What is the test for a plaintiff to be awarded damages for failing to follow a recommended course of medical treatment?

…If a plaintiff has not pursued a recommended course of medical treatment, the defendant must prove that the plaintiff acted unreasonably in declining the medical treatment and the extent, if any, by which the plaintiff’s damages would have been reduced had she acted reasonably: Chiu v. Chiu, 2002 BCCA 618 at para. 57.

The question of whether a person has been reasonable in refusing recommended treatment is one for the trier of fact to decide based on the circumstances of the case, taking into account the degree of risk from the treatment, the gravity of the consequences for refusing it, and the potential benefit to be derived from it: Janiak v. Ippolito, 1985 CanLII 62 (SCC), [1985] 1 S.C.R. 146 at 151-52, 162-3.