Background/Purpose: To examine the time-trends in hospitalized infections in lupus and the factors associated with healthcare utilization and in-hospital mortality.

Methods: We used the U.S. National Inpatient Sample data from 1998-2016 to examine the epidemiology, time-trends and outcomes of five, common hospitalized infections in people with lupus, namely, pneumonia, sepsis/bacteremia, urinary tract infection (UTI), skin and soft tissue infections (SSTI) and opportunistic infections (OI). Time-trends were compared using the Cochran Armitage test. Multivariable-adjusted logistic regression models examined the factors associated with healthcare utilization (hospital stay >3 days, hospital charges above median, or discharge to non-home setting) and in-hospital mortality.

Results: There were 49,637,826 hospitalizations with infections in people without lupus and 328,744 in those with lupus. The average age of patients with lupus with a primary diagnosis of one of the infections was 52.5 years, with a median of 51.9 years (Table 1). Deyo-Charlson score greater than two accounted for 65% of people with lupus and infection, and lowest income quartile for 30% . The lowest income quartile accounted for a third of all lupus and lupus with primary infection hospitalizations.

Hospitalization for any of these 5 infections (composite) increased from 10.7% of all lupus hospitalizations in 1998-2000 to 15.6% in 2015-16 (10,748 vs. 15,645 per 100,000). The corresponding rate of composite infection in the general NIS population increased from 5.8% in 1998-2000 to 10.2% in 2015-16 (5,836 vs. 10,171 per 100,000).

The hospitalization rate /100,000 claims in 1998-2000 versus 2015-2016 (and increase) were as follows: OI, 1.13 vs. 1.61 (1.2-fold); SSTI, 4.78 versus 12.2 (2.5-fold); UTI, 1.94 versus 6.12 (3.2-fold); pneumonia, 15.09 vs. 17.05 (1.1-fold); and sepsis, 6.31 vs. 39.64 (6.3-fold; Figure 1).  In 2011-12, sepsis surpassed pneumonia as the most common hospitalized infection in people with lupus. In multivariable-adjusted models, sepsis diagnosis, older age, Deyo-Charlson score ≥2, Medicare or Medicaid insurance, and urban hospital location were significantly associated with increased odds of in-hospital mortality and all healthcare utilization outcomes; and the black race was significantly associated with increased odds of healthcare utilization (Table 2).

Conclusion: Our study found increasing rates of hospitalized infections in lupus over time, and the surpassing of pneumonia by sepsis as the most common infection. We identified risk factors associated with poorer healthcare utilization outcomes and in-hospital mortality. These findings can inform patients, providers and policy-makers regarding lupus infection burden and lead to interventions/pathways to improve outcomes.

Table 1. Demographic characteristics of infection hospitalizations in people with versus without lupus

Table 2. Multivariable-adjusted correlates of healthcare utilization and mortality for hospitalized infections in lupus

Figure 1 title. Time-trends in the rates of various infections in people with lupus with varying denominator of total National Inpatient Sample claims (A) or total lupus claims (B) Figure 1 legend Infection rates are per 100,000 NIS claims (A) and per 100,000 lupus claims (B). The y-axis scales are different for the two panels. The x-axis shows study time-periods from 1998 to 2016

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/hospitalized-infections-in-lupus-a-nationwide-study-of-types-of-infections-time-trends-healthcare-utilization-and-in-hospital-mortality/