Microsoft Dragon Copilot vs Nabla (2026)
This is the only pair in the category where both vendors were arms in the same randomized controlled trial, and the result favours the challenger. In Lukac et al, published in NEJM AI in November 2025, 238 UCLA Health physicians across 14 specialties were randomized to Dragon Copilot, Nabla or usual care over two months. Nabla reduced time in note by 9.5 percent and was the only arm to meet the primary endpoint; the Dragon arm reached 1.7 percent and was not statistically significant. Both improved burnout measures by roughly 7 percent. That does not settle the purchase on its own, because Dragon Copilot covers roles Nabla does not, carries deeper Epic embedding and publishes more about its own limitations. But when a buyer asks which of these two demonstrably saved documentation time in a trial neither of them ran, there is now an answer, and it is Nabla.
- The published documentation set is the most complete in this category and it names failure modes rather than gesturing at them: background noise and overlapping speech, omitted findings and hallucinated details in summarization, and underperformance on accents and dialects not well represented in training data.
- Roles beyond the physician. Distinct editions for nurses and radiologists, including bedside conversation converted into structured flowsheet entries, against a competitor built around the clinician note.
- Regulatory posture is stated in the markets that ask for it. Registered with the United Kingdom regulator as a Class 1 medical device and available across ten countries, which is a materially different position from a product that is unregulated everywhere it ships.
- It is the only ambient scribe in this index with a positive result in a randomized controlled trial it did not run, reducing time in note by 9.5 percent against control across roughly 72,000 encounters, and the only arm in that trial to meet its primary endpoint.
- The widest EHR footprint in the category, more than 15 platforms named including Epic, Oracle Health, athenahealth, NextGen, Greenway and Altera. For a system running mixed record systems across hospital and clinic, that is one scribe contract instead of several.
- The data lifecycle is published end to end, which almost nothing else here does. Audio is not stored, models are not trained on user data, clinical data is retained for a configurable 14 days sized around clinician review, and backups expire seven days after that so the deletion claim reaches the backup layer.
This comparison is published by AI Health Index, an independent research platform that compares healthcare AI vendors objectively. Microsoft Dragon Copilot and Nabla are each graded against the same capability taxonomy, from each vendor's own public materials and the regulatory record, under the AI Health Index verification standard. No vendor pays for placement, and no vendor has reviewed this page. How this evidence is graded
Plain facts
| Fact | Microsoft Dragon Copilot | Nabla |
|---|---|---|
| Primary category | Ambient Scribes | Ambient Scribes |
| Founded | 2025 | 2018 |
| Headquarters | Redmond, Washington, United States | Paris, France |
| Website | microsoft.com | nabla.com |
Side by Side
Each record in one paragraph
Written to be quoted whole. Each paragraph states what the AI Health Index verified about the vendor, with the caveats attached. Generated from this pair’s live capability grades, so it moves when a grade moves.
The AI Health Index awards Microsoft Dragon Copilot its top capability grade on several axes, including AI Centrality, Model Supply Chain Disclosure and FDA and Regulatory Status. Set against Nabla, Microsoft Dragon Copilot grades higher on several axes, including Model and Technology Transparency, Model Supply Chain Disclosure and FDA and Regulatory Status. Grades reflect evidence the AI Health Index could verify at the last review, so a low grade records disclosure the vendor has not published rather than a capability it has been shown to lack.
Source: AI Health Index, August 2026
The AI Health Index awards Nabla its top capability grade on several axes, including AI Centrality, Clinical and Operational Evidence and AI Safety and PHI Stewardship. Set against Microsoft Dragon Copilot, Nabla grades higher on several axes, including Clinical and Operational Evidence, AI Safety and PHI Stewardship and HIPAA and BAA Posture. Grades reflect evidence the AI Health Index could verify at the last review, so a low grade records disclosure the vendor has not published rather than a capability it has been shown to lack.
Source: AI Health Index, August 2026
Questions buyers ask
Should we choose Microsoft Dragon Copilot or Nabla?
On the axes where the AI Health Index separates them, Microsoft Dragon Copilot grades higher on several axes, including Model and Technology Transparency, Model Supply Chain Disclosure and FDA and Regulatory Status, and Nabla grades higher on several axes, including Clinical and Operational Evidence, AI Safety and PHI Stewardship and HIPAA and BAA Posture. Microsoft Dragon Copilot leads on the greater share of scored axes, but the split means the decision turns on which constraint is binding rather than on an overall winner.
Where do Microsoft Dragon Copilot and Nabla differ most?
The widest separation the AI Health Index records between Microsoft Dragon Copilot and Nabla is on AI Governance and Bias Disclosure, where Microsoft Dragon Copilot grades A and Nabla grades C. That axis sits in the Regulatory and Compliance group, so it should carry the most weight for a buyer whose binding constraint is where regulatory exposure sits and who carries it.
Where do Microsoft Dragon Copilot and Nabla grade the same?
The AI Health Index grades Microsoft Dragon Copilot and Nabla the same on several axes, including AI Centrality, Autonomy and Oversight Model and EHR and Interoperability Depth. Neither holds an advantage the index can evidence on those axes, so they should not carry weight in a selection between these two.
Related comparisons
Other published head to head assessments involving these vendors or their closest peers. The full set for this category is on the Ambient Scribes page.
The trial cited is Lukac et al, NEJM AI, 26 November 2025, registered as NCT06792890. It measured time in note and burnout over two months in an outpatient population at a single academic health system, so it does not establish note quality, coding accuracy or performance in inpatient and emergency settings, and a two month window may not capture proficiency gains.
Nabla moved off published per month pricing during 2026 toward a demo and contract motion, so evaluate on the tier you would actually contract. An earlier version of this note said its free tier did not include a business associate agreement; that claim traced to competitor comparison pages and Nabla's own terms say the opposite, making agreement to the attached instrument a precondition of use for any customer subject to HIPAA. Corrected 13 September 2026. Microsoft publishes no rate card.