. Quality-adjusted life years (QALYs) were calculated using EQ-5D score as a measure of health utility. Medical costs obtained from the hospital accounting system and other costs of staff, drugs, materials, and angiographic equipment were calculated for each procedure. Cost-effectiveness was analyzed using incremental cost-effectiveness ratio (ICER) as the medical cost/gain of QALYs.

RESULTS

Median EQ-5D scores improved from 0.768 (range, 0.705-1) to 1 (range, 0.768-1) after 6 months (P = .023) and 1 (range, 0.768-1) after 12 months (P = .063). The gain of QALYs at 12 months was 0.043. The mean medical cost was ¥281,228 ($2,337). The pain group (baseline bodily pain scale of SF-36 score < 70) showed greater improvement in median EQ-5D score, from 0.705 (range, 0.661-0.768) to 0.768 (range, 0.705-1) after 6 months (P = .041) and 0.768 (range, 0.768-1) after 12 months (P = .049). ICER at 12 months was ¥6,600,483 ($54,840) in the overall group and decreased to ¥3,998,113 ($33,218) in the pain group, < ¥6,000,000 ($49,850), threshold for acceptance of a public health benefit in Japan, even accounting for 50% increase in costs.

CONCLUSIONS

Sclerotherapy was cost-effective for improving QOL for symptomatic VMs, especially for patients with moderate to severe pain.

Experimental Animal Models of Arteriovenous Malformation: A Review

Arteriovenous malformations (AVMs) are congenital lesions that cause brain haemorrhage in children and young adults. Current treatment modalities include surgery, radiosurgery and embolization. These treatments are generally effective only for small AVMs. Over one third of AVMs cannot be treated safely and effectively with existing options. Several animal models have been developed with the aims of understanding AVM pathophysiology and improving treatment. No animal model perfectly mimics a human AVM. Each model has limitations and advantages. Models contribute to the understanding of AVMs and hopefully to the development of improved therapies. This paper reviews animal models of AVMs and their advantages and disadvantages.

Durable thrombosis in a rat model of arteriovenous malformation treated with radiosurgery and vascular targeting

OBJECT

Radiosurgical treatment of brain arteriovenous malformations (AVMs) has the significant shortcomings of being limited to lesions smaller than 3 cm in diameter and of a latency-to-cure time of up to 3 years. A possible method of overcoming these limitations is stimulation of thrombosis by using vascular targeting. Using an animal model of AVM, the authors examined the durability of the thrombosis induced by the vascular-targeting agents lipopolysaccharide and soluble tissue factor conjugate (LPS/sTF).

METHODS

Stereotactic radiosurgery or sham radiation was administered to 32 male Sprague-Dawley rats serving as an animal model of AVM; 24 hours after this intervention, the rats received an intravenous injection of LPS/sTF or normal saline. The animals were killed at 1, 7, 30, or 90 days after treatment. Immediately beforehand, angiography was performed, and model AVM tissue was harvested for histological analysis to assess rates of vessel thrombosis.

RESULTS

Among rats that received radiosurgery and LPS/sTF, induced thrombosis occurred in 58% of small AVM vessels; among those that received radiosurgery and saline, thrombosis occurred in 12% of small AVM vessels (diameter < 200 μm); and among those that received LPS/sTF but no radiosurgery, thrombosis occurred at an intermediate rate of 43%. No systemic toxicity or intravascular thrombosis remote from the target region was detected in any of the animals.

CONCLUSIONS

Vascular targeting can increase intravascular thrombosis after radiosurgery, and the vessel occlusion is durable. Further work is needed to refine this approach to AVM treatment, which shows promise as a way to overcome the limitations of radiosurgery.