JD v Mather

In a clinical negligence claim, causation must be proved on the balance of probabilities by evidence relating to the individual claimant. Population statistics may assist, but cannot alone establish that a particular patient would probably have avoided the relevant outcome.

Where negligent delay leaves a claimant with a chance of surviving ten years below 50 per cent, a claim for the loss of that chance fails under the majority decision in Gregg v Scott [2005] 2 AC 176. A distinct claim may nevertheless succeed for an acceleration of suffering or reduction in life expectancy caused by the delay. The court may assess that loss where the evidence permits a fair determination and a further hearing would be disproportionate.

The claimant consulted the defendant general practitioner about a changing, itching and bleeding groin lesion. The defendant wrongly diagnosed it as a seborrhoeic wart and failed to refer him urgently. Liability for breach of duty had been admitted following an earlier fact-finding hearing.

By October 2006 the lesion was an ulcerated malignant melanoma with regional lymph-node involvement. The issue at trial was causation: whether prompt diagnosis and treatment in March 2006 would probably have avoided the claimant’s later disease and, alternatively, whether the delay reduced his period of disease-free survival or life expectancy.

1. Principal claim. The claimant’s melanoma was probably already ulcerated and had at least microscopic regional lymph-node spread in March 2006. It was therefore at AJCC Stage IIIB. The court accepted that the claimant’s prospects of surviving a further ten years, even with prompt treatment, were below 50 per cent. His principal claim accordingly failed in accordance with the majority decision in Gregg v Scott [2005] 2 AC 176.
2. Statistical evidence. Population statistics concerning melanoma relapse assisted the court but did not by themselves establish individual causation. The difficulty of applying such statistics to an individual claimant was recognised in Gregg v Scott [2005] 2 AC 176 and Sinkiewicz v Greif UK Ltd [2011] 2 AC 229. The evidence showed that palpable nodal involvement within seven or eight months was rare where the tumour had not already spread, making microscopic spread by March more probable than not.
3. Alternative claim. The claimant could recover for a distinct reduction in life expectancy caused by delayed treatment, even though he could not recover damages for losing a less-than-even chance of ten-year survival. Earlier treatment would probably have left him at Stage IIIB rather than Stage IIIC, producing a material difference in median survival. The court found that the negligent delay had reduced his life expectancy by three years.
4. Judgment was entered for the claimant on the alternative claim only, with damages to be assessed. A further liability hearing was refused as unacceptable and disproportionate; the parties were invited to agree quantum, failing which it was to be tried without delay.