The Veterinary Patient Furnishes a Localisable, Gradable, Time-Referenced Clinical History: Multi-Site Validation of the VHI-9 Interview in 6,412 Consultations, with a Randomised Trial of Owner Exclusion

Medicine takes the history from the patient. Veterinary medicine takes it from whoever drove. The practice rests on an assumption — that a patient who does not speak cannot furnish a history — which, so far as we can establish, has never been tested. We tested it. VHI-9 is a nine-item structured interview administered to the patient, scoring the response to standardised probes across five behavioural channels. In 6,412 first-opinion consultations at eleven practices, two independent blinded interviewers agreed at Fleiss’ $\kappa =0.83$ (95% CI 0.81–0.85), with internal consistency $\alpha =0.88$ and 48-hour test–retest $\mathrm{ICC}=0.79$. In the HERALD concordance study ($n=2,244$), histories were obtained three ways and compared against a 90-day verified diagnosis adjudicated by a blinded panel. Top-1 concordance was 61.2% for the owner’s account, 84.7% for the patient’s, and 79.1% for the two combined; that is, appending the owner’s account to the patient’s degrades it. Two mechanisms account for the loss. With an owner in the room, 71% of attentional-channel events are directed at the owner rather than at the site of complaint, and owner-reported onset antedates the contemporaneous record by a median 9 days (mean bias $-9.1$ days, limits of agreement $-31.4$ to $+13.2$). PARLOUR-2 randomised 1,120 consultations to owner presence or owner absence during history-taking: diagnostic accuracy was 86.1% against 68.4% (risk difference 17.7 percentage points, 95% CI 12.9–22.5, $p<0.001$; number needed to exclude 5.6). The instrument does not work in rabbits, and we do not know why. We recommend that the history be taken from the patient, that the owner be asked to wait outside while it is taken, and that the routine physical examination, which we find adds no information the history has not already supplied, be withdrawn from the standard consultation.