West Midlands Key Health Data 2009/10
CHAPTER FIVE: THE EPIDEMIOLOGY OF CHRONIC LIVER
Dr Irfan Ghani: West Midlands Public Health Observatory
Main Body
7: Changes in Heart Attack Admissions since the Smoking Ban
8: Measuring Disability Across the West Midlands
9: Surveillance of Clostridium Difficile in the West Midlands
5.1 Introduction
Chronic liver disease (CLD) is a progressive destruction and scarring of the liver tissue. Early changes can progress via inflammation (hepatitis) and scarring (fibrosis) to irreversible damage (cirrhosis). Cirrhosis is regarded as a possible end stage of many liver diseases and occurs when healthy liver tissue becomes damaged and is replaced by scar tissue1.
A variety of risk factors and diseases can result in chronic liver disease including blood borne viruses, toxin related disorders, obesity, auto-immune diseases and metabolic causes. The three commonest risk factors for CLD are excessive alcohol consumption; blood borne viruses, in particular Hepatitis B and C, and obesity1. Risk factors can have a multiplicative effect: an individual with more than one risk factor (e.g. Hepatitis C/obesity as well as excess alcohol consumption) can further increase their risk of CLD2. Metabolic disease and auto-immune disease are relatively rare.
The mortality and admission rates related to liver disease are on the rise in England. These trends are in the opposite direction to the general world trends; where liver disease rates are falling3. There is also an increase in the risk factors for CLD including higher alcohol related mortality and morbidity, obesity and hepatitis C. A number of national and local policies are implemented across England to tackle the risk factors for CLD but there is no specific national policy to reduce health burden of CLD.
This chapter aims to describe the pattern of mortality and morbidity of CLD across the West Midlands.
5.2 The Epidemiology of Chronic Liver Disease
The following ICD 10 codes are used by the National Centre for Health Outcomes Development (NCHOD, www.NCHOD.nhs.uk) to identify data for CLD including as well as by other organisations across the UK.
Table 5.1: ICD 10 – Codes for Chronic Liver Disease
|
The World Health Organisation (WHO) uses a slightly different set of ICD 10 codes for the definition of CLD including K70, K73, K74 and K764 (described later in the chapter).
The ICD-10 codes K70, K73-K74 have been used in this chapter to describe the epidemiology, for consistency with the NCHOD and other NHS organisations. The difference in mortalities rates between the NCHOD and WHO definitions for CLD is highlighted later in this chapter.
5.3 Mortality
The mortality data has been sourced from the Office for National Statistics (ONS) and the analysis is produced by the West Midlands Public Health Observatory
In 2008, there were 52,132 registered deaths for both males and females in the West Midlands. Of these deaths 765 deaths were CLD deaths, contributing 1.5% of all registered deaths in West Midlands in 2008.
West Midlands has the third highest CLD mortality rate in England (Figure 5.1). The West Midlands mortality rates are significantly higher than the national rates for both males and females. The mortality rates for males are (directly standardised rates (DSR) 16.7/100,000) significantly higher than females (DSR 8.6/100,000). A similar pattern is seen across England.
The North West has the highest mortality from CLD followed by the North East and West Midlands (significantly higher than the national average for both males and females).The East of England has the lowest mortality from CLD followed by the Strategic Health Authorities (SHA) in the South and the East Midlands (significantly lower than the national average for males and females except in the East Midlands where no statistically significant difference was found in females).
Figure 5.1: Directly Standardised CLD Mortality Rates by SHA, deaths registered 2006-08 (pooled)
|
No deaths for CLD occurred in those aged less than 20 years in the West Midlands between 2006 and 2008. Mortality rates then increase with age peaking at 50-54 years in males and 55-59 years in female and thereafter fall with age (Figure 5.2).
Figure 5.2: Age Profile of CLD Mortality in the West Midlands, deaths registered 2006-2008 (pooled)
|
The mortality from CLD has risen in England since 2002 and there has been a significant increase in mortality rates in the West Midlands from 2002-04 to 2006-08 for both males (14% rise in mortality) and females (14% rise in mortality). The gap between the West Midlands and England has also widened from 1.1/ 100,000 deaths to 2.0/100,000 deaths (Figure 5.3).
Figure 5.3: CLD Mortality Rates in the West Midlands and England, 2002-2004 to 2006-2008
|
Years of life lost (YLL) is a measure of premature mortality. Its primary purpose is to compare the relative importance of different causes of premature death within a particular population and it can therefore be used by health planners to define priorities for the prevention of such deaths. It can also be used to compare the premature mortality experience of different populations for a particular cause of death5. A similar pattern for years of life lost from CLD was observed at the SHAs (Figure 5.4) as with the CLD mortality (Figure 5.1)
Figure 5.4: Years of Life Lost from CLD by SHA, deaths registered 2006-2008 (pooled)
|
Analysis of ICD 10 codes for CLD (Figure 5.5) shows that the increase in the CLD mortality is due to increase in the mortality from alcoholic liver disease (ICD 10 code: K70) which has increased significantly from 2002-2004 to 2006-2008 while the mortality from other causes including chronic hepatitis not elsewhere classified (ICD 10 code: K73) and fibrosis & cirrhosis of liver (ICD 10 code: K74) has remained stable over this time period.
Figure 5.5: Directly Standardised CLD Mortality Rates in the West Midlands by ICD 10 codes, deaths registered 2002-2008 (pooled)
|
The North West Public Health Observatory has produced synthetic estimates for harmful drinking6 (Mid-2005 synthetic estimate of the proportion (%) of the population aged 16 years and over who report engaging in harmful drinking, defined as consumption of more than 50 units of alcohol per week for males, and more than 35 units of alcohol per week for females). Mortality due to CLD across England shows a positive association with harmful drinking estimates (Figure 5.6).
Figure 5.6: Directly Standardised CLD Mortality Rates by synthetic estimates for harmful drinking, by SHA, deaths registered 2006-2008 (pooled)
|
CLD mortality among the PCTs (Figure 5.7) in the West Midlands SHA varies greatly. The Solihull PCT and the PCTs in the shire counties have lower mortality rates for CLD. Wolverhampton PCT has the highest mortality (3 times more than the Solihull PCT which has the lowest mortality).
Figure 5.7: Directly Standardised CLD Mortality Rates by the West Midlands PCTs, deaths registered 2006-2008 (pooled)
|
Figure 5.8 shows that the West Midlands CLD Mortality rates decreases with decreasing levels of deprivation
Figure 5.8: Directly Standardised CLD Mortality Rates in the West Midlands by Deprivation, deaths registered 2006-2008 (pooled)
|
Analysis of the West Midlands PCT clusters shows that CLD mortality among males is significantly lower in West Mercia and Arden than the West Midlands average and significantly higher in Birmingham and Black Country clusters than the regional average. No statistically significant differences found among females (Figure 5.9)
Figure 5.9: Directly Standardised CLD Mortality Rates by West Midlands PCT Clusters (groupings shown below), deaths registered 2006-2008 (pooled)*
|
West Midlands PCT Clusters
West Mercia Cluster (Shropshire County PCT, NHS Herefordshire, NHS Telford and Wrekin & NHS Worcestershire)
Arden Cluster (Solihull NHS Care Trust, NHS Coventry & NHS Warwickshire)
Staffordshire Cluster (South Staffordshire PCT, NHS North Staffordshire & NHS Stoke-on-Trent), Birmingham Cluster (NHS Birmingham East and North, Heart of Birmingham teaching PCT & NHS South Birmingham)
Black Country Cluster (NHS Dudley, Sandwell PCT, NHS Walsall & Wolverhampton City PCT)
CLD can lead to hepatocellular carcinoma (HCC), portal hypertension, hepatorenal syndrome and hepatopulmonary syndrome. 70 to 90 % of the hepatocellular carcinomas are caused by cirrhosis7. London has the highest mortality from HCC followed by the North East and North West (significantly higher than England rates). The West Midlands has the fourth highest mortality from HCC (not significantly different from the national rates) (Figure 5.10).
Figure 5.10: Directly Standardised Mortality rates from Hepatocellular Carcinoma by PCT Clusters, deaths registered 2006-2008 (pooled) - ICD 10 Code: C22
|
The definition used by the WHO for CLD is slightly different from the NCHOD definition.
Table 5.2: ICD 10 – Codes for Chronic Liver Disease used by the NCHOD & WHO
|
*ICD 10 code 76 includes fatty (change of) liver, not elsewhere classified, chronic passive congestion of liver, central haemorrhagic necrosis of liver, infarction of liver, peliosis hepatis, hepatic veno-occlusive disease, portal hypertension, hepato-renal syndrome and other specified and unspecified diseases of liver.
Comparison of the both sets shows that the mortality rates from CLD in England increase significantly if the WHO definition of CLD is used as compared to the NCHOD Definition (Figure 5.11). Significant increases in mortality rates were also observed in the West Midlands, Yorkshire and Humber, East Midlands, South East Coast, North West and London. 47% of the additional deaths in the WHO definition are classified as unspecified liver disease followed by fatty (change) of liver, not classified anywhere (36%).
Figure 5.11: Directly Standardised CLD Mortality Rates in the West Midlands, by NCHOD Definition and WHO Definition, deaths registered 2006-08 (pooled)
|
The three commonest risk factors for CLD are excessive alcohol consumption; blood borne viruses, in particular Hepatitis B and C, and obesity. The number of deaths from chronic viral hepatitis has risen since 2002. The ICD-10 codes for CLD used by the NCHOD and WHO don’t include mortality from chronic viral hepatitis. The mortality from chronic viral hepatitis is small (139 deaths among males and 65 deaths among females in England between 2006 and 2008). Due to confidentiality concerns with the small numbers at the regional and PCT level, the analysis is not presented in this chapter.
5.4 Morbidity
Hospital Episode Statistics (HES) is a data warehouse containing details of all admissions to NHS hospitals in England. It includes private patients treated in NHS hospitals, patients who were resident outside of England and care delivered elsewhere funded by the NHS (www.HESonline.nhs.uk). Inpatient data is available for every financial year from 1989/90. Healthcare providers submit data via the secondary users service (SUS). The HES data is validated, cleaned and processed by the Information Centre for Health and Social care.
In this section CLD has been defined by ICD 10 K70, K73-K74, for consistency with the mortality data shown earlier.
Age specific admission rates for CLD in the West Midlands between 2006 and 2008 (Figure 5.12) show a similar pattern to the mortality rates (Figure 5.2) for CLD.
Figure 5.12: Age Profile for CLD Admission Rates by Age Groups, 2006/2007-2008/2009 (pooled)
|
Unlike the mortality rates (Figure 5.1), the admission rates for CLD are significantly lower in the West Midlands than the national average (Figure 5.13). The lower admission rates can be due to various factors including quality of coding, completeness of data and different clinical pathway for management of CLD in the West Midlands whereby majority of the CLD patients are treated in primary care or specialist clinics in the acute trusts. For the North West and North East SHAs, both mortality and admission rates are significantly above the national average and for the South East coast and South Central SHAs, both mortality and admission rates are significantly below the national average. As with the mortality rates the admission rates are higher in males than females.
Figure 5.13: Directly Standardised Admission Rates for CLD by SHA, 2006/07-08/09 (pooled)*
|
*4 PCTs split between SHAs. These PCTs have been included in the SHA to which they report to.
The CLD related admissions have increased in both West Midlands and England over the years. The percentage increase is lower in the West Midlands (7%), as compared to England (12%) over the same period (Figure 5.14). The increase in admission rates for females is statistically significant, but not for males.
Figure 5.14: Directly Standardised Admission Rates for CLD, England and West Midlands, 2002/2003- 2004/2005 to 2006/2007- 2008/2009
|
As with the mortality rates, the admission rates are lower in the shire PCTs and the Solihull PCT. The admission rates among females show no clear pattern (Figure 5.15).
Figure 5.15: Directly Standardised Admission Rates for CLD by PCTs 2006/2007-2008/2009 (pooled)
|
Figure 5.16 shows that the West Midlands CLD admission rates decreases with decreasing levels of deprivation (Figure 5.16). This mirrors the pattern for mortality (Figure 5.8)
Figure 5.16: Directly Standardised CLD Admission Rates in the West Midlands by Deprivation, deaths registered 2006-2008 (pooled)
|
The recently proposed PCT clusters analysis shows that CLD related admissions are significantly lower in West Mercia and Staffordshire than the West Midlands average and significantly higher in Birmingham and Black Country than the regional average.
Figure 5.17: Directly Standardised Admission Rates for CLD by Clusters, 2006/2007-2008/2009 (pooled)
|
5.5 Conclusions
- Reduction of CLD should focus on preventive measures. The three commonest risk factors for CLD are excessive alcohol consumption; blood borne viruses, in particular Hepatitis B and C, and obesity.
- The mortality and admission rates related to liver disease are on the rise in England. These trends are in the opposite direction to the general world trends; where liver disease rates are falling
- In 2008, there were 52,132 registered deaths for both males and females in the West Midlands. Of these deaths 765 deaths were CLD deaths, contributing 1.5% of all registered deaths in West Midlands in 2008.
- West Midlands has the third highest CLD mortality in England. The West Midlands mortality rates are significantly higher than the national rates for both males and females. The admission rates related to CLD are significantly lower than national rates for males. The mortality and admission rates for males are significantly higher than females.
- The mortality and admissions rates for CLD increases up to the age groups of 50-54 years and 55-59 years among males and females respectively, showing higher mortality rates in males than females. This is followed by a downward trend in mortality for both sexes.
- The PCTs in the shire counties and the Solihull PCT have lower mortality and admission rates related to CLD than regional rates.
- The West Midlands CLD mortality and admission rates decrease with decreasing levels of deprivation.
- There is a significant increase in mortality and admission rates over the last 7 years. The increase in the CLD mortality is due to increase in the mortality from alcoholic liver disease (ICD 10 code: K70) which has increased significantly from 2002-2004 to 2006-2008.
References
- ‘Scottish Public Health Observatory. Chronic Liver Disease. http://www.scotpho.org.uk/home/Healthwell-beinganddisease/Chronicliverdisease/chronicliverdisease_intro.asp (Accessed on 23rd June 2010)
- Corrao G, Aricò S Independent and combined action of hepatitis C virus infection and alcohol consumption on the risk of symptomatic liver cirrhosis. Hepatology 2003;27(4):914-919.
- E Kaner et al. A rapid review of liver disease epidemiology, treatment and service provision in England. Institute of Health and Society, Newcastle University. December 2007
- World Health Organisation. Health for All Database. http://www.euro.who.int/en/what-we-do/data-and-evidence/databases/european-health-for-all-database-hfa-db2 (Accessed on 23rd April 2010)
- The Information Centre. Clinical and Health Outcomes Knowledge Base. www.nchod.nhs.uk (Accessed on 23rd April 2010)
- North West Public Health Observatory. Local Alcohol Profiles for England. http://www.nwph.net/alcohol/lape/pctProfile.aspx?reg=q34 (Accessed on July 16th, 2010)
- Chronic Liver Disease Foundation. http://www.chronicliverdisease.org/library/slide/slide_topic.cfm?topic=hcc2009 (Accessed on 23rd April 2010)
Acknowledgements
-
Dr John Kemm and the Information team at the West Midlands Public Health Observatory
For more information please contact Sarafina
Cotterill
© Public Health, Epidemiology and Biostatistics Unit, School of Health and Population Sciences, University of Birmingham