Does providing the correct diagnosis as feedback after self-explanation improve medical students diagnostic performance?

BACKGROUND: Self-explanation without feedback has been shown to improve medical students' diagnostic reasoning. While feedback is generally seen as beneficial for learning, available evidence of the value of its combination with self-explanation is conflicting. This study investigated the effect on medical students' diagnostic performance of adding immediate or delayed content-feedback to self-explanation while solving cases. METHODS: Ninety-four 3rd-year students from a Canadian medical school were randomly assigned to three experimental conditions (immediate-feedback, delayed-feedback, control). In the learning phase, all students solved four clinical cases by giving i) the most likely diagnosis, ii) two main arguments supporting this diagnosis, and iii) two plausible alternative diagnoses, while using self-explanation. The immediate-feedback group was given the correct diagnosis after each case; delayed-feedback group received the correct diagnoses only after the four cases; control group received no feedback. One week later, all students solved four near-transfer (i.e., same final diagnosis as the learning cases but different scenarios) and four far-transfer cases (i.e., different final diagnosis from the learning cases and different scenarios) by answering the same three questions. Students' diagnostic accuracy (score for the response to the first question only) and diagnostic performance (combined score of responses to the three questions) scores were assessed in each phase. Four one-way ANOVAs were performed on each of the two scores for near and far-transfer cases. RESULTS: There was a significant effect of experimental condition on diagnostic accuracy on near-transfer cases (p < .05). The immediate-feedback and delayed-feedback groups performed equally well, both better than control (respectively, mean = 90.73, standard deviation =10.69; mean = 89.92, standard deviation = 13.85; mean = 82.03, standard deviation = 17.66). The experimental conditions did not significantly differ on far-transfer cases. CONCLUSIONS: Providing feedback to students in the form of the correct diagnosis after using self-explanation with clinical cases is potentially beneficial to improve their diagnostic accuracy but this effect is limited to similar cases. Further studies should explore how more elaborated feedback combined with self-explanation may impact students' diagnostic performance on different cases.

Challenges of global surveillance during an influenza pandemic.

Surveillance is an essential foundation for monitoring and evaluating any disease process, and is especially critical when new disease agents appear. The H1N1 influenza pandemic of 2009 tested the capacities of countries to detect, assess, notify and report events as required by the 2005 International Health Regulations (IHR). As detailed in the IHR, the World Health Organization drew on official reports from Member States as well as unofficial sources (e.g., media alerts) to quickly report and disseminate information about the appearance of the novel influenza virus. The pre-existing Global Influenza Surveillance Network for virological surveillance also provided crucial information for rapid development of a vaccine and for detection of changes in the virus. However, the pandemic also highlighted a number of shortcomings in global epidemiological surveillance for respiratory disease. These included the lack of standards for reporting illness, risk factor and mortality data, and a mechanism for systematic reporting of epidemiological data. Such measures would have facilitated direct comparison of data between countries and improved timely understanding of the characteristics and impact of the pandemic. This paper describes the surveillance strategies in place before the pandemic and the methods that were used at global level to monitor the pandemic. Enhancements of global surveillance are proposed to improve preparedness and response for similar events in the future.

Pandemic (H1N1) 2009 influenza in the UK: clinical and epidemiological findings from the first few hundred (FF100) cases.

The UK was one of few European countries to document a substantial wave of pandemic (H1N1) 2009 influenza in summer 2009. The First Few Hundred (FF100) project ran from April-June 2009 gathering information on early laboratory-confirmed cases across the UK. In total, 392 confirmed cases were followed up. Children were predominantly affected (median age 15 years, IQR 10-27). Symptoms were mild and similar to seasonal influenza, with the exception of diarrhoea, which was reported by 27%. Eleven per cent of all cases had an underlying medical condition, similar to the general population. The majority (92%) were treated with antiviral drugs with 12% reporting adverse effects, mainly nausea and other gastrointestinal complaints. Duration of illness was significantly shorter when antivirals were given within 48 h of onset (median 5 vs. 9 days, P=0.01). No patients died, although 14 were hospitalized, of whom three required mechanical ventilation. The FF100 identified key clinical and epidemiological characteristics of infection with this novel virus in near real-time.

Tissue-specific activity of the pro-opiomelanocortin gene promoter.

The pro-opiomelanocortin (POMC) gene is specifically expressed in corticotroph cells of the anterior pituitary. To define the POMC promoter sequences responsible for tissue-specific expression, we assessed POMC promoter activity by gene transfer into POMC-expressing pituitary tumor cells (AtT-20) and fibroblast L cells. The rat POMC promoter was only efficiently utilized and correctly transcribed in AtT-20 cells. 5'-End deletion analysis revealed two promoter regions required for activity in AtT-20 cells. When tested by fusion to a heterologous promoter, DNA fragments corresponding to both regions exhibited tissue-specific activity, suggesting the presence of at least two tissue-specific DNA sequence elements within the promoter. In summary, POMC promoter sequences from -480 to -34 base pairs appear sufficient to mimic the specificity of anterior pituitary expression.

Specific protein-protein interaction between basic helix-loop-helix transcription factors and homeoproteins of the Pitx family.

Homeoproteins and basic helix-loop-helix (bHLH) transcription factors are known for their critical role in development and cellular differentiation. The pituitary pro-opiomelanocortin (POMC) gene is a target for factors of both families. Indeed, pituitary-specific transcription of POMC depends on the action of the homeodomain-containing transcription factor Pitx1 and of bHLH heterodimers containing NeuroD1. We now show lineage-restricted expression of NeuroD1 in pituitary corticotroph cells and a direct physical interaction between bHLH heterodimers and Pitx1 that results in transcriptional synergism. The interaction between the bHLH and homeodomains is restricted to ubiquitous (class A) bHLH and to the Pitx subfamily. Since bHLH heterodimers interact with Pitx factors through their ubiquitous moiety, this mechanism may be implicated in other developmental processes involving bHLH factors, such as neurogenesis and myogenesis.

Antagonism between Nur77 and glucocorticoid receptor for control of transcription.

Two important functions of glucocorticoids (Gc), namely, suppression of immune system function and feedback repression of the hypothalamo-pituitary-adrenal (HPA) axis, are mediated through repression of gene transcription. Previous studies have indicated that this repression is exerted in part through antagonism between the glucocorticoid receptors (GR) and the AP-1 family of transcription factors. However, this mechanism could not account for repression of the pro-opiomelanocortin (POMC) gene, an important regulator of the HPA axis. Our recent identification of the orphan nuclear receptor Nur77 as a mediator of CRH induction of POMC transcription led us, in the present work, to show that Gc antagonize this positive signal at two levels. First, Gc partly blunt the CRH induction of Nur77 mRNA, and second, they antagonize Nur77-dependent transcription. GR repression is exerted by antagonism of Nur77 action on the NurRE element of the POMC gene. Gc antagonism of NurRE activity was observed in response to physiological stimuli in both endocrine (CRH induction of POMC) and lymphoid (T-cell receptor activation) cells. In transfection experiments, transcriptional activation by Nur77 and the repressor activity of liganded GR titrated each other on their cognate DNA target. In vitro binding experiments as well as mutation analysis of GR suggest that the mechanism of GR antagonism of Nur77 is very similar to that of the antagonism between GR and AP-1. The convergence of positive signals mediated by Nur77 (and also probably by related family members) and negative signals exerted by GR appears to be a general mechanism for control of transcription, since it is active in both endocrine and lymphoid cells.

Neurophysiological evidence of preserved connectivity in tuber tissue.

We present a case of preserved corticospinal connectivity in a cortical tuber, in a 10 year-old boy with intractable epilepsy and tuberous sclerosis complex (TSC). The patient had multiple subcortical tubers, one of which was located in the right central sulcus. In preparation for epilepsy surgery, motor mapping, by neuronavigated transcranial magnetic stimulation (nTMS) coupled with surface electromyography (EMG) was performed to locate the primary motor cortical areas. The resulting functional motor map revealed expected corticospinal connectivity in the left precentral gyrus. Surprisingly, robust contralateral deltoid and tibialis anterior motor evoked potentials (MEPs) were also elicited with direct stimulation of the cortical tuber in the right central sulcus. MRI with diffusion tensor imaging (DTI) tractography confirmed corticospinal fibers originating in the tuber. As there are no current reports of preserved connectivity between a cortical tuber and the corticospinal tract, this case serves to highlight the functional interdigitation of tuber and eloquent cortex. Our case also illustrates the widening spectrum of neuropathological abnormality in TSC that is becoming apparent with modern MRI methodology. Finally, our finding underscores the need for further study of preserved function in tuber tissue during presurgical workup in patients with TSC.

Structure of the rat pro-opiomelanocortin (POMC) gene.

The gene encoding pro-opiomelanocortin (POMC) presents unique regulatory features. In particular, glucocorticoids inhibit transcription of the POMC gene in the anterior pituitary, but not in the intermediate pituitary. In order to study the mechanism leading to transcriptional inhibition of POMC by glucocorticoid and the interaction of the glucocorticoid receptor complex with specific DNA sequences along the POMC gene, we have cloned the rat POMC gene and determined its structure. The gene is composed of three exons and appears to be present at a single copy per haploid genome. Besides the usual regulatory signals like 'TATA' and 'CCAAT' boxes, the upstream region contains sequences homologous to known enhancer sequences and to the glucocorticoid receptor binding site observed in glucocorticoid-responsive genes.

Impact of the 1987 revision of the case definition of acquired immune deficiency syndrome in the United States.

To measure the impact of the 1987 expansion of the definition of acquired immune deficiency syndrome on the number and characteristics of cases in the United States, we reviewed the 28,920 cases diagnosed since the revision and reported through 1988. The proportion meeting only new criteria was 28% overall, with a range of 0 to 82% in different states and territories. This proportion was 26% in the last quarter of 1987 and increased to 31% in the last quarter of 1988. It was higher in heterosexual intravenous drug abusers (IVDAs) (43%) and lower in homosexual male non-IVDAs (21%) than in other groups. The new criteria, but not earlier (pre-1985) criteria, generally require a positive test for human immunodeficiency virus (HIV) infection; however, use of HIV testing varies among states, as demonstrated by differences in the percentage of pre-1985-criteria cases with a reported HIV test (39 to greater than 95%). The revision has changed the distribution of characteristics of cases (e.g., heterosexual IVDAs composed 18% of cases meeting old criteria, 35% of cases meeting only new criteria, and 23% of all cases). Interpretation of trends in both the number and characteristics of cases should take into account the variable impact of the revision on reporting.

Surveillance for bloodborne infections.

At the close of the 20th century, the blood supply in the U.S. is among the safest in the world. Multifaceted and overlapping strategies that include comprehensive donor history-taking and screening (soon to include nucleic acid testing for HCV and HIV), and viral inactivation of plasma derivatives have resulted in significant declines in transfusion-transmitted infections. Nonetheless, we and our blood supply remain vulnerable to new or re-emerging infections as a consequence of changes in human behavior and demographics, improvements in technology and industry, economic development and land use, and microbial change. The second phase of CDC's strategic plan to improve our national capacity against emerging infectious diseases targets diseases transmitted through blood and blood products as one of its nine special focus areas. One of our mainstays against emerging threats must include surveillance, integrated with a multi-disciplinary approach that includes epidemiology and laboratory sciences. Enhanced surveillance can play an important role in helping to ensure the continued safety of blood and plasma products.

The nature and frequency of blood contacts among home healthcare workers.

OBJECTIVE: To estimate the frequency of, and assess risk factors for, percutaneous, mucous membrane, and cutaneous blood contacts sustained by healthcare workers (HCWs) during the delivery of infusion therapy and the performance of procedures involving sharp instruments in the home setting. DESIGN: Prospective surveillance of percutaneous, mucous membrane, and cutaneous blood contacts. SETTING: Eleven home healthcare agencies in the United States and Canada from August 1996 through June 1997. PARTICIPANTS: HCWs who provided home infusion therapy or performed procedures using hollow-bore needles and other sharp instruments in the home setting. METHODS: Each participating worker recorded information about the procedures performed and blood contacts experienced during each of his or her home visits for a 2- to 4-week period using standard questionnaires. HCWs also completed questionnaires regarding job duties, reporting of previous occupational blood contacts, and their use of protective barriers in the home setting. RESULTS: Participating HCWs provided information about 33,606 home visits. A total of 19,164 procedures were performed during 14,744 procedure visits. Fifty-three blood contacts occurred during these visits, for a blood-contact rate of 2.8 blood contacts per 1,000 procedures and 0.6 percutaneous injuries per 1,000 procedures with needles or lancets. Gloves were worn for 52%, masks for 5%, gowns for 3%, and protective glasses or goggles for 2% of all procedure visits. HCWs used barriers for 53% of visits during which at least 1 procedure was performed and for 27% of other visits. CONCLUSIONS: HCWs involved in home health care are at risk for blood contact. Infection control barrier use was low in our study. The majority of skin contacts could have been prevented by glove use.

Skin and mucous membrane contacts with blood during surgical procedures: risk and prevention.

OBJECTIVE: To study the epidemiology and preventability of blood contact with skin and mucous membranes during surgical procedures. DESIGN: Observers present at 1,382 surgical procedures recorded information about the procedure, the personnel present, and the contacts that occurred. SETTING: Four US teaching hospitals during 1990. PARTICIPANTS: Operating room personnel in five surgical specialties. MAIN OUTCOME MEASURES: Numbers and circumstances of contact between the patient's blood (or other infective fluids) and surgical personnel's mucous membranes (mucous membrane contacts) or skin (skin contacts, excluding percutaneous injuries). RESULTS: A total of 1,069 skin (including 620 hand, 258 body, and 172 face) and 32 mucous membrane (all affecting eyes) contacts were observed. Surgeons sustained most contacts (19% had > or = 1 skin contact and 0.5% had > or = 1 mucous membrane-eye contact). Hand contacts were 72% lower among surgeons who double gloved, and face contacts were prevented reliably by face shields. Mucous membrane-eye contacts were significantly less frequent in surgeons wearing eyeglasses and were absent in surgeons wearing goggles or face shields. Among surgeons, risk factors for skin contact depended on the area of contact: hand contacts were associated most closely with procedure duration (adjusted odds ratio [OR], 9.4; > or = 4 versus < 1 hour); body contacts (arms, legs, and torso) with estimated blood losses (adjusted OR, 8.4; > or = 1,000 versus < 100 mL); and face contacts, with orthopedic service (adjusted OR, 7.5 compared with general surgery). CONCLUSION: Skin and mucous membrane contacts are preventable by appropriate barrier precautions, yet occur commonly during surgery. Surgeons who perform procedures similar to those included in this study should strongly consider double gloving, changing gloves routinely during surgery, or both.

Emerging issues in blood safety.

Improvements in donor selection, testing of donors for markers of infection, and viral inactivation of plasma-derived products have helped reduce the risk of transfusion-associated infections, including hepatitis B (HBV), hepatitis C (HCV), and human immunodeficiency viruses (HIV). The potential for transmission of emerging infections is illustrated by current concerns about group O strains of HIV, nonenveloped viruses, newly discovered microbial agents, prions, Chagas' disease, tick-borne infections, and the need to assess the frequency of transfusion reactions associated with bacterial contamination.

Occupational risk of infection with human immunodeficiency virus.

The risk of HIV infection in surgical settings is a composite of overlapping risks related to the local prevalence of HIV, the route of exposure to HIV-infected blood, and the susceptibility of the worker. Studies continue to suggest that the risk of blood contact, including percutaneous injuries, remains appreciable. Prevention of such exposures in the operating and delivery room by adoption of safer instruments, work practices, and techniques and by the consistent use of appropriate personnel protective equipment must be viewed as a priority.

Preventing bloodborne pathogen transmission from health-care workers to patients. The CDC perspective.

The development of recommendations to manage the risk of bloodborne pathogen transmission from health-care workers to patients during invasive procedures has been difficult, primarily because of the limitations of available scientific data. Ultimately, both health-care workers and patients will be protected best by compliance with infection control precautions and by development of new instruments, protective equipment, and techniques that reduce the likelihood of intraoperative blood exposure without adversely affecting patient care.

Use of the hepatitis-B vaccine and infection with hepatitis B and C among orthopaedic surgeons. The American Academy of Orthopaedic Surgeons Serosurvey Study Committee.

We used a questionnaire, with a guarantee of anonymity to the respondents, and conducted serological testing of 3411 attendees at the 1991 Annual Meeting of The American Academy of Orthopaedic Surgeons to evaluate the prevalences of infection with the hepatitis-B and C viruses and the use of the hepatitis-B vaccine among orthopaedic surgeons. There was evidence of infection with hepatitis B in 410 (13 per cent) of 3239 participants who had reported having no non-occupational risk factors; 2103 (65 per cent) reported that they had been immunized with the hepatitis-B vaccine. Of 3262 participants who reported having no non-occupational risk factors and who were evaluated for infection with hepatitis C, twenty-seven (less than 1 per cent) tested positive for the antibody to the hepatitis-C virus. The prevalence of previous infection with hepatitis B increased with increasing age; four (3 per cent) of 136 surgeons who were twenty to twenty-nine years old had evidence of infection, whereas ninety-six (27 per cent) of 360 surgeons who were sixty years old or more had evidence of infection. The prevalence of infection with hepatitis C also increased with increasing age; none of 135 surgeons who were twenty to twenty-nine years old had evidence of infection, and five (1 per cent) of 360 surgeons who were sixty years old or more had evidence of the virus. The prevalence of vaccination decreased steadily with age: 123 (90 per cent) of 136 surgeons who were twenty to twenty-nine years old reported that they had received the hepatitis-B vaccine, whereas 127 (35 per cent) of 360 surgeons who were sixty years old or more reported that they had received the vaccine. The prevalence of infection with hepatitis B or hepatitis C was not associated with the measured indices of exposure to the blood of patients (the number of cutaneous or mucosal contacts with blood that had occurred within the previous month or the number of percutaneous injuries that had occurred within the previous month or year, as recalled by the participants). In conclusion, the prevalence of immunization with the hepatitis-B vaccine was high among the orthopaedic surgeons studied. Although the prevalence of infection with the hepatitis-C virus was several times greater in the current investigation than has been reported in studies of blood donors in the United States, infection with this virus was not associated with the indices of occupational exposure to blood measured in this study.

Methods of surveillance for HIV infection in primary care outpatients in the United States.

Primary care outpatients provide a good sentinel population for monitoring levels and trends of HIV infection in the United States. Because a broad cross section of the population seeks primary medical care, excess blood from specimens routinely collected for other purposes is available for anonymous, unlinked HIV testing, and all age groups and both sexes can be sampled. The CDC family of surveys includes two surveys of primary care outpatients: (a) a survey of 100,000 blood specimens per year submitted by more than 6,000 primary care physicians to a national diagnostic laboratory for complete blood count or hematocrit and (b) a survey of approximately 10,000 blood specimens per year from a network of 242 primary care physicians. Each survey has different advantages: the laboratory-based survey has a large sample from a large population base, and the physician network survey has a well-defined patient population in which each patient's clinical condition can be determined. In the primary care physician network, a concurrent study of clinical patterns of disease in patients with recognized HIV infection provides additional information on the clinical syndromes associated with HIV infection and estimates of the occurrence of unrecognized HIV infection.

Percutaneous injuries in dentistry: an observational study.

The authors conducted an observational study of the frequency and circumstances of percutaneous injuries among dental residents. Their findings suggest that most percutaneous injuries sustained by these dental residents occurred extraorally and were associated with denture impression procedures. Some injuries may be preventable with changes in techniques or instrument design.

The RADAR repository: a resource for studies of infectious agents and their transmissibility by transfusion.

BACKGROUND: An ongoing issue in transfusion medicine is whether newly identified or emerging pathogens can be transmitted by transfusion. One method to study this question is through the use of a contemporary linked donor-recipient repository. STUDY DESIGN AND METHODS: The Retrovirus Epidemiology Donor Study Allogeneic Donor and Recipient (RADAR) repository was established between 2000 and 2003 by seven blood centers and eight collaborating hospitals. Specimens from consented donors were collected, components from their donations were routed to participating hospitals, and recipients of these units gave enrollment and follow-up specimens for long-term storage. The repository was designed to show that zero transmissions to enrolled recipients would indicate with 95 percent confidence that the transfusion transmission rate of an agent with prevalence of 0.05 to 1 percent was lower than 25 percent. RESULTS: The repository contains pre- and posttransfusion specimens from 3,575 cardiac, vascular, and orthopedic surgery patients, linked to 13,201 donation specimens. The mean number of RADAR donation exposures per recipient is 3.85. The distribution of components transfused is 77 percent red cells, 13 percent whole blood-derived platelet concentrates, and 10 percent fresh frozen plasma. A supplementary unlinked donation repository containing 99,906 specimens from 84,339 donors was also established and can be used to evaluate the prevalence of an agent and validate assay(s) performance before accessing the donor-recipient-linked repository. Recipient testing conducted during the establishment of RADAR revealed no transmissions of human immunodeficiency virus, hepatitis C virus, or human T-lymphotropic virus. CONCLUSIONS: RADAR is a contemporary donor-recipient repository that can be accessed to study the transfusion transmissibility of emerging agents.