The use of diagnostic codes for mast cell disorders, including systemic mastocytosis (SM), appears to be on the rise, according to a recently published study in JACI: In Practice.
Diagnostic codes are standardized alphanumeric identifiers that represent specific diseases, conditions or health-related problems in clinical databases. The most widely used diagnostic code system is the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10). In this system, SM is represented as D47.02, and unspecified mast cell activation is coded as D89.40.
The authors aimed to analyze the current prevalence of mast cell disorders in claims databases in the United States. They used the IBM MarketScan Commercial Claims and Encounters database, which includes data from over 260 million insurance beneficiaries.
Use of the code specifying SM (D47.02) increased over fivefold between 2017 (when it was used for fewer than one in 100,000 patients) and 2022 (four per 100,000). This represents less than 4,000 patients in 2017 and over 13,000 patients in 2022.
“Increases in SM diagnoses may reflect, in part, increased disease awareness among providers; wider availability of diagnostic tools like droplet PCR to check for the D816V mutation frequently linked to SM in peripheral blood or bone marrow; and creation of mast cell disorder-focused multidisciplinary centers,” the study’s authors said.
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The authors observed that the use of mast cell disorder codes tripled between 2017 (10 per every 100,000 patients ) and 2022 (36 per every 100,000 patients ). This translates to approximately 49,000 patients in 2017 and over 100,000 patients in 2022. The change was mainly driven by an increase in the use of the unspecified mast cell activation code (D89.40).
D89.40 is a broad diagnostic label used in cases where there is clinical evidence of excessive mast cell activation without a clearly defined cause. These patients may present with symptoms such as flushing, skin rash, itchiness and diarrhea, or show transiently elevated serum tryptase levels, without meeting the criteria for SM or other defined mast cell disorders.
The researchers noted that the rise in mast cell diagnostic codes was more pronounced in women, who had a prevalence of 57 per 100,000 in 2022, compared to 17 per 100,000 in men. The highest prevalence was observed in children under the age of five and in women aged 40 to 44.
The authors hypothesize that the increase in D89.40 usage may be due to inappropriate use of diagnostic codes and increased specialty referrals to immunology and allergology.
“Nevertheless, these trends provide important insight into the frequency with which mast cell disorders and associated conditions are considered in practice, including clonal and non-clonal disorders and hereditary alpha-tryptasemia,” the study’s authors noted.
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