Abstract
AimsThe usefulness of mortality statistics relies on the validity of death certificate diagnosis. However, diagnosing the causal sequence of conditions leading to death is not simple. We examined diagnostic support for fatal acute myocardial infarction (AMI) and investigated its association with regional variation.Methods and resultsFrom Danish nationwide registers, we identified the study population (N = 3,244,051) of whom 36,669 individuals were recorded with AMI as the underlying cause-of-death between 2002 and 2015. We included clinical diagnoses, procedures, and claimed prescriptions related to atherosclerotic disease to evaluate the level of diagnostic support for fatal AMI in three diagnostic groups (Definite; Plausible; Uncertain). Adjusted mortality rates, rate ratios, and odds ratios were estimated for each AMI category, stratified by hospital region using multivariable regression models. More than one-third (N = 12,827, 35%) of deaths reported as fatal AMI had uncertain diagnostic support. The largest regional variation in AMI mortality rate ratios, varying from 1.16 (95%CI:1.02;1.31) to 1.62 (95%CI:1.43;1.83), was found among cases with uncertain diagnostic supportive data. Substantial inter-regional differences in the degree to which death occurs outside hospital [OR: 1.01 (95%CI:0.92;1.12) - 1.49 (95%CI:1.36;1.63)] and general practitioners determining the cause-of-death at home were present. Minor regional differences [OR: 0.96 (95%CI:0.85;1.07) - 1.16 (95%CI:1.04;1.29)] in in-hospital AMI mortality were observed.ConclusionThere is significant regional variation associated with recording AMI as a cause-of-death. This variation is predominately based on death certificate diagnoses without diagnostic supportive evidence. Studies of fatal AMI should include a stratification on supportive evidence of the diagnosis.
Highlights
Cause-of-death statistics derived from death certificates are important for monitoring epidemiologic patterns and developing new healthcare strategies
To assess diagnostic support for fatal acute myocardial infarction (AMI) we examined these deaths using individually based comparison of death certificates with hospitalisations and discharge diagnoses, surgery, outpatient procedures, and prescriptions related to ischemic heart disease (IHD)
Among the 36,667 citizens recorded with AMI as the underlying cause-of-death, 56.3% occurred in men, 54.2% occurred in hospitals, and the median age at death in the study population was 80.5 [Q1,Q3: 71.3, 87.1]
Summary
Cause-of-death statistics derived from death certificates are important for monitoring epidemiologic patterns and developing new healthcare strategies. Whether low validity of the cause-of-death statements in death certificates is responsible for the variation remains unexplored. Mortality statistics rely on the coding done by the individual physicians in which the underlying cause-of-death is estimated with some degree of uncertainty when an autopsy is not performed. The data available for the physicians producing the death certificates may vary markedly. The physician may have a hospital file with multiple diagnostic information or, at the other extreme, the physician may have hardly any information. Coding practices in the latter case could, in principle, markedly influence the mortality rate of reported acute myocardial infarction (AMI) and other diseases that physicians are inclined to diagnose when there is little clinical information available
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