New BCBS analysis on AI-powered clinical documentation: upcoding crisis or long-overdue accuracy?

BenefitsPRO recently headlined the Blue Cross Blue Shield Association analysis showing that AI-driven hospital coding contributed to a 1.8% increase in claims costs. That finding has ignited a critical debate. Are hospitals using AI to inflate bills, or are these systems finally capturing clinical complexity that manual processes systematically missed for decades?

The answer is likely both, and the implications point toward a fundamental reckoning with how we structure healthcare payment in the digital age.

The historic underdocumentation problem

Manual clinical coding has long suffered from profound accuracy limitations. Research demonstrates error rates of 40% to 70%, with approximately 26% of diagnoses completely undercoded in manual processes. Concordance between physicians and coders for the most responsible diagnosis can be as low as 20% to 35%.

But these are not just statistics about code accuracy. They reflect a fundamentally broken workflow. Physicians provide care and document clinical findings as best they can within crushing time constraints. Days or weeks later, medical coders asynchronously review charts and attempt to translate clinical narratives into billing codes, often submitting clarification queries back to already-overwhelmed clinical teams. This process is fraught with errors, gaps, and behavioral adoption hurdles at every step.

The barriers are well-documented. Illegible handwriting, variability in documentation quality, time constraints, and the fundamental limitation that coding professionals cannot interpret clinical nuance. They can only code what is explicitly documented. The American College of Physicians noted that traditional evaluation and management coding guidelines transformed documentation from "what was done" to "what was documented," creating systems where "much of the documentation includes often irrelevant elements" rather than actual clinical decision-making.

AI's double-edged sword

AI-powered ambient documentation systems demonstrate genuine efficiency gains. Recent meta-analyses show these tools reduce documentation burden with a standardized mean difference of -0.71, representing a moderate effect. Documentation time decreases by 46% for complex cases, with F1-scores of 0.62 to 0.85 for ICD coding accuracy.

More importantly, AI collapses the asynchronous physician-coder workflow by capturing clinical conversations in real time and generating both clinical notes and billing codes simultaneously. This eliminates the communication gaps, query cycles, and weeks-long delays that plague manual coding and further drag out a rather long revenue cycle.

However, the BCBS analysis identified a concerning pattern. At 10% of hospitals, postpartum anemia diagnoses surged from 4% to 12.3% while blood transfusion rates remained constant at 1%. This suggests coding that may not reflect treatment-relevant clinical acuity. When one insurer audited a hospital with such spikes, "less than 20% of the cases met established clinical criteria for postpartum anemia."

Yet this does not necessarily indicate fraud. It could represent AI systems capturing diagnoses that were clinically present but previously undocumented due to the workflow barriers described above. These are conditions mentioned in conversation but never making it into the formal record because physicians lacked time or coders lacked context.

The critical question is whether we are trading one set of systematic errors, underdocumentation due to workflow friction, for another, overdocumentation of clinically irrelevant findings. AI removes the human coder as a quality check, but that "check" was itself producing 40% to 70% error rates.

The fundamental limitation: a broken workflow built on inadequate codes

Even when physicians document thoroughly and coders work diligently, CPT, DRG, HCPCS, and ICD-10 codes themselves were designed for billing and statistics, not differential diagnosis or comprehensive clinical documentation. They lack the compositional structure and semantic richness needed to distinguish between three very different situations:

1. Legitimate capture of previously undocumented complexity.
2. Documentation of clinically present but treatment-irrelevant findings.
3. Actual inappropriate coding.

SNOMED CT offers a solution. As a compositional system, it can represent complex concepts by combining discrete observations. Acute inflammation, plus perforation, plus appendix structure, resolves to acute perforated appendicitis. It provides a consistent and computable framework that ICD fundamentally lacks. The whole range of medical terminology is covered by SNOMED CT in ways that ICD-10 and ICHI cannot achieve.

This semantic precision could enable payment systems to distinguish between a diagnosis that was documented because it required treatment versus one that was simply observed during an encounter. Current ICD-based payment models cannot make this distinction, regardless of whether humans or AI generate the codes.

The path forward: FHIR, SNOMED, and payment evolution

The federal government is already moving in this direction. The CMS Interoperability and Patient Access Final Rule (January 2024) identified FHIR as the chosen standard for interoperability and required payers to establish Patient Access APIs using FHIR. The HTI-2 proposed rule extends this framework to create greater transparency across healthcare delivery, payment, and public health domains.

FHIR combined with SNOMED CT achieves both structural and semantic interoperability, with studies demonstrating 0% data loss in transfers between systems. This granularity could enable payment models that distinguish between documentation of clinical findings and documentation of treatment-relevant complexity, the very distinction that current billing codes cannot make.

The transition will not be simple. A 2025 scoping review identified 73 challenges to FHIR adoption across organizational, technical, individual, data management, and legal and ethical domains. Yet 43 facilitators were also identified, and federal investments through the CDC Public Health Infrastructure Grant are funding implementation centers to provide technical assistance.

Where the burden falls: payers, not providers

Here is the critical asymmetry in this transition. Providers have already done much of the heavy lifting, and the data asymmetry may be at the root of the problem in payer-provider abrasion. Modern EHR systems already support FHIR, SNOMED, and LOINC standards. The clinical data is being captured in these richer formats today. The infrastructure exists on the provider side.

The real transformation must happen on the payer side. Actuaries will need to develop entirely new frameworks for understanding risk and pricing when working with compositional ontologies rather than categorical billing codes. Contracting models built around DRGs, CPT bundles, and HCPCS will require fundamental restructuring. CMS and state Medicaid agencies will need to lead foundational shifts in how they define, measure, and reimburse clinical complexity.

This is not a small undertaking. Decades of actuarial science, contract templates, and regulatory frameworks are built on the assumption that clinical reality can be adequately represented by billing codes. Unwinding that assumption while maintaining payment system stability will require careful, phased implementation.

But the key insight is that this is primarily a payer-side and regulatory transformation, not another massive provider rebuild. Providers have already invested billions in EHR infrastructure that captures clinical data in modern standards. The question is whether payment systems will evolve to use what is already being captured, or continue forcing that rich clinical data through the narrow funnel of billing codes.

The approaching breaking point

We are indeed approaching a breaking point where coarse-grained administrative datasets and ontologies used for payment have underrepresented clinical data for years.

The question is not whether to embrace AI-assisted documentation, but how to evolve payment systems to handle the clinical granularity that modern technology can now capture. The asynchronous physician-coder workflow was never a feature. It was a workaround for inadequate documentation tools and insufficient physician time. AI removes that workaround, forcing us to confront what we are actually trying to measure and pay for.

In my mind, the evolution toward FHIR, SNOMED, and LOINC-based payment models represents the next horizon. These standards can provide the semantic precision needed to validate AI-assisted coding accuracy while preserving the efficiency gains that reduce clinician burnout and improve documentation quality.

The alternative is continuing to force increasingly sophisticated clinical documentation through billing codes designed in an analog era, whether generated by humans or AI. This will only deepen the disconnect between clinical reality and payment systems.

The workflow was already broken. AI is just making it impossible to ignore.

All views, analyses, and services presented here reflect my independent professional perspective, informed by more than two decades of real-world experience, and do not represent the views or positions of any current or former employer or affiliated organization.