Part 1: Comorbidities in neurological admissions
Part 2: Volume of neurological admissions
Part 3: Characteristics of people admitted with neurological conditions
Part 4: Appendix

Comorbidities in neurological admissions

The purpose of this document is to highlight the complexities of comorbidities in patients with neurological conditions by using interactive graphics. The work focuses on high level groupings of comorbidities by 14 neurological categories and by 22 ICD-10 chapters (International Classification of Diseases). The appendix at the end of this document provides more details of these groups.

In this work, a comorbidity is a simultaneous record of more than one disease in a patient within their continuous hospital stay. ICD-10 codes are used to check Hospital Episode Statistics (HES) admitted patient data records for the presence of comorbidities. In cases when the neurological category and the ICD-10 chapter include a selection of the same codes, these codes are not counted as comorbidities.

Neurology, dementia and neurovascular adult patients presented with a wide variety of comorbidities during admission to hospitals in England for the financial year 2019 to 2020. Vast majority of admissions (70.05%) have at least one comorbidity from ‘factors influencing health status and contact with health services’ chapter. More than half (55.00%) present with ‘diseases of circulatory system’ and 42.28% with ‘endocrine, nutritional and metabolic diseases’.

Neurology patients are a very varied cohort and the comorbidities they present with are no more homogeneous. It is therefore worth looking at sub-groups as well as the whole cohort. For example, traumatic brain and spine injury patients present often with comorbidities like ‘external causes of morbidity and mortality’ (81.78%), other ‘factors influencing health status and contact with health services’ (70.60%) and ‘injury, poisoning and certain other consequences of external causes’ (60.26%). Double click the ‘Traumatic brain and spine injury’ legend item below, click the ‘Autoscale’ button above the legend and hover over the data points displayed to see that information. In the hover over data label you can also see what the reverse comorbidity is for each of the points, i.e. what percentage of admissions in the ICD-10 chapter have a record of ‘Traumatic brain and spine injury’. Double click the ‘Traumatic brain and spine injury’ legend item again and ‘Reset axes’ button above the legend to return to all data and explore other categories.

Dementia patients frequently present with ‘diseases of the circulatory system’ (78.98%), ‘factors influencing health status and contact with health services’ (79.14%), ‘symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified’ (64.29%), ‘endocrine, nutritional and metabolic disorders’ (52.65%) and ‘diseases of the genitourinary system’ (44.06%) to list the top 5. However, these patients show a high comorbidity level across most ICD10 chapters. Admissions with tumours of the nervous system will in 54.22% of cases have another neoplasm recorded and are likely to present with ‘diseases of the circulatory system’ (45.90%) and ‘endocrine, nutritional and metabolic disorders’ (35.31%).

Admissions with encephalitis are likely to have a record of another ‘infectious or parasitic disease’ (35.42%) as well as ‘symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified’ (57.30%), ‘endocrine, nutritional and metabolic disorders’ (51.08%) ‘mental and behavioural disorders’ (47.56%) and ‘diseases of the circulatory and nervous systems’ (56.24% and 44.55% respectively).

Looking at the reverse comorbidities, i.e. when the neurology, dementia or neurovascular disease is an additional comorbidity in an ICD10 chapter admission, the proportions vary from 3.8% in ‘pregnancy, childbirth and the puerperium’ to 39.4% in ‘certain conditions originating in the perinatal period’. While the latter is based on relatively small number of total admissions (n= 533), it is worth noting the very high proportion of accompanying neurological issues.

The following chapters have an additional neurology, dementia or neurovascular comorbidity recorded:

Volume of neurological admissions

An admission is a continuous period of time spent as a patient within a trust, and may include more than one episode. For the purpose of this work only in-year admissions are analysed, i.e. ones that started between April 2019 and March 2020, hereafter called ‘admissions’.

The interactive treemap chart below allows to drill down the volumes of admissions in that period by whether there was a neurological mention and then, by the main reason for the hospital stay. Of the 15 million admissions, 2.1 million (14.3%) had a neurological, dementia or neurovascular mention and over 664 thousand (4.4%) recorded it as the primary reason for the hospital stay. To drill down, click on a rectangle of interest. To zoom out, click on the bar along the top of the treemap chart. The percentages in the lower level rectangles are calculated to the immediate parent category (rectangle) they are contained in.

Treemap chart showing adult in year admissions between 2019 and 2020 in England

Characteristics of people admitted with neurological conditions

Numbers of people admitted to hospitals are counted using PERSON HES TOKEN ID. Section below shows numbers and characteristics of those admitted with a neurological condition. The totals will be different to the numbers of admissions, as some patients have multiple admissions to a hospital in a year.

Of the 1.3 million people in treatment with neurological, dementia and neurovascular conditions, most (1.1 million) were neurological. There were also 270 thousand dementia and 110 thousand neurovascular patients. On average, people in hospital with neurological conditions had 1.64 admissions between 2019 and 2020. That is lower for those with neurovascular conditions (1.2 admissions per person) and higher for patients with dementia (1.69 admissions per person).

Deprivation, as defined by the Index of Multiple Deprivation (IMD), is showing a gradient with more people from the deprived areas in treatment with neurological, dementia and neurovascular conditions. Of these patients, 11.34% are in the most deprived decile and 8.5% in the least deprived one. More information on how IMD can be used to describe the relative level of deprivation in an area is available at gov.uk

Population structure illustrates the age and sex distribution for patients with neurological, dementia and neurovascular conditions. The cohort has more women (56.39%) than men (43.61%) and 48.30% are 70 years or older. Further 27.29% are between 50 and 69 years old and 20.93% are younger working age adults (25-49 years old).


Demographics charts

People in treatment

Deprivation

Population structure

Appendix

Definitions of neurological condition categories and ICD-10 chapters

This work explores 14 adult neurological condition categories:

Details of the codes included in each category are available at: https://fingertips.phe.org.uk/profile-group/mental-health/supporting-information/ndi-code-collections

Comorbidities were explored by 22 ICD-10 chapters:

  1. Certain infectious and parasitic diseases (including tuberculosis and other viral and bacterial infections)
  2. Neoplasms (malignant, in situ, benign and other neoplasms)
  3. Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (including nutritional, haemolytic, aplastic and other anaemias)
  4. Endocrine, nutritional and metabolic diseases (including disorders of thyroid & other endocrine glands, glucose regulation, malnutrition and obesity)
  5. Mental and behavioural disorders (behavioural and emotional disorders, dementia in other diseases)
  6. Diseases of the nervous system (including many of the neurology diseases)
  7. Diseases of the eye and adnexa (including visual disturbances, blindness)
  8. Diseases of the ear and mastoid process
  9. Diseases of the circulatory system (chronic, hypertensive, ischaemic, pulmonary and other forms of heart disease, as well as cerebrovascular and diseases of the arteries & veins)
  10. Diseases of the respiratory system (respiratory infections, influenza, pneumonia, lung and other diseases of the respiratory system)
  11. Diseases of the digestive system (oesophagus, stomach, appendix, intestines, liver, hernia, colitis, gallbladder, biliary tract, pancreas)
  12. Diseases of the skin and subcutaneous tissue (dermatitis, eczema, urticaria, erythema and infections of the skin)
  13. Diseases of the musculoskeletal system and connective tissue (including arthropathies, dorsopathies, osteopathies and chondropathies)
  14. Diseases of the genitourinary system (kidney, ureter, urinary system and genital tract)
  15. Pregnancy, childbirth and the puerperium (including oedema, proteinuria and hypertensive disorders in pregnancy, labour and delivery and complications)
  16. Certain conditions originating in the perinatal period (including birth trauma, infections, respiratory and cardiovascular disorders specific to the perinatal period)
  17. Congenital malformations, deformations and chromosomal abnormalities
  18. Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (This chapter includes symptoms, signs, abnormal results of clinical or other investigative procedures, and ill-defined conditions regarding which no diagnosis classifiable elsewhere is recorded. Signs and symptoms that point rather definitely to a given diagnosis have been assigned to a category in other chapters of the classification. In general, categories in this chapter include the less well-defined conditions and symptoms that, without the necessary study of the case to establish a final diagnosis, point perhaps equally to two or more diseases or to two or more systems of the body. Practically all categories in the chapter could be designated ‘not otherwise specified’, ‘unknown etiology’ or ‘transient’.)
  19. Injury, poisoning and certain other consequences of external causes (including fractures, burns, lacerations as well as complications of trauma, surgical and medical care and sequelae of injuries)
  20. External causes of morbidity and mortality (including accidents, self-harm, assault, operations of war, complications of medical and surgical care)
  21. Factors influencing health status and contact with health services (These codes are provided for occasions when circumstances other than a disease, injury or external cause classifiable to categories A00-Y89 are recorded as “diagnoses” or “problems”. This can arise in two main ways: (a) When a person who may or may not be sick encounters the health services for some specific purpose, such as to receive limited care or service for a current condition, to donate an organ or tissue, to receive prophylactic vaccination or to discuss a problem which is in itself not a disease or injury. (b) When some circumstance or problem is present which influences the person’s health status but is not in itself a current illness or injury. Such factors may be elicited during population surveys, when the person may or may not be currently sick, or be recorded as an additional factor to be borne in mind when the person is receiving care for some illness or injury.)
  22. Codes for special purposes (including provisional assignment of new diseases of uncertain etiology or emergency use and resistance to antimicrobial and antineoplastic drugs)

Details of the codes included in each ICD-10 chapter are available via the World Health Organisation International Statistical Classification of Diseases and Related Health Problems website: https://icd.who.int/browse10/2019/en