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Insurance Claim Denial Statistics

Denial rates, appeal success rates, and documentation requirements by procedure and denial reason. This data is intended for patients, attorneys, journalists, and researchers.

Note: Figures represent estimated averages across major US health plans and may vary by insurer, state, and plan type. Updated 2026.

27%
Average Denial Rate
across tracked procedures
71%
Average Appeal Success
when appealed correctly
24
Procedures Tracked
procedure × reason combinations
88%
Top Appeal Rate
Mammogram screenings

Key Findings

  • Prior authorization denials are the most common and most frequently overturned on appeal
  • Documentation errors have the highest resolution rate — these are administrative, not clinical, decisions
  • Emergency care denials are overturned at high rates, particularly under the No Surprises Act (US)
  • Mental health claim denials are disproportionately high relative to physical health — often violating parity laws
  • Less than 1% of denied claims are appealed, yet a majority of appeals succeed when properly structured
  • Spinal and bariatric surgery denials have lower appeal success rates due to high insurer scrutiny

Denial Data by Procedure

ProcedureDenial ReasonDenial RateAppeal SuccessAvg Claim (USD)
MRI ScanPrior Authorization Denied
34%
71%
$1,800
MRI ScanMedical Necessity Denied
28%
74%
$1,800
CT ScanPrior Authorization Denied
31%
68%
$2,200
CT ScanMedical Necessity Denied
26%
70%
$2,200
Emergency Room VisitOut-of-Network Claim Denied
22%
78%
$4,500
Emergency Room VisitPrior Authorization Denied
15%
82%
$4,500
ChemotherapyExperimental Treatment Denied
18%
65%
$15,000
ChemotherapyMedical Necessity Denied
12%
79%
$15,000
Mental Health TherapyMedical Necessity Denied
38%
69%
$800
Mental Health TherapyOut-of-Network Claim Denied
29%
72%
$800
Knee Replacement SurgeryMedical Necessity Denied
23%
76%
$35,000
Knee Replacement SurgeryPrior Authorization Denied
19%
73%
$35,000
Hip Replacement SurgeryMedical Necessity Denied
21%
74%
$38,000
Spinal Fusion SurgeryMedical Necessity Denied
31%
62%
$50,000
Physical TherapyBenefits Exhausted
45%
58%
$1,200
Physical TherapyMedical Necessity Denied
32%
71%
$1,200
ColonoscopyNot Covered Service
14%
80%
$2,500
MammogramNot Covered Service
8%
88%
$400
Sleep StudyPrior Authorization Denied
27%
67%
$1,500
ICU StayMedical Necessity Denied
11%
84%
$25,000
Ambulance TransportMedical Necessity Denied
33%
69%
$1,800
Genetic TestingExperimental Treatment Denied
41%
61%
$3,000
Infertility TreatmentNot Covered Service
52%
44%
$12,000
Bariatric SurgeryMedical Necessity Denied
38%
66%
$22,000

Commonly Required Appeal Documents

The following documents are most frequently required when appealing denied claims.

Letter of medical necessity from treating physician
94%
Required in almost all medical necessity appeals
Denial letter and Explanation of Benefits (EOB)
100%
Required in all appeals as the starting document
Insurer's clinical policy bulletin
88%
Must be requested from the insurer — legally required to provide
Published clinical guidelines (e.g. NCCN, ACS)
76%
Used to demonstrate medical standard of care
Physician treatment notes and records
92%
Required to support clinical justification
Prior authorisation correspondence
71%
Required when the denial involves prior authorisation

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