Elsevier

Annals of Epidemiology

Volume 13, Issue 2, February 2003, Pages 144-150
Annals of Epidemiology

Original report
Acute Pyelonephritis in US Hospitals in 1997: Hospitalization and In-hospital Mortality

https://doi.org/10.1016/S1047-2797(02)00272-7Get rights and content

Abstract

PURPOSE: To describe the 1997 incidence of hospitalization for acute pyelonephritis in the US and the risk factors for in-hospital mortality associated with acute pyelonephritis.

METHODS: Cases were defined as those with ICD9-CM codes corresponding to acute pyelonephritis in the 1997 Health Care Cost and Utilization Project (HCUP) Nationwide Inpatient Sample (NIS). Frequencies and calculations were weighted to produce either national or state estimates. Hospitalization rates were calculated using 1997 US Census Bureau population projections for the denominator.

RESULTS: Females were almost five times as likely as males to be hospitalized for acute pyelonephritis (11.7/10,000 vs. 2.4/10,000), but males had higher mortality rates (16.5/1000 vs. 7.3/1000); 30% greater after adjustment. Hospitalization and in-hospital mortality rates increased with age, but not with diabetes. Mortality rates increased with number of procedures, diagnoses and having a major diagnostic category other than disorders of the kidney and urinary tract. Persons living in zip codes with lower median incomes were also at higher risk of mortality. There was little variation in mortality by hospital size, ownership, location or teaching status.

CONCLUSION: In hospital mortality for pyelonephritis was associated with patient rather than hospital characteristics suggesting uniform application of standard care across hospitals and populations.

Section snippets

Selected Abbreviations and Acronyms

HCUP = Healthcare Cost and Utilization Project

NIS = Nationwide Inpatient Sample

AHRQ = Agency for Healthcare Research and Quality

IRB = Institutional Review Board

Data Source

Hospitalization rates and in-hospital mortality rates were determined using the 1997 Healthcare Cost and Utilization Project (HCUP) Nationwide Inpatient Sample (NIS) Release 6. The NIS is the largest inpatient database in the United States that includes all medical insurance payers. It contains over 100 clinical and non-clinical variables describing approximately 7.1 million discharges from 1012 hospitals in 22 states. This approximates a 20-percent sample of US community hospitals for 1997,

Demographic Characteristics

For every age and ethnic group, females had higher hospitalization rates than males, with the exception of Asian/Pacific islanders, native Americans, and persons aged 80 years and older, the rates of in-hospital mortality were lower (Table 1). For both males and females, hospitalization rates increased with age. Males hospitalized with acute pyelonephritis tended to be older than females (average: 51 versus 39 years) and mortality occurred almost exclusively among those aged 40 years and older.

Discussion

Acute pyelonephritis resulted in the hospitalization of 191,566 people in the US in 1997, somewhat higher than the 172,000 inpatients with an all-listed diagnosis of acute pyelonephritis discharged from short-stay nonfederal hospitals in 1993 (8). After adjustment for gender, age, race, median income of the patient's zip code, number of procedures, number of diagnoses, and major diagnosis category, there was no association of in-hospital mortality with hospital characteristics such as admission

Conclusions

We describe the 1997 incidence of hospitalization for acute pyelonephritis in the US and the risk factors for in-hospital mortality associated with acute pyelonephritis. In hospital mortality for pyelonephritis was more associated with patient rather than hospital characteristics suggesting uniform application of standard care across hospitals and populations. Males, individuals over age 60, and individuals with serious co-morbidities are at the highest risk of in-hospital mortality. While

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