Risk-adjusted capitation based on the Diagnostic Cost Group Model: an empirical evaluation with health survey information.
OBJECTIVE: To evaluate the predictive accuracy of the Diagnostic Cost Group (DCG) model using health survey information. DATA SOURCES/STUDY SETTING: Longitudinal data collected for a sample of members of a Dutch sickness fund. In the Netherlands the sickness funds provide compulsory health insurance coverage for the 60 percent of the population in the lowest income brackets. STUDY DESIGN: A demographic model and DCG capitation models are estimated by means of ordinary least squares, with an individual's annual healthcare expenditures in 1994 as the dependent variable. For subgroups based on health survey information, costs predicted by the models are compared with actual costs. Using stepwise regression procedures a subset of relevant survey variables that could improve the predictive accuracy of the three-year DCG model was identified. Capitation models were extended with these variables. DATA COLLECTION/EXTRACTION METHODS: For the empirical analysis, panel data of sickness fund members were used that contained demographic information, annual healthcare expenditures, and diagnostic information from hospitalizations for each member. In 1993, a mailed health survey was conducted among a random sample of 15,000 persons in the panel data set, with a 70 percent response rate. PRINCIPAL FINDINGS: The predictive accuracy of the demographic model improves when it is extended with diagnostic information from prior hospitalizations (DCGs). A subset of survey variables further improves the predictive accuracy of the DCG capitation models. The predictable profits and losses based on survey information for the DCG models are smaller than for the demographic model. Most persons with predictable losses based on health survey information were not hospitalized in the preceding year. CONCLUSIONS: The use of diagnostic information from prior hospitalizations is a promising option for improving the demographic capitation payment formula. This study suggests that diagnostic information from outpatient utilization is complementary to DCGs in predicting future costs. (+info)
Model for bacteriophage T4 development in Escherichia coli.
Mathematical relations for the number of mature T4 bacteriophages, both inside and after lysis of an Escherichia coli cell, as a function of time after infection by a single phage were obtained, with the following five parameters: delay time until the first T4 is completed inside the bacterium (eclipse period, nu) and its standard deviation (sigma), the rate at which the number of ripe T4 increases inside the bacterium during the rise period (alpha), and the time when the bacterium bursts (mu) and its standard deviation (beta). Burst size [B = alpha(mu - nu)], the number of phages released from an infected bacterium, is thus a dependent parameter. A least-squares program was used to derive the values of the parameters for a variety of experimental results obtained with wild-type T4 in E. coli B/r under different growth conditions and manipulations (H. Hadas, M. Einav, I. Fishov, and A. Zaritsky, Microbiology 143:179-185, 1997). A "destruction parameter" (zeta) was added to take care of the adverse effect of chloroform on phage survival. The overall agreement between the model and the experiment is quite good. The dependence of the derived parameters on growth conditions can be used to predict phage development under other experimental manipulations. (+info)
Using imperfect secondary structure predictions to improve molecular structure computations.
MOTIVATION: Until ab initio structure prediction methods are perfected, the estimation of structure for protein molecules will depend on combining multiple sources of experimental and theoretical data. Secondary structure predictions are a particularly useful source of structural information, but are currently only approximately 70% correct, on average. Structure computation algorithms which incorporate secondary structure information must therefore have methods for dealing with predictions that are imperfect. EXPERIMENTS PERFORMED: We have modified our algorithm for probabilistic least squares structural computations to accept 'disjunctive' constraints, in which a constraint is provided as a set of possible values, each weighted with a probability. Thus, when a helix is predicted, the distances associated with a helix are given most of the weight, but some weights can be allocated to the other possibilities (strand and coil). We have tested a variety of strategies for this weighting scheme in conjunction with a baseline synthetic set of sparse distance data, and compared it with strategies which do not use disjunctive constraints. RESULTS: Naive interpretations in which predictions were taken as 100% correct led to poor-quality structures. Interpretations that allow disjunctive constraints are quite robust, and even relatively poor predictions (58% correct) can significantly increase the quality of computed structures (almost halving the RMS error from the known structure). CONCLUSIONS: Secondary structure predictions can be used to improve the quality of three-dimensional structural computations. In fact, when interpreted appropriately, imperfect predictions can provide almost as much improvement as perfect predictions in three-dimensional structure calculations. (+info)
Sexual harassment and generalized workplace abuse among university employees: prevalence and mental health correlates.
OBJECTIVES: This study hypothesized that interpersonal workplace stressors involving sexual harassment and generalized workplace abuse are highly prevalent and significantly linked with mental health outcomes including symptomatic distress, the use and abuse of alcohol, and other drug use. METHODS: Employees in 4 university occupational groups (faculty, student, clerical, and service workers; n = 2492) were surveyed by means of a mailed self-report instrument. Cross-tabular and ordinary least squares and logistic regression analyses examined the prevalence of harassment and abuse and their association with mental health status. RESULTS: The data show high rates of harassment and abuse. Among faculty, females were subjected to higher rates; among clerical and service workers, males were subjected to higher rates. Male and female clerical and service workers experienced higher levels of particularly severe mistreatment. Generalized abuse was more prevalent than harassment for all groups. Both harassment and abuse were significantly linked to most mental health outcomes for men and women. CONCLUSIONS: Interpersonally abusive workplace dynamics constitute a significant public health problem that merits increased intervention and prevention strategies. (+info)
Impact of diet on lead in blood and urine in female adults and relevance to mobilization of lead from bone stores.
We measured high precision lead isotope ratios and lead concentrations in blood, urine, and environmental samples to assess the significance of diet as a contributing factor to blood and urine lead levels in a cohort of 23 migrant women and 5 Australian-born women. We evaluated possible correlations between levels of dietary lead intake and changes observed in blood and urine lead levels and isotopic composition during pregnancy and postpartum. Mean blood lead concentrations for both groups were approximately 3 microg/dl. The concentration of lead in the diet was 5.8 +/- 3 microg Pb/kg [geometric mean (GM) 5.2] and mean daily dietary intake was 8.5 microg/kg/day (GM 7.4), with a range of 2-39 microg/kg/day. Analysis of 6-day duplicate dietary samples for individual subjects commonly showed major spikes in lead concentration and isotopic composition that were not reflected by associated changes in either blood lead concentration or isotopic composition. Changes in blood lead levels and isotopic composition observed during and after pregnancy could not be solely explained by dietary lead. These data are consistent with earlier conclusions that, in cases where levels of environmental lead exposure and dietary lead intake are low, skeletal contribution is the dominant contributor to blood lead, especially during pregnancy and postpartum. (+info)
Financial incentives and drug spending in managed care.
This study estimates the impact of patient financial incentives on the use and cost of prescription drugs in the context of differing physician payment mechanisms. A large data set was developed that covers persons in managed care who pay varying levels of cost sharing and whose physicians are compensated under two different models: independent practice association (IPA)-model and network-model health maintenance organizations (HMOs). Our results indicate that higher patient copayments for prescription drugs are associated with lower drug spending in IPA models (in which physicians are not at risk for drug costs) but have little effect in network models (in which physicians bear financial risk for all prescribing behavior). (+info)
User fees and patient behaviour: evidence from Niamey National Hospital.
Evidence is presented on the effects of price changes on the delay before seeking care and on referral status in a sample of hospital patients in Niger. Price changes are measured as differences across patients at one hospital in whether or not they pay for care, rather than as differences in prices across several hospitals. User fees are charged, but the fee system allows exemptions for some payor categories such as government employees, students, and indigent patients. Evidence is also presented on the effect of income on the delay before seeking care and referral status. The analysis demonstrates a technical point on whether household consumption or current income is a more appropriate measure of income. The analysis shows that user fees affect patient behaviour, but the effects are not the same for outpatients and inpatients. Outpatients who pay for care wait longer before seeking care, but inpatients do not. Inpatients who pay for care are more likely to be referred, but outpatients are not. Patients with more income wait less time to seek care and are less likely to be referred than other patients. Further, household consumption explains patient behaviour better than current income. (+info)
The length and eruption rates of incisor teeth in rats after one or more of them had been unimpeded.
The eruption rate and length of all four incisor teeth in rats were measured under ether anaesthesia by recording the position of marks on their labial surfaces at 2-day intervals, using calibrated graticules in microscope eyepieces. The rats were divided into four groups and either a lower, an upper, both a lower and an upper, or no incisors were unimpeded. This paper describes the changes when the unimpeded incisors returned to the occlusion. Neither the unimpeded nor the impeded incisors simply returned to control values immediately the period of unimpeded eruption ended, but showed transient changes in their lengths and eruption rates. The results confirm that eruption rates are determined by the sum of the lengths of the lower and upper incisors, rather than by their own lengths, with longer teeth erupting more slowly. Specifically, restoring the bevel to the incisors did not slow their eruption below normal impeded rates. The slowing of the eruption of the longer of two adjacent incisors was related to the length differences of the incisors in the same jaw, not to the sum of the differences in both jaws. Contact with the contralateral incisor in the opposite jaw slowed the eruption of an incisor more than contact with the ipsilateral incisor. (+info)