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Biomedical subjects

Chris M White

Publications and source records attributed to Chris M White.

3 recordsLinked to original sources

Use of endoscopic ultrasound to guide combination medical and surgical therapy for patients with Crohn's perianal fistulas.

BACKGROUND: This study was performed to assess if using endoscopic ultrasound (EUS) to assess and guide combination medical and surgical therapy during fistula healing will lead to a high rate of durable fistula closure and a low or absent incidence of perianal abscess formation in patients with Crohn's perianal fistulas. METHODS: This is a retrospective analysis of 21 patients who presented with a symptomatic Crohn's perianal fistula. Patients were enrolled in a clinical practice protocol of serial EUS exams. All patients underwent a baseline rectal EUS and were placed on maximal medical treatment with 6-mercaptopurine (6-MP) or azathioprine, Cipro, and infliximab (5 mg/kg at 0, 2, and 6 wk and then every 8 wk). Patients were also assessed at baseline by a colorectal surgeon who was aware of the EUS findings. Seton placement and incision and drainage were performed when appropriate. Serial EUS examinations were performed, and the findings were used to guide therapy (i.e., the presence of fistula healing on EUS was used to guide seton removal, discontinuation of infliximab, and Cipro). RESULTS: In the 21 patients enrolled, the median duration of active perianal symptoms was 9 wks (1-36). 10 patients (48%) had previous perianal surgery and 5 (24%) had received infliximab previously. The fistulas treated included 8 trans-sphincteric, 2 superficial, 3 recto-vaginal, and 7 with multiple and horseshoe fistulas. 13 patients (62%) had associated abscesses at presentation. Eighteen of 21 patients (86%) had complete cessation of drainage initially. Median time to cessation of drainage was 10.6 weeks (range, 4-32 wk). Sixteen of 21 patients (76%) maintained long-term cessation of drainage. The median length of follow-up was 68 weeks (range, 35-101 wk). No abscess developed during treatment in any patient. EUS evidence of persistent fistula activity was seen in 10 patients (48%). Of the 11 patients (52%) in whom EUS showed no persistent fistula activity, 7 (64%) have maintained fistula closure off of infliximab and Cipro. Median duration from last infliximab infusion was 47 weeks (range, 20-80 wk). The remaining 4 patients continued infliximab to maintain remission of their luminal disease. Only 1 patient with a horseshoe fistula showed complete healing on EUS. CONCLUSION: In conclusion, using EUS to guide therapy for Crohn's perianal fistulas with infliximab, an immunosuppressive, and an antibiotic is associated with a high short and long-term fistula response rate. EUS may identify a subset of patients who can discontinue infliximab without recurrence of fistula drainage.

Adolescent↗

Missing information in multiple-cue probability learning.

In a multiple-cue probability learning task, participants learned to use six discrete symptoms (i.e., cues) to diagnose which of three possible flu strains a hypothetical patient suffered from. For some patients, information regarding the status of certain symptoms was not available. Various possible ways in which the missing cue information might be processed were distinguished and tested in a series of three experiments (Ns = 80, 109, and 61). The results suggest that the judged probability of the outcome variable (i.e., flu strain) was assessed by "filling in" the missing cue information with a mean value based on previous observations. The predictions of other methods of processing missing cue information are inconsistent with the data.

Cues↗

An evidential support accumulation model of subjective probability.

A model of cue-based probability judgment is developed within the framework of support theory. Cue diagnosticity is evaluated from experience as represented by error-free frequency counts. When presented with a pattern of cues, the diagnostic implications of each cue are assessed independently and then summed to arrive at an assessment of the support for a hypothesis, with greater weight placed on present than on absent cues. The model can also accommodate adjustment of support in light of the baserate or prior probability of a hypothesis. Support for alternatives packed together in a "residual" hypothesis is discounted; fewer cues are consulted in assessing support for alternatives as support for the focal hypothesis increases. Results of fitting this and several alternative models to data from four new multiple-cue probability learning experiments are reported.

Cues↗