Comparing causes of death of Hodgkin lymphoma and breast cancer patients between medical records and cause-of-death statistics.

Abstract

METHODS

Two hospital-based cohorts comprising 1,215 HL patients who died in the period 1980-2013 and 714 BC patients who died in the period 2000-2013 were linked with cause-of-death statistics files. The level of agreement was assessed for common underlying causes of death using Cohen's kappa, and original death certificates were reviewed when COD_DC and COD_MR showed discrepancies. We examined the influence of using COD_DC or COD_MR on standardized mortality ratio (SMR) estimates.

RESULTS

Agreement for the most common causes of death, including selected malignant neoplasms and circulatory and respiratory diseases, was 81% for HL patients and 97% for BC patients. HL was more often reported as COD_DC (COD_DC=33.1% vs. COD_MR=23.2%), whereas circulatory disease (COD_DC=15.6% vs. COD_MR=20.9%) or other diseases potentially related to HL treatment were more often reported as COD_MR. Compared to SMRs based on COD_DC, SMRs based on COD_MR complemented with COD_DC were lower for HL and higher for circulatory disease.

OBJECTIVE

Obtaining accurate data about causes of death may be difficult in patients with a complicated disease history, including cancer survivors. This study compared causes of death derived from medical records (COD_MR) with causes of death derived from death certificates (COD_DC) as processed by Statistics Netherlands of patients primarily treated for Hodgkin lymphoma (HL) or breast cancer (BC).

CONCLUSION

Overall, we observed high levels of agreement between COD_MR and COD_DC for common causes of death in HL and BC patients. Observed discrepancies between COD_MR and COD_DC frequently occurred in the presence of late effects of treatment for HL.