Blue Cross Blue Shield says AI coding tools pushed 55,000 hospital stays into higher billing tiers. Treatment for those patients did not change.
Complex inpatient cases went from 37% in early 2023 to 40% by late 2025. About 70% of that rise came from secondary diagnoses that bumped claims into a higher-paying severity tier.
The tell is what did not move. Top-quartile hospitals diagnosed anemia 38% more often than peers but transfused those patients less: 16.9% versus 19.3%. ICU use and length of stay were flat or lower.
Ambient scribes and record-scanning tools surface anything codable on a routine lab report. Acidosis, low sodium, posthemorrhagic anemia. All real findings. All newly billable.