This bulletin presents the latest figures for deaths where Clostridium difficile (C. difficile) infection was mentioned on the death certificate: by sex, age group and place of death, in England and Wales. Figures are presented for deaths registered in 2010, with previously released figures for 2006 to 2009 for comparison purposes. Information is also given about the context and use of the statistics, and the method used to produce them.
C. difficile is a spore forming anaerobic bacterium that was first described in the 1930s (Hall and O’Toole 1935). According to the Health Protection Agency (2011a), it is present in the gut of up to 3 per cent of healthy adults and 66 per cent of infants. However, C. difficile rarely causes problems in children or healthy adults, as it is kept in check by the normal bacterial population of the intestine. When certain antibiotics disturb the balance of bacteria in the gut, C. difficile can multiply rapidly and produce toxins which cause illness.
C. difficile infection ranges from mild to severe diarrhoea to, more unusually, severe inflammation of the bowel (pseudomembranous colitis). People who have been treated with broad spectrum antibiotics (those that affect a wide range of bacteria), people with serious underlying illnesses and the elderly are at greatest risk. Over 80 per cent of C. difficile infections reported are in people aged over 65 years.
C. difficile infection is usually spread on the hands of healthcare staff and other people who come into contact with infected patients or with environmental surfaces contaminated with the bacteria or its spores (for example floors, bedpans and toilets). Spores are produced when C. difficile bacteria encounter unfavourable conditions, such as being outside the body. They are very hardy and can survive on clothes and environmental surfaces for long periods.
Actions to reduce levels of healthcare associated infections have been detailed in various reports (Department of Health 2003a, 2003b; Department of Health and Health Protection Agency 2009) and have been implemented in healthcare settings. These include reducing the infection risk from medical instruments, better antibiotic prescribing, isolating infected patients, environmental cleaning and disinfection, and improved hand hygeine.
Figures on the number of deaths from C. difficile in England and Wales are used by various organisations, including the Department of Health (DH), the Health Protection Agency (HPA), and Public Health Wales, for monitoring and evaluation purposes. They are also used by primary care organisations (PCOs), local health boards (LHBs) and individual healthcare establishments.
The Operating Framework for the NHS in England 2011/12 (Department of Health 2010) states:
The NHS has made good progress in reducing MRSA bloodstream and Clostridium difficile infections. There is still scope to drive these and other healthcare associated infections (HCAIs) down further. NHS organisations should aim for a zero tolerance approach to all HCAIs and all organisations must identify and adjust plans so that they can operate at the level of the best. NHS providers and commissioners should ensure that their HCAI improvement plans deliver at least the level of performance set by the HCAI indicators.
Specifically, there are two HCAI measures which require PCOs in England to reduce the number of C. difficile and MRSA infections. Organisations with higher baseline rates are required to deliver larger reductions.
C. difficile infections occurring in England are monitored monthly using data collected by the HPA. The latest figures show that a total of 21,695 cases of C. difficile occurring in patients aged two years and over were reported in England between April 2010 and March 2011 (2010/11) (Health Protection Agency 2011b). This represents a reduction of 15 per cent on the 25,604 cases of C. difficile reported in 2009/10 and a 40 per cent reduction on the 36,095 cases reported in 2008/09.
In Wales, surveillance of C. difficile is managed by the Welsh Healthcare Associated Infection Programme (WHAIP), which is part of Public Health Wales. The latest figures for April 2010 to March 2011 (2010/11) show that there were 2,280 cases of C. difficile reported (Public Health Wales 2011). This represents a reduction of 27 per cent on the 3,127 cases reported in 2009/10.
Deaths involving C. difficile statistics have been produced by the Office for National Statistics (ONS) for 1999 and for 2001 onwards (see ‘Methods’ below for more information). Figures for recent years show a large decrease in the number and rate of deaths where C. difficile was the underlying cause of death or was mentioned anywhere on the death certificate among both males and females. This finding is consistent with the incidence figures reported by the HPA and Public Health Wales. The decreases may be due to the actions taken to reduce healthcare associated infections described above.
The number of death certificates in England and Wales mentioning C. difficile peaked in 2007 at 8,324 (Table 1). Deaths have since decreased and the number fell to 2,704 in 2010, which was 67.5 per cent lower than in 2007. The percentage of cases where C. difficile was recorded as the underlying cause decreased from 54 per cent in 2006 to 42 per cent in 2010.
In England, the number of deaths where C. difficile was mentioned on the death certificate was highest in 2007 at 7,916. This figure fell by 70.5 per cent to 2,335 in 2010. The percentage of deaths where C. difficile was recorded as the underlying cause decreased from 54 per cent in 2006 to 41 per cent in 2010.
In Wales, the number of deaths involving C. difficile peaked a year later than in England at 461 in 2008. This figure fell to 381 in 2009 and 368 in 2010. The percentage of cases where C. difficile was recorded as the underlying cause was lowest in 2007 and 2008 at 44 per cent. In 2010 the figure was 9 percentage points higher than in England at 50 per cent.
|England and Wales1|
|Certificates mentioning C. difficile||6,480||8,324||5,931||3,933||2,704|
|Certificates where C. difficile was the underlying cause of death||3,490||4,056||2,502||1,712||1,130|
|Percentage of mentions selected as underlying cause||54||49||42||44||42|
|Certificates mentioning C. difficile||6,301||7,916||5,465||3,550||2,335|
|Certificates where C. difficile was the underlying cause of death||3,393||3,875||2,298||1,510||946|
|Percentage of mentions selected as underlying cause||54||49||42||43||41|
|Certificates mentioning C. difficile||170||399||461||381||368|
|Certificates where C. difficile was the underlying cause of death||93||177||203||201||184|
|Percentage of mentions selected as underlying cause||55||44||44||53||50|
Most of the deaths involving C. difficile occur among older people. For the combined 2006 to 2010 period, age-specific mortality rates were highest in those aged 85 years and over (Table 2). In England and Wales, rates for deaths mentioning C. difficile in this age group were 2,186 per million population for men and 2,194 per million for women. Figures were similar for England but slightly higher for Wales at 2,228 and 2,418 per million for men and women respectively, although this difference was not statistically significant.
In comparison with those aged 85 years and over, the rates for men and women aged 75 to 84 years in England and Wales were much lower at 653 and 643 per million respectively. Figures for England were similar but higher for Wales at 694 per million for men and 690 per million for women, although this difference was also not statistically significant.
Rates were lowest in the under 45 age group with less than one death per million population for both sexes.
|Rate per million population|
|England and Wales1||England||Wales|
|85 and over||2186.4||2193.9||2181||2178.5||2228.3||2417.7|
Age-standardised mortality rates for deaths involving C. difficile are similar for both sexes. In England and Wales, rates were highest in 2007 at 84.7 and 80.4 per million for males and females respectively (Table 3). Rates have since fallen each year and in 2010 they decreased to 25.4 per million for males and 25.7 million for females.
The trend is similar for England. However, rates have varied in Wales. In 2006 the male and female rates for deaths involving C. difficile were less than half the rates recorded in England. Rates increased in 2007 and peaked in 2008 at 80.9 per million for males and 75.1 per million for females. They have since decreased but were recorded at more than double the rates for England in 2010, which was statistically significant.
|Rate per million population|
|England and Wales1||England||Wales|
Due to improvements in the classification and coding of communal establishments, the place of death definition used by ONS has been revised. In particular, the NHS and non-NHS nursing home and private residential home categories have been replaced with local authority and non-local authority care home categories, which reflects current user needs. The allocation and coding of individual establishments to place of death categories is a continual exercise which will improve the quality of this new classification.
Between 2006 and 2010 deaths involving C. difficile accounted for 1.1 per cent of all deaths in England and Wales (Table 4). Death certificates rarely specify the place where an infection was acquired, although the place of death is routinely recorded.
The majority of deaths in England and Wales occur in hospital. It is therefore expected that most deaths involving C. difficile infection will occur in hospital. At present, ONS does not routinely produce figures by individual hospital establishment.
During the period 2006 to 2010 combined, 92.7 per cent of C. difficile deaths in England and Wales occurred in NHS hospitals. This represents 1.8 per cent of all deaths that occurred in NHS hospitals.
For England the percentage of deaths involving C. difficile which occurred in NHS hospitals was 92.5 per cent in comparison with 95.4 per cent in Wales. These figures both represent 1.8 per cent of all deaths in NHS hospitals in England and in Wales.
In England and Wales, 5.1 per cent of deaths involving C. difficile occurred in care homes. This represents 0.3 per cent of all deaths which occurred in these establishments. The percentage of C. difficile deaths occurring in care homes in England was similar at 5.3 per cent, but lower in Wales at 2.4 per cent.
The workbook contains the following results for England and Wales:
The number of death certificates with Clostridium difficile mentioned and as the underlying cause of death, by country, 1999 and 2001 to 2010
The number of death certificates with Clostridium difficile mentioned and as the underlying cause of death, by country and annual registration quarters, 1999 and 2001 to 2010
Age-standardised mortality rates for deaths where Clostridium difficile was mentioned on the death certificate, by country and sex, 1999 and 2001 to 2010
All deaths in England and Wales are coded by ONS according to the International Classification of Diseases (ICD) supplied by the World Health Organisation (WHO). In the Tenth Revision (ICD–10), used by ONS from 2001 onwards, there is a specific code (A04.7) for ‘Enterocolitis due to Clostridium difficile’. While this code identifies the vast majority of deaths involving C. difficile, a small number of C. difficile-related deaths are not captured by this code alone.
Since 1993 ONS has stored the text of death certificates on a database, in addition to all the ICD codes relating to causes identified on the death certificate. This means that it is possible to identify records where C. difficile is mentioned, but is not coded under the specific ICD–10 code.
In addition to extracting all deaths related to the specific A04.7 ICD–10 code, deaths mentioning a number of other ICD categories to which diseases including C. difficile could be coded were also extracted. The text of these death certificates was then searched manually for mentions of Clostridium difficile, C. difficile or pseudomembranous colitis. The ICD–10 codes used to select deaths in order to search manually are shown in Box 1.
Deaths registered in 1999 were coded to both ICD–9 and ICD–10 as part of a special study to compare the two ICD revisions, and have therefore been used to give an additional year of data on deaths involving C. difficile.
|Specific codes1||Non-specific codes1|
|A04.7 (Enterocolitis due to Clostridium difficile)||A05.8 (Other specified bacterial food borne intoxications)|
|A41.4 (Septicaemia due to anaerobes, excludes gas gangrene)|
|A48.0 (Gas gangrene: Clostridial; cellulites, myonecrosis)|
|A49.8 (Other bacterial infections of unspecified site)|
|P36.5 (Sepsis of newborn due to anaerobes)|
Deaths with an underlying cause of C. difficile were identified by selecting those deaths with a mention of C. difficile that also had an underlying cause of one of the following ICD-10 codes: A04.7, A41.4 and A49.8. As in previous C. difficile reports (Office for National Statistics 2010a), death certificates which mention C. difficile and record the code A09 (Diarrhoea and gastroenteritis of presumed infectious origin) as the underlying cause of death, are also taken to indicate that C. difficile was the underlying cause of death.
Since 1986, ONS has used the internationally recommended death certificate for neonatal deaths (infants aged under 28 days). This means that these deaths cannot be assigned an underlying cause of death. However, as the data were based on deaths where C. difficile or pseudomembranous colitis were mentioned on the death certificate, neonates have been included. Neonatal deaths were extracted in the same way as described above for post-neonatal deaths.
The number of deaths due to C. difficile is difficult to estimate. Trends in mortality are normally monitored using the underlying cause of death (the disease which initiated the train of events leading directly to death). However, C. difficile (and other healthcare associated infections) are often not the underlying cause of death. Those who die with C. difficile are usually patients who were already very ill, and it may be their existing illness, rather than C. difficile, which is designated as the underlying cause of death. There is therefore an interest in the number of deaths where C. difficile contributed to the death – only conditions which contribute directly to the death should be recorded on the death certificate. Results presented in this bulletin identify deaths where the underlying cause was C. difficile and also where C. difficile was mentioned as the underlying cause or as a contributory factor in the death.
Although C. difficile is commonly referred to as a healthcare associated infection, it is not possible to state from the information on a death certificate where the infection was acquired, nor can assumptions be made about quality of care. People are often transferred between hospitals, care homes and other establishments, and may acquire infections in a different place from where they died.
Guidance on death certification, with specific reference to healthcare associated infections, was issued to doctors in May 2005 (revised in 2010) (Office for National Statistics 2010b). This was followed by a message from the Chief Medical Officer to all doctors reminding them of their responsibilities with respect to death certification and drawing their attention to the guidance (Department of Health 2005). More recently, the Department of Health and Health Protection Agency (2009) released a report detailing good practice and recommendations on completing death certificates for deaths involving C. difficile.
There are two types of rates reported in this bulletin; age-specific and age-standardised. Age-specific (also known as ‘crude’) rates may be calculated for given age groups and are defined as the number of deaths in the age group per million (or thousand) population in the same age group. They do not allow comparison between populations which may contain different proportions of people of different ages. Age-standardised (also known as directly-standardised) rates make allowances for differences in the age structure of the population, over time and between sexes. The age-standardised rate for a particular disease is that which would have occurred if the observed age-specific rates for the disease had applied in a given standard population. In this bulletin, the European standard population has been used. This is a hypothetical population standard, which is the same for both males and females, allowing standardised rates to be compared over time and between sexes.
Rates were not calculated where there were fewer than three deaths in a cell, denoted by ‘:’. It is ONS practice not to calculate rates where there are fewer than three deaths in a cell, as rates based on such low numbers are susceptible to inaccurate interpretation. Rates which were calculated from less than 20 deaths are distinguished by italic type as a warning to the user that their reliability as a measure may be affected by the small number of events.
Within this bulletin, a difference which is described as ‘statistically significant’ has been assessed using confidence intervals. Confidence intervals are a measure of the statistical precision of an estimate and show the range of uncertainty around the estimated figure. Calculations based on small numbers of events are often subject to random fluctuations. As a general rule, if the confidence interval around one figure overlaps with the interval around another, we cannot say with certainty that there is more than a chance difference between the two figures.
Special extracts and tabulations of deaths involving C. difficile data for England and Wales are available to order for a charge (subject to legal frameworks, disclosure control, resources and agreement of costs, where appropriate). Such requests or enquiries should be made to:
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|Secretary of State for Health||Department of Health|
|Private Secretary to Secretary of State for Health||Department of Health|
|Special Adviser to Secretary of State for Health||Department of Health|
|Minister of State for Health||Department of Health|
|Assistant Private Secretary to Minister of State for Health||Department of Health|
|National Director, Health Care Associated Infections||Department of Health|
|Health Care Associated Infections Policy Team Leader||Department of Health|
|Statistician||Department of Health|
|Senior Press Officer||Department of Health|
|Press Officer||Department of Health|
|Chief Medical Officer||Welsh Government|
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Department of Health (2003a) The National Clostridium difficile Standards Group: Report to the Department of Health, accessed 9 August 2011, available at: www.dh.gov.uk/en/Publicationsandstatistics/Publications/PublicationsPolicyAndGuidance/DH_4067649
Department of Health (2003b) Winning Ways: Working together to reduce Healthcare Associated Infection in England: Report of the Chief Medical Officer, accessed 9 August 2011, available at: www.dh.gov.uk/en/Publicationsandstatistics/Publications/PublicationsPolicyAndGuidance/DH_4064682
Department of Health (2005) CMO Update, Issue 42, Summer 2005, accessed 9 August 2011, available at: www.dh.gov.uk/en/Publicationsandstatistics/Lettersandcirculars/CMOupdate/DH_4115663
Department of Health and Health Protection Agency (2009) Clostridium difficile infection: how to deal with the problem, accessed 9 August 2011, available at: www.dh.gov.uk/en/Publicationsandstatistics/Publications/PublicationsPolicyAndGuidance/DH_093220
Department of Health (2010) The Operating Framework for the NHS in England 2011/12, accessed 9 August 2011, available at: www.dh.gov.uk/en/Publicationsandstatistics/Publications/PublicationsPolicyAndGuidance/DH_122738
Hall, I.C and O’Toole, E. (1935) ‘Intestinal flora in new-born infants: with a description of a new pathogenic anaerobe, Bacillus difficilus’, American Journal of Diseases in Childhood 49 pp 390–402
Health Protection Agency (2011a) Clostridium difficile, accessed 9 August 2011, available at: www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/ClostridiumDifficile/
Health Protection Agency (2011b) Results of the mandatory Clostridium difficile reporting scheme, accessed 9 August 2011, available at: www.hpa.org.uk/web/HPAweb&HPAwebStandard/HPAweb_C/1195733750761
Office for National Statistics (2010a) Deaths involving Clostridium difficile: England and Wales, 2009, accessed 9 August 2011, available at: www.ons.gov.uk/ons/rel/subnational-health2/deaths-involving-clostridium-difficile/2009/index.html
Office for National Statistics (2010b) Guidance for doctors completing Medical Certificates of Cause of Death in England and Wales, accessed 9 August 2011, available on the General Register Office website at: www.gro.gov.uk/gro/content/medcert/index.asp
Public Health Wales (2011) All Wales infection surveillance reports, accessed 9 August 2011, available at: www.wales.nhs.uk/sites3/page.cfm?orgid=379&pid=23910
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