Diabetes mellitus as cause of death

Certification and coding of diabetes mellitus as a cause of death were investigated by sending a random sample of 300 physicians a set of 6 case histories. Of these, 228 (76%) participated in the study by completing a death certificate for each of these cases. The certificates were subsequently coded by the Central Bureau of Statistics. The main finding was that doctors varied enormously in the way in which diabetes mellitus was mentioned on the death certificate: not at all, as a contributory cause of death, or as an underlying cause of death. Coding removes some of the inconsistencies, but induces additional variation: a higher age of the deceased is associated with a lower probability of having diabetes mellitus coded as the underlying cause of death, and a higher probability of not receiving a code of diabetes mellitus at all. It is concluded that the cause-of-death registration does not provide an accurate picture of the contribution of diabetes mellitus to the cause-of-death pattern of the Netherlands. This is due, amongst other things, to the conceptualization of causes of death on which the registration is based. On the other hand, changes in certification and coding practice within the current system may already lead to some improvement.