A tri-layer hybrid simulation of health-related quality of life (HRQoL) from diagnosis through survivorship in adolescent and young adult (AYA) cancer patients, ages 15–39, coupling an agent-based model of patients, an evolving social-support network, and a system-dynamics model of population and services.
Agent-Based ModelingNetwork Modeling and Analysis System DynamicsHybrid Modeling MATLAB, reproducibleOpen to Collaboration AYA CancerQuality of LifeBackground. Health-related quality of life (HRQoL) in adolescent and young adult (AYA) cancer patients is worse than population norms, with the largest deficits in physical and emotional functioning, and persists for years after diagnosis[1, 2] Clinical and observational studies capture HRQoL at limited time points and cannot represent the joint, evolving influence of patient heterogeneity, social support, and service-system feedback.
Methods. A tri-layer hybrid simulation model couples an agent-based model of individual patients, an evolving social-support network, and a system-dynamics model of population and services. The three layers exchange information through six explicit interfaces, each of which can be disabled independently to measure the contribution of each interface. No prior model is known to couple all three layers for AYA HRQoL[16, 17]
Results. Over 20 simulation seeds and a 24-month horizon, the model reproduces patterns it was not fitted to, including a treatment nadir, persistent emotional deficits, and a durable-remission fraction near 78% among treated agents, within the band anchored to AYA 5-year relative survival[1, 5] Each interface acts in the direction predicted by the governing mechanism, with effect sizes that differ sharply: social support dominates the outcome while the population-feedback loop is near-dormant under baseline parameters. All interface verification checks pass, including a no-leak test, a structural verification method used to ensure that stocks (accumulations) do not gain or lose material spontaneously. It checks that all inflows and outflows are properly accounted for and that no hidden or "leaking" flows exist[9]
Conclusions. The model stands as an exploratory scaffold for theory and decision support. Predictive validation against a longitudinal AYA cohort remains open. OPEN
Purpose, anchoring evidence, and stated limitations, each expanded in the sections that follow.
| Purpose | Theory development and decision-support scaffold for AYA HRQoL trajectories and candidate interventions, for example NCCN distress screening and financial navigation. |
|---|---|
| Intended users | Researchers and clinician-scientists in AYA oncology, survivorship, and health-systems modeling. |
| Not for | Individual prognosis or clinical decisions for a specific patient. |
| Population | AYA cancer patients, ages 15–39, diagnosis through about 24 months (extensible). |
| Empirical anchors | AYA HOPE,[1] SURVAYA,[3] SEER survival,[5] EORTC QLQ-C30[15] reference values,[4] and pooled intervention effect sizes including nulls. |
| Key limitations | Predictive validation open; long-term heterogeneity under-dispersed; several parameters flagged for provenance; the population-feedback layer is near-dormant under baseline parameters and activates only under stress; single network, with the psychometric/social distinction left to future work. |
| Reproducibility | MATLAB R2024b, no toolboxes; fixed seeds; one-command figure regeneration. |
| Status | Verified prototype; iterative validation in progress. |
Understanding how HRQoL evolves after an AYA cancer diagnosis is essential to improving survivorship care. Three findings define the burden this work addresses:
Clinical and observational studies capture HRQoL at limited time points and cannot represent these factors as they interact and evolve. Simulation can. Most simulation work, however, couples only one or two paradigms; the difficulty, and the contribution here, is the interfaces between three. This work develops a tri-layer hybrid model and tests whether each layer earns inclusion.
This model explores which mechanisms and interventions plausibly shape AYA HRQoL; it does not predict outcomes for an individual patient. Predictive validation remains open.
The model targets the adolescent and young adult (AYA) population and distinguishes outcomes by diagnosis. The first three figures give the empirical basis from published evidence. The fourth is a model output: cancer type enters the verified simulation only through cited inputs (5-year survival and treatment intensity), and HRQoL emerges by diagnosis. Inputs taken from the project AYA dataset are literature-informed estimates flagged for provenance verification, so these figures are exploratory; comparisons across pediatric and older-adult groups stay empirical, since the simulation spans ages 15-39.
The model comprises three layers, each with a separate state and separate update rules. The layers exchange information through six explicit interfaces, and each interface can be disabled independently, which allows the contribution of each one to be measured.
Hybrid simulation most often nests system dynamics inside agents: each agent
carries an internal set of continuous dynamics, and the agents interact, often over a network.
Population structure and finite shared services are then implicit in the aggregate of
agent states. This model retains per-agent dynamics but also promotes the support
network and a finite-capacity services subsystem to peer layers, coupled through
six explicit, switchable interfaces, so the contribution of each can be isolated and
measured. A fuller treatment is in docs/CONCEPTUAL_FRAMING.md.
| Layer | State it owns | Autonomy |
|---|---|---|
| ABM (patients) | physical and psychological wellbeing, tumor burden, side effects, financial toxicity, adaptation | runs standalone |
| Network (ties) | who supports whom; ties form and dissolve over time | evolves under independent rules |
| System dynamics | referral-queue stock, service capacity, population stress | integrates genuine stock-flow state |
The feedback structure is the essential part of the coupling. The causal loop diagram
below renders it in the convention used by system-dynamics articles: named variables,
causal links carrying a plus or minus polarity, and labeled balancing (B) and
reinforcing (R) loops. A stock-and-flow view of the services layer is in the
diagrams section, and a guide to constructing such interfaces is
in docs/CONSTRUCTING_INTERFACES.md.
Each node is an AYA patient-agent, the same agents as the ABM layer; an edge is a peer support tie between two patients. Support reaches a patient through the single N→A operator, built from two literature-grounded parts. The first is structural emotional support set by network closure: the local clustering coefficient of a patient sets how much emotional and esteem support that position affords, since closure (densely interconnected contacts) predicts emotional and esteem support, while brokerage predicts informational support[59, 60, 61] The term is weighted by tie strength, since strong, multiplex ties carry emotional aid,[62] and saturates with connectedness, the diminishing returns implied by the dose-response between network size and outcomes[6] The second, smaller part is complex-contagion reinforcement: wellbeing lifts only when several neighbors are thriving, so the effect travels along clustered, wide-bridge ties rather than single shortcuts, the form social reinforcement takes for behavioral and psychosocial spread[58, 63] Referral diffusion runs the opposite direction through brokerage: the N→S interface routes help-seeking along non-redundant broker ties, since brokerage carries informational support while closure carries emotional support[59, 60] An isolated patient (degree zero) carries a small penalty.
The simplification is deliberate. Real AYA support systems are heterogeneous and ego-centric, but small: a typical support network holds roughly 2 to 10 members (mean about 6), about 40% family and 60% non-family, alongside 3 to 5 clinicians[70, 6, 20] Each run draws a network size from this distribution (mean 6, SD 2.2, range 2 to 10), so the simulated cohort spans sparsely to well connected patients rather than sharing one fixed degree. The current model collapses family, peer, clinician, navigator, and digital ties into one homogeneous patient-peer tie type. Peer structure is the AYA-distinct, intervention-relevant channel, through peer-mentoring programs,[21] so it is modeled first; a typed support network is identified as future work.
The default initial topology is a Watts-Strogatz small-world graph[55] Real social networks combine high local clustering with short global path lengths, the small-world signature, which neither a regular lattice (clustered but distant) nor an Erdos-Renyi random graph (short but unclustered) reproduces[57] Because emotional support here is driven by network closure and the wellbeing-contagion term is a complex, reinforcement contagion, both of which reward clustering, the choice of topology now changes the outcome[59, 63] Both mechanisms favor more clustering, so the ring lattice, the most clustered graph, scores highest. The small-world topology is used regardless, because it matches the realistic structure of human social networks, high clustering with short paths[55] The comparison below holds mean degree constant across topologies to isolate the effect of network structure.
The verified model uses one homogeneous patient-peer tie. A typed-support extension replaces it with an ego-network of providers for which tie strength and support profile are set by relationship type: family and partners are the strongest emotional sources for AYAs, clinicians carry informational support, and social workers and navigators carry instrumental support[59, 62] Provider nodes have no HRQoL and are colored by type; patients are colored by HRQoL. The tie-type weights are literature-informed estimates flagged for provenance, so this extension is exploratory and is not part of the calibrated core.
Model parameters, the observation layer, and the validation targets are anchored to published evidence and public datasets. The diagram below traces each source to the model component it informs, the table lists what each one contributes, and full citations appear in the references section.
Six categories of evidence, spanning public datasets, longitudinal cohort studies, mechanism and theory literature, validated instruments, care guidelines, and reference models, feed the model components they inform. The map below shows the relative contribution of each category. The breakdown that follows adds the provenance-tier composition, the source counts, and a worked example of how several sources reconcile into model terms.
| Data source | What it provides | Feeds | Ref. |
|---|---|---|---|
| SEER (NCI) | AYA incidence; 5-year relative survival (~86%) | ABM remission; SD population | [5] |
| AYA HOPE (Smith 2013) | Baseline HRQoL; ~20% vulnerable subgroup at diagnosis | ABM initialization | [1] |
| NHANES (CDC) | AYA depression prevalence | ABM psychological baseline | [54] |
| Social-network meta-analysis (Pinquart & Duberstein) | Direction and magnitude of the social-support effect | Network to patient (N→A) | [6] |
| Response-shift theory (Sprangers; Bellizzi) | Adaptation / recalibration mechanism | ABM adaptation | [10][11] |
| EORTC QLQ-C30 (Aaronson) + reference values (Hinz) | Instrument scales; normative values | Measurement layer | [15][4] |
| PROMIS (Siembida); MMQL (Bhatia; Goodman) | AYA-validated HRQoL instruments | Measurement layer | [29][27][28] |
| SURVAYA (Janssen); Husson | Long-term and 24-month HRQoL distributions | Validation targets | [3][2] |
| NCCN AYA guidelines | Distress-screening and financial-navigation care processes | SD scenarios | [30] |
| AYA HRQoL review (Sodergren); SD-in-cancer precedents (Williams; Homer & Hirsch) | Parameter ranges; design precedent | Model structure | [20][37][32] |
| Reference models: Q-PRIMA (Hasgul); CLD (Beaulieu) | Structure and docking comparison | Whole model | [16][17] |
Beyond the data sources above, every model parameter and embedded constant is traced to a data source, a
paper, or an explicit assumption in the provenance register
(docs/PARAMETER_PROVENANCE.md); the model code carries inline
[Cited] / [Derived] / [Assumption] tags that point to it. Values
fall into three tiers.
| Tier | Meaning | Approx. count | Examples |
|---|---|---|---|
| Cited | Value or narrow range taken from a data source or paper | ~14 | AYA age 15–39 [SEER]; 20% vulnerable subgroup [Smith 2013]; ~86% 5-year survival [SEER]; complex-contagion threshold ≥2 [Centola & Macy 2007]; closure to emotional support [Meng 2016] |
| Derived | Calibration value for which the mechanism or range is cited | ~14 | financial-toxicity ceiling at ~55% prevalence [65] and the effect on wellbeing [64]; distress threshold within 19.6–61.6% prevalence [66]; tie formation as networks expand after diagnosis [68]; symptom trajectory [69]; service capacity [67] |
| Assumption | Structural, computational, or calibration choice with no direct empirical anchor | ~22 | tumor kinetics; the wellbeing-equation coefficients; beta_social; alpha_macro;
equal weighting of physical and psychological HRQoL |
The full parameter table, the stock / flow / auxiliary equation listing, and a written justification for every assumption are in the Parameters & equations section below.
About half of the values are calibration or structural assumptions, and several are swept in the sensitivity and stress experiments. The Derived sources were retrieved and checked (author, year, and the cited value or finding confirmed). One parameter is flagged as weakest-supported: the tie-dissolution rate rests on qualitative withdrawal reports,[31] whereas the strongest longitudinal evidence finds networks net-expand after diagnosis,[68] a pattern the model in fact reproduces. The equal-weight composite is a known simplification relative to the regression-weighted SF-12 summary scores.
The model is specified in the stock / flow / auxiliary form used by published system-dynamics models, so the structure can be read and audited directly. The temporal design is diagnosis-anchored (the clock starts at diagnosis) over a 24-month horizon, with fast patient dynamics integrated every half day and the service queue and network restructuring resolved monthly. Every parameter traces to a source or a flagged assumption, and each assumption carries a written justification. A workbook in a four-sheet layout available: AYA_parameters_and_equations.xlsx.
| Setting | Value | Unit | Note |
|---|---|---|---|
| Initial time | 0 | day | Anchored at diagnosis / cohort enrollment |
| Final time | 730 | day | 24-month horizon |
| Time step (patient layer) | 0.5 | day | Explicit Euler step for the agent-based layer |
| Structural cadence | 30 | day | Monthly service queue and network restructuring |
| Treatment window | 30 to 120 | day | Active-treatment block; nadir near month 4 |
| Population | 100 | agents | Inference at the run level, not the agent |
The diagnosis-anchored, population-level, hybrid design departs deliberately from an
event-anchored single-patient pure-SD model such as Q-PRIMA
(Hasgul 2024)[16] Full discussion and the
complete equation listing are in docs/MODEL_TIMELINE_AND_EQUATIONS.md.
| Dimension | This model | Q-PRIMA (Hasgul 2024) |
|---|---|---|
| Paradigm | Hybrid: ABM + network + SD | Pure system dynamics |
| Time anchor | Diagnosis (t = 0) | Infusion event (t = 0) |
| Time span | 0 to +730 days (24 months) | −60 to +180 days (~8 months) |
| Unit of analysis | 100 heterogeneous agents | 1 representative patient |
| Stocks | 1 service stock + per-agent states + network | 14 continuous stocks |
| Feedback | 6 switchable cross-layer interfaces | 7 reinforcing + 2 balancing loops |
ABM patient layer NET network layer SD services layer
| Layer | Stock | Units | Integral form |
|---|---|---|---|
| ABM | Physical wellbeing P | Dmnl [0.2,1] | ∫ (P adjustment) dt + P(0) |
| ABM | Psychological wellbeing Ψ | Dmnl [0.2,1] | ∫ (Ψ adjustment) dt + Ψ(0) |
| ABM | Tumor burden | Dmnl [0.001,1] | ∫ (growth − removal) dt + Tumor(0) |
| ABM | Side-effect severity SE | Dmnl [0,1] | ∫ (development − removal) dt |
| ABM | Financial toxicity Fin | Dmnl [0,1] | ∫ (accrual) dt |
| ABM | Adaptation Adapt | Dmnl [0,1] | ∫ (adaptation rate) dt |
| NET | Support ties A ij | Dmnl {0,1} | formation − dissolution (monthly) |
| NET | Tie weights W ij | Dmnl [0,1] | assigned on formation |
| SD | Referral queue Wq | persons | ∫ (demand − served) dt |
Derived (not integrated): HRQoL
Q = (P + Ψ)/2; closure Ci (recomputed monthly);
in_remission (a latch).
| Layer | Flow | Cadence | Equation |
|---|---|---|---|
| ABM | tumor growth | 0.5 d | g · Tumor · (1 − Tumor) |
| ABM | tumor removal | 0.5 d | treated: tx_resp · Tumor; remission: remission_decay · Tumor |
| ABM | SE development | 0.5 d | in treatment: se_dev_rate · (1 − SE) |
| ABM | SE removal | 0.5 d | se_rem_rate · SE |
| ABM | financial accrual | 0.5 d | fin_accrual · [day > tx_start] · (fin_cap − Fin) |
| ABM | adaptation rate | 0.5 d | adapt_rate · (1 − Adapt) |
| ABM | P adjustment | 0.5 d | (target_P − P) / adjustT |
| ABM | Ψ adjustment | 0.5 d | (target_Ψ − Ψ) / 21 |
| SD | referral demand (inflow) | 30 d | see auxiliaries (SW_AS, SW_NS) |
| SD | served (outflow) | 30 d | min(Wq, Cpsy) |
| NET | tie formation | 30 d | round(formation_rate · served) (SW_SN) |
| NET | tie dissolution | 30 d | prob = dissolve_rate · 0.5 · (withdrawal_i + withdrawal_j) (SW_AN) |
| Layer / interface | Auxiliary | Equation |
|---|---|---|
| ABM | HRQoL Q | (P + Ψ) / 2 |
| ABM | target_P | clip(0.90 − 0.5·Tumor − 0.4·SE + ben_phys, 0, 1) |
| ABM | target_Ψ | clip(0.75 + support + ben_psy − stress − 0.30·SE − eff_chronic, 0, 1) |
| ABM | eff_chronic | (identity_pen + fertility_pen + fin_weight·Fin) · (1 − adapt_efficacy·Adapt) |
| NET N→A | structural support | beta_social · closure_gain · conn |
| NET N→A | connectedness conn | 1 − exp(−strength / support_scale) |
| NET N→A | closure gain | (1 − closure_share) + closure_share · (Ci / clustering_ref) |
| NET N→A | contagion | beta_social · cont_w · logistic((n_supp − 2)/reinforce_width) |
| SD S→A | service-mediated stress | macro_stressor · (1 − min(1, service_avail)) |
| SD | macro stressor | alpha_macro · max(0, poor_prev − 0.1) |
| ABM A→S | self-referral demand | sum_i [Q_i < distress_threshold] · self_referral_rate |
| NET N→S | brokerage ES (Burt) | deg − 2·tri / max(deg, 1) |
| NET N→S | brokered demand | sum_i distressed_i · (0.5 + 0.5·reach_i) |
| SD | service availability | served / max(demand, 1) |
| ABM A→N | withdrawal | max(0, withdraw_thresh − Ψ) |
| SD S→N | served → tie formation | round(formation_rate · served) |
The six switchable interfaces are the cross-layer auxiliaries in bold: N→A support, S→A stress, A→S demand, N→S brokerage, S→N formation, A→N dissolution. Setting a switch to 0 removes exactly one of these, which is the basis of the ablation ladder.
Cited value or narrow range from a source Derived mechanism/range cited, value calibrated Assumption no direct anchor; each value carries a written justification
| Parameter | Value | Tier | Source / basis |
|---|---|---|---|
age_range | [15, 39] | Cited | Standard AYA definition (SEER / NCI) |
T (horizon) | 730 d | Derived | 24-month follow-up (Smith 2013; Husson 2017) |
| vulnerable fraction | 0.20 | Cited | Lowest baseline HRQoL quartile (Smith 2013) |
responder_fraction | 0.86 | Cited | SEER AYA 5-year relative survival ~86% |
intervention_effect | 0.13 | Cited | Pooled AYA psychosocial intervention SMD |
k_neighbors | 2–10 (mean 6) | Cited | AYA support-network size, drawn per run (Cloyes 2022) |
p_rewire | 0.15 | Cited | Small-world regime (Watts & Strogatz 1998) |
reinforce_count | 2 | Cited | Complex contagion ≥2 contacts (Centola & Macy 2007) |
adapt_efficacy | 0.60 | Derived | A-priori from benefit-finding theory; swept (Bellizzi 2012) |
closure_share | 0.5 | Derived | Closure predicts emotional support (Meng 2016) |
formation_rate | 0.5 | Derived | Networks expand after diagnosis (Lehto 2024) |
fin_weight | 0.20 | Derived | Financial toxicity worsens symptoms (Thom & Benedict 2019) |
distress_threshold | 0.5 | Derived | Distress prevalence band (Kirk 2021; NCCN) |
psy_capacity (Cpsy) | 8 / mo | Derived | Finite, variable psycho-oncology staffing (Melton 2020) |
Q = (P+Ψ)/2 | equal weight | Assumption | Same HRQoL definition as Q-PRIMA; flagged simplification |
tumor_growth_base | 0.045 | Assumption | Logistic form as in Q-PRIMA; rate calibrated |
beta_social | 0.04 | Assumption | Dose-response (Pinquart 2010); calibrated to ablation; swept |
alpha_macro | 0.4 | Assumption | Latent-amplifier gain; swept in stress scenarios |
Full table (~50 values) and the inline
prov: code tags are in docs/PARAMETER_PROVENANCE.md.
An assumption marks a value with no source for the exact number. Each one is justified in writing and classified by the type of support behind it. Several wellbeing-core choices inherit structure directly from the published Q-PRIMA model[16]
| Parameter | Category | Basis |
|---|---|---|
dt = 0.5 d | Numerical / Model precedent | Explicit Euler, as in Q-PRIMA; step well below the fastest time constant |
N = 100 | Computational | Monte Carlo sample; inference at run level, seed-averaged |
treated_fraction = 0.85 | Literature mechanism | Most AYA cancers treated with curative intent; value illustrative |
tx_start/tx_duration | Pattern-oriented | ~3-month block placed so the nadir lands near month 4 (Husson 2017) |
tumor_growth_base = 0.045 | Model precedent / Pattern-oriented | Logistic form as in Q-PRIMA; rate calibrated with tx_resp |
tx_resp = 0.06 | Pattern-oriented | Set with responder_fraction 0.86 so ~86% reach remission |
Q = (P+Ψ)/2 | Model precedent | Identical HRQoL definition published in Q-PRIMA; equal weighting flagged |
| target-seeking forms, 21-d lag | Model precedent / Lit. mechanism | Homeostatic restoring (gap / adjustment time) as in Q-PRIMA |
target_P, target_Ψ coeffs | Pattern-oriented / Lit. mechanism | Calibrated to SF-12 PCS/MCS anchors; emotional deficit (Smith 2013) |
fin_accrual = 0.02 | Lit. mechanism / Pattern-oriented | Financial toxicity accrues over treatment (Thom 2019) |
beta_social = 0.04 | Lit. mechanism / Swept | Support dose-response (Pinquart 2010); calibrated to ablation; swept |
W tie weights | Flagged limitation | Random placeholder; should be type-based (Wellman & Wortley 1990) |
withdraw_thresh = 0.55 | Pattern-oriented | Just above the 0.5 distress threshold |
alpha_macro = 0.4 | Swept / Pattern-oriented | Latent amplifier; swept in stress scenarios |
| poor-fraction trigger = 0.1 | Literature mechanism | 10% floor below cancer distress prevalence 20–50% (Kirk 2021) |
Pattern-oriented means a value is not free
but jointly constrained with others to reproduce several observed patterns at once
(baseline distribution, nadir timing, recovery plateau, persistent tail), the standard
defense in pattern-oriented modeling[7]
Swept parameters carry a further protection: the conclusions hold across a range
of values rather than resting on one tuned number. Full write-up:
docs/ASSUMPTION_JUSTIFICATIONS.md.
The model is implemented in plain MATLAB (R2024b, no toolboxes). Four excerpts show the design decisions that keep the layers separable and the validation sound.
1. Each interface is a binary switch, so the ablation experiment can turn any one of
them off in isolation (coupling_switches.m).
% {name, abm_on, AS, SA, AN, NA, SN, NS, description} 'C1', true, 0,0,0,0,0,0, 'ABM-only (heterogeneity baseline)' 'C3', true, 0,0,1,1,0,0, 'ABM + Network' 'C4', true, 1,1,1,1,1,1, 'Full model (all six interfaces on)'
2. Social support reaches a patient through exactly one channel, so disabling that
channel removes the effect completely (AYA_MVP_Coupled.m).
% N->A : social support (THE ONLY support channel; no leak) support = zeros(N,1); if sw.SW_NA deg = sum(A,2); WA = A .* W; support = baseline_sup + contagion + buffer; % connection, contagion, buffering support(deg==0) = -0.01; % isolation penalty end
3. System dynamics holds a real integrated stock, a referral queue, rather than a simple count of agents in a category.
Wq = Wq + demand; % inflow: referrals from distressed agents served = min(Wq, Cpsy); % outflow bounded by service capacity Wq = max(0, Wq - served); service_avail = served / max(demand,1); % feeds back to patients via SW_SA
4. Verification: turning a coupling off must change the outcome, proving no hidden
proxy leaks (verify_interfaces.m)[9]
cOff = cOn; cOff.SW_NA = false;
v9 = (run_mean(cOn,1:15) - run_mean(cOff,1:15)) > 1e-3; % PASS = separable
Three UML views document the implementation at the level a reader needs to reproduce or audit it: an
activity diagram for control flow within one run, a sequence diagram for the order in which the six
interfaces fire over a monthly cycle, and a component diagram for the static structure of the code. A
fourth view, a stock-and-flow diagram, documents the internal mechanics of the system-dynamics layer.
All are rendered from editable sources in
website/diagrams/ (provided as both .drawio and .xml) and use a
fixed layer color key: blue for the ABM (patient) layer, green for the network (support) layer, and
orange for the system-dynamics (services) layer.
docs/ACTIVITY_DIAGRAM_WALKTHROUGH.md
AYA_MVP_Coupled engine holds the
three layer sub-components and is configured by coupling_switches, driven by the experiment
and verification harness, observed through the measurement layer, and read by the visualization code.
coupling_switches configures the engine and the experiment harness drives it, which keeps experiment definitions out of the model codefigure_code) depends only on engine outputs, which is why every site figure regenerates from one master script without touching the model
The model was run over 20 simulation seeds and a 24-month horizon. Inference operates at the level of the simulation run rather than the individual agent.
docs/READING_THE_RESULTS.md.
The animations are rendered directly from a single full-model run (cell C4, all six interfaces on, seed 42) over the 24-month horizon. The first depicts the whole simulation; the rest isolate each layer and the interfaces.
With sparse, non-equivalent data, a model like this cannot be validated the way a prediction model is. The argument separates four claims and states which are established and which remain open.
An early held-out instrument test failed on emotional functioning, passing 1 of 4 targets. The failure was diagnostic: it located a missing response-shift adaptation mechanism[10, 11] Adding that one theory-grounded mechanism brought the test to 4 of 4 across a wide parameter range. Because the mechanism was added in response to the failure, those bands now serve as development targets rather than independent validation. Genuine predictive validation requires new external data.
Full argument, all objections, and references:
MODEL_CREDIBILITY_AND_VALIDATION.md.
The exercise below is comparative validation by docking: the novel hybrid is placed alongside pre-existing system-dynamics and agent-based models from the AYA HRQoL literature and reduced to the scope of those models. It is a confidence check, not a change to the model. The model code and every result elsewhere on this page are unchanged; the benchmark only reads the model and compares it.
Five arms were run over the same diagnosis-anchored 24-month horizon, each at a separately documented initialization: an SD-only model (with a common-initialization variant), an ABM-only ablation, an older ABM + static-network hybrid, and the full hybrid. Two literature models are structural comparators only: Q-PRIMA (the published implementation is incomplete and will not run as shipped) and Beaulieu (2022), which is a causal loop diagram rather than a runnable model.
Where this sits in the field. A 2025 PRISMA systematic review of system-dynamics cancer models (Chen et al., Journal of Medical Economics) identified sixteen studies. All are single-paradigm system dynamics, most addressing screening, prevention, or treatment operations at the population level, and produce cases, deaths, quality-adjusted life years, and costs rather than an individual health-related quality-of-life trajectory. None couples an agent-based patient layer, an evolving support network, and a finite-service subsystem, and none tracks HRQoL across survivorship. This architecture addresses that gap. Because those models compute different quantities, they serve as structural comparators only; the graph above does not plot them as additional lines.
| Model | Time-avg HRQoL | Distance from empirical anchor 0.6375 |
|---|---|---|
| SD-only (documented init 0.85) | 0.892 | 39.9% |
| SD-only (common init) | 0.889 | 39.5% |
| ABM + static-network | 0.835 | 30.9% |
| ABM-only (C1) | 0.668 | 4.8% |
| Full hybrid (novel, C4) | 0.683 | 7.2% |
benchmark_comparison/mat/adjacency_over_time.mat.Reproducible as a standalone folder: benchmark_comparison/ with
run_benchmark(20). Details in benchmark_comparison/README.md, the anchor
trace in ANCHOR_RECONCILIATION.md, and the structural comparison in
tables/structural_docking.csv.
The model is a verified prototype with an open predictive-validation claim and several scoped limitations. The priorities below would close those gaps, ordered from the most decisive (external validation) to incremental refinements.
A model of this scope needs data and domain expertise that no single project holds. The project seeks:
The figure traces the studies and datasets this project already relies on (due diligence, each tied to the parameter-provenance register) and identifies the one dataset requested to close the open validation question: individual-level EORTC QLQ-C30 longitudinal data in AYA patients. An EORTC data-request has been placed to compare individual-level, longitudinal quality-of-life data against the tri-layer model.
References grounding the parameters, instruments, methodology, and validation of the model, drawn from the project literature review and the source papers used to build the model.
AYA cancer HRQoL: field, outcomes, and policy
HRQoL measurement instruments and care guidelines
Social, psychological, and survivorship mechanisms
System-dynamics and hybrid simulation of cancer and health
Agent-based and computational oncology
Simulation verification and validation methodology
Network science and social contagion
Parameter-provenance sources (verified)
Public datasets