The Dangers of DIY Diagnosis

I spend all day talking to patients about their health and disease, explaining the rationale for tests and discussing the possible outcomes of different treatment strategies. This is often difficult and complex. I struggle to articulate risk, uncertainty, and the art of medicine; the shades of grey that are a day to day reality, and which medical school does not necessarily prepare you for.  I was therefore outraged when, on my way home after a hard day at work, I saw this advert on the Tube:

An advert on London Underground for an over the counter blood test.

I should sue Myrios for emotional distress: I almost fell onto the tracks. What shocked me was the cynical, and cheerful, exploitation of people’s worries about their health.

On their website Myrios say “with all conditions, preventative medicine is key, so it is important to check your health and well-being periodically.” I have no objection to this statement and wholeheartedly endorse the “prevention is better than cure” message. But to suggest that this can be achieved by having a random panel of blood tests is outrageous.

The advert offers testing for a number of ailments, ranging from anaemia to syphilis. Below I offer my initial reaction to each of these, and a reason why you should not buy the test (I suggest you spend your hard-earned money on a giant Easter egg, lunch and an exhibition at the Tate Modern, a subscription to the LRB, or a nice bottle of red).

What concerns me about this advert, and others like it, are the ethics of marketing to vulnerable individuals and the validity of consent to the tests.

I imagined I was one of the patients I often see in clinic and typed “do I have lung cancer?” into Google. The top hit (if you don’t have the wonderful Adblock installed) is Insight Medical offering “peace of mind” from a CT scan of the Chest. This test could indeed reveal a Lung Cancer, and if detected early the outlook is better. But the test involves exposure to radiation, and should only be offered to those with the right risk factors and symptoms or signs to make sure the potential benefit outweighs the known harm. In this context, the test will be offered by a Respiratory Physician, for free on the NHS.

An example of a particularly advanced CT scanner, capable of producing amazing images in seconds

Research is ongoing for an effective lung cancer screening programme for asymptomatic individuals, and progress has been made in the use of CT for screening (a low dose protocol). I hope that in my lifetime we create an effective programme to find early cancers, amenable to aggressive curative treatment. But disappointingly there is currently insufficient evidence that CT screening makes a difference to outcomes, even in carefully selected high risk populations, which is why it is not offered as an NHS screening programme, which are subject to rigorous controls and quality assurance.

I could go on for pages about the complexities of screening; about the need to evaluate the sensitivity and specificity of a test and to know the prevalence in the population you’re testing to have a good idea of false positive and false negative rates; about the need to have a good knowledge of the natural history of the disease you’re screening for and consider lead time; about the need for precise protocols on patient selection, frequency of screening; about  how important it is to know what the intervention will be if an abnormality is detected; about the need to have systems set up to manage and perform these interventions, with appropriate after-care. I recommend The Pod Delusion Episode 129 for a great discussion with GP Dr Margaret McCartney on this subject, and also her BMJ article.

What is not often talked about is the difficulty in dealing with incidental and indeterminate findings.  What if you go for a CT Chest looking for “complete peace of mind” and it identifies a small nodule? It doesn’t look like cancer, the rest of the scan is normal and you are otherwise well. But it’s there. And you’re “high risk” as you’re a smoker. It’s too small to biopsy and your doctor recommends “watching it” with a repeat scan in 6 months (which you pay for and have.) The nodule is unchanged and your doctor recommends a further scan at 12 months. It is again unchanged so, as per guidelines,  she recommends one further check CT at 24 months. The nodule is still unchanged so she says there is no need to watch it anymore. What started as a desire for “peace of mind” has resulted in 2 years of repeat scans (with the associated cost and radiation exposure) and the unquantifiable psychological cost of knowing there is something there. Even at the end of this period you may feel uneasy that this nodule exists and there may be longterm anxiety about it. I wonder whether a scenario like this is discussed in the consent process for the initial CT. I also wonder how many patients switch to NHS care after the initial scan, leaving the NHS to pick up the bill for ongoing care and tests. As always private companies want all the profit, none of the responsibility.

I absolutely encourage you to be an empowered patient, to take control of your health, to research your condition (from evidence-based and peer-reviewed sources) and to practice preventative medicine yourself. I encourage you to talk to your doctor about your concerns. In this model of healthcare delivery there is a partnership between the patient and physician; the physician providing the expertise necessary to evaluate and contextualise the evidence, in order to advise patients on their options. Admittedly not all doctors will respond well to this, and many are still uncomfortable with the “medical Googler” but as healthcare providers we need to get better at this – our duty of care extends to protecting patients from exploitation and worry. I expect to have more and more conversations that centre around critical analysis of evidence found on the Internet. I expect to be challenged and educated by my patients in the future, and hope to steer them far away from exploitation and harm.

Don’t be taken in by cynical marketing. If you are ill or are worried about your health see your doctor. The NHS is a wonderful system and, for now, remains free at the point of need. If you need it, use it, and save your money for enjoying life.

Below are the specific tests offered by Myrios and reasons why not to buy them. 

1. Anaemia. This is a condition in which the Haemoglobin (Hb) level is low. Hb carries oxygen from the lungs to the tissues and if it is low you may feel tired or breathless. Your GP would routinely do this test (for free) if you had these symptoms. There are many, many reasons for anaemia that would require your doctor to talk to you and examine you, in order to decide on subsequent tests.

2. Cholesterol. An important and necessary component of cell membranes, but high circulating levels of some forms of cholesterol (LDL) and relatively low levels of other forms (HDL) promote atherosclerosis and so are linked to cardiovascular disease (heart attacks, strokes). This test is offered for free in NHS Health Check schemes to everyone aged 40-74, and is part of a comprehensive assessment taking into consideration personal and family history, lifestyle factors and other risk factors.

3. Diabetes. A diabetes assessment forms part of the free NHS Health Check, and  is not just an isolated blood glucose test but takes into consideration other risk factors. An isolated single test of high blood sugar does not diagnose diabetes, so further tests such as an oral glucose tolerance test might be needed, in addition to lifestyle advice and support.

4. Glandular fever. This is a viral infection caused by Epstein Barr Virus, also known as infectious mononucleosis. It often affects young adults and is contagious. Common symptoms include fever, sore throat and swollen glands/lymph nodes. For most people this condition is unpleasant but not dangerous and they get better in a few weeks. There is no reason at all for a healthy person to be tested for this disease. A doctor can advise on when the test could be helpful (including when a simple monospot is appropriate, and when other antibody tests may be needed), as part of an overall assessment of a patients’ signs and symptoms. Available for free on the NHS.

5. Gout. A condition in which patients suffer from recurrent inflammatory arthritis. They have attacks of hot, swollen, painful, red joints; often the joint at the base of the big toe, but other joints can also be affected. It is caused by elevated uric acid levels in the blood, which crystallise in joints and cause inflammation. Unfortunately a blood test for uric acid levels is very inaccurate in the diagnosis of gout. High levels are not always associated with a patient suffering from gout, and low levels do not rule out gout. In fact in an acute attack the patient may have low levels as the crystals leave the blood and enter the tissue. A hot, swollen, painful joint needs assessment by a doctor as it may have many possible causes, requiring different tests and treatments. This is available for free on the NHS.

6. Hepatitis B and C. These are viruses which are transmitted through bodily fluids, including blood and sexual contact. They may cause chronic liver disease, which puts patients at risk of cirrhosis and liver cancer. There are vaccines available to help prevent transmission. If you think you are at risk of Hepatitis B or C you need a comprehensive assessment, taking into consideration risk factors, travel and sexual history, signs and symptoms. You may need tests for other blood-borne and sexually transmitted infections such as HIV. You may need further liver tests such as an ultrasound. All for free on the NHS.

7. Hypothroidism. This refers to an underactive thyroid gland. It has many causes ranging from iodine deficiency (rare in the Western world), autoimmune diseases, to pituitary disease. Symptoms are often vague and include tiredness, cold intolerance, weight gain, constipation and depression. These symptoms also have many other possible causes. If you think you may have hypothyroidism you need to see your doctor so that they can consider other possible explanations for your symptoms, and arrange the appropriate tests. For free on the NHS.

8. Iron, Vitamin B12 and Folic acid. These are all substances needed for many functions, but specifically as part of the process producing red blood cells that carry oxygen to the tissues. If they are low you may become anaemic. There are many reasons why your iron, B12 or folic acid level may be low, ranging from dietary deficiencies, to stomach and bowel diseases, so you need to be seen by your doctor to evaluate what the most likely cause is in your case, and they can then suggest relevant further tests. For free on the NHS.

9. Menopause. This is a normal stage in the reproductive life of a woman, when menstruation stops. During the transition some women experience symptoms for which they seek help, such as hot flushes, sleep disturbance, vaginal and urinary symptoms. There is no definitive test for the menopause, although changes in hormone levels may be detectable. There is no reason to check hormone levels in most cases. If you are having distressing symptoms your GP would want to see you to talk and support you through them. For free on the NHS.

10. Stomach ulcer. A stomach ulcer (which can actually be in the stomach or first part of the small bowel, the duodenum) may lead to abdominal pain, nausea, bloating and blood in the vomit. It has a number of causes, but by far the most common is infection with Helicobacter pylori. A small minority are caused by gastric cancer. If you have symptoms you need to see your GP to assess you and consider whether a blood test (for H pylori serology) will be helpful, whether you would benefit from a trial of treatment, or whether you should have further tests such as an endoscopy. All this is available for free on the NHS.

11. Syphilis. This is a sexually transmitted infection caused by a spirochete, Treponema pallidum. The initial stage of infection stage presents with a single “chancre” a firm, painless, non-itchy skin ulceration. Syphilis is very easily cured with antibiotics. If left untreated it can eventually spread to other areas of the body, including the central nervous system, and cause serious illness. If you think you are at risk of having contracted syphilis you need to be tested for other sexually transmitted diseases and need to be seen at a GU Medicine or Sexual Health clinic. For free on the NHS.

12. Vitamin D. Humans get this from diet and from synthesis in the skin in response to sun exposure. Severe deficiency leads to rickets, a childhood bone disease (almost unheard of now in the Western world) or osteomalacia in adults. Your doctor may test your Vitamin D levels if you have certain bone diseases (for free, on the NHS). There has been recent interest in Vitamin D and its role in multiple health problems including cardiovascular disease, asthma, MS and neurodegenerative diseases. There is a lack of evidence to support Vitamin D supplements unless a patient is severely deficient (uncommon in those with a normal diet who occasionally see the sun), therefore there is little value in testing.

6 responses to “The Dangers of DIY Diagnosis

  1. Great post. Are you familiar with writings of H. Gilbert Welch on this subject?

    • I am now! Thanks. Overdiagnosis and the medicalisation of normality seem to be increasing – HG Welch was ahead of the game with his warnings.

  2. Great post!! As a family doctor in Canada, though we don’t have these “over the counter” blood tests, I still see plenty of patients who want “such and such blood test” because they saw it on Oprah or Dr. Oz.

  3. Great post, very well written and informative

  4. You don’t state why people shouldn’t buy or use these test kits. Writing that there are many possible causes for an abnormal result or that the tests are free on the NHS is not reason enough. People use these kits for reassurance or to sate curiosity, not to completely replace their relationship with the NHS.
    Are the test kits inaccurate? Are they potentially harmful to consumers? Are the company’s business practices unethical? These are the important questions to answer.
    The market for these kits exists because many GPs are apathetic, unhelpful or lazy.
    While people gaining medical knowledge and breaking down the status relationship between doctor and patient may make you feel threatened and less special, the net result of these tests will be that most purchasers will be reassured that they do not have a disease or deficiency. Also, NHS costs are reduced and GPs will have less work to do.

    • I state several reasons why I don’t think these tests are useful and cost effective. The problem is that tests performed without an appropriate context will not necessarily reassure or sate curiosity. Most tests do not produce a binary yes/no answer – they give a result which falls inside or outside a reference range and need to be interpreted in the context of other tests and a patients’ symptoms and clinical signs. There are very few conditions for which a single test at a single time point is sufficient for diagnosis or exclusion. I believe the way these tests are marketed is unethical.

      I am sorry you have a negative view of GPs. Most GPs are hardworking caring individuals trying to do the best for their patients, and are certainly not lazy. As I say in my post I am in favour of patients being more empowered and I don’t feel threatened or ‘less special’ when my patients come to appointments with prior knowledge. But I disagree that the net result of directly purchased tests is positive. I look forward to working with my patients as partners in maximising their quality and quantity of life, but do not see a place for heavily-marketed, irrelevant, directly-purchased tests in this relationship.

      Thanks for your comments.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s