Evaluating diagnosis-based case-mix measures: how well do they apply to the VA population?

BACKGROUND: Diagnosis-based case-mix measures are increasingly used for provider profiling, resource allocation, and capitation rate setting. Measures developed in one setting may not adequately capture the disease burden in other settings. OBJECTIVES: To examine the feasibility of adapting two such measures, Adjusted Clinical Groups (ACGs) and Diagnostic Cost Groups (DCGs), to the Department of Veterans Affairs (VA) population. RESEARCH DESIGN: A 60% random sample of veterans who used health care services during FY 1997 was obtained from VA inpatient and outpatient administrative databases. A split-sample technique was used to obtain a 40% sample (n = 1,046,803) for development and a 20% sample (n = 524,461) for validation. METHODS: Concurrent ACG and DCG risk adjustment models, using 1997 diagnoses and demographics to predict FY 1997 utilization (ambulatory provider encounters, and service days-the sum of a patient's inpatient and outpatient visit days), were fitted and cross-validated. RESULTS: Patients were classified into groupings that indicated a population with multiple psychiatric and medical diseases. Model R-squares explained between 6% and 32% of the variation in service utilization. Although reparameterized models did better in predicting utilization than models with external weights, none of the models was adequate in characterizing the entire population. For predicting service days, DCGs were superior to ACGs in most categories, whereas ACGs did better at discriminating among veterans who had the lowest utilization. CONCLUSIONS: Although "off-the-shelf" case-mix measures perform moderately well when applied to another setting, modifications may be required to accurately characterize a population's disease burden with respect to the resource needs of all patients.

Multiregional evaluation of the SimPlate heterotrophic plate count method compared to the standard plate count agar pour plate method in water.

A new SimPlate heterotrophic plate count (HPC) method (IDEXX Laboratories, Westbrook, Maine) was compared with the pour plate method at 35 degrees C for 48 h. Six laboratories tested a total of 632 water samples. The SimPlate HPC method was found to be equivalent to the pour plate method by regression analysis (r = 0. 95; y = 0.99X + 0.06).

Effects of endotracheal suction versus apnea during interruption of intermittent or continuous positive pressure ventilation.

The hypoxemia, elevated vascular pressure, and cardiac arrhythmias occurring during endotracheal suction may be related both to suction and the interruption of ventilation during suction. Although effects of suction vs. apnea have been compared in healthy patients, interruption of ventilation for purely investigational purposes precludes such a study in critically ill patients. Thus, in the present study, cardiovascular and blood gas changes attendant to endotracheal suction or equivalent periods of apnea were compared in anesthetized, paralyzed dogs in acute respiratory failure induced by oleic acid. Suction of 45-sec duration during interruption of intermittent positive pressure ventilation (IPPV) was associated with decreases in PaO2, pH, and heart rate and increases in PaCO2, cardiac output, pulmonary arterial and systemic arterial pressure. These changes were not different from those observed during interruption of ventilation (apnea) alone. Cardiovascular and blood gas changes were also similar when suction and apnea were compared during interruption of continuous positive pressure ventilation (CPPV). Neither apnea nor suction was associated with cardiac arrhythmias.

Evaluation of catheter placement in the treatment of venous air embolism.

Venous air embolism is a potential complication of many surgical, therapeutic, and diagnostic procedures. Aspiration of air via a catheter placed in the superior vena cava or right atrium or placed in the pulmonary outflow tract and pulled through the right heart chambers had been advocated for the treatment of venous air embolism. In this study, three catheter positions were analyzed to determine which was best for removal of gas after induction of massive venous air embolism in dogs. In 18 dogs, 9 of which were suspended by their forelegs to simulate the sitting position used in posterior fossa exploration and 9 of which were supine, a Swan-Ganz catheter was placed in the right atrium, right ventricle, or pulmonary artery. A measured amount of air was injected into the left jugular vein and syringe aspiration of the air was attempted through the catheter. In the group with the catheter in the pulmonary artery, aspiration was continuous while the catheter was withdrawn through the right heart chambers. The amount of air aspirated varied widely among the three catheter positions, and no one catheter position proved superior to the other two.