Component NMA: Solving Puzzles of Complex Interventions
Brian Hutton
Research scientist - network meta-analysis, indirect comparisons, real-world evidence, medical writing, systematic reviews
What is this article about?
While the research and health technology assessment (HTA) crowds have continued to build familiarity and expertise with 'standard' network meta-analysis (NMA) in recent years as a vital methodology in situations requiring the comparison of multiple health technologies, component NMA (or CNMA) still remains relatively unknown. CNMA is a meaningful advancement in the field of evidence synthesis that offers distinct advantages when compared to standard NMA in certain situations. Below I share some core considerations and a motivating example along with some key resources for those who may have an interest in learning more about this technique.
Standard NMA vs CNMA: When to Use?
While both NMA and CNMA can play a key role in comparing the relative efficacy and safety of multiple treatments for a health condition, CNMA can be uniquely helpful in situations where some of the treatments involve, not just one, but multiple components that may act synergistically. This can include situations involving a regimen of multiple drugs, combinations of different psychosocial interventions, exercise regimens consisting of different aerobic and strength training tasks, mode of treatment delivery (e.g., in-person versus virtual), or other aspects of complex intervention. CNMA allows researchers to establish a more granular understanding of which specific components of a complex intervention contribute to its overall effectiveness. CNMA can be particularly beneficial when dealing with interventions wherein there is variability in the components across studies or when the contributions of different components to the overall treatment effect are unclear. A motivating example from the medical literature is re-created in Figure 1 below (Freeman et al, Journal of Clinical Epidemiology, 2018), where the authors were interested to compare psychological preparation interventions for surgery and looked at the impact of different strategies on length of hospital stay; complex interventions were broken down into their components involving procedural information, sensory information, behavioral instruction, cognitive intervention, relaxation, emotion-focused techniques, and usual care.
How Does CNMA Help with Multi-Treatment Questions?
In contrast to standard NMA which treats all interventions as uniform entities (single ‘nodes’), CNMA recognizes the heterogeneity within treatments and provides a more comprehensive and tailored evaluation of efficacy. CNMA's capacity to dissect these components facilitates a deeper comprehension of treatment effects (e.g., what is the ‘best’ component? What is the ‘best’ combination of components?), aiding in making more informed decisions. Within the example by Freeman et al which considered multiple types of surgical patients (including cardiovascular, orthopedic, and other procedures), all but emotion focused therapies were found helpful in reducing length of hospital stay; importantly, the benefits of the individual components of psychological preparation varied by surgical population, an insight we could not glean from standard NMA. In their review, the authors also discuss nuances regarding the best combinations of these components of psychological preparation within different populations. ?
CNMA and Future Directions
Currently we have not yet fully experienced the influx of CNMAs as has been seen with standard NMAs over the past decade. However, we have seen: (1) a rapid growth in methods articles on key topics such as model selection (e.g., additive vs interaction models) and visualization of both evidence structure and findings; (2) a clear growth in the number of published protocols for CNMAs, demonstrating an increase in forthcoming applications of the approach; and (3) availability of more education and tutorials on the topic. All are signs that this technique is on the rise in terms of uptake. In my own research, we’re in the midst of our first pair of CNMAs related to surgery pre-habilitation regimens and treatment of individuals with substance use disorders, and we look forward to sharing these findings in 2024.
Wrap-Up
CNMA is growing in uptake given the unique insights it can provide, especially in the context of dealing with complex/combination interventions. This method not only enhances the comprehensiveness of evidence syntheses, but also provides a valuable tool for optimizing the design of interventions and tailoring them to individual patient needs. If you’re interested to learn more about this method, some key resources are provided below. Thanks for reading!
References for Interested Readers
领英推荐
Clinical Example:
Overview Articles:
Recent Work on Model Fitting and Visualization:
Online Educational Sessions:
Cochrane Training Sessions (2 parts; Drs. Deborah Caldwell and Nicky Welton):
Dr. George Seitidis on visualization (ESMAR 2023): https://www.youtube.com/watch?v=RnGbsmUWx3U