Avoiding "Rash" Conclusions: Challenge of IgA Vasculitis in Adults.

IgA vasculitis is primarily a pediatric disease that is rarely encountered in adults. With adults, gastrointestinal manifestations are quite common, yet are nonspecific and may overlap with other diseases, particularly Crohn's disease, which can make the diagnosis a challenging task. Treatment is controversial given the disease course is usually self-limited with few serious complications. We present a case of IgA vasculitis in an adult patient with limited extraintestinal findings illustrating the complexity of arriving at the correct diagnosis.

General principles to enhance practice patterns in gastrointestinal endoscopy.

AIM: To develop general rules on how to pursue a therapeutic goal of interventional endoscopy without getting lost in abundant details. METHODS: The influences of various medical interventions on the survival of a patient with gastrointestinal haemorrhage are modelled by an influence diagram. Survival is the focal point of multiple influences affecting its overall strength. Any downstream influence can represent the focal point of other preceding upstream influences. The mathematics underlying the influence diagram are similar to those of a decision tree with some notable exceptions. Its formalism allows one to consider inhibitory and additive influences and to include in the same analysis non-commensurable qualities, such as correct diagnosis, haemostasis or survival. RESULTS: The analysis reveals five general rules. First, the large number of factors involved in successful endoscopy render the influence of each individual factor less important. Second, a single factor that exerts its influence on many subsequent factors tends to be associated with an overall greater relevance. Third, remote influences are of lesser relevance than those directly linked to the final outcome. Fourth, factors multiplied by several consecutive probabilities lose their influence. Fifth, endoscopists need to assess the relevance of individual factors with respect to the immediate goals of endoscopy, as well as the general goals of patient well-being. CONCLUSIONS: The influence model of endoscopic haemostasis reveals several general principles that can be utilized as tools in endoscopy training.

Timing of surgery for enterovesical fistula in Crohn's disease: decision analysis using a time-dependent compartment model.

OBJECTIVES: Previous decision analyses of inflam matory bowel diseases (IBD) have used decision trees and Markov chains. Occasionally IBD patients present with medical problems that are difficult or even impossible to phrase in terms of such established decision tools. This article aims to introduce modeling by a time-dependent compartment mode and demonstrate its feasibility for decision analysis in IBD METHODS: A Crohn's disease patient presented with a pelvic abscess and an enterovesical fistula. Being hesitant to operate in an acutely inflamed area, the surgeon recommended that the patient continue antibiotic therapy until the abscess had re solved. The gastroenterologist argued that the patient had already been treated with antibiotics for a prolonged time period and expressed concern that the patient's overall diminished health status would deteriorate by further delay of surgery. The occurrence of fistula, abscess, urinary tract infection, antibiotic therapy, surgical operation, and health-related quality of life were modeled as separate compartments, with time-dependent relationships among them. The simulation was carried out on an Excel spreadsheet. RESULTS: In the model, the surgeon's predictions were associated with rapid resolution of the pelvic abscess under antibiotic therapy and improvement of the patient's health status. The gastroenterologist's predictions resulted in a smaller decline in abscess size and further deterioration of the patient's health while waiting for a definitive treatment. The disagreement between surgery and gastroenterology arose from predicting different time courses for the individual disease events, in essence, from assigning different time constants to the time-dependent influences of the disease model. CONCLUSIONS: The compartment model provides a simple and generally applicable method to assess time dependent-changes of a complex disease. The present analysis also serves to illustrate the usefulness of such models in simulating disease behavior.

Evidence that iron stores regulate iron absorption--a setpoint theory.

To evaluate the concept of a predetermined "setpoint" for iron stores, 20 healthy elderly individuals (12 blood donors and 8 nondonors) were studied to examine the effects of changes in iron stores on iron absorption. Oral iron-absorption tests revealed a statistically significant increase (P < 0.001) in iron absorption in donors, 7.4 +/- 3.6% (mean +/- SD) compared with 2.5 +/- 1.4% in nondonors. In a comparison of percent iron absorption with changes in baseline iron stores, a statistically significant correlation was noted (r2 = 0.702, P < 0.001). Thus, reductions in iron stores were correlated with increases in iron absorption. Basal gastric acid output was found to be within normal limits (1.62-10.20 mmol/h) in all elderly subjects and unrelated to iron stores. These findings are consistent with iron absorption being regulated according to the degree of depletion of iron stores from predonation values and is consistent with a proposed setpoint theory of iron stores.