Critical patch size generated by Allee effect in gypsy moth, Lymantria dispar (L.).

Allee effects are important dynamical mechanisms in small-density populations in which per capita population growth rate increases with density. When positive density dependence is sufficiently severe (a 'strong' Allee effect), a critical density arises below which populations do not persist. For spatially distributed populations subject to dispersal, theory predicts that the occupied area also exhibits a critical threshold for population persistence, but this result has not been confirmed in nature. We tested this prediction in patterns of population persistence across the invasion front of the European gypsy moth (Lymantria dispar) in the United States in data collected between 1996 and 2008. Our analysis consistently provided evidence for effects of both population area and density on persistence, as predicted by the general theory, and confirmed here using a mechanistic model developed for the gypsy moth system. We believe this study to be the first empirical documentation of critical patch size induced by an Allee effect.

E. coli promotes human Vγ9Vδ2 T cell transition from cytokine-producing bactericidal effectors to professional phagocytic killers in a TCR-dependent manner.

γδT cells provide immune-surveillance and host defense against infection and cancer. Surprisingly, functional details of γδT cell antimicrobial immunity to infection remain largely unexplored. Limited data suggests that γδT cells can phagocytose particles and act as professional antigen-presenting cells (pAPC). These potential functions, however, remain controversial. To better understand γδT cell-bacterial interactions, an ex vivo co-culture model of human peripheral blood mononuclear cell (PBMC) responses to Escherichia coli was employed. Vγ9Vδ2 cells underwent rapid T cell receptor (TCR)-dependent proliferation and functional transition from cytotoxic, inflammatory cytokine immunity, to cell expansion with diminished cytokine but increased costimulatory molecule expression, and capacity for professional phagocytosis. Phagocytosis was augmented by IgG opsonization, and inhibited by TCR-blockade, suggesting a licensing interaction involving the TCR and FcγR. Vγ9Vδ2 cells displayed potent cytotoxicity through TCR-dependent and independent mechanisms. We conclude that γδT cells transition from early inflammatory cytotoxic killers to myeloid-like APC in response to infectious stimuli.

Changing patterns of disease on an inpatient medical service: 1961-1962 to 1981-1982.

To assess changes in disease on an internal medicine teaching service, the records of 292 patients admitted to University Hospital, Denver, Colorado, in the academic years 1961-1962 or 1981-1982 were reviewed. It was hypothesized that patients admitted more recently would be older, more chronically and catastrophically ill, and more likely to have multiple illnesses than patients of an earlier era. Over time, length of stay and mortality rates decreased and acuteness of illness increased, whereas age, chronicity, and co-morbidity remained constant. Changes in the prevalence of some common diseases reflected evolving medical and social influences on hospital use. Modern medical residents are exposed to more patients for a shorter time. They see more acute illness but less of the ongoing process of diagnosis and treatment. Awareness of such changes can help educators design residency programs that better prepare internists for practice.

Seroepidemiological evidence for a relationship between Neospora caninum infections in dogs and cattle.

Dogs from dairy farms with a known prevalence of Neospora caninum antibodies in the cattle were examined for the presence of N. caninum antibodies using an ELISA. Data of farm dogs were compared with those of dogs examined at a university clinic, which originated mainly in urban areas. Of the 152 farm dogs, 36 (23.6%) were seropositive to N. caninum, which was significantly higher than the proportion of seropositives in the clinic dog population (19 of 344, 5.5%). Seroprevalence was significantly higher (P = 0.01) in female dogs than in male dogs. Seroprevalence in dogs increased with age, indicating postnatal infection. Seropositivity to N. caninum in farm dogs was strongly correlated with a high prevalence of N. caninum antibodies in the cattle. At farms where no dogs were present, the seroprevalence to N. caninum in the cattle was significantly lower (P = 0.0002) than in farms where dogs were present. These findings suggest that there is a relationship between N. caninum infection of farm dogs and cattle. Since dogs have been shown to be definitive hosts of N. caninum, cattle may be infected by exposure to canine oocysts. Further research is needed to find out whether and how dogs may acquire the infection from cattle.

Geriatric care approaches in health maintenance organizations.

The objective of this project was to describe geriatric care provided under Medicare-risk contracts in HMOs with established Medicare programs. These findings provided the basis for an invitational workshop, sponsored by the National Institute on Aging and the Robert Wood Johnson Foundation, to formulate a research agenda for geriatric care in HMOs. The case study method involved site visits to seven HMOs by a physician with expertise in geriatrics, a managed care specialist, and a program development specialist. Representatives from the HMOs included senior executive officials, physicians recognized for providing and promoting geriatric care, research and program development staff, and various clinical staff including pharmacists, geriatric nurse practitioners, nurses, and social workers. The most frequently encountered geriatric care programs were categorized by the following six objectives: (1) identifying high risk patients, (2) assessing multi-problem patients, (3) treating multi-problem patients, (4) rehabilitating patients following acute events, (5) reducing medication problems, and (6) providing long-term care and home health care. Unique programs identified from these site visits included screening methods for new enrollees, approaches to comprehensive geriatric assessment, use of skilled nursing facilities for intensive rehabilitation and postacute care, and drug profiling and review. Utilization of geriatric nurse specialists and programs aimed at coordination with social services were pervasive in many of these HMOs. Workshop participants proposed several research and demonstration projects in all six areas. Overall consensus emerged that HMOs with Medicare-risk contracts provide a valuable setting for experimentation in geriatric care. Given the current health policy emphasis on managed care and capitated payment methodologies, geriatric care research in HMOs should be a high priority.

Academic affiliation with a nursing home. Impact on patient outcome.

In a prospective study, 46 patients discharged from a teaching hospital to a "teaching unit" nursing home, where primary medical care was provided by faculty geriatricians, medical students, and medical housestaff, were compared with 78 similar patients discharged to one of five community nursing homes without a teaching affiliation. At the time of hospital discharge, patients were determined to have a terminal, rehabilitative, or long stay prognosis based on a review of hospital discharge summaries using specific criteria. Among 34 study and 55 control patients with a long stay prognosis, ten of the study group compared with seven of the control group returned home (P = .03). Seven of 34 long stay patients in the study group were rehospitalized, while 15 of a matched control group of 34 required hospitalization (P = .04). There was no increase in mortality or emergency service use in the study population. Patients considered to be terminal or rehabilitative showed no difference in ultimate outcome or hospital use. In the study group patients experienced an average reduction in total medications prescribed from 6.2 to 5.3, while patients in the control group had an increase from 5.4 medications prescribed to 7.6 (P less than .001). Of 16 study patients discharged from the teaching unit nursing home, all remained home at least three months after discharge; only 12 of 18 control group patients discharged from the nursing home remained at home at three months (P less than .01). Long-term care by geriatric faculty, students, and housestaff appeared to have favorably influenced patient outcomes.

Prospective payment for nursing homes increased therapy provision without improving community discharge rates.

OBJECTIVES: To determine the impact of the prospective payment system (PPS) for skilled nursing facilities (SNFs) on therapy use and community discharge rates. DESIGN: Quasi-experimental study examining the predemonstration (1994) to demonstration (1997) change in amount of therapy provided, and in community discharge rates at PPS participating and nonparticipating facilities. SETTING: Eighteen PPS participating and 17 nonparticipating SNFs in five states. PARTICIPANTS: Two thousand sixty-seven admissions to 18 PPS participating and 17 nonparticipating SNFs in five states. MEASUREMENTS: We compared changes in number of physical and occupational therapy visits per stay for patients receiving therapy and likelihood of being located in the community 60 days after admission between 1994 and 1997. Analyses were stratified by functional category and risk adjusted using multivariate methods. RESULTS: Demographics and percentage of patients in each stratum were similar in participating and nonparticipating sites and between 1994 and 1997. Amount of therapy received by the highest-functioning patients increased in participating sites (19.3 to 26.5 visits per stay, P = .005), but not in nonparticipating sites (23.3 to 18.2, P = .98). After adjusting for covariates, likelihood of community discharge for the highest-functioning patients did not change between participating and nonparticipating sites. CONCLUSIONS: The highest-functioning patients treated under the SNF PPS demonstration experienced great increases in therapy, without any improvement in rate of community discharge.

Outcomes of older persons receiving rehabilitation for medical and surgical conditions compared with hip fracture and stroke.

OBJECTIVE: Older persons with general medical and surgical conditions increasingly receive posthospital rehabilitation care in nursing homes and rehabilitation hospitals. This study describes the characteristics of such patients, contrasted with patients with traditional rehabilitation diagnoses of hip fracture and stroke. DESIGN: Prospective cohort study. SETTING: Seventeen skilled nursing facilities and six rehabilitation hospitals in seven states. PARTICIPANTS: Medicare patients age 65 or older receiving posthospital rehabilitation. METHODS: A total of 290 medical/surgical patients were compared with 336 hip fracture and 429 stroke patients. Data were collected prospectively from charts, nursing assessments, and patient interviews. Patient characteristics associated with functional recovery and mortality were estimated using multivariate regression. RESULTS: Medical/surgical patients had greater premorbid activities of daily living (ADL) (P < .001) and instrumental activities of daily living (IADL) (P < .01) disability, but suffered less decline with the acute event than hip fracture or stroke patients (P < .001). Medical/surgical patients were more likely to recover premorbid ADL function (P < .05) but 1-year mortality was significantly greater (30% vs. 14% hip fracture; 18% stroke; P < .001). Predictors of functional recovery and mortality differed between the three groups. Among medical/surgical patients, premorbid ADL difficulty, cognitive impairment, a pressure ulcer at rehabilitation admission, and depression were associated with failure to recover premorbid function whereas increasing comorbidity and incontinence were associated with mortality. CONCLUSIONS: Medical/surgical patients represent a unique rehabilitation population. They experienced greater premorbid functional disability, less acute decline, but greater mortality than patients with traditional rehabilitation diagnoses. Further study of this distinct rehabilitation population may help identify patients most likely to benefit from rehabilitation.

Development and validation of a clinical prediction rule for prolonged nursing home residence after hip fracture.

OBJECTIVES: To develop and validate a clinical prediction rule for nursing home residence 6 months after a hip fracture. DESIGN: Two prospective cohort studies, a development study (DS) and a validation study (VS). SETTING: The DS included hip fracture patients admitted to 92 rehabilitation units or skilled nursing facilities; the VS included hip fracture patients from 11 integrated healthcare systems. PARTICIPANTS: A total of 344 community-dwelling hip fracture patients aged 65 and older participated in the DS; 239 similar patients were enrolled in the VS. INTERVENTION: None. MEASUREMENTS: The acute hospital record, nursing evaluations, and patient questionnaires provided information about demographics, physical and neuropsychological function, and comorbidity. Residence 6 months after fracture was determined by phone interview. Multivariate analysis identified predictors for a risk score to assess the likelihood of nursing home residence. RESULTS: 18.7% of patients in the DS resided in nursing homes 6 months after hip fracture. The four independent risk factors for institutionalization were (1) being unmarried (OR = 6.7 [95% CI 2.4 to 19]), (2) incontinence (OR = 2.3 [CI 1.2 to 4.7]), (3) dependence in ambulation (OR = 5.0 [CI 2.1 to 12.3]), and (4) cognitive impairment (OR = 6.6 [CI 3.3 to 13.2]). Of patients with all four risk factors, 73.2% were institutionalized at 6 months, compared with 0% of patients with no risk factors. In the VS, 6.1% of patients resided in nursing homes after 6 months, with a range from 50.0% of patients with four risk factors to 0% of those with no risk factors. Areas under receiver-operating characteristic curves for the prediction rule were 0.84 +/- .03 in the DS, and 0.81 +/- .06 in the VS. CONCLUSION: A clinical prediction rule using four easily measurable characteristics can identify individuals at high or low risk of nursing home residence 6 months after hip fracture.

Outcome and utilization differences for older persons with stroke in HMO and fee-for-service systems.

OBJECTIVES: To compare treatment and outcomes for older persons with stroke in Medicare health maintenance organizations (HMOs) and fee-for-service (FFS) systems. DESIGN: Inception cohort stratified by payer and followed for 1 year. SETTING: Six HMOs and five FFS systems with large Medicare populations in the West, Midwest, and Eastern United States. PARTICIPANTS: A total of 429 randomly selected stroke patients receiving rehabilitation in nursing homes or rehabilitation hospitals (RHs) from June 1993 to June 1995. MEASUREMENTS: Improvement in activities of daily living (ADLs) during rehabilitation, and ADL recovery, community residence, and utilization until 12 months after stroke. Outcomes were adjusted for premorbid function, marital status, comorbid illness, posthospital function, cognition, psychological problems, and stroke deficits. RESULTS: At baseline, HMO patients were more likely to be married, and less likely to be blind or have psychiatric diagnoses. HMO patients had shorter hospitalizations (P < .001), were less likely to be admitted to RHs (13% vs 85%, P < .001), and received fewer therapy and physician specialist visits (P < .001) but more home health visits (P < .001). During rehabilitation, FFS patients made greater improvement in ADLs (difference, 0.73 ADLs; 95% CI, .37-1.09). At 1 year, there was no difference in ADL recovery (difference, -0.24 ADL; 95% CI, -0.64-0.16), but FFS patients were more likely to reside in the community (adjusted OR, 1.8; 95% CI, 1.1-3.1), and HMO patients were more likely to reside in nursing homes (adjusted OR, 2.4; 95% CI, 1.1-5.5). CONCLUSION: Study findings suggest that short-term functional outcomes and eventual community residence rates are poorer for Medicare HMO patients with stroke than for stroke patients receiving FFS care, consistent with the lower intensity of rehabilitation (in nursing homes vs RHs) and less specialty physician care.

Stereotypy and hyperactivity in rats receiving ethanol and a monoamine oxidase inhibitor.

The combined administration of tranylcypromine (TCP) and ethanol to rats produced both a marked increase in general locomotion such as walking and running and the appearance of repetitive stereotyped head and trunk weaving, forepaw padding, and circling movements. Pretreatment with p-chlorophenylalanine (pCPA) abolished the stereotyped behaviors. In contrast, animals pretreated with alpha-methyl-p-tyrosine (AMPT) were virtually indistinguishable from those receiving only TCP + ethanol, except for a decrease in running behaviors. The above results are consistent with a serotonergic mediation of these specific stereotypes. The mechanisms by which TCP + ethanol might produce these effects are discussed.

Cost-effectiveness implications based on a comparison of nursing home and home health case mix.

Case-mix differences between 653 home health care patients and 650 nursing home patients, and between 455 Medicare home health patients and 447 Medicare nursing home patients were assessed using random samples selected from 20 home health agencies and 46 nursing homes in 12 states in 1982 and 1983. Home health patients were younger, had shorter lengths of stay, and were less functionally disabled than nursing home patients. Traditional long-term care problems requiring personal care were more common among nursing home patients, whereas problems requiring skilled nursing services were more prevalent among home health patients. Considering Medicare patients only, nursing home patients were much more likely to be dependent in activities of daily living (ADLs) than home health patients. Medicare nursing home and home health patients were relatively similar in terms of long-term care problems, and differences in medical problems were less pronounced than between all nursing home and all home health patients. From the standpoint of cost-effectiveness, it would appear that home health care might provide a substitute for acute care hospital use at the end of a hospital stay, and appears to be a more viable option in the care of patients who are not severely disabled and do not have profound functional problems. The Medicare skilled nursing facility, however, is likely to continue to have a crucial role in posthospital care as the treatment modality of choice for individuals who require both highly skilled care and functional assistance.

Quality of long-term care in nursing homes and swing-bed hospitals.

By 1989, more than 1,100 hospitals in rural communities throughout the United States were using hospital beds as swing beds to provide both long-term and acute care. In this study, the quality of long-term care in swing-bed hospitals was compared with the quality of nursing home care, using patient outcomes along with both process and structural measures of quality. Several methodological and conceptual points on measuring and analyzing the quality of long-term care are discussed in this article. Data were analyzed on approximately 2,000 patients in four different primary data samples, three of which were longitudinal involving multiple follow-up points. An analysis of changes in patient status over time, hospitalization rates, rates of discharge to independent living, services provided, and certain structural indicators showed that (1) relative to nursing home care, swing-bed care is more effective in enhancing functional outcomes and discharge to independent living and in reducing hospitalization for long-term care patients, and (2) nursing home care appears more desirable than swing-bed care for long-stay, chronic care patients with no rehabilitation potential. Swing-bed hospitals have gravitated largely to admitting postacute long-term care patients. They do not typically compete directly with community nursing homes for chronic care patients. The greater effectiveness of swing-bed care for patients with near-acute long-term care needs suggests that this approach should be considered in urban communities and that we should scrutinize our current tendency to place in traditional nursing homes many patients who have at least some rehabilitation potential.

Rehabilitation costs: implications for prospective payment.

OBJECTIVE: To obtain information relevant to development of prospective payment for Medicare rehabilitation facilities (RFs) and skilled nursing facilities (SNFs): compares service utilization, length of stay (LOS), case mix, and resource consumption for Medicare patients receiving postacute institutional rehabilitation care. DATA SOURCES/STUDY SETTING: Longitudinal patient-level and related facility-level data on Medicare hip fracture (n = 513) and stroke (n = 483) patients admitted in 1991-1994 to a sample of 27 RFs and 65 SNFs in urban areas in 17 states. STUDY DESIGN: For each condition, two-group RF-SNF comparisons were made. Regression analysis was used to adjust RF-SNF differences in resource consumption per stay for patient condition (case mix) and other factors, since random assignment was not possible. DATA COLLECTION/EXTRACTION METHODS: Providers at each facility were trained to collect patient case-mix and service utilization information. Secondary data also were obtained. PRINCIPAL FINDINGS: RF patients had shorter LOS, fewer total nursing hours (but more skilled nursing hours), and more ancillary hours than SNF patients. After adjustment, ancillary resource consumption per stay remained substantially higher for RF than SNF patients, particularly for stroke. The adjusted nursing resource consumption differences were smaller than the ancillary differences and not statistically significant for hip fracture. Supplemental outcome findings suggested minimal differences for hip fracture patients but better outcomes for RF than SNF stroke patients. CONCLUSIONS: Much can be gained from an integrated approach to developing prospective payment for RFs and SNFs. In that context, consideration of condition-specific per-stay payment methods applicable to both settings appears warranted.

Quality of care in teaching nursing homes: findings and implications.

This article explores policy implications and selected methodological topics relating to long-term care (LTC) quality. We first discuss the Teaching Nursing Home Program (TNHP), in which quality of care in teaching nursing homes (TNHs) was found to be superior to the quality of care in comparison nursing homes (CNHs). A combination of outcome and process/structural measures was used to evaluate the effects of care and underlying reasons for superior TNH outcomes. Second, we explore policy and analytic ramifications. Conceptual, methodological, and applied issues in measuring and improving the quality of LTC are discussed in the context of TNH research and related research in home care.

Measuring and assuring the quality of home health care.

The growth in home health care in the United States since 1970, and the exponential increase in the provision of Medicare-covered home health services over the past 5 years, underscores the critical need to assess the effectiveness of home health care in our society. This article presents conceptual and applied topics and approaches involved in assessing effectiveness through measuring the outcomes of home health care. Definitions are provided for a number of terms that relate to quality of care, outcome measures, risk adjustment, and quality assurance (QA) in home health care. The goal is to provide an overview of a potential systemwide approach to outcome-based QA that has its basis in a partnership between the home health industry and payers or regulators.

The physician and resource allocation.

Even though there is substantial pressure on physicians to significantly reduce the amount of public monies spent on geriatric health care, it is improper for physicians to let financial concerns take precedence over their obligations to care for the patients who seek their services and assistance. The doctor/patient relationship demands that the physician be faithful to the cause of meeting the needs of patients. This faith is kept by taking all necessary steps to respect and promote the autonomy of patients. This is best done by adhering to a commitment of pursuing a process of communication with patients that leads to the attainment of informed consent or refusal from patients. Two consequences likely to follow are protection of many patients from protracted, miserable deaths because of less use of invasive medical procedures, and subsequent financial savings from this lower degree of use.

Stroke rehabilitation in nursing homes: how do we measure quality?

Over one-third of Medicare stroke patients are admitted to nursing homes for rehabilitation. Patients with stroke who are admitted to nursing homes are extremely heterogeneous, including both those with minimal physical and cognitive impairment and those who are totally physically dependent. Quality measures that are appropriate for evaluating stroke care in nursing homes include outcome measures, particularly those that are patient-centered, such as self-reported functional recovery and return to the community; process measures involving essential services such as screening for depression and pain; and structural measures such as the availability of a psychologist or presence of an interdisciplinary team. In measuring quality, nursing home professionals must allow sufficient time for outcomes to unfold, such as 3 to 6 months, rather than measuring outcome at discharge from a setting. Nursing home professionals must also take into consideration patient heterogeneity in terms of risk factors for outcomes of interest.

Nursing home case-mix differences between Medicare and non-Medicare and between hospital-based and freestanding patients.

Case-mix differences between Medicare and non-Medicare nursing home patients and between hospital-based and freestanding nursing home patients were assessed for a sample of 756 patients from 26 nursing homes in six states in 1983. Significant differences were found between Medicare and non-Medicare patients and between hospital-based and freestanding nursing home patients. Thus, two attributes, the percentage of Medicare patient days and whether a nursing home is hospital-based or freestanding, probably should be taken into consideration as facility-level case-mix indicators in determining Medicare reimbursement until a more refined approach to case-mix reimbursement can be developed. Hospital-based/freestanding case-mix differences also suggest that Medicaid reimbursement should recognize potential differences in cost structure between these two types of facilities.

Stroke Rehabilitation in Nursing Homes.

Increasing numbers of stroke patients with profound functional, psychological, and cognitive impairments are receiving rehabilitation in Medicare skilled nursing facilities. These facilities vary substantially in the patients they admit, the volume and intensity of therapy they provide, and the outcomes they achieve. Facilities with an orientation toward rehabilitation and community discharge providing more intensive therapy services by a wider range of skilled professionals have better outcomes.