If you don’t have celiac disease, but are reading this because you have a friend who does, have you wondered if you or your family members should be screened for it? Since celiac disease is no longer considered rare, affecting approximately 1% of many populations, doctors and patients alike are asking the question, should everyone be screened for celiac disease? If not, why not? If only some people should be screened, who should they be?
This is not a question about testing people with gastrointestinal symptoms of celiac disease, or adults with celiac-related problems like osteoporosis or anemia without adequate explanation. This is a question about screening people with no specific reason for screening.
The basic principles used to decide if a test should be used for screening were first outlined by the World Health Organization (WHO) in 1968. They have been revised since then, but the general ideas are still sound. In order for screening for a disease to be a reasonable idea, the following should be true:
- There should be a simple, safe and accurate screening test for the disease
- There should be a definite cut-off separating people with the disease from those without the disease
- The population to be tested should be defined
- The test should be available to the defined population
- There should be an agreed way to further investigate screened patients and
- Effective treatment should be available for patients who are found to have the disease
What screening is looking for are true positives and true negatives. False positives expose people without disease to unnecessary testing. False negatives lead people with a disease to believe they do not have it. It is generally considered that screening programs need to be carefully considered and that the pros must outweigh the cons.
Who to screen for celiac disease is not yet clear.
What are the reasons for screening celiac disease and are they valid?
Unfortunately, there is not enough information to answer these questions with certainty. People who have celiac disease have a higher risk of dying than those without celiac disease. It is also believed that people with celiac disease have a higher rate of a number of certain cancers. People with celiac disease can develop other autoimmune disorders including diabetes, thyroid disease, and certain kinds of liver and biliary diseases.
What might happen to people with no symptoms of CD who are not diagnosed? Possible problems include:
- An elevated risk of certain types of cancer, especially lymphoma
- An increased risk of developing other kinds of autoimmune disorders like diabetes
- An increased risk of earlier death (mortality)
- Worse quality of life
The research on whether or not diagnosing celiac disease in these people who do not have symptoms does not prove unequivocally that early diagnosis will change outcomes.
It is now believed that the increased risk of cancer in celiac disease patients may not be as high as once believed. There is a somewhat elevated risk of certain cancers in people with CD.
For one specific type, enteropathy associated T-cell lymphoma (EATL), celiac disease is definitely a risk factor, and the risk goes down for people on a gluten-free diet. However, in one large study, only a single person with celiac disease developed this cancer.
Some studies have shown that the risk of intestinal lymphoma is higher in people with CD, but most cases are found between 2 years before the diagnosis and 2 years afterwards. An increase in the number of thyroid cancers in patients with CD has been noted in diagnosed and treated patients.
It is not certain that diagnosing symptom-free patients with celiac disease will reduce their risk of cancer.
There is some evidence that finding CD in patients with diabetes and starting a gluten-free diet may improve control of the diabetes. There are also studies indicating that fewer new autoimmune diseases may develop. There are also studies showing no difference.
The higher mortality rate in people with celiac disease has been shown in some studies to decrease on a gluten-free diet, but not all the way to normal. There are also studies that do not show a higher mortality rate in people with celiac disease.
There are some indications that the mortality rate is higher in people who have positive blood tests but normal intestinal biopsies. Anyone who was screened and then found to have normal intestinal biopsies would not be put on a gluten-free diet.
Conflicting information means that it is not certain that diagnosing CD without symptoms will affect the risk of death.
Quality of Life
Quality of life is definitely impacted by the diagnosis of CD, especially in the United States, where getting gluten-free food is difficult and expensive. Many studies have documented that people diagnosed by screening do not always stay on the diet, and many studies document the negative effect of the diagnosis on quality of life.
Obviously, if people who are diagnosed with celiac disease do not stay on the gluten-free diet, there will be no possible health benefits. People without symptoms are much less likely to follow the diet than those who feel sick when they consume gluten.
Because the natural history of celiac disease, including what happens to people with asymptomatic disease, or positive blood tests but negative biopsies, it is far from certain that diagnosing people by screening will improve their health or quality of life. Most groups looking at all of the information are not in favor of mass screening.
Many groups advocate selective screening of people at higher risk than normal, such as those whose relatives have CD or who have autoimmune diseases associated with CD.
At this time, it seems best to remain aware of this problem and for people at risk to be screened. To answer the original question, if you have a friend with celiac disease but have no symptoms or associated medical problems, you do not need to be screened. If you are a close relative of someone with celiac disease, you probably should be screened.