Projecting future medical care costs using four scenarios of lifestyle risk rates

PURPOSE

This study predicts medical care expenditures over 10 years for Union Pacific Railroad (UPRR) under alternative health risk factor scenarios for the UPRR workforce.

DESIGN

This paper describes the development of an economic forecasting model to predict medical care expenditures assuming four different scenarios of population risk. The variables used to predict medical care expenditures are employee demographics and health risk profiles.

SETTING

UPRR is a transportation company with more than 56,000 employees in 25 states west and south of the Mississippi River.

SUBJECTS

Employees of UPRR.

MEASURES

Intermediate outcomes included health risk measures related to exercise patterns, body weight, eating habits, smoking, alcohol consumption, total cholesterol, blood glucose, blood pressure, stress, and depression. Major outcome measures included projected total annual payments by UPRR for medical care services for the decade following 1998.

RESULTS

The UPRR work force is projected to grow by 500 employees per year over the 10-year study period. The average age is expected to increase from 44 to 48 years. Without further health promotion intervention, 7 of the 11 risk factors assessed would likely worsen among UPRR's workforce. Medical care cost increases are projected to range from $22.2 million to $99.6 million in constant 1998 dollars over the next decade, depending on the effectiveness of risk factor modification programs. With an expected health promotion budget averaging $1.9 million annually over 10 years, health risks must decline at least 0.09% per year for the program to pay for itself.

CONCLUSIONS

Estimating various risk and cost scenarios can facilitate program planning and produce an economic justification for worksite health programs.

The relationship between modifiable health risks and group-level health care expenditures. Health Enhancement Research Organization (HERO) Research Committee

PURPOSE

To assess the relationship between modifiable health risks and total health care expenditures for a large employee group.

DESIGN

Risk data were collected through voluntary participation in health risk assessment (HRA) and worksite biometric screenings and were linked at the individual level to health care plan enrollment and expenditure data from employers' fee-for-service plans over the 6-year study period.

SETTING

The setting was worksite health promotion programs sponsored by six large private-sector and public-sector employers.

SUBJECTS

Of the 50% of employees who completed the HRA, 46,026 (74.7%) met all inclusion criteria for the analysis.

MEASURES

Eleven risk factors (exercise, alcohol use, eating, current and former tobacco use, depression, stress, blood pressure, cholesterol, weight, and blood glucose) were dichotomized into high-risk and lower-risk levels. The association between risks and expenditures was estimated using a two-part regression model, controlling for demographics and other confounders. Risk prevalence data were used to estimate group-level impact of risks on expenditures.

RESULTS

Risk factors were associated with 25% of total expenditures. Stress was the most costly factor, with tobacco use, overweight, and lack of exercise also being linked to substantial expenditures.

CONCLUSIONS

Modifiable risk factors contribute substantially to overall health care expenditures. Health promotion programs that reduce these risks may be beneficial for employers in controlling health care costs.

Prospective assessment of patient reported urinary continence after radical prostatectomy

PURPOSE

Reported urinary continence rates after radical prostatectomy vary. Although modifications of radical prostatectomy meant to improve outcome, such as nerve sparing or bladder neck preservation, are in widespread use, to our knowledge evidence to support these practices based on patient report is scant. We evaluated the potential effects of nerve sparing and bladder neck preservation on urinary continence after radical prostatectomy, and assessed the impact of various urinary continence definitions on the observed outcome.

MATERIALS AND METHODS

We prospectively evaluated a cohort of men with prostate cancer who elected surgery with and without nerve sparing, and bladder neck preservation as primary therapy. A total of 482 men completed a brief urinary continence questionnaire preoperatively and postoperatively at a median followup of 18 months. Urinary continence was followed prospectively using the questionnaire and patient reported urinary continence recovery was based on 3 definitions of continence.

RESULTS

Median time to continence recovery based on patient reporting was significantly shorter in the nerve sparing than in the nonnerve sparing group when continence was defined as no urinary leakage (5.3 versus 10.9 months, p <0.01). A multivariate model controlling for baseline factors revealed that significant predictors of continence outcome were preoperative continence, patient age, nerve sparing and the interaction of nerve sparing with age (p <0.05). The definition of urinary continence also affected outcome.

CONCLUSIONS

The nerve sparing technique of radical prostatectomy was associated with improved recovery of urinary continence in an age dependent manner, whereas bladder neck preservation was not beneficial. Patient age and the sensitivity of the incontinence definitions, as reflected by the associated variable rates of preoperative baseline incontinence, are significant contexts for interpreting urinary function data after radical prostatectomy. These factors may partially explain the variation in continence rates in the literature.

Loss of fhit expression in invasive cervical carcinomas and intraepithelial lesions associated with invasive disease

Allelic losses involving chromosome 3p are frequently observed in cervical cancers. Deletion mapping studies of primary cervical carcinomas have localized common regions of deletion to 3p14.2 and 3p21. The candidate tumor suppressor gene FHIT has been mapped to 3p14.2, and previous studies have demonstrated reduced or aberrant FHIT transcripts and reduced or absent Fhit protein expression in a large percentage of cervical cancer-derived cell lines and primary cervical carcinomas. To expand these observations to preinvasive cervical epithelial lesions and to determine whether loss of Fhit protein expression might be associated with tumor progression, immunohistochemical methods were used to examine Fhit expression in 95 invasive cervical carcinomas, 33 high-grade squamous intraepithelial lesions (HSILs) associated with concurrent invasive cancer, 38 HSILs unassociated with invasive cancer, 24 low-grade squamous intraepithelial lesions, and 22 normal cervix samples. All normal cervical epithelia and low-grade squamous intraepithelial lesions exhibited diffuse cytoplasmic immunostaining of moderate to strong intensity. Fhit protein expression was markedly reduced or absent in 67 of 95 (71%) invasive cancers, 17 of 33 (52%) HSILs associated with invasive cancer, and 8 of 38 (21%) HSILs without associated invasive cancer. The results confirm that Fhit protein expression is reduced or absent in the majority of cervical carcinomas and suggest that loss of Fhit expression often accompanies cervical tumor progression. Moreover, absent or reduced Fhit protein is observed at a significantly higher frequency in HSILs associated with progression to invasive cancer than in HSILs with unknown risk for progression (P = 0.012). These findings suggest that loss of Fhit expression in HSILs could serve as a useful marker of high-grade preinvasive lesions that have an increased likelihood of progression to invasive carcinoma.

Sustained suppression of pituitary-gonadal axis with an injectable, in situ forming implant of leuprolide acetate

The objective of these studies was to develop a leuprolide acetate depot based on an in situ forming drug delivery system (Atrigel(R)) to suppress the pituitary-gonadal axis and in turn the serum testosterone to chemical castration levels for a period of at least 3 months. Formulations with biodegradable lactide/glycolide copolymers that varied in molecular weight, lactide/glycolide ratio, and hydrophilicity were evaluated in rats for their efficacy by measuring serum testosterone levels. The effect of polymer irradiation was also investigated. Molecular weight of the polymers was characterized by gel-permeation chromatography, and retrieved implants at the termination of animal studies were assayed for residual drug content by high-performance liquid chromatography. These initial rat studies showed that a formulation containing a 75/25 lactide/glycolide copolymer dissolved in N-methyl-2-pyrrolidone with 3% w/w leuprolide acetate suppressed serum testosterone for a period of 3 months or longer. This formulation with its advantages of biodegradability, biocompatibility, ease of injection, and no need for removal after use should be beneficial in treating patients with hormonal-dependent prostate and mammary cancers, endometriosis, and precocious puberty. In addition, this formulation with its simple manufacturing process is expected to provide an economic benefit to the user compared with products currently available on the market.

Hypersensitivity of Escherichia coli Delta(uvrB-bio) mutants to 6-hydroxylaminopurine and other base analogs is due to a defect in molybdenum cofactor biosynthesis

We have shown previously that Escherichia coli and Salmonella enterica serovar Typhimurium strains carrying a deletion of the uvrB-bio region are hypersensitive to the mutagenic and toxic action of 6-hydroxylaminopurine (HAP) and related base analogs. This sensitivity is not due to the uvrB excision repair defect associated with this deletion because a uvrB point mutation or a uvrA deficiency does not cause hypersensitivity. In the present work, we have investigated which gene(s) within the deleted region may be responsible for this effect. Using independent approaches, we isolated both a point mutation and a transposon insertion in the moeA gene, which is located in the region covered by the deletion, that conferred HAP sensitivity equal to that conferred by the uvrB-bio deletion. The moeAB operon provides one of a large number of genes responsible for biosynthesis of the molybdenum cofactor. Defects in other genes in the same pathway, such as moa or mod, also lead to the same HAP-hypersensitive phenotype. We propose that the molybdenum cofactor is required as a cofactor for an as yet unidentified enzyme (or enzymes) that acts to inactivate HAP and other related compounds.

Sustained activity and release of leuprolide acetate from an in situ forming polymeric implant

The primary objective of this study was to evaluate the effect of drug loading on the release of leuprolide acetate from an injectable polymeric implant, formed in situ, and efficacy of the released drug in suppressing serum testosterone levels in dogs for at least 90 days. An additional objective was to compare the optimum implant formulation with a commercial microsphere product. Evaluated implant formulations contained 45% w/w 75/25 poly (DL-lactide-co-glycolide) polymer having an intrinsic viscosity of 0.20 dL/g, dissolved in N-methyl-2-pyrrolidone. Irradiated polymer solution was mixed with leuprolide at different drug loads (3%, 4.5%, and 6% w/w) prior to subcutaneous administration to dogs. Dog serum was analyzed for testosterone (RIA) and leuprolide (LC/MS/MS) levels and comparisons within the three implant formulation groups were made. Varying the drug load did not significantly affect the release of leuprolide or efficacy of the implant formulation. Thus, the 6% w/w formulation with the smaller injection volume was selected for comparison with the commercial LUPRON Depot product, which was administered intramuscularly at a similar dosage. These comparisons of serum testosterone and leuprolide levels showed no significant difference in the pharmacologic efficacy even though drug levels were different at a number of points. This was mainly due to associated high standard deviations. Based on these studies, the 6% w/w leuprolide implant formulation was considered to be a suitable candidate for further development. Additional benefits of this system include its simple manufacturing and lower costs.

Restored expression of fragile histidine triad protein and tumorigenicity of cervical carcinoma cells

BACKGROUND

Allelic losses in the short arm of chromosome 3 are common in cervical carcinomas. The fragile histidine triad (FHIT) gene at chromosome region 3p14.2 is a candidate tumor suppressor gene that may play a role in cervical tumorigenesis. We and others have identified aberrant FHIT transcripts and frequent loss of Fhit protein expression in primary cervical cancers and high-grade noninvasive lesions but not in normal cervical tissues. The altered expression of FHIT may be due to somatic mutations or integration of human papillomavirus DNA at the FHIT locus. The purpose of this study was to determine whether ectopic expression of Fhit can suppress the tumorigenic properties of cervical cancer cells.

METHODS

We employed infection with recombinant retroviruses as well as transfection of plasmid DNA to restore Fhit protein expression in cervical cancer cell lines lacking full-length FHIT transcripts and endogenous Fhit protein. The effects of Fhit expression on tumor cell morphology, anchorage-independent growth, and tumorigenicity in nude mice were examined.

RESULTS

Stable overexpression of Fhit had no discernible effect on the tumorigenic properties of two cervical carcinoma cell lines or on a lung carcinoma cell line previously reported by others to be suppressed for tumorigenicity by Fhit.

CONCLUSIONS

Restoration of Fhit expression does not suppress anchorage-independent growth or tumorigenicity of cervical carcinoma cell lines. However, it remains possible that FHIT inactivation may be important early in cervical tumor progression or that FHIT may suppress tumorigenesis in ways distinct from those measured by the assays employed in this study.

Parameters affecting the efficacy of a sustained release polymeric implant of leuprolide

The objective of this study was to evaluate the formulation parameters critical to the efficacy of an injectable polymeric implant of leuprolide acetate, formed in situ, in suppressing and maintaining serum testosterone levels of animals in the range 0.5 ng/ml for over 90 days. The formulation evaluated contained 45% (w/w) 75/25 poly (DL-lactide-co-glycolide) polymer having an intrinsic viscosity of 0.20 dl/g, dissolved in 55% (w/w) N-methyl-2-pyrrolidone with 3% (w/w) leuprolide acetate added either as a homogeneous solution or a two-part suspension (A/B) system, in which the drug was dispersed within the polymer solution immediately prior to use. The formulation parameters evaluated in this study included polymer molecular weight, polymer concentration, and drug loading. Both rat and dog models were used to evaluate efficacy. Serum testosterone was assayed by radioimmunoassay to determine efficacy, and retrieved implants from the rats at the termination of the study were analyzed by HPLC for residual drug content to determine the extent of drug release. With the candidate formulation, testosterone levels in dogs diminished to the targeted levels of 0. 5 ng/ml by day 14 and remained suppressed up to day 91, reproducing the results seen in rats. Variations in polymer concentration (40-50%), and drug load (3-6% (w/w)) did not have a significant effect on the apparent level and duration of efficacy. However, employing lower molecular weight polymer decreased the duration of efficacy of the formulation.

Controlling for systematic selection in retrospective analyses: an application to fluoxetine and sertraline prescribing in the United Kingdom

BACKGROUND

Criticism has been made of observational studies in clinical practice because of their failure to control for unobserved factors that correlate with both initial treatment selection and observed outcomes.

METHOD

A two-stage statistical model was applied to data obtained from a large general practitioner medical records database (DIN-LINK) to estimate the effect of initial antidepressant selection on the duration of antidepressant therapy and on the likelihood of being prescribed an average daily dose above the minimum recommended dose. The statistical model controlled for unobserved factors correlated with initial treatment selection and the observed outcomes as well as for observed confounders.

RESULTS

Unobserved factors correlated with treatment selection were not a statistically significant determinant of the number of days of antidepressant therapy. However, unobserved factors correlated with treatment selection were a statistically significant determinant of the likelihood of receiving an average dose during therapy greater than the minimum recommended. After controlling for relevant confounders, those patients who began treatment with sertraline as opposed to fluoxetine had fewer days of antidepressant therapy and were more likely to receive average doses greater than the minimum recommended during therapy.

CONCLUSION

Unobserved factors correlated with treatment selection can impact outcomes in observational studies and should be tested and controlled for whenever possible.

Growth factors regulate expression of osteoblast-associated genes

BACKGROUND

The goal of periodontal regenerative therapies is to reconstruct periodontal tissues such as bone, cementum, and periodontal ligament cells (PDL). The need to establish predictable treatment modalities is important for reconstruction of these tissues. The aim of this study was to determine the effects of a low molecular extract of bovine bone protein (BP) containing bone morphogenetic proteins (BMPs) 2, 3, 4, 6, 7, 12, and 13, alone or in combination with platelet-derived growth factor (PDGF) and/or insulin-like growth factor (IGF) on osteoblast differentiation in vitro.

METHODS

BP, mixed with a collagen matrix, was added to a poly (DL-lactide-co-glycolide) polymer (PLG) and placed at orthotopic sites in the skullcaps of Sprague-Dawleys rats. At day 28, rats were sacrificed for histological analysis. All sites treated with the polymer/BP produced bone while control sites (without BP) showed no bone formation. Having established the biological activity of BP, in vitro studies were initiated using MC3T3-E1 cells, a mouse osteoprogenitor cell line. The ability of BP and other growth factors to alter cell proliferation was determined by Coulter counter, and differentiation was determined by Northern analysis for specific genes.

RESULTS

When compared with cells treated with 2% serum alone, PDGF enhanced cell numbers at 10 and 20 ng/ml; IGF produced no significant effect at these doses; and BP at 10 and 20 microg/ml decreased cell proliferation. Northern analysis revealed that PDGF blocked gene expression of osteopontin (OPN) and osteocalcin (OCN), while BP and IGF promoted gene expression of bone sialoprotein (BSP) and OPN. The combination of BP and IGF enhanced expression of OPN beyond that of either BP or IGF alone. PDGF was able to block the effects of IGF on gene expression, but not those of BP.

CONCLUSIONS

These results indicate that BP, PDGF, and IGF influence cell activity differently, and thus raise the possibility that combining factors may enhance the biological activity of cells.

Longitudinal patterns of antidepressant prescribing in primary care in the UK: comparison with treatment guidelines

The objective of this study was to determine whether patients beginning therapy on the most common tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs) differed in their likelihood of having antidepressant treatment that was consistent with recommended treatment guidelines in the UK. An analytical file constructed from a large general practitioner medical records database (DIN-LINK) from the UK for the years 1992-97 was constructed. A total of 16,204 patients with a new episode of antidepressant therapy who initiated therapy on one of the most often prescribed TCAs (amitriptyline, dothiepin, imipramine and lofepramine) or SSRIs (fluoxetine, paroxetine and sertraline) were analysed. A dichotomous measure was defined to indicate whether subjects were prescribed at least 120 days of antidepressant therapy at an adequate average daily dose within the first 6 months after initiation of therapy. Only 6.0% of patients initiating therapy on aTCA and 32.9% of patients initiating therapy on a SSRI were prescribed antidepressant treatment that was consistent with treatment guidelines. After controlling for observable characteristics, patients who initiated therapy on a SSRI were much more likely (odds ratio=7.473, p<0.001) to have a prescribed average daily dose and duration consistent with recommended treatment guidelines within the first 6 months of initiating therapy than were patients who initiated therapy on a TCA. These findings suggest that initial antidepressant selection is an important determinant of whether the subsequent course of treatment is consistent with current national guidelines for the treatment of depression in the UK.

A return on investment evaluation of the Citibank, N.A., health management program

OBJECTIVES

Citibank, N.A., initiated a comprehensive health, demand, and disease management program in 1994, using program services offered by Healthtrac, Inc., of Menlo Park, California. Program components included an initial screening of employees, computerized triage of subjects into higher and lower risk intervention programs, extensive follow-up with the higher risk subjects, and general health education and awareness building. The objective of this study was to estimate the financial impact of this program on medical expenditures.

METHODS

A quasiexperimental design was applied comparing medical expenditures before vs. after the intervention for program participants and nonparticipants. The 22,838 subjects (11,194 program participants and 11,644 nonparticipants) were followed for an average of 38 months before and after administration of a Healthtrac health risk appraisal (HRA) instrument that triggered the start of the program. To adjust for selection bias to the extent possible with these data, multiple regression models were used to estimate the savings in medical expenditures associated with program participation. The resulting dollar savings were compared to program costs to estimate the economic return on the company's investment in the program.

RESULTS

The return on investment (ROI) was estimated to be between $4.56 and $4.73 saved per dollar spent on the program, depending on the discount rate applied. These results are similar to published evaluations of Healthtrac programs implemented with other populations.

CONCLUSIONS

Despite limitations inherent in any retrospective observational study, the strong, positive ROI shown here suggests that a well-designed health management program (HMP), which focuses interventions on high risk populations, can result in monetary savings to an organization.

Biocompatibility of a biodegradable in situ forming implant system in rhesus monkeys

Formulations of a polymeric delivery system containing a 75/25 poly(DL-lactide-co-caprolactone dissolved in either N-methyl-2-pyrrolidone or dimethyl sulfoxide were injected both subcutaneously (SC) and intramuscularly (IM) into rhesus monkeys. Each monkey received an SC and IM injection of each of the two formulations, for a total injection volume of 4 mL. The monkeys were observed daily for overt signs of toxicity, and after 4 weeks biopsies of each implant site were fixed, stained, and evaluated histologically for tissue reaction to the polymer system. Tissue response was graded upon the presence and level of fibrous connective tissue and inflammatory cell infiltrate. The polymer formulations appeared to be safe, as the animals remained healthy and active throughout the study with no changes in food or water consumption, weight loss, or abnormal behavior observed. Tissue response to both formulations was considered mild and similar to that for other biodegradable polymers, in that the reaction was limited to tissue immediately adjacent to the residual polymer fragments and consisted of a mild fibroplasia with the presence of a few lymphocytes and macrophages. There were no differences between the two formulations in tissue response, and both formulations were considered acceptable for use as injectable implant systems.

Fluoxetine and dothiepin therapy in primary care and health resource utilization: Evidence from the United Kingdom

We attempted to evaluate differences in healthcare resource utilization following the initiation of antidepressant therapy with dothiepin or fluoxetine in primary care in the United Kingdom, by means of retrospective analysis of data from the Doctors Independent Network (DIN-LINK) records system, with a two-stage, multiple regression adjusted for potential bias stemming from non-random selection of initial drug choice in clinical practice. We counted patients' use of healthcare resources in the year following initiation of antidepressant therapy. After controlling for both observed and unobserved baseline characteristics correlated with initial drug selection, we found that dothiepin patients would have 0.18 additional non-accident and emergency (ACE) admission, 0.007 more ACE admissions, and 1.09 more general referrals than patients who started therapy with fluoxetine. Fluoxetine patients would have 0.35 more prescriptions for the initial antidepressant. Dothiepin patients would make 5.4 fewer visits to GPs' surgery, have 0.2 fewer prescriptions for hypnotic drugs, and 6.5 fewer prescriptions for other drugs than fluoxetine patients. This shows that the total economic impact of initial antidepressant selection is broader than the acquisition costs of antidepressants.

Gaps in antidepressant prescribing in primary care in the United Kingdom

An important determinant for achieving efficacy results in clinical practice comparable to those demonstrated in clinical trials is whether or not patients take their medication as prescribed. Recent studies have shown that 30-60% of patients do not take their medications as prescribed. Gaps between antidepressant prescriptions raise questions about the possibility of periods of nonadherence to medication in clinical practice. The purpose of conducting this study was to assess the likelihood of experiencing a gap of > 15 days between antidepressant prescriptions for patients with a depression-related diagnosis and to assess whether this likelihood varied across different antidepressants with tricyclic antidepressants and selective serotonin reuptake inhibitors. Episodes of antidepressant treatment were constructed using the Doctors' Independent Network general practitioner medical records database. For all antidepressant agents considered, approximately 50% of patients had a gap between prescriptions and 15-25% of patients had a gap of > 15 days between prescriptions. A significant proportion of patients in a general practitioner setting in the UK have gaps recorded of > 15 days between antidepressant prescriptions. Gaps between prescriptions raise the question of whether patients may be at risk for clinical consequences associated with nonadherence to therapy, such as reduced effectiveness or treatment interruption symptomatology.

Biodegradation and biocompatibility of a guided tissue regeneration barrier membrane formed from a liquid polymer material

Biodegradable barrier films were made by coagulating a solution of poly(DL-lactide) in N-methyl-2-pyrrolidone on porous polyethylene pads wetted with saline solution. The semisolid films were cut into 10 x 10 mm barriers and implanted subcutaneously in rabbits. At monthly intervals, the polymer implant sites were compared histologically to those implanted with USP negative control plastic. The polymer films were retrieved from the surrounding tissue, dried, weighed, and the changes in molecular weight determined using gel permeation chromatography. The molecular weight of the polymer decreased at a relatively constant rate over 5 months; however, no significant mass loss occurred until 5 months postimplantation. Also, no distinct histological differences were noted between the polymer barrier and the control plastic sites until 6 months when histiocytes and multinucleated giant cells showed a modest increase around fragmented polymer films. Similar barrier films also were fitted over naturally occurring buccal dehiscence defects in beagle dogs and the tissue sites compared histologically at 6 months to sham-operated control sites. New bone and dense connective tissues closely approximated segments of the remaining polymer and demonstrated the biocompatibility of the biodegradable films. Histomorphometric analyses of treated sites compared to sham controls showed that the polymer barrier is effective in promoting bone and cementum regeneration in periodontal defects in dogs.

Apparent interaction of dimethyl sulfoxide with cisplatin released from polymer delivery devices injected subcutaneously in dogs

Local tissue toxicity, systemic toxicity and platinum pharmacokinetics were evaluated in 6 normal healthy beagle dogs injected subcutaneously with two formulations of a polylactide biodegradable polymer (Atrigel) system containing cisplatin. Dogs were injected 4 times at 30 day intervals at platinum dosages of 70, 105 and 157.5 mg/m2 (dose escalation). Once pharmacokinetics were established, 29 dogs with spontaneous stage IIb appendicular osteosarcoma were treated with 4 injections of the same polymer system containing cisplatin at 70 mg/m2 (20 dogs) and 100 mg/m2 (9 dogs) to establish efficacy against micrometastatic disease. Local tissue toxicity was variable. Systemic toxicity, as judged by clinicopathologic evaluation was not noted at any dose level or injection number. Interim (6 month) survival analysis revealed a median disease-free interval of 180 days. Consistent platinum release characteristics were found, however, the lack of toxicity and decreased disease-free-interval raised concerns over the biologic activity of the cisplatin. Prior to completion of the study, it was discovered that dimethyl sulfoxide, the solvent used in the co-polymer system, may be responsible for biologic inactivation of cisplatin. This was subsequently demonstrated in tissue culture assays. The clinical trial was suspended and dogs were treated with traditional chemotherapy.

The relationship between modifiable health risks and health care expenditures. An analysis of the multi-employer HERO health risk and cost database

This investigation estimates the impact of ten modifiable health risk behaviors and measures and their impact on health care expenditures, controlling for other measured risk and demographic factors. Retrospective two-stage multivariate analyses, including logistic and linear regression models, were used to follow up 46,026 employees from six large health care purchasers for up to 3 years after they completed an initial health risk appraisal. These participants contributed 113,963 person-years of experience. Results show that employees at high risk for poor health outcomes had significantly higher expenditures than did subjects at lower risk in seven of ten risk categories: those who reported themselves as depressed (70% higher expenditures), at high stress (46%), with high blood glucose levels (35%), at extremely high or low body weight (21%), former (20%) and current (14%) tobacco users, with high blood pressure (12%), and with sedentary lifestyle (10%). These same risk factors were found to be associated with a higher likelihood of having extremely high (outlier) expenditures. Employees with multiple risk profiles for specific disease outcomes had higher expenditures than did those without these profiles for the following diseases: heart disease (228% higher expenditures), psychosocial problems (147%), and stroke (85%). Compared with prior studies, the results provide more precise estimates of the incremental medical expenditures associated with common modifiable risk factors after we controlled for multiple risk conditions and demographic confounders. The authors conclude that common modifiable health risks are associated with short-term increases in the likelihood of incurring health expenditures and in the magnitude of those expenditures.

Effect of Escherichia coli dnaE antimutator mutants on mutagenesis by the base analog N4-aminocytidine

Previous studies in our laboratory have identified a set of mutations in the Escherichia coli dnaE gene that confer increased accuracy of DNA replication (antimutators). The dnaE gene encodes the polymerase subunit of DNA polymerase III holoenzyme that replicates the E. coli chromosome. Here, we have investigated their effect on mutagenesis by the base analog N4-aminocytidine (4AC). For three different mutational markers, rifampicin resistance, nalidixic acid resistance and lacI forward mutagenesis, the dnaE911 allele reduced 4AC-induced mutagenesis by approximately 2.5-fold, while the dnaE915 allele reduced it by 2.5-, 3.5- and 6.5-fold, respectively. We also investigated the dependence of 4AC mutagenesis on mutations in the MutHLS mismatch repair system and the UvrABC nucleotide excision repair system. The results show that mutagenesis by 4AC is unaffected by defects in either system. The combined results point to the critical role of the DNA polymerase in preventing mutations by base analogs.

Differences between descriptive and multivariate estimates of the impact of Chevron Corporation's Health Quest Program on medical expenditures

This investigation focused on alternative methods for evaluating the impact of Chevron Corporation's Health Quest Fitness Center program on medical expenditures, comparing descriptive and multivariate research designs. Many uncontrolled studies of corporate health management programs base estimates of program effectiveness on descriptive analyses such as Student's tests. Unlike more sophisticated multivariate analyses, descriptive analyses often produce biased estimates of program cost savings. To test alternative research design methods, the investigators compared inpatient and pharmacy expenditures for program participants and non-participants over a 2.5-year period, using descriptive and multivariate regression analyses. Results showed that compared with non-participants, expenditures for participants were significantly lower for subjects who used a Health Quest fitness center at least twice weekly. Previous descriptive studies suggested a much broader impact. The results underscore the need to use multivariate analyses when evaluating the financial impact of corporate health management programs, especially when randomization cannot be used to assign participation status.

Change in serum prostate-specific antigen as a marker of response to cytotoxic therapy for hormone-refractory prostate cancer

PURPOSE

Prostate-specific antigen (PSA) has been used as a marker of advanced prostate cancer but remains controversial. To evaluate PSA as a predictor of survival, we analyzed data from sequential phase II trials of estramustine and etoposide.

METHODS

A landmark analysis that used data from 62 men with PSA levels at baseline and 8 weeks was conducted. The best PSA measure (of six evaluated) was incorporated into a multiple regression model with performance status (PS); relative change in PSA level; and pretreatment PSA, alkaline phosphatase, and hemoglobin values.

RESULTS

A decrease in PSA of 50% or greater at 8 weeks was associated with a significantly increased survival (P=.0005, two-sided log-rank test). Median survival from the landmark was 91 weeks in patients with a 50% or greater decrease at 8 weeks versus 38 weeks in those without this decrease. Modeling showed that PS, pretreatment hemoglobin level, and relative change in PSA level were significant prognostic factors, with a significant interaction between PS and pretreatment hemoglobin level. In the final model, a relative change in PSA level at 8 weeks of less than 50% had an adjusted relative risk of 2.20 (95% confidence interval, 1.21 to 4.00). A decrease in PSA level of 50% or greater at any time during therapy was associated with a response in measurable disease (P=.0369, two-sided Fisher's exact test).

CONCLUSION

The PSA value after 8 weeks of this cytotoxic regimen does predict survival. A decrease in PSA level is associated with both survival and response in soft tissue lesions and should be incorporated into the response criteria and reporting of trials of cytotoxic agents in prostate cancer.

Genetic requirements and mutational specificity of the Escherichia coli SOS mutator activity

To better understand the mechanisms of SOS mutagenesis in the bacterium Escherichia coli, we have undertaken a genetic analysis of the SOS mutator activity. The SOS mutator activity results from constitutive expression of the SOS system in strains carrying a constitutively activated RecA protein (RecA730). We show that the SOS mutator activity is not enhanced in strains containing deficiencies in the uvrABC nucleotide excision-repair system or the xth and nfo base excision-repair systems. Further, recA730-induced errors are shown to be corrected by the MutHLS-dependent mismatch-repair system as efficiently as the corresponding errors in the rec+ background. These results suggest that the SOS mutator activity does not reflect mutagenesis at so-called cryptic lesions but instead represents an amplification of normally occurring DNA polymerase errors. Analysis of the base-pair-substitution mutations induced by recA730 in a mismatch repair-deficient background shows that both transition and transversion errors are amplified, although the effect is much larger for transversions than for transitions. Analysis of the mutator effect in various dnaE strains, including dnaE antimutators, as well as in proofreading-deficient dnaQ (mutD) strains suggests that in recA730 strains, two types of replication errors occur in parallel: (i) normal replication errors that are subject to both exonucleolytic proofreading and dnaE antimutator effects and (ii) recA730-specific errors that are not susceptible to either proofreading or dnaE antimutator effects. The combined data are consistent with a model suggesting that in recA730 cells error-prone replication complexes are assembled at sites where DNA polymerization is temporarily stalled, most likely when a normal polymerase insertion error has created a poorly extendable terminal mismatch. The modified complex forces extension of the mismatch largely at the exclusion of proofreading and polymerase dissociation pathways. SOS mutagenesis targeted at replication-blocking DNA lesions likely proceeds in the same manner.

A two-step intervention of increase mammography among women aged 65 and older

OBJECTIVES

This study evaluated a two-step intervention for mammography screening among older women.

METHODS

Four hundred and sixty women, identified from physician practices, were randomized to a control or a two-step intervention (physician letter and peer counseling call) group. Women in the intervention group who obtained a mammogram received a grocery coupon.

RESULTS

Over the 12 months of the study, more women in the intervention group than in the control group obtained mammograms (38% vs 16%). The most dramatic difference was in the higher odds that women in the intervention group would obtain a mammogram within 2 months (odds ratio = 10.5).

CONCLUSIONS

The intervention significantly increased screening mammography. Future efforts must be multifaceted and incorporate the unique concerns of older women.

Periodontal regeneration in naturally occurring Class II furcation defects in beagle dogs after guided tissue regeneration with bioabsorbable barriers

THE EFFICACY OF A BIOABSORBABLE polylactic acid based barrier was evaluated using naturally occurring buccal Class II furcation defects in beagle dogs. Sixteen furcation sites (8 control and 8 experimental) were treated in 6 adult animals. After full thickness flap reflection, exposed furcations and root surfaces were thoroughly root planed. In experimental sites a customized barrier was formed and fitted to cover the defect. Surgical flaps were replaced slightly coronal to the cemento-enamel junction. Animals were sacrificed at 6 months and specimens processed for histologic evaluation. Histologic and histometric analyses were done using 6 micrograms step serial sections in the buccal-lingual plane, corresponding to the buccal-lingual extent of the furcation. Results were: mean total defect experimental sites 1.92 mm; control sites 1.47 mm. Mean new cementum formation experimental sites 1.36 mm (71% of initial defect); control sites 0.25 mm (17% of initial defect). Mean new bone formation experimental sites 1.42 mm (74% of initial defect); control sites 0.20 mm (14% of initial defect). Mean junctional epithelium formation experimental sites 0.42 mm (22% of initial defect); control sites 1.21 mm (82% of initial defect). Statistical analysis demonstrated significant differences in all healing parameters favoring experimental (barrier-treated) sites. In this model, regeneration (new bone, cementum, and periodontal ligament) of 71% of the original defect in experimental sites and only 14% in control sites demonstrated a response that highly favored use of the barrier.