Sims v MacLennan

In a medical negligence claim involving alleged delay in diagnosing and treating hypertension, the claimant must prove each factual step on the balance of probabilities before medical causation arises. A raised blood-pressure reading does not establish that hypertension would have been diagnosed, or that treatment would have been accepted, without evidential support.

The material-contribution exception to the but for test applies narrowly. It is concerned with cumulative causative agents that materially contribute to an injury, not merely with proof that the breach increased the risk of an indivisible injury. Where the evidence shows only an increased risk of stroke, causation is not established.

The claimant, acting as widow and administratrix of the estate, alleged that a general practitioner failed to advise the deceased to have a markedly raised blood-pressure reading checked after a licensing examination in 2002. She claimed damages under the Law Reform (Miscellaneous Provisions) Act 1934 and the Fatal Accidents Act 1976.

The court had to determine whether the advice was given, whether hypertension would probably have been diagnosed and treated, whether treatment would probably have prevented the deceased’s strokes in 2011, and whether any failure to attend for later blood-pressure testing affected causation.

1. Liability. The court found that the defendant had advised the deceased that his blood pressure was raised and that he should attend his GP for further checking. Mention of possible white-coat hypertension was not a diagnosis and did not remove the need for investigation.
2. The defendant was not under a duty, in the circumstances of the one-off licensing examination, to notify the deceased’s regular GP directly. Nor was failure to record the advice a breach causing loss. The pleaded allegations of negligence therefore failed.
3. Factual proof. The claimant would first have had to prove, on the ordinary balance of probabilities, that the deceased’s blood pressure would have remained raised in 2002, that hypertension would probably have been diagnosed, and that he would probably have followed treatment and lifestyle advice. The evidence did not establish those matters.
4. Medical causation. The court rejected the submission that proof of an increased risk of stroke was enough. The material-contribution exception described in [2008] EWCA Civ 883 and related authorities was confined to cases involving cumulative causative agents where medical science could not apportion the contribution. It did not extend to a case where untreated hypertension was said merely to have increased the risk of an indivisible stroke.
5. The relevant comparison was between the risk from untreated hypertension and the risk after treatment, not between a person with hypertension and a person without it. The evidence did not show that treatment would probably have prevented the stroke. The but for test therefore remained applicable and was not satisfied.
6. Contributory negligence. The observations about the deceased’s failure to attend for blood-pressure testing in 2007 were academic. Had liability been established, that omission would not have broken the chain of causation, but damages would have been reduced by 25 per cent for contributory negligence.
7. The claim was dismissed.