NHOS Children's Symptoms Checker™ A Client-Side Naive Bayes Pediatric Triage Aid with a 50-Level Triage Severity Score, 3,392-Condition Library, 17-System Coverage, Integrated Interactive Visualization, and a Nine-Module Complete Clinical Upgrade Pack Technical Research White Paper — Architecture, Methodology, Validation Framework, Reproducibility Specification, and Complete Clinical Upgrade Manifest

Abstract

The NHOS Children's Symptoms Checker™ (NHOS-CSC) is a fully client-side pediatric symptom-triage artifact released as informational research software. It is designed to answer a narrow methodological research question: can a compact, fully inspectable, browser-local pediatric symptom-triage tool expose its assumptions and computational pathway sufficiently for independent audit, replication, and critique — while still delivering a graded, safety-first triage recommendation? This release (v4.0.0) documents the artifact, its nine-module clinical upgrade pack, and its proposed validation framework. What the artifact is NHOS-CSC is architected for fully client-side execution: all inference runs locally within the client runtime, with no server-side inference, no hosted API dependency, and no embedded analytics. Its knowledge base — 3,392 unique pediatric conditions and 591 clinically weighted symptom attributes across 17 body systems — is parsed and indexed at application startup. Its inference engine implements a Naive Bayes classifier in log-space with age-aware condition filtering, explicit negative-evidence handling, a small co-occurrence adjustment, and posterior normalization. Output is a discrete 50-level Triage Severity Score (0–49) mapped to six clinically meaningful care bands: Self-Care, Routine, Soon, Urgent, Emergency, and Emergency-Ambulance. A mandatory 19-question red-flag screen intercepts life-threatening presentations before any statistical inference occurs. What is new in v4.0.0 — the Complete Clinical Upgrade Pack Version 4.0.0 introduces a nine-module Complete Clinical Upgrade Pack composed through an additive composition layer that wraps four well-defined core extension points without modifying the underlying inference, scoring, or knowledge-base modules. Zero lines of the core application are modified. The upgrade is fully reversible by removing a single add-on layer and is fully configurable through a single public configuration object exposing 13 documented tuning parameters. The nine modules are: Pediatric Vitals Interpretation Engine — age-banded physiological reference ranges across six pediatric cohorts (neonate, infant, toddler, preschool, school-age, adolescent) for heart rate, respiratory rate, systolic blood pressure, temperature, and peripheral oxygen saturation. Critical vitals readings escalate the triage score through hard constraints. Expanded Red-Flag Detection — the mandatory pre-inference safety screen expands from 9 to 19 binary questions, adding bulging fontanelle, petechiae, stridor, lethargy, poor neonatal feeding, toxic appearance, bilious vomiting, bloody stool, active seizure, and purpura. Developmental Milestone Reference — 16 age-matched milestone bands from 1 month to 17 years, displayed within a configurable ±2-year window around the child's age. Medication Safety Layer — 8 age-filtered medication entries with weight-aware dosing context and hard-coded aspirin contraindication for children under 16. Parental Guidance UX Layer — plain-language actionable guidance translating triage output into immediate steps and emergency escalation criteria. Clinician Dashboard Modal — a single-view clinical summary combining organ-system heatmap, ranked differential (top 6), vitals flags, predictive indices, and case timeline. Four Predictive Risk Indices — heuristic 0–10 screening scores covering early sepsis risk, respiratory distress, dehydration, and febrile illness risk. Explain-This-Result Panel — a plain-language "Why this band?" panel surfacing the top 2–5 contributing factors behind the assigned triage band. Clinical Content Versioning System — nine independent content version tracks that separate clinical knowledge versions from software release versions, enabling independent audit and staged clinical-content upgrades. Architecture and reproducibility The artifact preserves every architectural guarantee of the prior releases: client-side-only execution, zero server dependency, full inspectability, and no telemetry. All processing — condition parsing, symptom indexing, red-flag screening, vitals interpretation, Bayesian inference, triage scoring, milestone generation, medication filtering, guidance generation, predictive index computation, explanation reason extraction, and content versioning — executes locally within the client runtime. The only network requests are optional presentation resources (fonts, icons, and visualization libraries); none of them receive user inputs. A runtime library audit is emitted on application startup, reporting declared design targets versus actual loaded counts for every headline metric. The Triage Severity Score is fully specified by six base values, five adjustment terms, five hard constraint rules (including one vitals-derived), one integer clamp, six band boundaries, and eight vitals escalation thresholds — enabling bit-exact independent reproduction. What the artifact is not This artifact is not a medical device and is not cleared or approved by the FDA, EMA, MHRA, TGA, or any other regulatory authority. It has not been evaluated in a prospective clinical trial, subjected to retrospective chart review, validated against a gold-standard vignette set, or calibrated against clinical outcomes. The probabilities, rankings, and triage recommendations produced by the model are model-derived quantities, not clinically calibrated performance measures. They must not be interpreted as diagnostic, prognostic, or therapeutic guidance. In any emergency, contact emergency services immediately — 911 (US) · 999 (UK) · 112 (EU) · 000 (AU) — regardless of what this artifact displays. What this deposit contains The Zenodo record for this release contains the reference implementation of the artifact plus the Complete Clinical Upgrade Pack, the machine-readable condition and symptom libraries, the configuration schema reference, the triage-score specification, the vitals reference range specification, the milestone band specification, the medication reference specification, the predictive risk index specification, the clinician dashboard specification, the explain-this-result specification, the content versioning specification, the proposed validation protocol, the technical white paper (PDF and Markdown), a README with execution and tuning instructions, and license files (MIT for code; CC BY 4.0 for documentation). Intended use The artifact is offered as: An informational triage aid for parents and caregivers. A teaching artifact for health informatics and medical education. A reproducible research baseline for symptom-checker methodology. A transparent pediatric baseline for comparative evaluation. A worked example of client-side clinical decision support with integrated interactive visualization. It is explicitly not intended for diagnosis, replacement of clinical judgment, use as a regulated clinical workflow, or population-level epidemiological inference. Citation and licensing Software code is released under the MIT License. Documentation and research text are released under Creative Commons Attribution 4.0 International (CC BY 4.0). This artifact should be cited as software and methodology research. Its future scientific value will depend on independent review, empirical validation, calibration analysis, and transparent reporting of both successful and unsuccessful results.