ICD-10 A48.1
Billable / Specific HCC v28: 114 MCCLegionnaires' disease
About ICD-10-CM A48.1
ICD-10-CM code A48.1 represents Legionnaires' disease. This is a billable/specific code in the Infectious and Parasitic Diseases chapter (block A48). The 2026 edition of ICD-10-CM A48.1 became effective on October 1, 2025.
Coding Tips for A48.1
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
A48.1 is a CMS-HCC v28 risk-adjustment code (category 114). To count for the patient Risk Adjustment Factor (RAF), document the diagnosis with MEAT language each calendar year: Monitored, Evaluated, Assessed, Treated. A diagnosis on the problem list alone does not satisfy CMS RADV audit standards. Include the diagnosis in the assessment with current status and current treatment plan.
A48.1 is designated MCC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-MCC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag MCC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Medicare Advantage HCC Impact
Capture this diagnosis annually for accurate risk adjustment. Missed HCC captures are the #1 revenue leak in Medicare Advantage risk programs.
Inpatient DRG Impact, MCC
codes Legionnaires' disease. As a Major Complication/Comorbidity (MCC), this can shift the DRG assignment to a higher-weighted category, substantial reimbursement impact.
Medicare LCD Coverage for A48.1
Local Coverage Determinations (LCDs) from CMS MACs that list A48.1 as a covered diagnosis.
Showing top 10 of 551 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing A48.1.
2 Aetna
5 Medicare
CPT Codes Commonly Billed with A48.1
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- 99292 CMS LCD: Billing and Coding: Respiratory Therapy and Oximetry Services CMS LCD
Convert A48.1 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| A48.1 | 48284 | 00000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To A48.1
Other codes in section A30-A49 (Other bacterial diseases).
ICD-10 A48.1, Billing FAQ
Is ICD-10 code A48.1 billable? +
Yes, A48.1 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
Does A48.1 affect Medicare Advantage HCC risk adjustment? +
Yes. A48.1 maps to CMS-HCC v28 category 114. Capture this diagnosis annually for accurate Medicare Advantage risk score.
Is A48.1 a CC or MCC for inpatient DRG? +
Yes, this code is designated as MCC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What CPT codes are commonly billed with A48.1? +
Procedures frequently paired with A48.1 include: 99292.
What ICD-9 codes does A48.1 map to? +
Per CMS GEMs, A48.1 maps to ICD-9 codes: 48284. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on July 16, 2026.
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