Using the national registry of HIV-infected veterans in research: lessons for the development of disease registries.

Disease-specific registries have many important applications in epidemiologic, clinical and health services research. Since 1989 the Department of Veterans Affairs has maintained a national HIV registry. VA's HIV registry is national in scope, it contains longitudinal data and detailed resource utilization and clinical information. To describe the structure, function, and limitations of VA's national HIV registry, and to test its accuracy and completeness. The VA's national HIV registry contains data that are electronically extracted from VA's computerized comprehensive clinical and administrative databases, called Veterans Integrated Health Systems Technology and Architecture (VISTA). We examined the number of AIDS patients and the number of new patients identified to the registry, by year, through December 1996. We verified data elements against information obtained from the medical records at five VA sites. By December 1996, 40,000 HIV-infected patients had been identified to the registry. We encountered missing data and problems with data classification. Missing data occurred for some elements related to the computer programming that creates the registry (e.g., pharmacy files), and for other elements because manual entry is required (e.g., ethnicity). Lack of a standardized data classification system was a problem, especially for the pharmacy and laboratory files. In using VA's national HIV registry we have learned important lessons, which, if taken into account in the future, could lead to the creation of model disease-specific registries.

Effect of iron on production of a possible virulence factor by Plesiomonas shigelloides.

Plesiomonas shigelloides, when grown in an iron-poor medium (syncase), produces a substances that causes elongation of Chinese hamster ovary (CHO) cells similar to that produced by cholera toxin. When syncase is supplemented with iron, the ability of P. shigelloides (but not of Vibrio cholerae) to produce this elongation of CHO cells is lost. Iron depletion of the growth medium appears to be essential for the CHO cell elongation produced by P. shigelloides but is not essential for the production of toxin by V. cholerae. The possible role of iron regulation of this potential virulence factor warrants further study.

Clostridium difficile and cytotoxin in feces of patients with antimicrobial agent-associated pseudomembranous colitis.

Thirty patients with antimicrobial agent-associated pseudomembranous colitis (PMC) were studied for the presence of Clostridium difficile and its cytotoxin in feces. Either colonoscopy or barium enema radiography was required in three patients for the diagnosis of PMC because of nondiagnostic findings at sigmoidoscopy. Both the organism and cytotoxin were detected in 27 of the 30 patients; Staphylococcus aureus was excluded as the cause of PMC in two of the remaining patients. Eighteen of 19 patients with C. difficile-induced PMC who were treated with oral vancomycin had a salutary response; seven patients, however, had a relapse of colitis following the discontinuation of vancomycin. In general, relapses of colitis responded to retreatment with vancomycin. The implication of C. difficile as a cause of diarrhea is best achieved by the demonstration of colonic mucosal plaques or of a pseudomembrane. The value of fecal culture for C. difficile and cytotoxin assay is limited by the existence of asymptomatic carriers.