# Anthropic's Claude Sonnet 5.5 and OpenAI's GPT-6 Astra tie for top on medical reasoning leaderboard

Digest AI · Generative AI & Models · published 2026-10-21T08:59:00Z

Canonical: https://digestai.news/story/anthropic-s-claude-sonnet-5-5-and-openai-s-gpt-6-astra-tie-for-top-on

## Summary

On October 21, 2026 Artificial Analysis updated the MLCR‑AA leaderboard, a benchmark created by insurtech platform Wisedocs to test AI synthesis of long medical and insurance records. The update shows Anthropic’s Claude Sonnet 5.5 and OpenAI’s GPT‑6 Astra tied for first place with a 41.7% pass rate.

The median score across all 60 models stays below 15%, and no model exceeds 42%. Claude Sonnet 5.5 leads the completeness metric at 64.8%, while OpenAI’s GPT‑6.1 Sol tops accuracy at 96.7%. The benchmark feeds synthetic case files of 25,000‑64,000 tokens, allowing realistic testing without real patient data. The October update also added practical reviewer prompts and refined 15 of the 60 expert references.

For insurers, the results highlight a trade‑off: Anthropic’s models capture more information, whereas OpenAI’s reduce confident errors. Even the best models still fail the majority of expert‑level synthesis tasks, underscoring the current limits of AI in long‑context claims work.

## Key points

- Claude Sonnet 5.5 and GPT-6 Astra each achieved a 41.7% pass rate, tying for first on the MLCR-AA leaderboard (Oct 21 update).
- Median score across all models remains below 15%; completeness leader Claude Sonnet 5.5 scored 64.8%, accuracy leader GPT-6.1 Sol scored 96.7%.
- Benchmark uses synthetic medical/insurance records of 25,000‑64,000 tokens to assess AI’s ability to synthesize data for claims professionals.

## Why it matters

The tie shows AI can handle long‑context medical records better than before, but even top models miss most tasks, guiding insurers and vendors on the trade‑off between completeness and accuracy.

## Sources

1. [Claude Sonnet 5.5 and GPT-6 Astra tie for top spot on MLCR-AA medical reasoning leaderboard](https://cryptobriefing.com/claude-sonnet-gpt-6-astra-tie-mlcr-aa) (cryptobriefing.com, 2026-10-21)

Part of the developing story: [AI Model Showdown Across Platforms](https://digestai.news/thread/replit-ends-partnership-with-anthropic-cites-cost-and-performance) (2 stories)

## Cite

Digest AI, "Anthropic's Claude Sonnet 5.5 and OpenAI's GPT-6 Astra tie for top on medical reasoning leaderboard", 21 October 2026, https://digestai.news/story/anthropic-s-claude-sonnet-5-5-and-openai-s-gpt-6-astra-tie-for-top-on

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