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Diagnostic Accuracy of Large Language Models for Rare Diseases: A Systematic Review and Meta-Analysis

Nguyen MH, Yang CT, Cassini TA, Ma F, Hamid R, Bastarache L, Peterson JF, Xu H et al.

medRxiv : the preprint server for health sciences, 2026

39,529 participants

Abstract

BACKGROUND: Large language models (LLMs) have been evaluated as tools to assist rare disease diagnosis, yet evidence on their accuracy remains fragmented. We conducted a systematic review and meta-analysis to synthesize the available evidence on the diagnostic performance of LLMs, identify sources of heterogeneity, and evaluate the current evidence base for clinical translation.

METHODS: We searched PubMed, Embase, Web of Science, Cochrane Library, arXiv, and medRxiv (January 2020-February 2026). Full-text articles and preprints were considered for inclusion. Eligible studies applied LLM-based systems to generate differential diagnoses for rare diseases and provided Recall@l (R@1; proportion with the correct diagnosis ranked first). We pooled R@1 using Freeman-Tukey double arcsine transformation with DerSimonian-Laird random-effects models. Pre-specified subgroup analyses examined LLM knowledge augmentation strategy and input modality. Because both retained high residual heterogeneity, we conducted a post-hoc exploratory analysis of evaluation benchmark disease composition, mapping diseases from major benchmarks to Orphanet prevalence classifications. Risk of bias was assessed using a modified QUADAS-3 instrument.

FINDINGS: We identified 902 records, of which 564 were screened and 15 studies were eligible. These 15 studies contributed 19 system-dataset entries to the meta-analysis (total N=39,529 cases). The pooled R@1 was 43·3% (95% CI 35·1-51·6; I 2=99·6%). Augmented LLM…

How strong is the evidence?

Evidence Hub reads this as a meta-analysis. Its evidence level is 1 of 5 (Highest · pooled evidence). Pooled evidence from several studies sits at the top of the evidence pyramid. Reported size: 39,529 participants or records.

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