ICD-10 anaphylaxis algorithm and the estimate of vaccine-attributable anaphylaxis incidence in Medicare

• Published in: Vaccine 2021-09, Vol.39 (38), p.5368-5375
• Main Authors: Goud, Ravi, Thompson, Deborah, Welsh, Kerry, Lu, Michael, Loc, Julie, Lindaas, Arnstein, Arya, Deepa, Chillarige, Yoganand, Wernecke, Michael, MaCurdy, Thomas E., Kelman, Jeffrey A.
• Format: Article
• Language: English
• Subjects: Algorithm; Algorithms; Allergic reactions; Allergies; Anaphylaxis; Beneficiaries; Claims-data; Codes; Edema; Government programs; Hypersensitivity; ICD-10; Immunization; Influenza; Medical records; Medicare; Medicare Fee For Service; Positive predictive value (PPV); Vaccination; Vaccine; Vaccines
• ISSN: 0264-410X; 1873-2518
• DOI: 10.1016/j.vaccine.2021.08.004

•Anaphylaxis can occur after vaccine, drug, food, or environmental exposures.•Validated ICD-10 claims algorithms can help characterize anaphylaxis risk.•We describe construction and validation of an anaphylaxis ICD-10 algorithm in Medicare Fee For Service.•The algorithm revealed vaccine-attributable anaphylaxis is rare in Medicare Fee For Service. Anaphylaxis is a rare, serious allergic reaction. Its identification in large healthcare databases can help better characterize this risk. To create an ICD-10 anaphylaxis algorithm, estimate its positive predictive values (PPVs) in a post-vaccination risk window, and estimate vaccination-attributable anaphylaxis rates in the Medicare Fee For Service (FFS) population. An anaphylaxis algorithm with core and extended portions was constructed analyzing ICD-10 anaphylaxis claims data in Medicare FFS from 2015 to 2017. Cases of post-vaccination anaphylaxis among Medicare FFS beneficiaries were then identified from October 1, 2015 to February 28, 2019 utilizing vaccine relevant anaphylaxis ICD-10 codes. Information from medical records was used to determine true anaphylaxis cases based on the Brighton Collaboration’s anaphylaxis case definition. PPVs were estimated for incident anaphylaxis and the subset of vaccine-attributable anaphylaxis within a 2-day post-vaccination risk window. Vaccine-attributable anaphylaxis rates in Medicare FFS were also estimated. The study recorded 66,572,128 vaccinations among 21,685,119 unique Medicare FFS beneficiaries. The algorithm identified a total of 190 suspected anaphylaxis cases within the 2-day post-vaccination window; of these 117 (62%) satisfied the core algorithm, and 73 (38%) additional cases satisfied the extended algorithm. The core algorithm’s PPV was 66% (95% CI [56%, 76%]) for identifying incident anaphylaxis and 44% (95% CI [34%, 56%]) for vaccine-attributable anaphylaxis. The vaccine-attributable anaphylaxis incidence rate after any vaccination was 0.88 per million doses (95% CI [0.67, 1.16]). The ICD-10 claims algorithm for anaphylaxis allows the assessment of anaphylaxis risk in real-world data. The algorithm revealed vaccine-attributable anaphylaxis is rare among vaccinated Medicare FFS beneficiaries.