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International classification of diseases codes showed modest sensitivity for detecting community-acquired pneumonia

Ewoudt M W van de Garde1, Jan Jelrik Oosterheert, Marc Bonten

  • 1Division of Pharmacoepidemiology and Pharmacotherapy, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, PO Box 80082, 3506 TB Utrecht, The Netherlands.

Journal of Clinical Epidemiology
|July 4, 2007
PubMed
Abstract

Insights

International Classification of Diseases (ICD-9-CM) coding has modest sensitivity for detecting community-acquired pneumonia in hospital records. At least a quarter of pneumonia cases were missed, with sensitivity decreasing with longer hospital stays.

Area of Science:

  • Medical Informatics
  • Epidemiology
  • Health Services Research

Background:

  • Accurate coding of community-acquired pneumonia is crucial for epidemiological surveillance and resource allocation.
  • Hospital administrative databases rely on International Classification of Diseases (ICD-9-CM) codes for case identification.

Purpose of the Study:

  • To determine the sensitivity of ICD-9-CM codes in identifying hospitalized community-acquired pneumonia.
  • To explore factors influencing misclassification of pneumonia cases in administrative data.

Main Methods:

  • Microbiological data identified 293 community-acquired pneumonia patients across seven Dutch hospitals.
  • ICD-9-CM codes (principal and secondary) were extracted from discharge records.
  • Sensitivity was calculated, and patient characteristics were compared between correctly and incorrectly coded groups.

Main Results:

  • Overall ICD-9-CM coding sensitivity was 72.4% (principal code) and 79.5% (combined codes).
  • Sensitivity was notably lower for pneumococcal pneumonia (35%) and pneumonia with other specified organisms (18.3%).
  • Longer hospital stay duration negatively correlated with coding sensitivity (P=0.01).

Conclusions:

  • ICD-9-CM coding demonstrates limited sensitivity for detecting community-acquired pneumonia in hospital databases.
  • A significant proportion of pneumonia cases (at least 25%) may go undetected.
  • Coding sensitivity is inversely related to the length of a patient's hospital stay.

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