Stroke has fallen from the second to the fourth leading cause of death in the United States without large declines in stroke incidence or case fatality. We explored whether this decline may be attributable to changes in mortality attribution methodology.

Multicause mortality files from 2000 to 2008 were used to compare changes in reporting of stroke as underlying cause of death (UCOD) with changes in death certificates reporting any mention (AMCOD) of stroke. In addition, the UCOD/AMCOD ratio was calculated for the 6 leading organ and disease-specific causes of death. If stroke mortality is underestimated by the system of mortality attribution, we hypothesized that we would find: (1) a greater decline in stroke as UCOD than as AMCOD; and (2) a decline in the UCOD/AMCOD ratio compared with other causes of death.

Age-adjusted death rates for stroke as UCOD (61 per 100 000 in 2000 versus 41 in 2008) and AMCOD (102 per 100 000 versus 68) both declined by 33%. The ratio of UCOD to AMCOD for stroke did not change over time (0.595 in 2000 versus 0.598 in 2008). Changes in UCOD/AMCOD ratio for the diagnoses that surpassed stroke as UCOD were too small (no change for lung cancer and a slight increase from 0.49 to 0.52 for chronic lower respiratory diseases) to explain stroke's decline as UCOD.

Changes in mortality attribution methodology are not likely responsible for stroke's decline as a leading cause of death. The discordant trends in incidence, case fatality, and mortality require further study.