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Inflammatory Bowel Disease
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Some Questions and Answers
What is Inflammatory Bowel Disease (IBD)?
IBD is a collective term used to describe a group of several
disorders of the digestive tract characterised by chronic
(i.e. ongoing) inflammation which can lead to swelling, injury
to the intestinal tissues, and ulceration. The commonest IBD
disorders are ulcerative colitis and Crohn’s disease.
What are the differences between ulcerative colitis and
Crohn’s disease?
The symptoms of these two disorders can be very similar,
but there are also two distinct differences: firstly the part
of the intestinal tract affected and secondly the extent (severity)
of the inflammation.
Which parts of the gut are affected in these conditions?
Ulcerative colitis only affects the large intestine (i.e.
the colon and rectum). The rectum is the only part involved
in around 55 per cent of people with colitis, known as proctitis),
while 30 per cent have only the left side of the colon affected.
The remainder (15 per cent) have total colon involvement (known
as pancolitis). By contrast, Crohn’s disease can affect
any part of the digestive tract, but is much more likely to
affect some parts than others. The commonest sites affected
are the small intestine, around 30 per cent, the junction
of the ileum with the caecum and colon (around 40 per cent),
and the colon itself (25 per cent). The mouth, oesophagus
and anus are less frequently affected (about 5 per cent).
The lesions in ulcerative colitis tend to occur in continuous
regions of the gut, albeit mostly within the rectum, and a
variable amount of the colon. By contrast, Crohn’s disease
lesions are often discontinuous – that is, an affected
part of the gut may be followed by an unaffected region in
which the tissue is normal (so-called ‘skip’ lesions).
Which layers of the intestine are affected in these conditions?
Both ulcerative colitis and Crohn’s disease are characterised
by powerful inflammation within the layers which form the
intestinal tract. In the former, the inflammation and damage
begin in the tissues beneath the epithelium (called
the lamina propria) which is rich in small blood vessels,
lymph ducts and nerves. This becomes swollen, and microscopic
abscesses form in the crypts. In serious cases, the inflammation
can also involve the submucosa, leading to surface ulceration.
In Crohn’s disease, the inflammation can be more widespread,
and the damage often penetrates more deeply. Here, the ulcers
can eat into the lower muscle and serosal layers (called fissuring).
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ULCERATIVE COLITIS |
CROHN’S DISEASE |
| Areas of the digestive tract possibly affected |
Colon (large intestine) and rectum |
Any part of the digestive tract from the mouth to the
anus |
| Extent of inflammation |
Mainly the inner lining of the bowel (the mucosa) |
All layers of the bowel from the inner mucosa to the
outer serosa |
Areas affected and extent of inflammation in Crohn’s and
ulcerative colitis
Sometimes a deep ulcer may break right through to the outside
of the intestine and form an abscess. Erosion may occur into
other structures (e.g. the bladder) or on to the skin of the
abdominal wall. A duct or track between the intestine and
another organ is described as a fistula. With repeated
attacks, the lining and underlayers of the intestine become
increasingly modified as scar tissue and inflammatory cells
increase, leading eventually to a further breakdown of function.
What are the main symptoms of Inflammatory Bowel Disease?
The damage described above can cause a range of symptoms which
vary greatly in their severity between people. Bloody diarrhoea
is the hallmark of ulcerative colitis and occurs in about
96 per cent of cases. However, it should be realised that
blood in the faeces may also be due to less serious conditions
such as haemorrhoids. The onset of ulcerative colitis may
be gradual or sudden. As the condition continues, the faeces
become more liquid and there may be mucus passed as well as
blood. Blood loss may cause anaemia, and fever, malaise, high
pulse rate and weight loss are common. Perforation of the
bowel is rare in ulcerative colitis, but acute swelling and
severe damage to the colon (toxic megacolon) are always
a risk during acute attacks and often require surgical intervention.
In Crohn’s disease, most people (70 to 90 per cent)
initially experience diarrhoea, with 45 to 66 per cent experiencing
abdominal pain and up to 75 per cent experiencing weight loss.
Visible blood loss is much less common than in ulcerative
colitis, but the loss of blood may cause anaemia and fatigue.There
may also be high temperature, and up to one-third may have
painful complications such as abscesses, ulcerated cracks,
or fistulas around the anus. During acute episodes, there
is also a small risk of blockage to the intestine and of perforation
of the intestinal wall which has to be treated as a serious
medical emergency.
About 4 per cent of people with either condition will also
have symptoms in other parts of the body (called extra-intestinal
symptoms), involving the joints, skin, eye, or liver. More
generalised symptoms such as malaise, anaemia, fatigue, and
high temperature are rather more common.
Can Inflammatory Bowel Disease reduce life expectancy?
There have been major improvements in the recognition and
management of IBD in the past 50 years. Hence the risk of
major complications such as toxic megacolon has now fallen
to below 1 per cent and the risk of death during the severest
attacks has fallen from around 30 to 60 per cent in the 1950s
to less than 3 per cent today. This has come about through
improved treatment with intravenous steroids, and better supportive
care and surgical techniques. In long-standing Crohn’s
disease and ulcerative colitis, the risk from colon cancer
is slightly higher than in the general population (about 3
to 5 per cent), but overall life expectancy in people with
these conditions is very similar to that in the general population
and need not be a cause for concern.
Is Inflammatory Bowel Disease related to diet?
No clear links with diet as a cause of IBD have been found.
However, some people find that cutting out certain food items
(such as dairy products) or decreasing fibre can help. Because
this is a complex area, any planned change of diet should
be discussed first with a gastroenterologist or dietician.
Crohn’s disease showing a deeply penetrating (fissured)
ulcer (cleft from top downward) and the accumulation of inflammatory
cells (bluish stained areas) around and below it
In Crohn’s, malnutrition is common and maintaining
an adequate diet is important. An elemental diet may be helpful
in some cases. This is a liquid feed already broken down so
that it has only to be absorbed by the small intestine. Elemental
diets improve symptoms, particularly crampy abdominal pains
in Crohn’s disease, and reduce inflammation. A special
booklet on IBD and diet is available from the NACC.
What causes Inflammatory Bowel Disease?
It is now generally believed that IBD is caused when
three main factors interact inappropriately, possibly in association
with dietary elements: our individual genes, the immune system
and the bacteria living in the gut. Of course, everyone has
bacteria in their gut and is constantly exposed to them and
their products as they penetrate the intestinal lining. In
a healthy person, such exposure triggers a defensive immune
response. Part of this is localised inflammation, one of the
first stages in the healing process.A normal inflammatory
response typically increases for a few hours or days and then
wanes and disappears as healing proceeds.
People with IBD seem to have a genetic make-up that causes
their immune system to over-react to stimulation by the bacteria
in the gut wall. The result is an excessive and ongoing inflammatory
response, leading to failure to heal and ulcer formation.
Over a period of time, this causes extensive and progressive
tissue damage.
Who is affected by Inflammatory Bowel Disease?
IBD is rare in early childhood, but otherwise affects
people of all ages. Two groups seem to have a greater risk
– those in early adult life and, to a lesser extent,
the over 65s. The conditions seem to affect people equally,
irrespective of wealth or status. Both ulcerative colitis
and Crohn’s occur with a broadly similar frequency in
both sexes. However, people from different races and cultures
vary in their risk from both ulcerative colitis and Crohn’s
disease and black people studied in North America were affected
less often than white-skinned individuals. The number of cases
of ulcerative colitis is rising in people of Asian origin
and people from Bangladesh born in the UK. Taken together,
these observations are consistent with the view that both
genetic background and environment play a part in triggering
IBD.
How many people suffer from Inflammatory Bowel Disease?
IBD is not a notifiable disease (i.e. records of the illnesses
do not have to be passed to the medical authorities), so that
the exact numbers are a little uncertain. Based on several
estimates, it appears that in Western Europe from 1 to 1.5
people per 1,000 have ulcerative colitis, and slightly fewer
(1 in 1,500) has Crohn’s. Taking account of under-recording,
the NACC suggests that the total of people with IBD in Britain
is approaching 150,000. New cases arise at the rate of about
8,000 per year. However, there are variations in the number
of new cases seen annually in different parts of the world.
For example, in northern hemisphere centres that have been
studied, the number of new cases per 100,000 of the population
per year of ulcerative colitis was 40 per cent higher in the
north than the south; the corresponding figure for Crohn’s
disease was 80 per cent. There is also evidence that both
conditions have become more common since the 1950s in the
UK and many other parts of the northern hemisphere. Increases
in Scotland have been especially notable in children under
16 years of age.
Are there any known risk factors for Inflammatory Bowel
Disease?
A risk factor is anything that might increase a person’s
chance of developing a particular condition. A great deal
of effort has been devoted to tracking down risk factors in
IBD, but no single one has been identified as dominant. Rather,
in large population studies, several factors have shown some
causal relationship with IBD, but only in people with some
other predisposing susceptibility. It seems clear from studies
in the past 10 to 15 years that this predisposition arises
from our pattern of inherited genes – in other words,
IBD arises from an interaction of environmental and genetic
factors. The main factors are considered to be:
- Smoking. This appears to give some protection against
ulcerative colitis, which has its lowest incidence in smokers
and highest in ex-smokers. However, it substantially increases
the risk for Crohn’s.
- Infective agents. These have been extensively investigated,
but proof of a causal relationship is still lacking. The
organisms that have received most attention are measles
virus and a bacterium called Mycobacterium paratuberculosis.
Treatment with conventional anti-tuberculosis medicines
has not been successful in IBD, but as such medicines do
not kill the TB bacteria, this is not entirely unexpected.
People who have had antibiotics in the past year appear
to be at greater risk from Crohn’s, while an operation
for appendicitis may confer some protection against ulcerative
colitis. Many micro-organisms (viruses and bacteria) have
been implicated.
- Intolerance to normal intestinal microbes. These
are normally tolerated by the immune system, because they
live in harmony with the body. However, there is good evidence
that in people with IBD this is not so. For example, people
with Crohn’s often have antibodies against common microbes
such as baker’s yeast and their blood often contains
special immune cells called memory T cells, which suggests
that they ‘see’ these normal organisms as foreign.
- Events in childhood. This has been studied in detail
and once again, the rate of some childhood illnesses seems
to be higher in people with IBD than in control groups,
for example, pharyngitis and eczema. By contrast, neither
gastric infections nor breast feeding, cereal consumption,
or many other factors appear to be related to IBD.
- Stress. Many people with IBD believe that stress
played a part in the onset of their condition. Certainly,
stress can influence immunity and there are plenty of stress-related
factors that may contribute to the development of IBD, but
further work is required before the role of stress can be
confirmed. Stress may also play a role in ‘flares’
of the disease.
Is Inflammatory Bowel Disease inherited by future generations?
In the 1970s and early 1980s, epidemiologists studying
disease patterns in large populations began to investigate
IBD. Depending on the particular study, it soon became clear
that in 6 to 15 per cent of families, IBD was more frequent
than in the general population. The data suggested that a
person with Crohn’s disease was about 10 times more likely
to have a close relative (parent, brother or sister, child)
with the disease than in the population as a whole.
In the late 1980s, several groups looked at pairs of identical
and non-identical twins. The former individuals are genetically
the same, so if the disorder was entirely due to the genes,
one would expect that both twins would be affected. However,
in a Swedish study of 18 pairs of identical twins, eight pairs
both had Crohn’s disease, while in only one pair out
of 26 non-identical twins was that the case. Based on this
and other similar studies, it is believed that there is a
significant genetic susceptibility to Crohn’s. However,
in terms of inheritance, this should not cause undue concern,
because identical twins are a very special case. In the case
of a single child, there is about a 10 to 15 per cent chance
of developing ulcerative colitis or Crohn’s disease if
a parent has it. So 85 to 90 out of every 100 children born
to affected parents should escape the illness themselves.
Overall, the data from family studies suggest two things.
Firstly, that there are definitely genes that increase the
risk of IBD and secondly, that there must be triggering factors
in the environment for the illness to manifest itself.
Though these studies suggest a genetic component in IBD,
the evidence has been greatly strengthened in the past four
or five years as knowledge of molecular genetics has grown.
Using such methods to look for single genes, or to search
the whole genome for candidate genes, scientists have been
able to identify several (probably 10 to 15) which appear
to be linked to IBD. However, having these genes does not
mean that IBD is inevitable, merely that susceptibility will
be increased with exposure to specific environmental triggers.
The genes suspected so far are scattered on different chromosomes,
notably 3, 5, 6, 7, 12 and 16. In 2001 two separate research
teams, one in France and one in the USA, reported that a gene
known as NOD2 on chromosome 16 was implicated in Crohn’s
disease. Genes carry the coded messages for the proteins that
are found in cells. Interestingly, the protein coded for by
NOD2 is centrally involved in the regulation of the inflammatory
process – just what goes wrong in IBD. However, NOD2
seems only to be associated with Crohn’s disease of the
small intestine and not to that affecting the colon, and is
not linked with ulcerative colitis.
Why does Inflammatory Bowel Disease keep recurring?
When we are vaccinated against a disease, immunity will
be conferred for months or, in some cases, for the rest of
our lives. This happens because the immune system has an in-built
memory which can respond to subsequent exposure to the same
agent. In IBD, this same memory system appears to respond
inappropriately to trigger antigens such as those from gut
bacteria such as E. coli. When the condition goes into
remission, the immune system subsides and can go into its
memory mode. In a flare-up, the memory is rapidly rekindled
by fresh exposure to an antigen and a renewed and excessive
immune attack mounted, with all the ensuing tissue damage.
Some of the medicines used in IBD are called immunosuppressives,
because they act to damp down an over-active immune system.
What range of treatments are available for Inflammatory
Bowel Disease?
After a diagnosis is confirmed, several parallel approaches
will be necessary to bring about adequate medical management.
These will include the use of appropriate medicines to bring
the attack under control (i.e. induce a remission), psychosocial
support to enable the person to adjust to the inevitable distress
such an illness will cause, an examination of diet and, if
necessary, the use of dietary supplements to ensure that essential
nutrients are being absorbed. These approaches will involve
a multi-disciplinary team of doctors, surgeons, pharmacists,
dieticians and specialist nursing staff. However, their involvement
will vary between individuals, with the exact history and
severity of the illness and, of course, will need to reflect
the wishes of the individual. A minority of people develop
their symptoms so suddenly that they have to enter hospital.
In a few cases, a surgical team may need to perform a life-saving
operation.
Even when the initial attack is under control, many people
subsequently become ill again (called a relapse), and often
the disease will develop a chronic course, when the symptoms
wax and wane over many years. Once a remission is achieved,
the aim will be to maintain it. It is also worthwhile to assess
diet to see if there are any items that seem to trigger episodes
of the illness. A minority of people seem to have such sensitivities,
while in most, the situation is much less clear.
In a small minority of people with severe IBD in whom attacks
keep recurring, it may eventually become necessary to consider
the surgical removal of the affected part of the bowel. In
a few cases, an artificial opening (called a stoma) may be
created. This can be a source of great anxiety in many people,
but in the past two decades there have been great advances
in this type of operation and in stoma care. For some people
such operations can transform life dramatically for the better.
More often though, these days, an operation to create an internal
pouch (ileo-anal pouch) is preferred, with similar
beneficial results.
What are the main types of medicines used in IBD?
There are several different classes of medicine used to
treat IBD. Some of them are designed to help bring active
inflammatory disease under control and produce a remission,
some aim to sustain the remission, while others seek to reduce
some of the symptoms. The medicines can be divided into groups,
depending on their chemical nature, namely:
- steroids (hydrocortisone, prednisolone, budesonide)
- derivatives of aminosalicylic acid, 5-ASA (sulphasalazine,
mesalazine, olsalazine, balsalazide)
- immunoactive medicines (azathioprine, 6-MP. Occasionally,
cyclosporin and methotrexate may be used, though they are
not specifically licensed for IBD)
- monoclonal antibodies (infliximab)
- antibiotics (metronidazole, ciprofloxacin, clarithromycin)
and
- medicines providing symptomatic relief such as
anti-diarrhoeals, agents for pain control, vitamins and
diets.
The first line of treatment for both forms of active disease
is usually a 5-ASA medicine and a corticosteroid. Where disease
is confined to the rectum and lower part of the colon, the
medication may be administered in the form of suppositories
or enemas. Cyclosporin, a powerful immune-suppressive agent,
is sometimes used in a severe attack of ulcerative colitis
if the person fails to respond to steroids. Aminosalicylates
also have a useful role in maintaining normal gut function
once a remission is achieved, but the choice of subsequent
medication depends on the response to initial therapy, disease
status and extent. Liquid formula diets are often helpful
for Crohn’s disease of the small bowel. The medications
used and the timing depend greatly on individual circumstances.
How will IBD affect the ability to lead a normal life?
The year following a first episode of IBD is particularly
stressful for the individual and is also the period of most
risk. However, over 90 per cent of people with ulcerative
colitis and 75 per cent with Crohn’s disease will be
able to hold down a normal job and do so for a normal life
time.
Despite this generally encouraging message, it is recognised
that there are a few people (about 5 per cent) who experience
severe forms of the disease which dominate their lives. In
such cases, a social life and regular work become all but
impossible. Many such individuals may eventually have to face
surgery, but the relief it can provide is usually very worthwhile.
Surgery should be considered as an extension of normal medical
treatment to restore health and working capacity. It is more
commonly needed in Crohn’s disease than in ulcerative
colitis. Numerically, about 75 per cent of people with Crohn’s
eventually need surgery, compared to only about 20 per cent
in ulcerative colitis.
What general information and support is available for
people with IBD?
If you or a near relative are diagnosed with either Crohn’s
disease or ulcerative colitis, it will be a worrying event
– though perhaps mixed with some relief that it is not
cancer. Even so, there is likely to be a period of shock while
the news sinks in, followed by a flood of questions about
the illness and how it might affect you in the future. During
this time, close support is essential, and opportunities must
be created to talk about the condition and get the answers
that are needed. Some may be provided by a GP or specialist,
but such people may not always be available when needed. The
NACC offers a comprehensive support service, including a telephone
helpline, and an extensive and well-written series of booklets
and fact sheets dealing with almost every aspect of IBD that
you are likely to meet. These include such issues as claiming
disability allowance if your condition warrants it.
The NACC also has a network of local support groups throughout
Britain. These provide an opportunity to meet other people
with conditions like your own and to share experiences. They
also often organise talks and social events. Smilie’s
People is a special group network for families who have a
child or a young person with IBD. The address and contact
details for the NACC are given at the end of this booklet.
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