Determining Cause of Death in Prostate Cancer: Are Death Certificates Valid?

Abstract

Accurate assessment of cause of death (COD) is important for determining cause-specific survival in cancer research. It is possible to reliably ascertain COD by meticulous review of inpatient and outpatient medical records with the use of predetermined clinical algorithms (1). Unfortunately, this method, although useful for small retrospective studies, is impractical for large datasets and national tumor registries that are commonly used for cancer research. When these large databases are used, COD is assigned with a standardized decision algorithm that uses International Classification of Diseases, ninth revision (2), codes to assign both immediate and underlying COD (3). However, this methodology is unreliable (4,5), particularly when patients are older or have considerable comorbidity, as is the case in prostate cancer (6,7). In a study of mortality trends, Grulich et al. (8) estimated that inaccuracies in death certification and coding accounted for up to 46% of the noted increase in prostate cancer mortality seen in England and Wales from 1970 through 1990. By contrast, in men with prostate cancer identified through the Connecticut Tumor Registry, Albertsen et al. (9) found a high level of agreement between the underlying COD, determined by a review of the medical records, and death certificate data. It is important that prostate cancer-related mortality ascertained by death certificate be reliable because studies that use large datasets, such as the Surveillance, Epidemiology, and End Results (SEER)¹ Program, may be used to determine whether interventions (e.g., screening, radical prostatectomy, or radiotherapy) are effective.