Background/Purpose: Streptococcus pneumoniae, Herpes zoster, and influenza infections are common and potentially preventable causes of morbidity and mortality. Vaccinations have been shown to reduce infection rates. Unfortunately, some patients are not offered or refuse these vaccinations. Additionally, younger patients are not eligible for pneumococcal and zoster vaccines based on the current age recommendations. In this, study we aimed to determine incidence, mortality, and national costs of hospital admissions for Streptococcus pneumoniae (Strep pneumo), Herpes Zoster, and influenza infections in patients with rheumatoid arthritis (RA).

Methods: Data were abstracted from the National Inpatient Sample (NIS) Database. This database is the largest collection of inpatient admission data in the USA. It is a nationally representative sample of 20% of hospitalizations from approximately 1000 hospitals.  The numbers in the databases are weighted to optimize national estimates. The NIS was searched for hospitalizations in 2016 containing ICD-10 RA codes M05 and M06 as the principal or secondary diagnosis. We further limited the RA cohort to hospitalizations with a principal discharge diagnosis of Strep pneumo infection (ICD 10 codes J13, M00.1x, A40.3, B95.3, or G00.1), Herpes Zoster (ICD-10 codes B02), and influenza (ICD 10 codes J09 or J10). The total number of discharges, age, race, length of stay (LOS), mortality and total hospital charges were recorded.

Results:

Adult RA patients had 564,835 hospitalizations in 2016. Among the RA patients, there were 1,120 hospitalizations for influenza, 640 hospitalizations for zoster, and 785 hospitalizations for Strep pneumo (table 1).

Of the RA patients hospitalized for influenza, mean age was 68 years, 76% were female, the mean LOS was 4.85 days, aggregate LOS 10,725  days, 2.7% (30/1,120) had in hospital mortality, the mean hospital charges were $46,087 and aggregate hospital charges were $50,696,057.

Of the RA patients hospitalized for zoster, mean age was 70 years, 84% were female, the mean LOS was 5.6 days, aggregate LOS 3,610 days, 2.3% (15/640) had in hospital mortality, the mean hospital charges were $42.909. and aggregate hospital charges were $26,818,325.

Of the RA patients hospitalized for Strep pneumo infections, the mean age was 66 years, 71% were female, the mean LOS was 7 days, aggregate LOS 5,020 days,  8.3% (65/785) had in hospital mortality, the mean hospital charges were $67,001, and the aggregate hospital charges were $52,595,942. These numbers do not account for outpatient or emergency department visits. Additionally, hospital charges are known to be higher than allowed or real charges.

Conclusion: Our analysis shows influenza, zoster, and Strep pneumo infections constituted only 0.5% of RA hospitalizations but in-hospital mortality was high. Additionally, the economic burden of these infections was large with aggregate national hospital charges totaling over $130 million and an aggregate LOS of 19,355 days. Universal vaccinations programs in RA patients should be studied to reduce hospitalizations, cost, morbidity, and mortality.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-incidence-mortality-and-economic-burden-of-potentially-preventable-infections-in-rheumatoid-arthritis-patients/