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MS-DRG 915 · MDC 21 · Medical

MS-DRG 915: Allergic Reactions with MCC

Reviewed by QuickIntell RCM Editorial Team · Last reviewed

Data effective
Data currency: IPPS Table 5 FY2027 final rule (effective October 1, 2026); Definitions Manual v44 (effective October 1, 2026). Next CMS release: April 1, 2027 (v44.1 mid-year update), then the FY2028 final rule in August 2027.

Key facts for DRG 915

FY2027 relative weight
1.6560
Higher than 51% of all MS-DRGs
Change vs FY2026
-1.6%
FY2026 weight 1.6820
Geometric mean LOS
3.4 days
Arithmetic mean 4.7 days
MDC
21
Assignment of Diagnosis Codes
Severity level
with MCC (major complication or comorbidity)
Transfer policy
Not a transfer DRG

TL;DR

MS-DRG 915 is a medical group in MDC 21 (Assignment of Diagnosis Codes) at the highest-severity level of its family. CMS assigns it a FY2027 relative weight of 1.6560 with a geometric mean length of stay of 3.4 days and an arithmetic mean of 4.7. Its weight moved down 1.6% from FY2026 (1.6820). That weight is higher than 51% of all medical and surgical MS-DRGs. Its CC/MCC family (DRG 916) spans weights 0.6930 to 1.6560. The v44 Definitions Manual assigns it through 25 principal diagnosis codes.

What changed from FY2026 to FY2027

CMS recalibrates every MS-DRG weight annually from the prior year's MedPAR claims. For DRG 915 the FY2027 relative weight is 1.6560 against 1.6820 in FY2026, a fall of 1.55%.

FY2026 versus FY2027 payment factors for MS-DRG 915
MetricFY2026FY2027Change
Relative weight1.68201.6560-0.0260
Geometric mean LOS (days)3.53.4-0.1
Arithmetic mean LOS (days)4.84.7-0.1
Weights shown are the FY2027 final values after the 10% cap on year-over-year reductions where applicable.

CC and MCC family

DRG 915 shares its base definition with 1 other MS-DRG split by severity. The family's weights span 0.6930 to 1.6560, a 2.39× spread, which is the payment effect of documenting qualifying complications and comorbidities.

MS-DRGs in the same base group as DRG 915
DRGTitleFY2027 weightGMLOS
915Allergic Reactions with MCC1.65603.4
916Allergic Reactions without MCC0.69301.8

Grouper logic (v44 Definitions Manual)

Principal Diagnosis: 25 ICD-10 codes drive assignment to this group; the first 12 are shown.

Principal Diagnosis codes assigned to DRG 915 (sample)
ICD-10 codeDescription
T7800XAAnaphylactic reaction due to unspecified food, initial encounter
T7801XAAnaphylactic reaction due to peanuts, initial encounter
T7802XAAnaphylactic reaction due to shellfish (crustaceans), initial encounter
T7803XAAnaphylactic reaction due to other fish, initial encounter
T7804XAAnaphylactic reaction due to fruits and vegetables, initial encounter
T7805XAAnaphylactic reaction due to tree nuts and seeds, initial encounter
T7806XAAnaphylactic reaction due to food additives, initial encounter
T78070AAnaphylactic reaction due to milk and dairy products with tolerance to baked milk, initial encounter
T78071AAnaphylactic reaction due to milk and dairy products with reactivity to baked milk, initial encounter
T78079AAnaphylactic reaction due to milk and dairy products, unspecified, initial encounter
T78080AAnaphylactic reaction due to egg with tolerance to baked egg, initial encounter
T78081AAnaphylactic reaction due to egg with reactivity to baked egg, initial encounter

Documentation and denial exposure

As a medical DRG, assignment depends on the principal diagnosis sequenced from the attending's documentation; a secondary condition sequenced first, or a symptom code in place of the confirmed diagnosis, changes the MDC or the DRG. Because this family splits by severity, auditors target CC and MCC capture: each secondary diagnosis must be documented as present, monitored, evaluated or treated during the stay to survive a DRG-validation review. Typical inpatient denial codes for this group: CARC 16 (claim lacks information needed to group the stay), CARC 50 (the admission or procedure is judged not medically necessary), CARC 97 (a service is bundled into the DRG payment).

How QuickIntell uses DRG 915 data

QuickCode groups inpatient encounters against the current v44 logic, flags CC and MCC candidates that lack supporting documentation, and shows the weight difference across the family before the claim drops. QuickScribe captures the attending's language that supports severity, and QuickRCM works DRG-validation denials with the grouper evidence attached.

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Frequently asked questions — DRG 915

What is MS-DRG 915?

MS-DRG 915 is "Allergic Reactions with MCC", a medical Medicare Severity Diagnosis-Related Group in MDC 21, Assignment of Diagnosis Codes. Medicare pays inpatient stays grouped here at the hospital's base rate multiplied by the DRG relative weight.

What is the FY2027 relative weight for DRG 915?

The FY2027 relative weight is 1.6560 (IPPS final rule Table 5, effective October 1, 2026). In FY2026 it was 1.6820, a change of -1.6%.

What is the average length of stay for DRG 915?

CMS reports a geometric mean length of stay of 3.4 days and an arithmetic mean of 4.7 days for FY2027. The geometric mean is used for transfer-payment calculations.

Which DRGs are in the same CC/MCC family as 915?

DRG 916 (Allergic Reactions without MCC, weight 0.6930). The family's weights range from 0.6930 to 1.6560, so documented complications and comorbidities change payment materially.

What documentation supports the severity level of DRG 915?

DRG 915 requires at least one secondary diagnosis on the CMS Major Complication or Comorbidity list, documented as present and clinically addressed during the stay (monitored, evaluated, treated or extending the stay). Conditions such as acute respiratory failure, severe sepsis or acute kidney injury with specified cause qualify only when the attending's note states the diagnosis itself, not just the lab values. Recovery auditors downgrade this group to the CC or base level when the MCC rests on an unconfirmed query or a resolved historical condition, so the query response and the discharge summary must agree.

Which codes group to DRG 915?

The v44 Definitions Manual lists 25 principal diagnosis codes for this group. Examples from the principal diagnosis list: T7800XA (Anaphylactic reaction due to unspecified food, initial encounter); T7801XA (Anaphylactic reaction due to peanuts, initial encounter); T7802XA (Anaphylactic reaction due to shellfish (crustaceans), initial encounter); T7803XA (Anaphylactic reaction due to other fish, initial encounter).

Is DRG 915 a post-acute transfer DRG?

No. DRG 915 is not on the FY2027 post-acute care transfer list, so the transfer per-diem policy does not apply to it.

Sources

Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-01. Verify against the primary file before billing or contracting decisions.

Disclaimer

This page is an operational reference compiled from the CMS IPPS FY2027 final rule (Table 5) and the v44 ICD-10 MS-DRG Definitions Manual. Relative weights are national factors; actual payment depends on each hospital's wage-adjusted base rate, add-ons, outliers and transfer adjustments. Nothing here is legal, clinical or billing advice; verify grouping against your encoder and the published CMS files.