Predicting the timing of wrong decisions with LATER.

Response time, or latency, is increasingly being used to provide information about neural decision processes. LATER (Linear Approach to Threshold with Ergodic Rate) is a quasi-Bayesian model of decision-making, with the additional feature that it introduces a degree of gratuitous randomisation into the decision process. It has had some success in predicting latencies under various conditions, but has not specifically been applied to an equally important aspect of decision-making, namely errors: a complete model of decision-making should not only account for latency distributions of correct decisions but also of wrong ones. We therefore used a decision task that generates large numbers of errors: subjects are told to look at suddenly appearing targets of one colour, but not another. We found that subjects' faster responses are as likely to be correct as wrong, but eventually the latency distributions diverge, with errors becoming infrequent. It seems that colour information, arriving after a delay, results both in cancellation of the developing response to the mere existence of the target and in delayed initiation of the correct response. A simple model, using LATER units in a similar way to one that has previously successfully modelled countermanding, accurately predicts latency distributions and proportions of all responses, whether correct or incorrect, demonstrating that the LATER model can indeed account for errors as well as correct responses.

Saccadometry: the possible application of latency distribution measurement for monitoring concussion.

Premature return to play after concussion may have debilitating or even fatal consequences. Computerised neuropsychological test batteries are widely used to monitor recovery, but none meet all specified criteria. One possible alternative is to measure saccadic reaction time or latency. Latency reflects the operation of cerebral decision mechanisms, and is strongly influenced by many agents that impair cortical function. A portable, micro-miniature device (saccadometer) was used to record the eye movements of amateur boxers before and after competitive bouts. Individual latency distributions were significantly affected after blows to the head, though the effects seemed to be reversible, with recovery over a few days. This quantitative, objective and easy to use technique should perhaps be deployed more widely to evaluate its potential in monitoring the effects of sports-related head injuries.

The effect of insurance status on use of recombinant erythropoietin therapy among end-stage renal disease patients in three states.

Recombinant human erythropoietin (rHuEPO) has been demonstrated to be effective in ameliorating anemia among persons with chronic renal failure, and is associated with improved functional status and quality of life. Access to rHuEPO has been examined by a variety of clinical, demographic, geographic, and facility characteristics. However, rHuEPO utilization based on insurance status has not been previously examined. All Medicare and Medicaid prevalent end-stage renal disease (ESRD) patients receiving dialysis services in California, Georgia, and Michigan in December 1991 were identified using state and federal administrative program data. The population in each state was stratified by insurance status as follows: Medicare-entitled, Medicare/Medicaid dually entitled, and Medicaid-only entitled. Insurance coverage of the ESRD population by Medicaid, as either a primary or secondary payer, differed greatly by state. In December 1991, the proportion of Medicaid-only and Medicaid/Medicare dually eligible dialysis patients ranged, respectively, from 8% and 43% in California, to 3% and 26% in Michigan, and to 3% and 18% in Georgia. Compared with the Medicare-entitled population, the Medicaid/Medicare dually eligible and Medicaid-only populations disproportionately comprised women, black patients, and individuals younger than 20 years. Using Lee's two-stage binary logit model, dual-eligibility was found to be associated with an increased access to rHuEPO. Compared with their state-specific, dually eligible counterparts, the odds of receiving rHuEPO was lower for Medicare-entitled patients in California (odds ratio [OR], 0.84; 95% confidence interval [CI], 0.76,0.93) and Georgia (OR, 0.65; 95% CI, 0.53,0.80), and lower for Medicaid-only patients in Georgia (OR, 0.02; 95% CI, 0.01,0.05) and Michigan (OR, 0.34; 95% CI, 0.23,0.52). We hypothesize that the absence of substantial copayments associated with rHuEPO, approximately $1,000 per year for a portion of Medicare-entitled patients, resulted in increased access among the dually eligible ESRD population. Dosing of rHuEPO was associated primarily with patient hematocrit level (P < 0.0001) and was unrelated to insurance status. Regardless of insurance status, an unexpectedly large number of Medicare prevalent dialysis patients receiving rHuEPO in each state (31%, 42%, and 41% in California, Georgia, and Michigan, respectively) had hematocrit values lower than 0.28, indicating inadequate treatment of anemia. Eleven percent of all patients receiving rHuEPO in California and nearly 20% in Georgia and Michigan were deemed to be severely anemic (hematocrit < 0.25). The wide variability in access to rHuEPO among the Medicaid-only populations may be indicative of state-specific differences in Medicaid prior approval, copayments, and other drug restrictions. We conclude that the Medicaid-only ESRD population excluded from Medicare coverage is particularly vulnerable to cost-containment measures that focus on expensive technologies such as rHuEPO.

Excluded from universal coverage: ESRD patients not covered by Medicare.

Medicaid is believed to serve as the major insurer for end stage renal disease (ESRD) patients who are ineligible for Medicare coverage. Demographics, receipt of dialysis services, and costs of Medicaid-only populations were compared with Medicare ESRD populations in California, Georgia, and Michigan. Notable differences in patient demographics, dialysis practice patterns, and inpatient health resource utilization between the Medicaid and Medicare ESRD populations were observed. Medicaid expenditures for Medicare-ineligible ESRD patients were considerable: in 1991, California spent $46.4 million for 1,239 ESRD patients; Georgia and Michigan each spent nearly $5 million for approximately 140 ESRD patients.

Degree of comfort in providing care to PWAs: effect of a workshop for baccalaureate nursing students.

A low-incidence area of HIV/AIDS was the site for this study, which examined baccalaureate nursing students' degree of comfort in providing basic nursing care to people with AIDS (PWAs), and determined the effect of a National Institutes of Health (NIH)-sponsored one-day workshop on HIV/AIDS on this degree of comfort. The pretest-posttest study revealed no statistically significant decrease after the workshop in the amount of discomfort associated with providing basic nursing care to PWAs. However, there were changes in the ranking of nursing procedures following the workshop. Included is a discussion of the workshop's effect on students' comfort level and implications for nurse educators. Ideas for related studies in the area of HIV health care are explored.