Accuracy in Using Pneumonia as an Underlying Cause in the Cause-of-Death Register
Boo Svartbo, Linda Nilsson, Anders Eriksson, Gösta Bucht, Lars Age Johansson, and Lars Olov Bygren
Background. Pneumonia is often mistakenly registered as the underlying cause of death, thus blurring the analysis of causes and correlations. The present study validated pneumonia as the underlying cause of death in patients aged up to 75 years in the official register. Methods. For a random sample of 1,376 cases, a new death certificate was completed "blind" on the basis of hospital records from the last episode of care. The degree of agreement with the original death certificate was measured with Cohens kappa. Results. Of 226 registered cases with pneumonia as the underlying cause of death, 53 (23%) were substantiated by the records. Conversely, of 1,079 cases registered as nonpneumonia, five were found to have pneumonia as the underlying cause of death. The degree of agreement was fair. For younger patients and for certificates from the Institutes of Forensic Medicine it was substantial. A clinical autopsy did not guarantee a high degree of agreement. Conclusion. Other causes of death are concealed in cases registered as pneumonia deaths. The error is probably important when (small) clinical cohorts are followed up.
Mortality statistics; validity; international classification of diseases; pneumonia.