In Henricks v. Nyberg, 41 Ill. App. 3d 25, 28, 353 N.E.2d 273 (1976), the court considered whether testimony by a physician that the plaintiff's prognosis was guarded was admissible when the last time the physician had examined the plaintiff was three years before trial. The court held that, because expert opinion testimony must be founded upon facts and not conjecture, an opinion at trial based upon an examination conducted three years prior would be unreliable and therefore improper. Henricks, 41 Ill. App. 3d at 28. The court was persuaded that the physician's testimony concerning the prognosis he made three years prior could not represent an opinion that he held at the time of trial. Henricks, 41 Ill. App. 3d at 28.