Statistical Expert Witnesses

Statistical expert witness support in medical litigations

Professor Jane Hutton is often asked to provide expert statistical advice in medical legal cases. Her statistical support highlights the problems posed by incomplete data, and how averaging can oversimplify complex results. In addition, she has supported personal injury cases with a total pay-out of over £150m. Her renown in the field has led her to give lectures and contribute to guides for lawyers.

The challenge

Selection bias, missing data and incorrect assumptions can have serious consequences in statistical modelling, with particularly severe consequences for individuals, medical practitioners and suppliers in medical legal cases. For example, using simple averages over time can lead to incorrect conclusions. Equally, patterns of missing data can be informative. Legal cases have to rely on expert witnesses to provide evidence on the reliability of data and inform the legal judgements where millions of pounds can be at stake.

Our approach

Professor Hutton investigates survival analysis, meta-analysis and non-random data to assess the quality of clinical trials and to understand the survival of people with conditions such as cerebral palsy and epilepsy. As an expert witness Professor Hutton is responsible for providing statistical evidence tailored to the legal case in question including consideration of:

• Complicated data patterns, missingness of data, and potential bias

• Limitations in data, including over-reporting and manipulation of measurement units and data

• Data registries, potential confounding factors and alternative registries

• Moral issues of screening programmes

Our impact

In addition to teaching lawyers statistical methods, Professor Hutton’s advice has had a significant impact on a number of legal cases. Professor Hutton has trained lawyers to improve their understanding of statistics and how data missingness can be wrongly exploited. Key insights have been taught through a series of lectures and legal guides.

When a case was raised that DePuy International supplied defective hip implants, Professor Hutton’s expert report demonstrated these claims were based on an incomplete data registry and measuring over a 10 year time span. Combined, these inflated the number of required medical interventions. The judgement ruled in favour of DePuy and prevented a pay-out of £100+ million. The case is a leading example under UK law of defect under the Consumer Protection Act 1987, being cited in two cases since as well as multiple legal guides.

In another commercial litigation, Inflamax Research argued it had successfully performed a clinical trial for its client Allergy Therapeutics (ATL). Professor Hutton revealed Inflamax had used averages over time to mask large variations in allergen concentration. A settlement of over $10m was awarded to ATL, covering both damages and legal costs. Professor Hutton’s legal reach extends even further as a life expectancy expert, covering personal injury cases for cerebral palsy, brain injuries, spinal injuries and road traffic accidents. With combined awards totalling in excess of £500m, compensation payments made to affected individuals directly impact their quality of life.

Discover more of Professor Hutton's research

See the BBC News article on the hip replacement case