"We will reverse for evidentiary error only if the erroneous evidentiary ruling was prejudicial." Dalbey v. Heartland Reg'l Med. Ctr., 621 S.W.3d 36, 51 (Mo. App. W.D. 2021). "To establish prejudice sufficient to justify reversal, the appellant must show that the erroneous exclusion of evidence materially affected the merits of the action," in other words, that the trial court's error "affected the outcome of the trial."
If the prejudicial effect of the evidence outweighs its probative value, then the evidence is not relevant and should be excluded. Dalbey v. Heartland Reg'l Med. Ctr. , 621 S.W.3d 36, 46 (Mo. App. W.D. 2021) (quoting Brummett v. Burberry Ltd. , 597 S.W.3d 295, 303-04 (Mo. App. W.D. 2019) ). While evidence of an employer's conduct (such as its hiring practices, supervision, policies, etc.) could be relevant and material to a claim for punitive damages based on a direct theory of liability (such as negligent hiring or negligent supervision), it is not relevant or material to a claim that rests solely on vicarious liability.
Neither a vicarious liability claim, nor a loss of consortium claim, can exist without a viable underlying negligence claim by the injured patient against the treating physician. See , e.g. , Dalbey v. Heartland Reg'l Med. Ctr. , 621 S.W.3d 36, 43 (Mo. App. W.D. 2021) (" ‘where the right to recover is dependent entirely on the doctrine of respondeat superior and there is a finding of no negligence by the servant there should be no judgment against the master’ " (citations omitted)); Kamerick v. Dorman , 907 S.W.2d 264, 267 (Mo. App. W.D. 1995) ("A consortium claim is derivative from the injured spouse's claim and depends on the validity of the underlying claim. Although the consortium claim and the underlying claim exist to compensate the two spouses for the different losses they sustain, both involve a claim for damages for malpractice or negligence related to health care.