Claims Data

Key facts

Federal rule

HIPAA transaction standards, 45 CFR Part 162

Medical and dental claim standard

ASC X12 837 (professional, institutional and dental)

Pharmacy claim standard

NCPDP Telecommunication Standard

Common code sets

ICD-10-CM diagnoses, CPT and HCPCS procedures, NDC drugs

What is claims data?

Every time a provider bills a payer, the claim becomes a structured record. Medicare, Medicaid programs and commercial insurers process vast numbers of these records, and in aggregate they form the largest source of information on what care is delivered in the United States.

Claims are created for payment, not research. They record billed codes, dates, identifiers and amounts, but not clinical detail such as lab results, symptoms or the reason a physician chose one treatment over another.

Types of claims

Electronic claims follow standards adopted under the Health Insurance Portability and Accountability Act (HIPAA): the Accredited Standards Committee (ASC) X12 837 for medical and dental claims and National Council for Prescription Drug Programs (NCPDP) standards for pharmacy claims. Claims datasets usually combine several claim types with an enrollment file that shows when each person was covered:

• Professional claims: services billed by physicians and other practitioners, sent as the X12 837P or on the CMS-1500 paper form.
• Institutional claims: hospital, skilled nursing, home health and other facility services, sent as the X12 837I or on the UB-04 paper form.
• Pharmacy claims: prescriptions filled at retail and mail-order pharmacies, sent in real time and identified by National Drug Code (NDC).
• Dental claims: sent as the X12 837D.

Why claims data matters

Claims data shows real-world treatment patterns at scale. Pharmaceutical teams use it to track prescribing and patient journeys, device companies to measure procedure volume, payers and health systems to study cost and utilization, and researchers to study outcomes across large populations.

Because each claim carries National Provider Identifiers (NPIs), claims data can be joined to provider directories such as NPPES and to facility data, and the NDC on pharmacy claims links to drug pricing benchmarks such as National Average Drug Acquisition Cost (NADAC).

Limitations of claims data

Analysts should account for several known gaps:

• Coverage: each source reflects only the patients insured by the payers it includes, and uninsured or cash-pay care is largely missing.
• Lag: claims can be submitted and adjusted for months after a service, so recent periods look incomplete until the claims run out.
• Final vs open claims: adjudicated claims reflect what the payer processed, while pre-adjudication claims arrive faster but may later be denied or changed.
• Coding behavior: diagnosis and procedure codes follow billing rules and incentives, so they can understate or overstate clinical reality.