["The Talpiot medical leadership program"--advancing the brightest young physicians and researchers to fill future leadership roles].

BACKGROUND: The modern medical world is dynamic and boundless. There is a need for the medical training system currently existing in Israel to undergo a thorough conceptual change in order to strive for excellence and innovation on the one hand and to prevent the "brain drain" from Israel on the other. OBJECTIVE: To report on the "Talpiot" program at the "Sheba Medical Center", which identifies, promotes and prepares the most talented young doctors to fill key positions in the fields of medicine and health in Israel. METHODS: This study is based on a project with the same name in the Israeli Defense Forces (IDF). It promotes an elite group of physicians and researchers at the medical center and includes the provision of scholarships, personal guidance and customized educational opportunities for its members. Conversely, every member in the program is committed to complete five years of training followed by another five years as a senior physician or a researcher at the medical center. RESULTS: Since 2002, there have been six cycles of "Talpionaires". The current 46 members of the program fill key leadership roles in the medical center and are considered leaders in their field. Among the program's alumni are managers of institutes, units and research institutes. This group is responsible for the publication of hundreds of scientific papers studies and dozens of patents in medical technology. Some of them have progressed academically far beyond their peers. CONCLUSIONS: Excellence programs are an integral part of any institution which considers itself a leader, both in medicine and beyond. The exciting and visionary "Talpiot" program is Sheba's contribution to the quality of the medical system in the country of Israel in the long run. Promoting young doctors and researchers to become leaders in the Israeli medical system is an integral part of national interests.

Responses to balance challenges in persons with panic disorder: A pilot study of computerized static and dynamic balance measurements.

INTRODUCTION: Several studies have shown an association between panic disorder (PD) and reduced balance abilities, mainly based on functional balance scales. This pilot study aims to demonstrate the feasibility of studying balance abilities of persons with PD (PwPD) using computerized static and, for the first time, dynamic balance measurements in order to characterize balance control strategies employed by PwPD. METHODS: Twelve PwPD and 11 healthy controls were recruited. PD diagnosis was confirmed using the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV), and the severity of symptoms was evaluated using the Hamilton Anxiety Scale (HAM-A), PD Severity Scales (PDSS), and Panic and Agoraphobia Scale (PAS). Balance was clinically assessed using the Activities-Specific Balance Confidence (ABC) scale and physically by the Mini-Balance Evaluation Systems Test (Mini-BESTest). Dizziness was evaluated using the Dizziness Handicap Inventory (DHI) scale. Postural control was evaluated statically by measuring body sway and dynamically by measuring body responses to rapid unexpected physical perturbations. RESULTS: PwPD had higher scores on the HAM-A (17.6 ± 10.3 vs. 3.0 ± 2.9; p < .001), PDSS (11.3 ± 5.1 vs. 0; p < .001), and PAS (20.3 ± 8.7 vs. 0; p < .001) questionnaires and lower scores on the balance scales compared to the controls (ABC scale: 156.2 ± 5.9 vs. 160 ± 0.0, p = .016; Mini-BESTest: 29.4 ± 2.1 vs. 31.4 ± 0.9, p = .014; DHI: 5.3 ± 4.4 vs. 0.09 ± 0.3, p < .001). In the static balance tests, PwPD showed a not-significantly smaller ellipse area of center of pressure trajectory (p = .36) and higher body sway velocity (p = .46), whereas in the dynamic balance tests, PwPD had shorter recovery time from physical perturbations in comparison to controls (2.1 ± 1.2s vs. 1.6 ± 0.9 s, p = .018). CONCLUSION: The computerized balance tests results point to an adoption of a ''postural rigidity'' strategy by the PwPD, that is, reduced dynamic adaptations in the face of postural challenges. This may reflect a nonsecure compensatory behavior. Further research is needed to delineate this strategy.

The Efficacy of a Virtual Reality Exposure Therapy Treatment for Fear of Flying: A Retrospective Study.

Background: Fear of flying (FoF) is a phobia with 10-40% prevalence in the industrialized world. FoF is accompanied by severe economic, social, vocational, and emotional consequences. In recent years, virtual reality (VR)-based exposure therapy (VRET) for FoF has been introduced. Positive long-term efficacy of FoF-VRET has been reported by several studies, which, however, were limited by relatively small, non-representative samples and a lack of comparative pre/post functional efficacy outcome measures. Our objective was to evaluate the efficacy of a VRET treatment utilizing a large-scale VR system, experienced by a representative sample of self-referred individuals. Methods: We conducted a retrospective survey. Of 274 individuals who received the treatment (over a period of 3 years), 209 met inclusion/criteria, and 98 agreed to participate. We mainly collected information regarding flight activity before and after treatment relying on evidence such as boarding passes and flight tickets. The primary outcome measures were (1) number of flights per month (FpM) and (2) number of flight hours per month (FHpM). For each participant, these outcomes were computed for the post-treatment period (≥6 months after FoF-VRET) and the corresponding pre-treatment period. Results: FpM (mean ± SD) increased from 0.04 ± 0.06 to 0.16 ± 14 flights (p < 0.0001). FHpM rose from 0.19 ± 0.35 to 0.79 ± 0.87 h per month (p < 0.0001). Conclusion: These results are indicative of FoF-VRET treatment efficacy. Future studies should evaluate long-term maintenance of the treatment effect and thus identify the optimal frequency for delivery of periodic booster treatments.

Early Trauma Predictors of Mobility in People with Spinal Cord Injury.

STUDY DESIGN: A retrospective cohort study. OBJECTIVE: This study aims to assess the potential value of very early trauma variables such as Abbreviated Injury Scale (AIS) and the Injury Severity Score for predicting independent ambulation following a traumatic spinal cord injury (TSCI). SUMMARY OF BACKGROUND DATA: Several models for prediction of ambulation early after TSCI have been published and validated. The vast majority rely on the initial examination of American Spinal Injury Association (ASIA) impairment scale and level of injury; however, in many locations and clinical situations this examination is not feasible early after the injury. METHODS: Patient characteristics, trauma data, and ASIA scores on admission to rehabilitation were collected for each of the 144 individuals in the study. Outcome measure was the indoor mobility item of the Spinal Cord Independence Measure taken upon discharge from rehabilitation. Univariate and multivariable models were created for each predictor, Odds ratios (ORs) were obtained by a multivariable logistic regression analysis, and area under the receiver operator curve was calculated for each model. RESULTS: We observed a significant correlation between the trauma variables and independent ambulation upon discharge from rehabilitation. Of the early variables, the AIS for the spine region showed the strongest correlation. CONCLUSION: These findings support using preliminary trauma variables for early prognostication of ambulation following a TSCI, allowing for tailored individual interventions.Level of Evidence: 3.

Refractive errors and schizophrenia.

BACKGROUND: Refractive errors (myopia, hyperopia and amblyopia), like schizophrenia, have a strong genetic cause, and dopamine has been proposed as a potential mediator in their pathophysiology. The present study explored the association between refractive errors in adolescence and schizophrenia, and the potential familiality of this association. METHODS: The Israeli Draft Board carries a mandatory standardized visual accuracy assessment. 678,674 males consecutively assessed by the Draft Board and found to be psychiatrically healthy at age 17 were followed for psychiatric hospitalization with schizophrenia using the Israeli National Psychiatric Hospitalization Case Registry. Sib-ships were also identified within the cohort. RESULTS: There was a negative association between refractive errors and later hospitalization for schizophrenia. Future male schizophrenia patients were two times less likely to have refractive errors compared with never-hospitalized individuals, controlling for intelligence, years of education and socioeconomic status [adjusted Hazard Ratio=.55; 95% confidence interval .35-.85]. The non-schizophrenic male siblings of schizophrenia patients also had lower prevalence of refractive errors compared to never-hospitalized individuals. CONCLUSIONS: Presence of refractive errors in adolescence is related to lower risk for schizophrenia. The familiality of this association suggests that refractive errors may be associated with the genetic liability to schizophrenia.

Impaired reading comprehension and mathematical abilities in male adolescents with average or above general intellectual abilities are associated with comorbid and future psychopathology.

Research indicates that persons with learning disorders often suffer from psychopathology. We assessed current and future psychopathology in male adolescents with discrete impairments in reading comprehension (IRC) or arithmetic abilities (IAA) but with average or above-average general intellectual abilities. Subjects were a population-based cohort of 174,994 male adolescents screened by the Israeli Draft Board with average or above-average intellectual abilities but with low scores (8.6th and 10th lowest percentile respectively) on reading or arithmetic tests. They were compared with adolescents who scored in the 10th percentile and above on these tests (comparison group). Relative to the comparison group, male adolescents with IRC, IAA, or IRC and IAA (0.69%), had poorer scores on most behavioral assessments and higher prevalence of current psychopathology: 4.2% (comparison group), 8.0% (IRC), 7.0% (IAA), and 9.8% (IRC and IAA). Adolescents with IRC were also at increased risk for later hospitalization for schizophrenia (hazard ratios = 1.8, 95% confidence interval: 1.3-2.6). Male adolescents with average and above-average general intellectual abilities but with IRC or IAA are more likely to have current and future psychopathology. Impairments in intellectual functioning and abnormal behaviors leading to mental illnesses may share common neurobiological substrates. The results support screening male adolescents with learning disorders for psychopathology.

A Nation-Wide Study on the Percentage of Schizophrenia and Bipolar Disorder Patients Who Earn Minimum Wage or Above.

OBJECTIVE: Although it is undisputable that patients with severe mental illness have impaired ability to work, the extent of this is unclear. This is a nation-wide, cross-sectional survey of patients who have been hospitalized with severe mental illness earning minimum wage or above. METHOD: Data from the Israeli Psychiatric Hospitalization Case Registry were linked with nation-wide data from the National Insurance Institute (the equivalent of US Social Security) on personal income. Hospitalization data were obtained on all consecutive admissions to any psychiatric hospital in the country between 1990-2008 with a diagnosis of schizophrenia, other nonaffective psychotic disorders, or bipolar disorder (N = 35 673). Earning minimum wage or more was defined as earning at least 1000 USD/month, which was equivalent to minimum wage in Israel in December 2010. RESULTS: The percentages of patients with only 1 admission who were earning minimum wage or above in December 2010 were as follows: 10.6% of patients with a diagnosis of schizophrenia; 21.6% of patients with a diagnosis of nonaffective psychotic disorders; and 24.2% of patients with bipolar disorder. The percentages of patients with multiple admissions who were earning minimum wage or above were as follows: 5.8% of patients with schizophrenia; 11.2% of patients with nonaffective psychotic disorders; and 19.9% of patients with bipolar disorder. CONCLUSIONS: Despite potential confounders, the results indicate that patients with schizophrenia, nonaffective psychotic disorders, or bipolar disorder have a poor employment outcome, even if they have only been admitted once. These results emphasize the importance of improving interventions to re-integrate these individuals into the work force.

A Novel Treatment of Fear of Flying Using a Large Virtual Reality System.

BACKGROUND: Fear of flying (FoF), a common phobia in the developed world, is usually treated with cognitive behavioral therapy, most efficiently when combined with exposure methods, e.g., virtual reality exposure therapy (VRET). We evaluated FoF treatment using VRET in a large motion-based VR system. The treated subjects were seated on a moving platform. The virtual scenery included the interior of an aircraft and a window view to the outside world accompanied by platform movements simulating, e.g., takeoff, landing, and air turbulence. Relevant auditory stimuli were also incorporated. CASE REPORT: Three male patients with FoF underwent a clinical interview followed by three VRETs in the presence and with the guidance of a therapist. Scores on the Flight Anxiety Situation (FAS) and Flight Anxiety Modality (FAM) questionnaires were obtained on the first and fourth visits. Anxiety levels were assessed using the subjective units of distress (SUDs) scale during the exposure. All three subjects expressed satisfaction regarding the procedure and did not skip or avoid any of its stages. Consistent improvement was seen in the SUDs throughout the VRET session and across sessions, while patients' scores on the FAS and FAM showed inconsistent trends. Two patients participated in actual flights in the months following the treatment, bringing 12 and 16 yr of avoidance to an end. DISCUSSION: This VR-based treatment includes critical elements for exposure of flying experience beyond visual and auditory stimuli. The current case reports suggest VRET sessions may have a meaningful impact on anxiety levels, yet additional research seems warranted.

Comments on risk for schizophrenia.

Recent developments have significantly furthered understanding of genetic and environmental factors affecting risk for schizophrenia. Environmental effects, such as immigration, living in a city, and substance abuse have been found to be associated with later schizophrenia. Although the highest risk for schizophrenia is still having a monozygotic twin with schizophrenia (50%), the candidate genes claimed to be associated to date only yield a very small excess risk and all of these effects (environmental and genetics) increase the risk for schizophrenia by only 2-3 fold. Thus, given the low prevalence of the disorder in the general population (0.5-1%), they are not practical in predicting future illness. One possible strategy to make the currently known risk factors for schizophrenia more useful clinically is based on findings indicating that many of the genetic and environmental risks cited above are not specific for schizophrenia, but increase risk for psychopathology in general. As up to 50% of the general population will be affected during their lifetime by a condition defined in DSM IV as psychopathology, due to this much higher base rate, factors increasing risk by 2-3 fold might become clinically relevant.

Describing the social environment of elderly persons at the time of death.

OBJECTIVES: To describe the social environment of elderly persons at the time of their death and its correlates. DESIGN: Telephone interviews with the next-of-kin of deceased elderly persons. PARTICIPANTS: Potential participants were the next-of-kin of all Jewish elderly individuals who died during the course of one year in a major city in the northern part of Israel. The final sample included 139 participants (58% response rate; 70% cooperation rate). MEASUREMENTS: Information was collected regarding the decedents' social environment three days before their death and at the time of death. Eight types of informal sources of support and four sources of formal support were examined. The correlates examined included the decedents' demographic, health, social, and death characteristics. RESULTS: The majority of the decedents died while surrounded by at least one family member. Having a larger social network was associated with a larger number of persons present at the time of death. Being informed about the impending death was associated with a larger number of persons from the formal and informal networks present at the time of death. CONCLUSIONS: The common fear of dying alone and isolated was not confirmed by this study. Increased efforts should be invested in helping professionals to deal with the difficulties inherent to the process of diagnosing an upcoming death.

Interpreting the association between cannabis use and increased risk for schizophrenia.

Recent longitudinal studies from Sweden, the Netherlands, New Zealand, and Israel report that cannabis use during childhood and adolescence doubles the risk of later appearance of psychosis or schizophrenia. These data have been interpreted as indicating that cannabis has a causal effect along the pathway to psychosis. In this paper, we will offer an alternative explanation of these data. Recent investigations of patients with schizophrenia found increased density of cannabinoid receptors in the dorso-lateral prefrontal cortex and the anterior cingulate cortex. Others reported higher levels of endogenous cannabinoids in the blood and cerebrospinal fluid of patients; these findings were independent of possible cannabis use. Several genetic studies have reported an association between genes encoding the cannabinoid receptor and schizophrenia. Thus, an alternative explanation of the association between cannabis use and schizophrenia might be that pathology of the cannabinoid system in schizophrenia patients is associated with both increased rates of cannabis use and increased risk for schizophrenia, without cannabis being a causal factor for schizophrenia.

The treatment of schizophrenia: from premorbid manifestations to the first episode of psychosis.

To achieve the best therapeutic results in schizophrenia--like most other disorders--primary prevention is preferable to early and prompt treatment, which, in turn, is preferable to treatment of chronically established illness. Unfortunately, there currently exist no accurate markers that can provide information regarding the future course of illness and guide treatment in asymptomatic or mildly symptomatic individuals. Therefore, most treatment efforts are currently focused on patients who have already experienced their first psychotic episode. This paper reviews the efforts to identify accurate markers heralding psychotic illness, as well as treatment considerations in the early phase of the disease.

Clinical characteristics of adolescents later hospitalized for schizophrenia.

Intellectual and behavioral abnormalities, non-psychotic psychiatric disorders, and drug abuse are sometimes present in adolescents who later develop schizophrenia. We followed a population-based cohort of adolescents with baseline assessments of intellectual and behavioral functioning, non-psychotic psychiatric disorders and drug abuse, and ascertained future hospitalization for schizophrenia. Results of the medical and mental health assessments on 16- to 17-year-old male adolescents screened by the Israeli Draft Board, were cross-linked with the National Psychiatric Hospitalization Case Registry, which contains data on all psychiatric hospitalizations in the country. Male adolescents who were later hospitalized for schizophrenia had significantly poorer test scores on all measures in comparison with adolescents not reported to the Psychiatric Registry, the magnitude of the differences was 0.3-0.5 standard deviation (SD). Adolescents (1.03%) of assigned a non-psychotic psychiatric diagnosis, compared to of the adolescents without any psychiatric diagnosis (0.23%), were later hospitalized for schizophrenia. Patients with schizophrenia (26.8%), compared to only 7.4% in the general population of adolescents, had been assigned a non-psychotic psychiatric diagnosis in adolescence (overall OR = 4.5, 95% CI = 3.6-5.6), ranging from OR = 21.5, (<2 >95% CI = 12.6-36.6) for schizophrenia-spectrum personality disorders to OR = 3.6 (<2 >95% CI = 2.1-6.2) for neurosis. The prevalence of self-reported drug abuse was higher in adolescents later hospitalized for schizophrenia (12.4%), compared to the prevalence of drug abuse in adolescents not later hospitalized (5.9%); adjusted RR = 2.033, 95% CI = 1.322-3.126. These results reflect the relatively common finding of impaired intellectual and behavioral functioning, the presence of non-psychotic psychiatric disorders, and drug abuse, in adolescents later hospitalized for schizophrenia, together with the relatively low power of these disorders in predicting schizophrenia.

Body mass index and future schizophrenia in Israeli male adolescents.

BACKGROUND: Compared with the general population, individuals suffering from schizophrenia are more likely to be overweight, a finding attributed to the effect of antipsychotic medications, poor nutrition, and sedentary lifestyle. As evidence accumulates indicating that some aspects of the illness manifest before the onset of psychosis and establishment of the diagnosis, it has been suggested that increased weight, like other metabolic dysfunctions, might precede active illness. METHOD: Data on height and weight of 203,257 male adolescents assessed by the Israeli Draft Board, and followed for 2-6 years for later hospitalization for schizophrenia using the Israeli National Psychiatric Hospitalization Case Registry, were analyzed. RESULTS: From the entire cohort, 309 (0.15%) were later hospitalized for schizophrenia (ICD-10). After removing adolescents with evidence of illness before or within 1 year of the Draft Board assessment, 204 future schizophrenia patients were available for analysis. Compared with the rest of the cohort, future schizophrenia patients had lower body mass indexes (21.24 +/- 3.3 kg/m2 vs. 21.77 +/- 3.5 kg/m2; F = 4.682, df = 1, p = .03) and weighed slightly but significantly less (64.2 +/- 11.6 kg vs. 66.3 +/- 12.0 kg; F = 6.615, df = 1, p = .01). The mean height of the future patients did not differ significantly from the mean height of the remaining cohort (173.63 +/- 6.7 cm vs. 174.40 +/- 6.9 cm; F = 2.520, df = 1, p = .112). When reanalyzing the data, controlling for physical activity and socioeconomic status, the differences between the groups remained significant. CONCLUSION: Before the onset of illness, future schizophrenia patients are not heavier compared with their peers. This implies that the increased weight of patients with schizophrenia is related to illness effects, including the effects of antipsychotic medication.

The role of cardiovascular risk factors in Alzheimer's disease.

The distinction between Alzheimer's disease and vascular dementia, the two most common types of dementia, has been undermined by recent advances in epidemiologic, clinical, imaging, and neuropathological studies. Cardiovascular risk factors, traditionally regarded as distinguishing criteria between the two entities, have been shown to be associated with both AD and vascular dementia. In this article, we propose mechanisms of action of cardiovascular risk factors in AD, suggest possible explanations for the overlap with vascular dementia and discuss the implications this might have on future differential diagnosis, research, and treatment strategies.

Measuring the suffering of end-stage dementia: reliability and validity of the Mini-Suffering State Examination.

Assessment of suffering is extremely important in dying end-stage dementia patients (ESDP). We have developed and examined the reliability and validity of the Mini-Suffering State Examination (MSSE), in 103 consecutive bedridden ESDP. Main outcome measures included inter-observer reliability and concurrent validity. Reliability of the MSSE questionnaire was satisfactory, with Cronbach alpha values of 0.735 and 0.718 for the two physicians (Ph-1, Ph-2), respectively. The kappa agreement coefficient was 0.791. There was a high agreement for seven items (kappa 0.882-0.972) and a substantial agreement for the other three items (kappa 0.621-0.682) of the MSSE. MSSE was validated versus the comfort assessment in dying with dementia (CAD-EOLD) scale and resulted in a significant Pearson correlation (r=-0.796, P<0.001). We conclude that the MSSE scale is a reliable and valid clinical tool, recommended for evaluating the severity of the patient's condition and the level of suffering of ESDP. Use of MSSE may improve medical management and facilitate communication between patients and caregivers.

Is the distinction between Alzheimer's disease and vascular dementia possible and relevant?

Advances in epidemiological, clinical, imaging, and neuropathological studies have undermined the clear distinction between vascular and Alzheimer-type dementia, which has characterized the last two decades of research in dementia. A significant degree of overlap between the two entities was demonstrated in terms of clinical expression, risk factors, and postmortem brain autopsy. In this article, we propose mechanisms by which cardiovascular risk factors might affect the manifestation of Alzheimer's disease, suggest possible explanations for the overlap with vascular dementia, and discuss the implications this might have on future differential diagnosis and treatment strategies.

The "Sheba" model of comprehensive orthogeriatric care for elderly hip fracture patients: a preliminary report.

BACKGROUND: The progressive increase in the number of elderly patients with hip fractures and the particular multidisciplinary needs of this population call for the investigation of other models of orthogeriatric care. OBJECTIVES: To describe the nature and assess the feasibility of a comprehensive orthogeriatric unit attending to patients' surgical, medical and rehabilitation needs in a single setting. METHODS: This retrospective chart review describes consecutive older patients with hip fractures admitted directly from the emergency ward to an orthogeriatric ward. RESULTS: The mean age of the 116 patients evaluated was 82.4 years. Delay to surgery was 3.6 +/- 3.1 days and total length of stay 23.9 +/- 11.0 days. No patient was transferred to other acute medical wards of the hospital and 66.4% were able to return to their previous living place. Rates of major complications and mortality were extremely low. CONCLUSION: The present model of a comprehensive orthogeriatric ward is a practical, applicable and feasible service for elderly hip fracture patients and can cover the various needs of these patients. The deployment arrangements needed to establish and operate the ward were minimal and there were only a few management and organizational problems. The cost-effectiveness and other comparative benefits of this type of service have yet to be clarified.

Further evidence of interrelation between homocysteine and hypertension in stroke patients: a cross-sectional study.

BACKGROUND: A high total plasma homocysteine level is an independent risk factor for cardiovascular and cerebrovascular disease, but the evidence connecting plasma tHcy level with hypertension is inconsistent. OBJECTIVE: To determine the association between plasma tHcy level and some common risk factors for cerebrovascular disease (recurrent stroke, diabetes mellitus, hypertension, ischemic heart disease and hyperlipidemia) in patients presenting with primary or recurrent acute ischemic strokes. METHODS: This retrospective cross-sectional chart analysis was conducted in a university-affiliated referral hospital. During an 18 month period we identified 113 acute ischemic stroke patients (mean age 71.2), 25 of whom had a recurrent stroke. Plasma tHcy level, obtained 2-10 days after stroke onset, was determined by the high performance liquid chromatography method with fluorescence detection. A multivariate logistic regression model was used to determine the independent relationship between each potential risk factor and tHcy level above or below the 75th percentile. RESULTS: Hypertension was more frequent among patients with plasma tHcy level above than below the 75th percentile (51.7% vs. 80.8%, respectively, P = 0.012). After adjusting for demographic and clinical variables, the odds ratio for recurrent stroke and hypertension, with tHcy above or below the 75th percentile, was 3.4 (95% confidence interval 1.01-10.4, P = 0.037) and 4.02 (95% CI 1.2-13.9, P = 0.028), respectively. CONCLUSIONS: A high plasma tHcy level is associated with history of hypertension and recurrent stroke among patients presenting with acute ischemic stroke. These results were independent of other risk factors such as atrial fibrillation, diabetes and hyperlipidemia. Hypertensive stroke patients with hyperhomocysteinemia should be identified as high risk patients as compared to non-hypertensive stroke patients, and more vigorous measures for secondary prevention may be warranted.

Management by constraints: considering patient volume when adding medical staff to the emergency department.

BACKGROUND: The emergency department is one of the hospital's busiest facilities and is frequently described as a bottleneck. Management by constraint is a managerial methodology that helps to focus on the most critical issues by identifying such bottlenecks. Based on this theory, the benefit of adding medical staff may depend on whether or not physician availability is the bottleneck in the system. OBJECTIVE: To formulate a dynamic statistical model to forecast the need for allocating additional medical staff to improve the efficacy of work in the emergency department, taking into account patient volume. METHODS: The daily number of non-trauma admissions to the general ED was assessed for the period 1 January 1992 to 1 December 1995 using the hospital computerized database. The marginal benefit to shortening patient length of stay in the ED by adding a physician during the evening shift was examined for different patient volumes. Data were analyzed with the SAS software package using a Gross Linear Model. RESULTS: The addition of a physician to the ED staff from noon to midnight significantly shortened patient LOS: an average decrease of 6.61 minutes for 80-119 admissions (P < 0.001). However, for less than 80 or more than 120 admissions, adding a physician did not have a significant effect on LOS in the ED. CONCLUSIONS: The dynamic model formulated in this study shows that patient volume determines the effectiveness of investing manpower in the ED. Identifying bottleneck critical factors, as suggested by the theory of constraints, may be useful for planning and coordinating emergency services that operate under stressful and unpredictable conditions. Consideration of patient volume may also provide ED managers with a logical basis for staffing and resource allocation.