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  • Open Access

Trend in the severity of illness and hospital mortality rates of ICU patients over a 10-year period

  • 1,
  • 1,
  • 1,
  • 1,
  • 1 and
  • 1
Critical Care200610 (Suppl 1) :P419

https://doi.org/10.1186/cc4766

  • Published:

Keywords

  • Mortality Rate
  • Logistic Regression
  • Medical Record
  • Retrospective Study
  • Logistic Regression Model

Objective

To describe the trend in the severity of illness and hospital mortality rate of patients admitted to the ICU over a 10-year period.

Methods

This retrospective study involves the analysis of a prospectively collected APACHE III database of patients admitted to the ICUs of a tertiary medical center from 1995 to 2004. We created a customized logistic regression model for predicting hospital mortality and calculated the severity of illness and the standardized mortality ratio (SMR) for each year of the 10-year study period.

Results

Excluding patients who did not authorize their medical records to be reviewed for research and readmissions, 46,618 admissions were included in the study. The mean (SD) first ICU day APACHE III score was 47.2 (25.5). The overall hospital mortality rate was 9.7%. The area under the curve (95% CI) for the customized model was 0.871 (0.866–0.876) and the Hosmer–Lemeshow statistics was 30. The average (95% CI) predicted and observed mortality rates and SMR for each year of the study period are presented in Table 1.

Table 1

Year

Predicted death [% (95% CI)]

Observed death [% (95% CI)]

SMR (95% CI)

1995

5.9 (5.6–6.3)

6.8 (6.0–7.8)

1.16(1.01–1.32)

1996

6.6 (6.3–6.9)

7.2 (6.5–7.9)

1.09(0.98–1.20)

1997

7.0 (6.7–7.3)

7.8 (7.1–8.5)

1.11(1.01–1.22)

1998

8.3 (7.9–8.6)

9.2(8.5–10.0)

1.11(1.01–1.21)

1999

9.0 (8.6–9.4)

10.7(9.9–11.7)

1.19(1.09–1.30)

2000

10.8(10.3–11.2)

10.8(9.9–11.8)

1.00(0.91–1.10)

2001

12.4(11.9–12.9)

12.7(11.8–13.7)

1.02(0.94–1.11)

2002

12.9(12.4–13.5)

12.7(11.4–13.4)

0.96(0.88–1.04)

2003

12.8(12.3–13.3)

11.2(10.4–12.2)

0.88(0.81–0.95)

2004

12.1(11.7–12.7)

8.8 (8.0–9.7)

0.73(0.66–0.80)

Conclusion

Despite the increase in the severity of illness, the adjusted mortality rate of patients admitted to the ICU has declined recently.

Authors’ Affiliations

(1)
Mayo Clinic College of Medicine, Rochester, MN, USA

Copyright

© BioMed Central Ltd 2006

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