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Using severity measures to predict the likelihood of death for pneumonia inpatients

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Abstract

OBJECTIVE: To see whether predictions of patients’ likelihood of dying in-hospital differed among severity methods.

DESIGN: Retrospective cohort.

PATIENTS: 18,016 persons 18 years of age and older managed medically for pneumonia; 1,732 (9.6%) in-hospital deaths.

METHODS: Probability of death was calculated for each patient using logistic regression with age, age squared, sex, and each of five severity measures as the independent variables: 1) admission MedisGroups probability of death scores; 2) scores based on 17 admission physiologic variables; 3) Disease Staging’s probability of mortality model; the Severity Score of Patient Management Categories (PMCs); 4) and the All Patient Refined Diagnosis-Related Groups (APR-DRGs). Patients were ranked by calculated probability of death; 5) rankings were compared across severity methods. Frequencies of 14 clinical findings considered poor prognostic indicators in pneumonia were examined for patients ranked differently by different methods.

RESULTS: MedisGroups and the physiology score predicted a similar likelihood of death for 89.2% of patients. In contrast, the three code-based severity methods rated over 25% of patients differently by predicted likelihood of death when compared with the rankings of the two clinical data-based methods (MedisGroups and the physiology score). MedisGroups and the physiology score demonstrated better clinical credibility than the three severity methods based on discharge abstract data.

CONCLUSIONS: Some pairs of severity measures ranked over 25% of patients very differently by predicted probability of death. Results of outcomes studies may vary depending on which severity method is used for risk adjustment.

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Authors and Affiliations

  1. the Division of General Medicine and Primary Care, Department of Medicine, Harvard Medical School, Beth Israel Hospital, 330 Brookline Avenue, 02215, Boston, MA

    Lisa I. Iezzoni MD, MSc & Yevgenia D. Mackiernan BA

  2. the Charles A. Dana Research Institute, USA

    Lisa I. Iezzoni MD, MSc & Yevgenia D. Mackiernan BA

  3. the Harvard-Thorndike Laboratory, USA

    Lisa I. Iezzoni MD, MSc & Yevgenia D. Mackiernan BA

  4. Health Care Management Program and Operations Management Department, School of Management, Boston University, USA

    Michael Shwartz PhD

  5. Health Care Research Unit, Section of General Internal Medicine, Evans Memorial Department of Clinical Research and Medicine, Boston University Medical Center, USA

    Arlene S. Ash PhD

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  1. Lisa I. Iezzoni MD, MSc
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  2. Michael Shwartz PhD
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  3. Arlene S. Ash PhD
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  4. Yevgenia D. Mackiernan BA
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Additional information

Supported by the Agency for Health Care Policy and Research, under grant RO1 HS06742-03. The views expressed are solely those of the authors.

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Iezzoni, L.I., Shwartz, M., Ash, A.S. et al. Using severity measures to predict the likelihood of death for pneumonia inpatients. J Gen Intern Med 11, 23–31 (1996). https://doi.org/10.1007/BF02603481

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