Direct diagnosis of tuberculosis by computer assisted pattern recognition gas chromatographic analysis of sputum.

Chemical detection of tuberculosis (TB) products in sputum was attempted by using gas chromatographic analysis in conjunction with different pattern recognition computer models. For the chromatographic separations, we used a 2 mm x 1.8 m packed column and a 0.25 mm x 30 m fused silica capillary column to analyse the methylated glycosides and fatty acid methyl ester derivatives. Three computer pattern recognition methods were applied: error score, TB score and discriminant analysis. These methods predicted the presence of active TB most often in sputa of active TB patients and less so in those from inactive, suspected and non-TB patients, in that order. Although the best true positive of 75% was obtained from the TB score method and best true negative of 98% from discriminant analysis, the accompanying false positive and false negative results (36% and 50%, respectively) were unacceptable. The use of capillary column or fatty acid methyl ester derivatives of the samples did not improve on the predictive values of chromatograms obtained from the packed column on trimethylsilylglycosidic derivatives. Additional work is needed before this method can have a direct clinical application.

Identifying Mycobacterium tuberculosis cultures by gas-liquid chromatography and a computer-aided pattern recognition model.

A procedure that uses gas-liquid chromatography and a pattern recognition computer model was developed for distinguishing cultures of Mycobacterium tuberculosis from cultures of other mycobacteria, common bacteria, and fungi. In this procedure, a sample of a culture preparation is methanolyzed and trimethylsilylated sequentially and injected into a gas chromatograph equipped with a flame ionization detector. A pattern recognition procedure computes an error score by comparing the gas-liquid chromatography peak responses of a culture to those of a standard M. tuberculosis culture. Ten M. tuberculosis cultures were used in the development of the pattern recognition model. Computed error scores of 5 or less were established for identifying an M. tuberculosis culture. The method was evaluated with two sets of test samples, non-M. tuberculosis and M. tuberculosis cultures. Sample identification was correct for all 14 M. tuberculosis cultures (M. tuberculosis or non-M. tuberculosis), 45 fungal cultures, 94 bacterial cultures, and all but 1 of 18 cultures of mycobacteria other than tuberculosis (MOTT). The false prediction represented an isolate of M. fortuitum. For M. tuberculosis, fungal, bacterial, and MOTT cultures, the ranges of error scores were 1 to 5, 16 to 33, 13 to 34, and 4 to 26, respectively. Therefore, we have demonstrated that this diagnostic model can distinguish M. tuberculosis from non-M. tuberculosis cultures with a high degree of accuracy.

Hospital expenses in a sector model.

This review summarizes the capabilities and contributions of quantitative sector models for understanding trends in hospital expenses and the effects thereon of various public policies. After some brief historical notes on the use of analogous models in other policy areas, the general classes of national, partial, and narrow health sector models are introduced with special attention to method of validation and behavioral structure. Fourteen published models, described and critically reviewed with regard to these criteria, are assessed for their individual application to important policy and behavioral issues. Suggestions are offered for improvements and new initiatives in the use of sector models both in forecasting and in the study of procompetitive policies and reimbursement rule changes.

A synopsis of federal-state sponsored preventive child health.

This synopsis presents data on the impact of services and evaluation issues for the nation's largest preventive child health program, the Early and Periodic Screening, Diagnosis and Treatment program (EPSDT). The information is drawn from a series of six EPSDT demonstration/evaluation (D/E) projects sponsored by the Health Care Financing Administration between 1972 and 1979. These projects were implemented in order to learn how to provide preventive services for children participating in the Medicaid program. The results of D/E activities are revised in a methodological framework as defined by principles of epidemiology and evaluation research. Consideration of the major threats to valid interpretation of the D/E findings shows self-selection to be the most serious methodological problem. Data pertaining to the history of use of preventive services, number of children found to have problems in screening, the treatment status and subjective seriousness of these problems, and the resolution of conditions referred to diagnosis and treatment are presented within the context of this methodological critique. The information thus assembled also provides the basis for further, more rigorous assessments of EPSDT program accountability.