Use and Characteristics of Clinical Coding for Post-COVID Conditions in a Retrospective US Cohort.

Context: Little is known about when and how the ICD-10-CM diagnosis code for Post-COVID Conditions (PCC; U09.9) is being used to document PCC.

Objectives: To examine the use and characteristics of clinical coding for PCC.

Design: A retrospective cohort.

Setting: Transaction-level medical encounters, laboratory testing results, pharmacy claims, and medical claims for inpatient and outpatient care from the HealthVerity database.

Participants: 382 400 US adults and children with private health insurance, Medicare, and Medicaid who had U09.9 code documented during October 1, 2021-June 30, 2023.

Outcome measures: Count of first use of the U09.9 code, (a) overall, over time, and proportion by provider type; (b) prevalence of PCC-associated incident conditions co-documented with U09.9; (c) number of documented SARS-CoV-2 infections preceding U09.9; (d) timing between infection and U09.9; (e) encounters during the 6 months following first use of U09.9.

Results: Overall, 0.6% of 65 556 068 patients had a PCC diagnosis code (64.6% female; 6 in 10 had ≥1 preexisting conditions). The highest count of new U09.9 codes occurred during Quarter 1 and Quarter 3 of 2022 and was documented by a variety of provider specialties. The most prevalent co-documented PCC-associated incident conditions were respiratory (13.4%) and malaise and fatigue (7.8%). Only 62% of patients had SARS-CoV-2 infection documented preceding U09.9; median time to PCC documentation was 17.0 days (interquartile range [IQR] = 5.0, 61.0). Patients with ≥1 encounters during which PCC was documented in the 6 months following their index encounter (n = 109 794) had, on average, 25.5 additional encounters (median = 14 [IQR = 7, 29]).

Conclusions: Our study describes the sociodemographic characteristics, complex clinical manifestations, and high healthcare use of patients following a PCC diagnosis. These findings may inform efforts to identify and treat PCC, inform healthcare planning, and support efforts to educate clinicians about the definition of PCC and accurate application of the code.