Vital Statistics Annual Report 2015

Standardised death rates comparison between EU member states

For comparison purposes between the EU member states, the age effect can be taken into account by using a standard population. The (age) standardised death rate is a weighted average of age-specific mortality rates. The weighting factor is the age distribution of a standard reference population. The standard reference population used is the European standard population as defined by Eurostat in 2012.  The new European Standard Population (ESP) is the unweighted average of the individual populations of EU-28 plus EFTA countries in each 5-years age band (with the exception of under 5 and the highest age group of 95+).  The ESP is calculated on the basis of the 2010-based population projections, averaged over the period 2011-30.

As method for standardisation, the direct method is applied.  Standardised death rates are calculated for the age group 0-64 ('premature death') and for the total of ages.  As most causes of death vary significantly with people's age and sex, the use of standardised death rates improves comparability over time and between countries.

The latest available European Union standardised death rates are for 2014 and these rates are presented in table I.  The standardised death rate presented for Ireland for 2014 is 981.07.  This rate is below the standardised rate for the European Union 28 countries for which a rate of 1,003.06 has been calculated.  The Irish standardised death rate in 2014 was above that of the United Kingdom, 981.07 compared with 971.17.  See table 3.I.

Standardised death rates comparison between counties

Variations in the age distribution of the population from one area to another have an effect on the comparability of death rates between different areas.  Comparisons over a period of years are also affected by changes in the age and sex structures of the population.  If a particular county contains a large proportion of elderly persons, the crude death rate per 1,000 of population will be relatively high even if the health conditions in that area are better than the general average.  In an attempt to overcome this, standardised rates are prepared.  For a particular county this is done by calculating the death rate in each age group of the population in that county and multiplying the death rate in each age group by the population in the whole country in that age group, summing the resulting products and dividing by the overall population.

The standardised death rate for Ireland per 1,000 of population in 2015 was 6.4 and the corresponding rate for 2014 was 6.3.  In certain areas the standardised death rates differ significantly from the crude rates, the extremes being Fingal which had a crude death rate of 3.5 and a standardised rate of 5.4 (reflecting the very young age structure in Fingal) and Roscommon where the standardisation had the effect of lowering the crude death rate from 8.1 to 6.2 because of the comparatively older age distribution in that county.

The standardised death rates in 2015 were lowest in South Dublin (at 5.3 per thousand population) and highest in Limerick City (at 8.2 per thousand population).  See table 3.3.

Causes of Death

Of deaths occurring in 2015, 74% were attributed to 3 main chapters in the ICD-10 classification: IX (I00-I99) diseases of the circulatory system (31.1%), II (C00-D48) neoplasms (30.1%), and X (J00-J99) diseases of the respiratory system (12.8%).  A similar overall breakdown is evident for males and females.  See table 3.8.

Within different age groups, there are significant differences in the assigned underlying causes of death. For those aged less than five years of age, the main cause of death was congenital malformations and chromosomal abnormalities (41.6%).  In this age group 36.1% of male deaths and 48.7% of female deaths were attributed to these causes.  Certain conditions originating in the perinatal period also accounted for a large volume of deaths (40.0%) in this age group.  The numbers of deaths in the 0-4 age group are very much dominated by infant deaths (87.5% aged under 1 year).  See tables 3.9 and 3.10 and chapter 4.

In the age group 5-14, neoplasms were the main underlying cause of death (42.1%) with 42.3% of male deaths and 41.7% of female deaths recorded in this category.  See tables 3.9 and 3.10.

A large proportion of deaths in age groups, from ages 15 to 34, were due to External causes of injury and poisoning (56.6%).   Almost two-thirds (63.7%) of males aged 15 to 34 died due to external causes of injury and poisoning.  The corresponding figure for females was 41.1%.  Additionally, there were almost 2.2 male deaths for every 1 female death in this age group.  External causes of injury and poisoning (43.0%) were also the main causes of death for males aged 35-44, while neoplasms (47.4%) were the main causes of female deaths in this age group.  See tables 3.9 and 3.10.

From 45 to 74 years of age, neoplasms were the main underlying cause of death (47.0%).  Within the female age cohort of 45 to 64 years, 57.8% of deaths were due to neoplasms compared to 40.2% of males in the same age group.  See tables 3.9 and 3.10.

In the older age groups (75 years and over), 22.6% of deaths were due to neoplasms.  See tables 3.9 and 3.10.

Neoplasms

There were 9,072 deaths due to neoplasms in 2015, 2.0 per 1,000 of population.  Of these, 8,877 were due to malignant neoplasms, 4,742 males and 4,135 females.  See tables 3.12, 3.13 and 3.14.

Malignant neoplasm of the digestive organs was the most common of these cancers (31.4%).  Deaths due to cancer of the digestive organs was the most common form of malignant neoplasm in males and females at 34.9% and 27.4% respectively.  Breast cancer was the most common type of malignant neoplasm for females aged between 35 and 54 years at 31.1%.   Cancer was the most common cause of death in females aged from 35 to 74 (52.9%) and in males aged from 45 to 74 (42.8%).  See tables 3.9, 3.10, 3.13, 3.14 and 3.15.

Waterford City had the highest age standardised death rate from cancer, 2.53 per 1,000 of population, while Monaghan had the lowest at 1.55 per 1,000 of population.  See table 3.12.

Diseases of the circulatory system

There were 9,371 deaths attributed to diseases of the circulatory system in 2015, of which 4,741 were deaths of males and 4,630 were deaths of females.

Overall, diseases of the circulatory system were the most common causes of death in 2015 (31.1%), 2.00 deaths per 1,000 of population.  Over 73.2% of deaths due to diseases of the circulatory system occurred where the person was aged 75 and over.  For deaths due to circulatory disease in those aged under 75 there were 2.4 male deaths to 1 female death.  See tables 3.9, 3.12 and 3.17.

For deaths caused by diseases of the circulatory system, 47.9% were due to Ischaemic heart diseases, accounting for 55.4% of males and 40.3% of females.   Over a fifth (20.5%) of these deaths were due to cerebrovascular diseases, accounting for 17.5% of males and 23.5% of females.  Acute myocardial infarction accounted for 1,957 of the 4,492 Ischaemic heart disease deaths.  See tables 3.16 and 3.18.

North Tipperary recorded the highest age-standardised death rate for diseases of the circulatory system, 2.81 per 1,000 of population, while South Dublin recorded the lowest at 1.59 per 1,000 of population.  See table 3.12.

Respiratory Diseases

(See causes of death note in Technical Notes in relation to the change in coding rules applied in cases of pneumonia).

Deaths from diseases of the respiratory system in 2015 numbered 3,865, of which 1,855 were males and 2,010 were females.  There were 1,701 deaths (44.0%) from chronic lower respiratory diseases and 1,199 deaths (31.0%) due to influenza and pneumonia.  See table 3.19, 3.20, 3.21 and 3.28.

Diseases of the respiratory system accounted for 12.8% of all deaths (0.82 per 1,000 of population), affecting, in particular the older age groups, with 79.4% of these occurring in persons aged 75 and over.  See tables 3.9, 3.12 and 3.20.

Limerick City recorded the highest age-standardised death rate for diseases of the respiratory system, 1.48 per 1,000 of population, while Fingal recorded the lowest at 0.61 per 1,000 of population.  See table 3.12.

Accidents, poisoning and violence

The number of deaths from external causes of injury and poisoning occurring in 2015 was 1,316, of which 903 were males and 413 females.  As has been mentioned, deaths not registered within the year of occurrence or the subsequent calendar year, have been excluded from the main body of this report. The exclusion of these cases may have a relatively more significant effect on the number of deaths classified to some external causes.  See tables 3.8 and 3.9.

Accidents accounted for 61.9% of all external causes of injury and poisoning while intentional self-harm accounted for a further 32.3%.  Events of undetermined intent accounted for 3.4% while deaths due to assaults accounted for 1.6%.  Complications of medical and surgical care and sequelae of external causes of morbidity and mortality accounted for the remaining 0.8%.  See table 3.22.

Almost 2.2 times as many males died due to external causes compared to females in 2015.  Differences in more specific causes of death and also within different age-groups were also significant.  Just under 1.7 as many males died due to accidents compared to females in 2015.  The majority of accidental deaths in males under 25 years of age were due to transport accidents (40.5%) while the greatest cause of accidental deaths in the male 25 to 54 year age groups was due to poisoning by and exposure to noxious substances (52.2%).  The majority of female accidents occurred in the older age-groups, particularly in females aged 75 and over which accounted for 46.7% of female accidents, 68.1% of these were from falls.  See table 3.23.

There were 425 deaths due to intentional self-harm in 2015, 335 (or 78.8%) males and 90 (or 21.2%) females.   The highest number of deaths, 89, recorded from intentional self-harm were in the 35-44 age group (20.9%).  There were 87 (20.5%) such deaths in the 45-54 age group. 

Events of undetermined intent accounted for an additional 45 deaths in 2015.  See tables 3.22, 3.23 and 3.24.

Cork City recorded the highest age-standardised death rate for external causes of injury and poisoning, 0.53 per 1,000 of population while Dun Laoghaire-Rathdown recorded the lowest at 0.10 per 1,000 of population.  See table 3.12.

Inquests and post-mortems

The number of deaths on certificates issued by coroners as a result of inquest and post-mortem examinations during 2015 was 4,732 compared with 4,912 in 2014 and 4,904 in 2013.

Technical Notes

International classification of Diseases, Injuries and Causes of Death (ICD-10)

The Tenth Revision of the International classification of Diseases, Injuries and Causes of Death (ICD-10), as recommended by the World Health Organisation, has been used to classify deaths in Ireland for the 2012 data. It replaces the Ninth Revision, which was used from 1979 to 2006.

Automated coding software produced by the National Centre for Health Statistics (NCHS) in the US is used in coding the underlying causes of death for Irish data, supplemented by manual coding in certain cases.

The main changes to the classification of diseases between ICD-9 and ICD-10 are as follows:

- ICD-10 has over 3,000 more codes than ICD-9
- Inclusion of additional underlying causes (eg AIDS/HIV, chromosomal abnormalities)
- Expansion of certain underlying causes existent in ICD-9, for certain diseases, providing for the recording of greater levels of detail (e.g. acute myocardial infarction, perinatal conditions, viral hepatitis)
- Movement of underlying causes of death between ICD chapters (e.g. haemorrhage moved from the circulatory chapter to the symptoms and signs chapter in ICD-10, certain disorders of the immune mechanism moved from the endocrine chapter to the blood chapter in ICD-10 and certain disorders of blood moved from the blood chapter to the neoplasm chapter in ICD-10)
- Contraction of certain underlying causes of death (e.g. autoimmune disease and connective tissue disease are given the same code in ICD-10)
- Changes in the inclusion and exclusion guidelines for certain underlying causes of death
- Re-ordering of certain chapters and underlying causes
- Alphanumeric codes used instead of numeric codes

Additionally, there have been changes to the selection rules applied to determine the underlying cause of death. The most significant change relates to Rule 3 which allows a condition from Part I or Part II of the death certificate to be selected as the primary condition if it is an obvious direct consequence of another reported condition. There are a number of guidelines presented for this rule, most significantly the guideline in relation to pneumonia. The effect of this rule change reduces the number of deaths assigned to pneumonia and alternatively assigns the underlying cause of death to the chronic debilitating disease.

Certain official updates to ICD-10 are also incorporated in the coding of the cause of death. In particular, mental and behavioural disorders due to psychoactive substance use (F10-F19), with mention of intestinal infectious diseases (A00-A09), accidental, intentional self and undetermined intent poisoning by and exposure to noxious substances (X40-X49, X60-X69, Y10-Y19) or assault by chemical or noxious substance (X85-X90), are now coded to the latter.
http://www.who.int/classifications/icd/OfficialWHOUpdatesCombined1996-2008VOLUME2.pdf

For further information on the difference listed above and additional changes and differences between ICD-9 and ICD-10, please go to http://www.who.int/classifications/help/icdfaq/en/index.html

These changes have the effect of data being coded to different underlying causes of death at the most detailed level of ICD-10 and at the higher chapter level of ICD-10. For this reason, data cannot be easily compared across ICD-9 and ICD-10.