Quantifying cause-related mortality in Australia, incorporating multiple causes: observed patterns, trends and practical considerations

What can multiple causes of death tell about cardiovascular mortality during COVID-19 pandemic in the United States?

BACKGROUND

The COVID-19 pandemic may have caused an underestimation of cardiovascular disease (CVD) mortality, as COVID-19 was predominantly recorded as the underlying cause of death. This study investigates CVD-related excess mortality and recording of CVD on the death certificates during 2020-2021, considering underlying (underlying causes of death (UCD)), immediate and contributory causes.

METHODS

We utilize US Multiple-Cause-of-Death Mortality Data. Excess deaths are assessed by comparing actual 2020-2021 deaths with Seasonal Autoregressive Integrated Moving Average model predictions. To understand changes in cause-of-death recording, we use the standardized ratio of multiple to underlying causes (SRMU).

RESULTS

Excess CVD mortality is most prominent in contributory causes, including hypertensive disease, essential hypertension, and acute myocardial infarction. While excess of contributory CVDs generally decreased in 2021, acute myocardial infarction, pulmonary heart diseases and other circulatory diseases showed a continual increase. Changes in SRMU from 2020 to 2021, compared to 2010-2019, reveal shifts in coding practices, particularly for pulmonary heart, cerebrovascular diseases, non-rheumatic valve disorders and heart failure.

CONCLUSIONS

The COVID-19 pandemic has significantly increased CVD-related mortality, which is not fully captured in conventional analyses based solely on the UCD. The trend of coding CVDs as non-underlying causes of death accelerated during 2020-2021. Multiple-causes-of-death should be employed to evaluate mortality when new leading cause of death emerges.

Prevalence of Multiple Causes of Death Within Young and Middle-Aged People Experiencing Sudden Cardiac Arrest

BACKGROUND

Multiple causes of death are increasingly reported, particularly in older populations. Rates of multiple causes of young sudden death have not been quantified.

METHOD

The End Unexplained Cardiac Death (EndUCD) registry was utilised to identify cases of young sudden death (aged 1-50 years) referred for forensic assessment from April 2019 to April 2022. Causes of death were coded according to whether one or more underlying causes of death were identified. Patients were compared according to the number of causes of death, with significant predictors assessed using logistic regression analysis.

RESULTS

1,085 cases of sudden death were identified. 263 (24.2%) cases had more than one competing cause of their sudden death. The most common multi-causal associations identified were dual non-cardiac causes of the sudden death (n=68), cardiomyopathy with non-cardiac event (n=64) and coronary artery disease with non-cardiac cause (n=63). Multi-causal death was more common in those undergoing comprehensive autopsy examination (95.8% vs 77.6%, p<0.0001), and in the setting of higher body mass index (median 31.3 kg/m2 vs 29.9 kg/m2, p=0.01), older age (44.3 years vs 41.4 years, p<0.0001), non-ventricular cardiac arrest rhythm (93.2% vs 87.3%, p=0.009), and smoking (22.8% vs 14.2%, p=0.001). The strongest predictor of multiple pathologies was comprehensive autopsy examination compared with external inspection, full-body post-mortem computed tomography and review of ancillary documentation and investigations (odds ratio 6.49, 95% confidence interval 3.47-12.14).

CONCLUSIONS

One-quarter of young sudden deaths have more than one underlying cause, highlighting the value of comprehensive investigations including autopsy. Awareness of the complexity of young sudden death is important, along with multidisciplinary involvement to ensure all contributors to death are identified.

Racial/Ethnic disparities in the chains of morbid events leading to death: network analysis of US multiple cause of death data

Multiple-cause-of-death data have not yet been applied to the study of racial/ethnic differences in causal chains of events leading to death, nor they have been used to examine racial/ethnic disparities in cause-of-death certification. We use publicly available 2019 US death certificate data to reassemble chains of morbid events leading to death. From them, we construct and analyze directed multiple cause of death networks by race and sex of deaths aged 60+. Three perspectives to measure disparities are employed: (i) relative prevalence of cause-of-death-pairs, (ii) strength of associations between diseases, (iii) similarities in transition matrices. Non-Hispanic Blacks (NHB) had overall lower prevalence of cause of death pairs, Hispanics (HIS) were burdened more by alcohol-related mortality and Asian and Pacific Islanders (API) exceeded in transitions to cerebrovascular diseases. Lower similarity was observed in transitions to external causes of death, dementia and Alzheimer's disease, pulmonary heart diseases, interstitial respiratory diseases, and diseases of the liver. After excluding rare diseases, the similarity further decreased for ill-defined conditions, diabetes mellitus, other cardiovascular diseases, diseases of the pleura, and anemia. To sum up, races/ethnicities not only vary in structure and timing of death but they differ in morbid processes leading to death as well.

Concordance between COVID-19 mortality statistics derived from clinical audit and death certificates in Östergötland county, Sweden

OBJECTIVES

Despite early notions that correct attribution of deaths caused by SARS-CoV-2 infection is critical to the understanding of the COVID-19 pandemic, three years later, the accuracy of COVID-19 death counts is still contested. We aimed to compare official death statistics with cause-of-death assessments made in a clinical audit routine by experienced physicians having access to the full medical record.

STUDY DESIGN

Health service quality evaluation.

METHODS

In Östergötland county (pop. 465,000), Sweden, a clinical audit team assessed from the start of the pandemic the cause of death in individuals having deceased after testing positive for SARS-CoV-2. We estimated the concordance between official data on COVID-19 deaths and data from the clinical audit using correlations (r) between the cause-of-death categories and discrepancies between the absolute numbers of categorised deaths.

RESULTS

The concordance between the data sources was poor regarding whether COVID-19 was the underlying or a contributing cause of death. Grouping of the causes increased the correlations to acceptable strength. Also including deaths implicated by a positive SARS-CoV-2 test in the clinical categorisation of COVID-19 deaths reduced the difference in absolute number of deaths; with these modifications, the concordance was acceptable before the COVID-19 vaccination program was initiated (r = 0.97; symmetric mean absolute percentage error (SMAPE) = 19%), while a difference in the absolute numbers of deaths remained in the vaccination period (r = 0.94; SMAPE = 35%).

CONCLUSIONS

This study highlights that carefulness is warranted when COVID-19 death statistics are used in health service planning and resonates a need for further research on cause-of-death recording methodologies.

Analysis of Multiple Causes of Death: A Review of Methods and Practices

BACKGROUND

Research and reporting of mortality indicators typically focus on a single underlying cause of death selected from multiple causes recorded on a death certificate. The need to incorporate the multiple causes in mortality statistics-reflecting increasing multimorbidity and complex causation patterns-is recognized internationally. This review aims to identify and appraise relevant analytical methods and practices related to multiple causes.

METHODS

We searched Medline, PubMed, Scopus, and Web of Science from their incept ion to December 2020 without language restrictions, supplemented by consultation with international experts. Eligible articles analyzed multiple causes of death from death certificates. The process identified 4,080 items of which we reviewed 434 full-text articles.

RESULTS

Most articles we reviewed (76%, n = 332) were published since 2001. The majority of articles examined mortality by "any- mention" of the cause of death (87%, n = 377) and assessed pairwise combinations of causes (57%, n = 245). Since 2001, applications of methods emerged to group deaths based on common cause patterns using, for example, cluster analysis (2%, n = 9), and application of multiple-cause weights to re-evaluate mortality burden (1%, n = 5). We describe multiple-cause methods applied to specific research objectives for approaches emerging recently.

CONCLUSION

This review confirms rapidly increasing international interest in the analysis of multiple causes of death and provides the most comprehensive overview, to our knowledge, of methods and practices to date. Available multiple-cause methods are diverse but suit a range of research objectives. With greater availability of data and technology, these could be further developed and applied across a range of settings.