Background/Purpose: Seasonal influenza poses a large burden on the healthcare system. Patients with certain chronic diseases, such as rheumatoid arthritis (RA), are especially vulnerable to developing severe complications due to influenza.

Methods: A retrospective claims analysis to assess whether influenza patients with RA who received antiviral therapy incur lower Healthcare Resource Use (HRU) and costs compared with propensity score matched untreated influenza RA patients by influenza season (October to April of the following year) for three consecutive years (2016–2019). Data from the IBM MarketScan® Commercial US Database for patients diagnosed with RA [1 hospitalization or 2 outpatient claims for RA on separate dates at least 30 days apart] were selected if they contracted influenza (first instance of an influenza diagnosis), in the outpatient or emergency department (ED) setting each season. HRU (hospitalizations, outpatient visits, or pharmacy fills) and costs were assessed at 14 days & 28 days post-fill date. For the matched untreated group, proxy fill date was determined based on the number of days from index flu diagnosis to first antiviral treatment of matched cases.

Results: From a total of 568,228 patients with a diagnosis of RA, 7743 (1.4%) were diagnosed with influenza during 1 of 3 influenza seasons (2016–2017, 2017–2018, or 2018–2019). Among the 4946 patients with RA meeting the study inclusion criteria (≥18 years old, continuous enrollment) who were diagnosed with influenza from 2016–2019, 3371 (68.2%) received antiviral influenza therapy, 3331 of these were not hospitalized before filling the treatment prescription, and 2638 remained in the sample after propensity score matching. Of 1442 (29.2%) patients with RA and influenza who did not receive antiviral influenza treatment within 30 days after diagnosis, 1348 were not hospitalized and 1319 remained in the sample after matching. At 14 days of follow-up after initiation of antiviral treatment fill, most ( >76%) treated and untreated patients had all-cause HRU, and >90% had all-cause HRU after 28 days of follow-up. Outpatient visits were the most common type of HRU and occurred among >70% of treated and untreated patients after 28 days of follow-up. The mean (SD) number of all-cause outpatient visits was 1.21 (1.84) versus 0.96 (1.20) after 14 days (p < 0.001) and 2.24 (2.91) versus 1.94 (2.10) after 28 days (p = 0.0010), for untreated vs treated, respectively. After 28 days, all-cause ED visits were more common among untreated (8.8%) than treated patients (6.5%) across all influenza seasons; (p = 0.0118). Inpatient visits occurred among ~2% of treated and untreated patients during 28 days of follow-up. Mean all-cause HRU-related costs after 28 days of follow-up were >$500 for treated vs $723 for untreated for inpatient stays and >$150 for outpatient visits across both treatment cohorts.

Conclusion: In a large real-world sample of patients with RA and influenza, antiviral treatment was associated with lower healthcare burden compared with no treatment in various categories evaluated.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/antiviral-use-and-healthcare-resource-utilization-among-patients-with-rheumatoid-arthritis-and-influenza-in-three-influenza-seasons-2016-2019/