---
title: "Comparing Observation and Coiling for Unruptured Intracranial Aneurysms in Octogenarians"
id: "plos-one-15-observation-versus-coiling-for-unruptured-intracranial-aneurysms-in"
canonical_url: "https://medichelpline.com/clinical-feed/plos-one-15-observation-versus-coiling-for-unruptured-intracranial-aneurysms-in"
content_type: "clinical_feed_article"
specialty: "Neurology"
source_name: "PLOS ONE (Medicine)"
source_url: "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0357374"
published_at: "2026-09-01T14:00:00.000Z"
evidence_level: "Journal Feed"
license: "CC-BY-NC-4.0 / Informational Use"
---
# Comparing Observation and Coiling for Unruptured Intracranial Aneurysms in Octogenarians
## Provenance & Clinical Metadata
- **Canonical URL:** https://medichelpline.com/clinical-feed/plos-one-15-observation-versus-coiling-for-unruptured-intracranial-aneurysms-in
- **Specialty:** [Neurology](https://medichelpline.com/clinical-feed/neurology.md)
- **Primary Source:** PLOS ONE (Medicine)
- **Source URL:** [Original Journal Publication](https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0357374)
- **Published At:** 2026-09-01T14:00:00.000Z
- **Evidence Rating:** Journal Feed
## Executive GIST (TL;DR)
- This study evaluates unruptured intracranial aneurysms (UIAs) in patients aged 80+ using a **Markov decision model**. - It compares **observation** versus **endovascular coiling**, incorporating various complications and mortality risks. - The **primary outcome** assessed was the cumulative incidence of aneurysm-related events across different age panels (80-90 years). - Results showed that in many scenarios, **observation** favored better outcomes especially in older age groups, whereas **coiling** was favored in select younger cohorts and specific demographics. - Structural sensitivity analyses highlighted the impact of treatment-risk estimates and post-treatment rupture risks on model outcomes, emphasizing the need for careful endpoint definitions. - The findings do not provide direct treatment recommendations but inform clinical decision-making regarding UIAs in elderly patients. - The analysis adds to the **octogenarian-focused** evidence base, which remains heterogeneous and requires cautious interpretation when considering treatment options for UIAs.
## Clinical Analysis & Structured Key Points
Observation versus coiling for unruptured intracranial aneurysms in octogenarians: A decision-analytic modeling study | PLOS One Browse Subject Areas ? Click through the PLOS taxonomy to find articles in your field. For more information about PLOS Subject Areas, click here . Article Authors Metrics Comments Media Coverage Peer Review Reader Comments Figures Figures Abstract Management of unruptured intracranial aneurysms in patients aged 80 years and older remains uncertain because treatment morbidity, rupture risk, post-rupture outcome, and competing mortality interact. We constructed a competing-risk Markov decision model comparing observation with endovascular coiling in Korean patients at index ages 80, 85, and 90 years; microsurgical clipping and stent-assisted coiling or flow diversion served as additional scenarios. The primary outcome was the undiscounted lifetime cumulative incidence of aneurysm- or treatment-attributable events—treatment morbidity, treatment death, rupture death, or rupture poor outcome—counted as a first-event composite in which all four components carry equal weight regardless of severity, duration, or reversibility. Periprocedural coiling morbidity and mortality were anchored to a U.S. National Inpatient Sample analysis from 2001–2008, and residual post-treatment rupture risk was fixed at 10% of the natural-history rate. Under this original endpoint, median differences favored observation in every age-90 panel and in all male panels at age ≥ 85, and favored coiling in selected age-80 panels and selected age-85 female panels; the probability that coiling was favored ranged from 0.000 to 0.984. A 24-panel, 3%-discounted severity-weighted quality-adjusted analysis was added, together with structural sensitivities for treatment-morbidity recovery, residual rupture risk, and coiling morbidity. Across 30 endpoint-direction comparisons, with each Ma panel mapped to its two legacy marginals, 21 were concordant; all nine discordant comparisons shifted from observation toward coiling, and eight had 95% quality-adjusted uncertainty intervals spanning zero. Median-direction changes under the executed structural sensitivities were confined to modified Rankin Scale-based panels with reference quality-adjusted differences near zero and uncertainty intervals spanning zero. Modeled treatment preference was therefore conditional on endpoint definition and key structural assumptions, including historical treatment-risk estimates and uncalibrated residual post-treatment rupture risk; these model outputs do not establish treatment recommendations for individual patients. Citation: Yoo HD, Kim JG, Chung SY (2026) Observation versus coiling for unruptured intracranial aneurysms in octogenarians: A decision-analytic modeling study. PLoS One 21(9): e0357374. https://doi.org/10.1371/journal.pone.0357374 Editor: Mario Tortora, Università degli Studi di Napoli Federico II: Universita degli Studi di Napoli Federico II, ITALY Received: June 17, 2026; Accepted: August 17, 2026; Published: September 1, 2026 Copyright: © 2026 Yoo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability: All data and code necessary to reproduce the model outputs reported in this study are publicly available in the Open Science Framework project associated with this study (OSF: https://osf.io/vnzrt/ ). The OSF project includes the model code, parameter table, cumulative PSA output summaries, figure-generation scripts, targeted evidence synthesis verification materials, protocol amendments, and supporting output files. Funding: The author(s) received no specific funding for this work. Competing interests: The authors have declared that no competing interests exist. Introduction The detection of unruptured intracranial aneurysms (UIA) in elderly patients has increased substantially over the past two decades, driven by broader use of cross-sectional imaging and population aging in countries with advanced imaging access. In Korea, where the population aged over 80 years is projected to continue expanding, clinicians increasingly face the question of whether preventive treatment confers net benefit over observation for an incidentally detected UIA in an octogenarian patient. The decision is difficult because the relevant competing risks — periprocedural treatment complications, residual lifetime rupture risk, and competing mortality from non-aneurysm causes — change rapidly with advancing age, while the published evidence base for outcomes in the ≥ 80 cohort remains limited compared with that for younger UIA cohorts. Several recent cohort studies have begun to address the octogenarian-specific evidence gap, but the available evidence is heterogeneous in important ways. Brinjikji and colleagues’ analysis of the National Inpatient Sample [ 1 ] provided periprocedural complication estimates for elderly clipping and coiling cohorts, but reported short-term in-hospital outcomes rather than lifetime trajectories. Single-center treated aneurysmal subarachnoid hemorrhage (aSAH) cohorts [ 2 ] and disposition-based proxy analyses of Medicare claims [ 3 ] provide partial information, but use heterogeneous outcome cutoffs (modified Rankin Scale (mRS) > 2, institutional discharge proxy, mRS ≥ 3, mortality only) and grade-mix definitions (all-grade vs poor-grade World Federation of Neurosurgical Societies (WFNS) IV-V). The single-center poor-grade Goldberg cohort [ 4 ] provides the closest match to the protocol-primary mRS 4–6 cutoff but is limited to WFNS IV-V patients with predominantly conservative management. The recent Ma cohort [ 5 ] reports all-grade ≥ 80 outcomes at longer follow-up but at broader outcome cutoffs. No single published cohort simultaneously satisfies all of the criteria — all-grade ≥ 80, mRS 4–6 cutoff, long-term follow-up, large N — that would constitute the protocol-primary target for a definitive octogenarian aSAH outcome anchor. Decision-analytic modeling can integrate periprocedural, natural-history, and post-rupture outcome evidence into a unified lifetime framework and quantify the conditions under which preventive treatment may confer net benefit over observation. A strength of this approach is that it makes the dependence of model output on input parameters explicit and allows model-inferred preference to be tested across reasonable parameter perturbations. A corresponding limitation is that the model inherits the heterogeneity of its source evidence; in the octogenarian UIA setting, this heterogeneity is dominated by the post-rupture outcome anchor mismatch described above. Because the available outcome evidence is heterogeneous, such a model must report results across plausible outcome scenarios rather than rely on a single assumption, so that the clinical robustness of any inferred preference can be judged. We report results in parallel across five heterogeneous post-rupture outcome scenarios. Continuous per-panel differences, uncertainty intervals, and preference probabilities are presented as the primary outputs, with the clinician-interpretable threshold-zone classification retained as a secondary summary. Parameters with weaker evidentiary support—including the SAC/FD proxy and the unanchored vascular access complexity stress test—are reported transparently, and the analysis examines how the endpoint definition and the choice among heterogeneous post-rupture outcome anchors influence the model-inferred preference. Following peer review, we additionally implemented a 24-panel severity-weighted quality-adjusted-life-year analysis, together with structural sensitivity analyses of recovery from treatment morbidity, residual post-treatment rupture risk, and the periprocedural coiling-morbidity anchor, specified in Protocol Amendment v1.5 before any extension results were generated. Materials and methods Study design and decision question We constructed a Markov decision-analytic model evaluating observation versus preventive treatment for a clinically detected UIA in Korean patients aged 80 years and older. The perspective was patient-clinical. The original analysis reported an unweighted cumulative-incidence endpoint and excluded utility and cost extensions per protocol. In response to peer review, a severity-weighted extension was implemented under a pre-execution amendment registered before any extension result was generated (Protocol Amendment v1.5), and quality-adjusted life-years are reported alongside the original endpoint rather than in place of it. Cost was not modeled. The model was developed and reported following established recommendations for decision-analytic modeling [ 6 – 11 ]. The primary comparator was observation versus coiling. The main PSA outputs were the continuous per-panel difference in lifetime cumulative incidence between observation and coiling with its uncertainty interval, and the probability that coiling produced the lower incidence; a threshold-zone classification using a ± 0.01 equipoise band is reported as a secondary summary. Two additional treatment strategies were modeled in parallel: microsurgical clipping and SAC/FD. Clipping was included because it remains a clinical alternative in some elderly UIA cohorts despite its higher morbidity profile in the available evidence base. SAC/FD was modeled as a scenario block representing complex-anatomy aneurysms for which simple coiling is not feasible. Because TES identified no direct ≥ 80 clinical-burden evidence, the SAC/FD scenario was built as a proxy that borrowed the coiling mean with a downweighted effective sample size (ESS), as described below under Parameters and sources and Outcome scenarios. The time horizon was lifetime (terminating at age 100, with a residual five-year computational margin); the base-case discount rate was 0%, with a 3% discounted cumulative-incidence analysis as the key sensitivity. Three index ages (80, 85, and 90 years) and two sexes (male and female) defined six demographic panels. Crossing these with five post-rupture outcome scenarios (Scenarios A, B, C, E, and F, defined below under Outcome scenarios) yielded 30 base-case panels, each evaluated by probabilistic sensitivity analysis at 10,000 iterations. The setting was Korean clinical practice, with competing mortality drawn from the 2024 Korean Statistical Information Service (KOSIS) life table [ 12 ] (see Parameters and sources below); the framework is country-portable by substituting the competing-mortality input. Model structure The Markov model consisted of a well-survival state and five mutually exclusive outcome states defined in the prespecified parameter specification. The five outcome states were (1) treatment death, (2) treatment morbidity without death, (3) rupture death, (4) rupture poor outcome without death, and (5) other-cause death. The definition of nonfatal rupture poor outcome was scenario-specific, because the poor-outcome cutoff varied across the five outcome scenarios described below. States 1, 3, and 5 were absorbing. States 2 and 4 represented living-with-disability states that could transition to other-cause death through competing mortality but did not generate additional aneurysm-related events. All cohorts began in state 0 (well-survival). Treatment arms partially exited state 0 in cycle 0 through periprocedural events and could exit progressively in subsequent cycles through residual rupture or competing mortality. Fig 1 shows the model state diagram and the hierarchical cycle ordering. Download: PNG larger image TIFF original image Fig 1. Markov state-transition model schematic. Schematic of the four-strategy Markov decision-analytic model. Each strategy (Observation, Microsurgical Clipping, Endovascular Coiling, and Stent-Assisted Coiling or Flow Diversion as a proxy scenario) uses the same six health states—well-survival, treatment morbidity, treatment death, rupture poor outcome, rupture death, and other-cause death—and the same competing risks, as applicable, including periprocedural events, post-treatment or natural-history rupture, and Korean life-table mortality. Strategy-specific transition probabilities are drawn from the distributions in Table 1 . The cycle length is one year, and the lifetime horizon uses the KOSIS terminal age with a residual five-year computational margin. The hierarchical within-cycle event ordering is described under Model structure. https://doi.org/10.1371/journal.pone.0357374.g001 Each annual cycle followed a prespecified hierarchical event ordering. Step 1: in the treatment arms, cycle 0 represented the treatment cycle, during which the cohort faced treatment mortality and treatment morbidity. Step 2: the observation arm faced the annual natural-history rupture probability in every cycle, anchored to the UCAS-derived elderly cohort of Hishikawa et al. [ 13 ]; in the treatment arms, the residual rupture probability was fixed at 10% of that rate. Step 3: rupture events were partitioned by case fatality and by the scenario-specific probability of poor outcome conditional on rupture, with ruptures followed by good recovery returning to well-survival. Step 4: the residual cohort that had not experienced an aneurysm- or treatment-attributable event in that cycle faced the KOSIS competing-mortality probability. Living cohorts in the treatment-morbidity and rupture-poor-outcome states remained subject to competing mortality but were not exposed to further aneurysm risk. The primary outcome was the undiscounted lifetime cumulative incidence of entry into any of four mutually exclusive aneurysm- or treatment-attributable event states: treatment morbidity, treatment death, rupture death, or rupture poor outcome. This endpoint was an unweighted first-event metric: because a cohort member exited the well-survival state after the first such event and could not re-enter it, each member could experience at most one counted aneurysm- or treatment-attributable event. The cumulative incidence is therefore bounded by 1 and is interpretable as the probability of ever experiencing an aneurysm- or treatment-attributable adverse event over the remaining lifetime. Events were accumulated as they occurred in each annual cycle and retained thereafter, including after any subsequent transition to competing other-cause mortality. This cumulative-incidence definition was adopted before journal submission, replacing an earlier terminal-state occupancy metric that did not retain nonfatal disability events after competing-mortality transitions and therefore approximated cumulative aneurysm/treatment mortality rather than an unweighted first-event cumulative-incidence metric. The principal comparison was observation versus coiling. For each panel and PSA iteration, the cumulative-incidence difference was computed as observation minus coiling. Coiling was classified as favored when this difference exceeded the + 0.01 equipoise band, observation was classified as favored when it was below −0.01, and intermediate differences were classified as equipoise. Parameters and sources All anchored parameters and their primary sources are summarized in Table 1 . Parameters were sourced through TES and verified against full text when available, or against abstract or first-page text when full text could not be obtained. Verification status and source-specific caveats are documented in the TES verification record available in the reviewer-accessible OSF materials. Beta distributions were specified by mean and ESS using the conventional method-of-moments approach (Beta α = mean × ESS; Beta β = (1 − mean) × ESS). Lognormal distributions were specified by their log-median and log-scale dispersion; implemented percentile intervals were reported when they differed from nominal bounds. KOSIS competing mortality was treated deterministically in the base case. Download: PNG larger image TIFF original image Table 1. Model parameter specification. https://doi.org/10.1371/journal.pone.0357374.t001 Three caveats apply to the parameter set in Table 1 . First, the SAC/FD morbidity and mortality means were borrowed from the coiling anchor because no direct ≥ 80 SAC/FD clinical-burden evidence was identified during TES verification. These entries are therefore proxy values, and their ESS was downweighted to 50 in the base case and 100 in sensitivity to reflect the absence of direct evidence. Second, the VAC modifier could not be directly anchored to available literature for the ≥ 80 cohort during TES verification. The VAC-High scenario therefore functions as an unanchored stress test rather than a calibrated effect size, and any inference drawn from VAC-High runs must be qualified accordingly. Third, KOSIS qx was treated deterministically in the base case. The prespecified parameter specification documents this convention; the alternative life-table-sampling sensitivity has not been executed in the present analysis. Targeted evidence synthesis Parameter sources were identified through TES rather than a full systematic review. Candidate studies were identified through structured PubMed and Embase searches for cohorts aged 80 years and older. Extracted values were verified against the primary source, using full text when available and abstract or first-page text otherwise; verification status was explicitly downgraded whenever full text could not be obtained. The candidate worklist and verification record are available in the OSF archive and provide an audit trail for each anchor parameter. Three operational decisions in the TES workflow merit specific disclosure. First, the Goldberg anchor [ 4 ] was originally extracted as a Scenario C value of 0.90 mRS 4–6 “at discharge” in an earlier model version but was re-verified during subsequent model development. The correct timepoint is 6–12 month follow-up, as documented in the re-verification addendum in the reviewer-accessible OSF materials, and the final Scenario C anchor reflects this correction. The at-discharge value (20/20 = 1.00) was retained as a deterministic acute-decision sensitivity (Scenario C_acute), not as a Beta prior, because 20/20 events yield a degenerate Beta. Second, the originally planned Dumont 2014 anchor for VAC could not be obtained during TES verification despite multiple search and citation-tracking attempts. A predefined fallback hierarchy was therefore applied, and VAC was demoted from a quantitatively anchored parameter to an unanchored stress-test scenario. Third, the SAC/FD scenario block was constructed as a proxy after TES verification identified no peer-reviewed direct ≥ 80 SAC/FD clinical-burden evidence. Post-rupture outcome scenarios The post-rupture outcome distribution after aSAH in octogenarians is highly heterogeneous across the published evidence base; anchor sources differ in outcome cutoff (mRS 4–6 versus mRS ≥ 3 versus mortality only), case-mix grade (poor-grade only versus all-grade), and timepoint of outcome ascertainment (at discharge versus 6–12 month follow-up). Rather than averaging over these heterogeneous anchors, we treated each as a separate scenario and reported all scenarios in parallel. This makes explicit the dependence of the model-inferred preference on the assumed outcome distribution and preserves structural uncertainty across non-exchangeable outcome definitions. Five outcome scenarios entered the base case as Beta-distributed PSA priors: Scenario A (Catapano et al. [ 2 ]): treated octogenarian aSAH cohort mRS > 2 = 39/43 = 90.7%, Beta(0.907, ESS = 43). Cutoff is mRS 3–6 (broader than mRS 4–6); treated cohort only. Scenario B (Dasenbrock et al. [ 3 ]): Medicare ≥ 80 aSAH disposition proxy (died/hospice + institutional discharge) = 64%, Beta(0.64, ESS = 1298). Not mRS; disposition-based proxy for post-rupture poor outcome under all-grad
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