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Main changes in ICD-10 by chapter

I Certain infectious and parasitic diseases
II Neoplasms
III Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism

IV Endocrine, nutritional and metabolic diseases
V Mental and behavioural disorders
VI Diseases of the nervous system
VII Diseases of the eye and adnexa and VIII Diseases of the ear and mastoid process
IX Diseases of the circulatory system
X Diseases of the respiratory system

XI Diseases of the digestive system
XII Diseases of the skin and subcutaneous tissue
XIII Diseases of the musculoskeletal system and connective tissue
XIV Diseases of the genitourinary system

XV Pregnancy, childbirth and the puerperium
XVI Certain conditions originating in the perinatal period and XVII Congenital malformations, deformations and chromosomal abnormalities
XVIII Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
XX External causes of injury and poisoning

 

I Certain infectious and parasitic diseases

Overall, the number of deaths assigned to this Chapter has increased by 11 per cent (a comparability ratio of 1.11) for females and 6 per cent (a comparability ratio of 1.06) for males. Significant changes within the Chapter are seen for intestinal infectious diseases, with a 34 per cent increase for females and a 22 per cent increase for males, and for septicaemia, with a 13 per cent increase for females and a 10 per cent increase for males.

For both of these causes, a proportion of the increase is due to the application of Rule 3 to deaths involving pneumonia. Intestinal infectious diseases have also increased due to the fact that various types of non-specific gastroenteritis are now indexed to diarrhoea of presumed infectious origin. Septicaemia has also increased because a variety of infections previously coded to non-specific Chapter codes have now been coded to septicaemia.

Two factors have affected the number of deaths allocated to non-respiratory tuberculosis. Firstly the application of Rule 3 means that more deaths have been allocated to this cause. Two assumptions used in ICD-9 are no longer used in ICD-10. These relate to some forms of abscess and lupus. In ICD-9 they were assumed to be tuberculous even if this was not stated on the death certificate. This assumption is not made in ICD-10, so the number of deaths allocated to non-respiratory tuberculosis has declined as a result. This has counter-acted the effect of Rule 3. The decline is significant for males but not for females.

II Neoplasms

The Neoplasms Chapter as a whole has been widened to include some "disorders of blood" from Chapter III, causing an increase of 3 per cent for females and 4 per cent for males in the number of deaths allocated to this Chapter. Malignant neoplasms as a whole have increased by about 2 per cent for females and 3 per cent for males.

A number of specific cancers showed no change in the number of deaths allocated to them in ICD-10 compared to ICD-9 for both males and females. These include pancreas, cervix, testis, kidney, eye, brain and other parts of the central nervous system and non-Hodgkin's lymphoma.

A number of cancers have shown small increases or decreases in one or both sexes which are statistically significant because of the relatively large number of deaths coded to them.

The following codes are newly introduced in ICD-10 - C45 Mesothelioma, C46 Kaposi's sarcoma and C97 Independent primary multiple sites.

The number of deaths assigned to Malignant melanoma (C43) has decreased and the number of deaths assigned to Other malignant neoplasm of skin (C44) has increased. Both causes have gained deaths as a result of the application of Rule 3. However, other malignant neoplasm of skin has gained some deaths coded to malignant melanoma in ICD-9, but malignant melanoma has not gained any deaths from other malignant neoplasm of skin. In addition, both have lost deaths to the new C97 code.

Larger changes of note are an increase in deaths allocated to malignant neoplasms of lymphoid, haematopoietic and related tissue, especially multiple myeloma and leukaemia. The exact definitions of these cancers have changed slightly in ICD-10, however, the increases are still apparent if the exact ICD-9 equivalents to the new groups in ICD-10 are used rather than the ICD-9 codes formerly in use.

These and other changes to deaths from cancer as a result of the introduction of ICD-10 will be explored in more detail in later work. This will be published on the National Statistics website.

III Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism

The number of deaths assigned to this Chapter has decreased overall. This is because myelodysplastic syndromes and chronic myeloprolific diseases have been reclassified to "In situ and benign neoplasms and neoplasms of uncertain behaviour " in Chapter II. Although this Chapter has gained "certain disorders involving the immune mechanism" from Chapter IV, the numbers involved are small.

IV Endocrine, nutritional and metabolic diseases

There has been an increase of 5 per cent in females and 4 per cent in males in the number of deaths allocated to this Chapter. Diabetes has shown an increase of around 4 per cent for both males and females, due to the application of Rule 3. This increase in diabetes is not as great as the decrease seen following the introduction of automatic cause coding in 1993, which was around 20 to 25 per cent.

V Mental and behavioural disorders

The number of deaths allocated to mental and behavioural disorders has increased by around 20 per cent. This is as a result of the application of Rule 3. Within the Chapter, large increases are seen in the number of deaths allocated to dementia (an increase of over 50 per cent in females and over 60 per cent in males). There has been no increase in the number of deaths allocated to drug use (excluding alcohol and tobacco). There has been no change in the number of deaths allocated to mental and behavioural disorders due to use of alcohol for males, but a decline of 11 per cent was seen for females. There appears to have been some reassignment of deaths from this group to Alcoholic liver disease (K70).

VI Diseases of the nervous system

Diseases of the nervous system have also shown an increase in ICD-10; due to the application of Rule 3. Within the Chapter, meningitis showed no change and increases were seen for motor neuron disease, Parkinson's disease, Alzheimer's disease and multiple sclerosis, with very substantial increases for Parkinson's disease (49 per cent for both sexes) and Alzheimer's disease (89 per cent for females, 110 per cent for males). The relationship between the changes to dementia and Alzheimer's disease is complex and will be examined in more detail in later work. This will be published on the National Statistics website.

VII Diseases of the eye and adnexa and VIII Diseases of the ear and mastoid process

These are new Chapters in ICD-10, having previously been part of Chapter VI, Diseases of the nervous system and sense organs, in ICD-9. The number of deaths classified to these Chapters is extremely small and has not shown a significant change for females or males.

IX Diseases of the circulatory system

Diseases of the circulatory system showed a 4 per cent increase between ICD-9 and ICD-10 for females and a 3 per cent increase for males. Within the Chapter, ischaemic heart disease (IHD) showed little change, whereas cerebrovascular diseases (CVD) showed increases of 9 per cent for females and 13 per cent for males. This latter change is due to the application of Rule 3 to deaths involving pneumonia. Within the CVD group, there has been a small increase in stroke (not specified as haemorrhage or infarction) and a larger increase in cerebral infarction. However, the numbers for the latter are much smaller, and they have less of an impact on the overall comparability ratio for CVD.

Among deaths from IHD there has been movement between codes, resulting in a decrease in the number of deaths assigned to acute myocardial infarction. This is because in ICD-9, acute ischaemic heart disease or ischaemic heart disease with a stated duration of less than 4 weeks were coded to Acute myocardial infarction (410). In ICD-10 these deaths are coded to Acute ischaemic heart disease (I24.9), which is a new code. This accounted for about 260 deaths. A further 3,600 deaths coded to 410 in ICD-9 have been coded to Chronic ischaemic heart disease (I25) in ICD-10. These are deaths which had acute myocardial infarction or other acute ischaemic heart disease on the death certificate, but with a stated duration of over 4 weeks.

X Diseases of the respiratory system

This Chapter has shown a decrease of around 25 per cent between ICD-9 and ICD-10. This is largely as a result of the application of Rule 3 to deaths involving pneumonia, which has itself declined by over 35 per cent for females and over 40 per cent for males.

The number of deaths assigned to influenza did not change significantly.

Chronic lower respiratory diseases increased by 3 per cent overall, but within this group chronic bronchitis and emphysema showed a decrease, whereas other chronic obstructive pulmonary disease showed an increase. This is because if both chronic bronchitis and emphysema are mentioned on the death certificate then the death is coded to Other chronic obstructive pulmonary disease (J44.8).

Asthma showed an increase for females, but not for males.

XI Diseases of the digestive system

Diseases of the digestive system showed a small increase between ICD-9 and ICD-10 (1 per cent for females, 2 per cent for males). Within the Chapter, increases of less than 10 per cent for both males and females were seen for hernia, diseases of the liver and alcoholic liver disease. The changes to alcoholic liver disease are likely to be as a result of the reassignment of other alcohol-related deaths.

XII Diseases of the skin and subcutaneous tissue

The number of deaths assigned to this Chapter did not show a significant change between ICD-9 and ICD-10.

XIII Diseases of the musculoskeletal system and connective tissue

This Chapter showed an increase of around 40 per cent in the number of deaths allocated to it in ICD-10 compared to ICD-9. This is largely due to the application of Rule 3. Arthritis showed an increase of 67 per cent for males and 57 per cent for females. Osteoporosis showed an increase of around 30 per cent. This may also reflect a reassignment of deaths previously coded as falls (see Chapter XX). This will be examined in more detail in later work, which will be published on the National Statistics website.

XIV Diseases of the genitourinary system

Diseases of the genitourinary system showed no overall change between ICD-9 and ICD-10. Within the Chapter increases were seen for diseases of the kidney and ureter for males and renal failure for both males and females. This is largely due to changes in the classification of diseases within the Chapter, with exact equivalence of codes being difficult to obtain.

XV Pregnancy, childbirth and the puerperium

The number of deaths assigned to this Chapter did not show a significant change between ICD-9 and ICD-10.

XVI Certain conditions originating in the perinatal period and XVII Congenital malformations, deformations and chromosomal abnormalities

These Chapters have not been examined in this report. A substantial number of the deaths from these causes are neonatal. The WHO-recommended perinatal certificate for stillbirths and neonatal deaths is used in England and Wales. No single underlying cause can be selected. This means that these deaths cannot be coded by the software used for automatic coding of cause of death. The text for each of the conditions mentioned is coded to ICD-10 using a modified version of the special ONS software that was used to code cause of death for neonates in ICD-9. An updated version of the ONS Hierarchical classification of causes of stillbirths and neonatal deaths is being developed.

XVIII Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified

This Chapter showed no change between ICD-9 and ICD-10. Sudden Infant Death Syndrome (SIDS) headline figures are based on all mentions of SIDS, not just underlying cause, and so will not be affected by the move to ICD-10. Most deaths in this chapter are certified as due to 'old age' or 'senility', without mention of dementia and with no disease or injury mentioned.

XX External causes of injury and poisoning

Overall the number of deaths allocated to external causes has not changed between ICD-9 and ICD-10. However, this masks changes within the Chapter.

The number of deaths assigned to the accidents group as a whole has remained largely unchanged. In addition, no significant changes were seen for transport accidents, or land transport accidents. However, it should be noted that it is no longer possible to obtain an exact equivalent of the old 'Motor Vehicle Traffic Accidents' group from ICD-9. This is because of a change in the axis of classification. In ICD-9, the focus was on the nature of the accident and type of vehicle. With ICD-10, the focus is on the person involved in the accident. In order for a death to be coded as a motor vehicle accident, ICD-10 coding rules require the word 'motor' or the type of vehicle, such as car, pick-up truck, or van, to be listed on the death certificate. For example, if the death certificate lists 'one-vehicle accident' or 'head-on collision', but the type of vehicle is not stated, the cause of death is coded as Other land transport accident (V80-V89). Details of the changes within the land transport accidents group will be published on the National Statistics website in the future.

The number of deaths allocated to falls has seen a decrease of over 50 per cent for females and around 30 per cent for males. This is largely due to the fact that fractures with cause unspecified (E887 in ICD-9) are no longer assumed to be due to a fall and are therefore not included with them as they were in ICD-9. There may also be some reassignment of deaths to causes such as osteoporosis.

Some deaths due to injury have very little information provided about them. In these situations, in ICD-10 the code X59, Accidental exposure to unspecified factor, is assigned to the death, whereas in ICD-9 the limited detail provided may have been sufficient to assign a more specific code. Over 1,700 female deaths were assigned to this code, compared to over 700 male deaths. This is likely to be as a result of the fact that more of these deaths occur at older ages, and more deaths at older ages are to females. Most of these deaths (1,600) were coded as Fracture of unspecified cause (E887) in ICD-9. A further 400 were assigned to the nearest equivalent to the code in ICD-9 (E928.9). The rest have come from a variety of ICD-9 codes. These changes will be examined in later work on falls and on accidents as a whole.

Accidental poisonings showed no significant changes. However, at the 4-digit level there is not an exact equivalence between ICD-9 and ICD-10. The details of the changes for drugs and medicaments will be explored in the next report from the ONS database of drug-related poisoning deaths. Some deaths have been reclassified from accidental poisoning due to alcohol to mental and behavioural disorders due to alcohol.

Suicide and homicide are based on verdict, and so have not changed significantly between ICD revisions. In ICD-10, the code Y33.9 is used to identify adjourned inquests in the same way as E988.8 was used in ICD-9. 

Content from the Office for National Statistics.
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