Acute Kidney Injury Due to Diarrheal Illness Requiring Hospitalization: Data from the National Inpatient Sample

Abstract

Background: Diarrheal illness is a major reason for hospitalization, but data on consequent acute kidney injury (AKI) are sparse.

Objective: To determine the incidence of AKI in infectious and non-infectious diarrheal illness requiring hospitalization and to identify correlates and outcomes of diarrhea-associated AKI.

Design: Using data from the 2012 National Inpatient Sample (NIS), we created a cohort of patients with a primary diagnosis of diarrheal illness. Diarrheal illness, disease correlates, and AKI were defined by ICD-9 diagnosis codes. We used logistic regression with backward variable selection to determine factors independently associated with AKI in infectious and non-infectious diarrheal illness, as well as to determine the association of AKI with in-hospital mortality. We used generalized linear models to assess differences in length of stay and costs of hospitalization.

Main measures: The primary outcome was AKI in hospitalized diarrheal illness. Secondary outcomes were in-hospital mortality, length of stay, and cost of hospitalization associated with AKI.

Key results: One in ten adults hospitalized with diarrheal illness experienced AKI, with higher incidence rates in older adults. Chronic kidney disease (CKD) and hypertension were associated with increased odds of AKI (all diarrhea OR 4.81, 95% CI 4.52 to 5.12 and OR 1.33, 95% CI 1.27 to 1.40, respectively). AKI in diarrheal illness was associated with substantial increase in mortality (OR 5.05, 95% CI 4.47 to 5.72), length of stay (mean increase 1.7 days [95% CI 1.6 to 1.8]), and cost of hospitalization (mean increase $4411 [95% CI 4023 to 4800]).

Conclusion: Acute kidney injury is common and consequential among patients hospitalized for diarrheal illness. Persons with CKD and hypertension are the most susceptible, possibly due to diminished renal reserve and exacerbating effects of treatment with diuretics and renin-angiotensin-aldosterone system blockers. Proactive management of these unique pharmacologic and physiologic factors is necessary to prevent AKI in this vulnerable population.

Keywords: clinical epidemiology; hospital medicine; prevention; renal disease.

Figure 1

Incidence of AKI in infectious, non-infectious, and all diarrheal illness among hospitalized adults, by age-group (18–44, 45–64, 65–79, and 80 and above). Incidence rates are expressed per 100 person-years. Brackets represent 95% CI.

Figure 2

Comorbidities associated with increased odds of AKI in hospitalized infectious diarrheal illness (a). Comorbidities associated with increased odds of AKI in hospitalized non-infectious diarrheal illness (b). Bar length represents relative importance score based on the absolute standardized coefficient.