Need to know

Informed consent is a core principle of medical and dental care but few patients want a lecture in statistics

MOST people know the story. In 1998, an article was published in The Lancet by Dr Andrew Wakefield and 12 other authors suggesting a link between the MMR vaccine, autism and bowel disease, based on a study of only 12 children. In a subsequent press conference Wakefield called for the suspension of the vaccine until further research could establish its safety.

The resulting scare led to a drop in MMR vaccination rates in the UK from 92 per cent to below 80 per cent and a consequent resurgence in measles that is still being felt today, with a recent outbreak bringing a 10-fold increase in the disease in England and Wales in the first four months of 2011.

Even now, despite the research being discredited and Wakefield himself struck off the GMC register, MMR inoculation rates still stand below 90 per cent. The case well 16 illustrates how the notion of risk in medical procedures is not just a numbers game – it’s as much about attitudes and perception.

Just how patients perceive risk is a crucial factor in the regulatory duty of healthcare professionals to engage in shared decisionmaking with patients and obtain informed consent. MDDUS case files contain numerous examples of doctors and dentists failing in this regard and facing civil court judgements and disciplinary action by the GMC and GDC.

One typical case dealt with a 71-year-old woman diagnosed with a L4/L5 disc protrusion compressing the L5 nerve root, causing her severe hip pain. The surgeon recommended surgical decompression and briefed the patient on the procedure but did not bother to discuss the slight risk of deep post-operative infection (spondylodiscitis/ osteomyelitis).

The patient subsequently suffered a severe post-operative infection that took many painful months to clear with antibiotics. A claim of negligence based on the fact that the patient had not been informed of the infection risk was lodged and eventually settled by MDDUS on behalf of the surgeon.

Shared decision-making

Consent is a bedrock principle for healthcare professionals and both the GMC and GDC have separate guidance documents devoted to the topic. In Consent: patients and doctors making decisions together, the GMC states: "You must work in partnership with your patients. You should discuss with them their condition and treatment options in a way they can understand, and respect their right to make decisions about their care."

But this is sometimes easier said than done when you consider the wide range of patients that doctors interact with and their varying ability to understand sometimes complex medical procedures, not to mention the reluctance of some patients to even engage in the decision-making process. The GMC advises that doctors should “not make assumptions about what information a patient might want or need, the clinical or other factors a patient might consider significant and the patient's level of knowledge or understanding of what is proposed”.

Baseline consent calls for healthcare professionals to provide patients details of any uncertainties over diagnosis and prognosis and options for treating the condition, including ‘not to treat’. The purpose of any proposed investigation or treatment and what it will involve should be explained along with potential benefits, risks and burdens, and likelihood of success. In private care, dentists and doctors must also make clear to the patient the nature of the contract for care including all charges and the probable costs of further treatment.

One key passage in GMC guidance regarding informed patient consent states: "You must tell patients if an investigation or treatment might result in a serious adverse outcome, even if the likelihood is very small. You should also tell patients about less serious side-effects or complications if they occur frequently, and explain what the patient should do if they experience any of them."

Stick men and smiley faces

Communicating risk to patients can be problematic at the best of times. Just as the MMR vaccine example above demonstrates, decision-making among patients is not always “rational”. Research has shown that people often use shortcuts to simplify decision-making and risk, such as categorising something as either “dangerous” or “safe.” One commonly cited example comes from the mid-1990s when the press publicised results of a study reporting a 100 per cent increase in the risk of thromboembolism in women using a particular contraceptive. The actual risk was still slight but thousands of British women panicked and stopped taking the pill leading to an increase in unwanted pregnancies.

Most doctors and dentists understand risk according to basic concepts such as relative risk (RR) or absolute risk reduction (ARR) or number needed to treat or harm (NNT or NNH). But many patients will grow frustrated or simply ‘turn off’ if a discussion aimed at joint decision-making becomes a lecture in statistics. Nor can risk be treated in too simplistic a fashion. Descriptive terms such as ‘common’ or ‘rare’ assume a shared perspective when in fact patients may judge risk by a different order of magnitude. One study looking at the probabilities of harm and benefit from treatments found that the term “frequent” was interpreted on average as equivalent to around 70 per cent but with a wide range from 30 to 90 per cent.

Common wisdom is that people will usually best understand absolute risk expressed in percentages or natural frequencies, such as one in 200 patients suffer a particular post-operative complication. Such figures can be presented in comparison with everyday risks such as the chance of having a car crash while driving over a certain distance. Presenting absolute risk figures alone has been shown to lead to either an overweighting of low probabilities or an underweighting of high probabilities.

Some centres have found most success by communicating risk using visual representations, such as diagrams displaying 100 stick figures or other graphic elements designed to represent patients and possible outcomes. Such devices offer a handy short-hand of risk and can be utilised as part of a range or “shopping basket” of complementary data formats with enough flexibility to address the needs of a variety of patients. These might include other “decision aids” such as leaflets and booklets, websites, CDs and interactive computer programmes.

Life is a risky business

A common feature of USA magazine advertisements for proprietary drugs is screeds of additional text listing in minute detail every possible contra-indication and attendant clinical risk. No doubt this keeps lawyers and regulators happy but it also serves to highlight another dilemma facing healthcare professionals seeking informed consent. No medical procedure is completely risk free so when is a particular risk likely or severe enough to merit being divulged to patients?

Law courts tend to support a ‘test’ based on what a “reasonable doctor” would divulge in similar circumstances but this still leaves a grey area when it comes to low risks with severe consequences as in the spinal surgery case example above. Robert Heywood, a lecturer in law at Sheffield Hallam University, commented in an article on risk disclosure: “It now seems the profession have ‘got together’ and taken it upon themselves to set professional standards of disclosure at around all risks within the 1-2 per cent region and above.” This was the specific risk factor cited in the landmark medico-legal case of Chester v Afshar, which established that a doctor is liable if he fails to warn of a known risk of harm which then occurs. But the figure has never been formally suggested as benchmark for risk disclosure.

Clearly what the GMC considers a “serious adverse outcome, even if the likelihood is very small” or “less serious side effects or complications if they occur frequently” is subject to interpretation. It is probably best to air on the side of disclosure if in doubt and be willing to back-up any decisions made with comprehensive notes recorded in the consent process.

Ask colleagues if in doubt or seek advice from MDDUS – the decision to disclose a risk may be yours but there is no need to make it alone.

Article by Dr Gail Gilmartin, MDDUS medical adviser, and Jim Killgore, editor of Summons