Bart J. Harvey

A Severe Outbreak of Escherichia coli O157:H7–Associated Hemorrhagic Colitis in a Nursing Home

In September 1985, an outbreak of Escherichia coli O157:H7 enteritis affected 55 of 169 residents and 18 of 137 staff members at a nursing home. The outbreak was characterized by two phases: a primary wave whose source was probably a contaminated sandwich meal and a secondary wave compatible with person-to-person transmission of infection. Among the elderly residents, the incubation period was 4 to 9 days (mean, 5.7 +/- 1.2). Older age and previous gastrectomy increased the risk of acquiring the infection (P = 0.01 and 0.03, respectively). Antibiotic therapy during exposure was associated with acquiring a secondary infection (P = 0.001). Hemolytic uremic syndrome developed in 12 affected residents (22 percent), 11 of whom died. Overall, 19 (35 percent) of the affected residents died, 17 (31 percent) from causes attributable to their infection. Antibiotic therapy after the onset of symptoms was associated with a higher case fatality rate in the more severe cases, possibly because patients with more severe disease tended to be treated with antibiotics. There were no complications or deaths among the affected members of the staff. Evidence of infection by verotoxin-producing E. coli O157:H7 was detected in 30 of 70 cases on the basis of isolation of this organism or demonstration of free verotoxin in stools. All isolates belonged to the same phage type. The high morbidity and mortality associated with this condition emphasize the need for proper food hygiene, rapid identification of outbreaks of disease, and prompt institution of infection-control techniques among the institutionalized elderly.

Determining the need for hip and knee arthroplasty: the role of clinical severity and patients' preferences.

Background.Area variation in the use of surgical interventions such as arthroplasty is viewed as concerning and inappropriate. Objectives.To determine whether area arthroplasty rates reflect patient-related demand factors, we estimated the need for and the willingness to undergo arthroplasty in a high- and a low-use area of Ontario, Canada. Research Design. Population-based mail and telephone survey. Subjects.All adults aged ≥55 years in a high (n = 21,925) and low (n = 26,293) arthroplasty use area. Measures.We determined arthritis severity and comorbidity with questionnaires, established the presence of arthritis with examination and radiographs, and evaluated willingness to have arthroplasty with interviews. Potential arthroplasty need was defined as severe arthritis, no absolute contraindication for surgery, and evidence of arthritis on examination and radiographs. Estimates of need were then adjusted for patients’ willingness to undergo arthroplasty. Results.Response rates were 72.0% for questionnaires and interviews. The potential need for arthroplasty was 36.3/1,000 respondents in the high-rate area compared with 28.5/1,000 in the low-rate area (P <0.0001). Among individuals with potential need, only 14.9% in the high-rate area and 8.5% in the low-rate area were definitely willing to undergo arthroplasty (P = 0.03), yielding adjusted estimates of need of 5.4/1,000 and 2.4/1,000 in the high- and low-rate areas, respectively. Conclusions.Demonstrable need and willingness were greater in the high-rate area, suggesting these factors explain in part the observed geographic rate variations for this procedure. Among those with severe arthritis, no more than 15% were definitely willing to undergo arthroplasty, emphasizing the importance of considering both patients’ preferences and surgical indications when evaluating need and appropriateness of rates for surgery.

A population-based nested case-control study of the costs of hip and knee replacement surgery.

Background:Studies of total joint arthroplasty (TJA) have not evaluated the costs and outcomes in the context of expected arthritis worsening. Objectives:Using a cost-consequence approach, to examine changes in direct health care costs and arthritis severity after TJA for hip/knee arthritis compared with contemporaneous changes in matched controls. Research Design:Case control study nested in a population-based prospective cohort. Subjects:In a population cohort with disabling hip/knee osteoarthritis followed from 1996 to 2003, primary TJA recipients were matched with cohort nonrecipients on age, sex, region of residence, comorbidity, and inflammatory arthritis diagnosis. Measures:Pre- and postoperative total and arthritis-attributable direct health care costs, arthritis severity, and general health status were compared for cases and matched controls. Results:Of 2109 participants with no prebaseline TJA, 185 cases received a single elective TJA during the follow-up period; of these, 183 cases and controls were successfully matched. Mean age was 71 years, 77.6% were female, 35.5% had ≥2 comorbidities, and 81.5% had ≥2 joints affected. At baseline, controls had less pain and disability and lower total and arthritis-attributable health care costs than cases. After surgery, although overall health care utilization was unchanged, cases experienced significant decreases in arthritis-attributable costs (mean decrease

Effect of an undergraduate medical curriculum on students' self-directed learning.

278 including prescription drugs) and pain and disability (P < 0.0001 for all). Over the same time period, controls experienced a significant increase in total health care costs (mean increase

Measuring data reliability for preventive services in electronic medical records

1978 including prescription drugs, P = 0.04) and no change or worsening of their arthritis status. Conclusion:Compared with matched controls, arthroplasty is associated with significant reductions in pain, disability, and arthritis-attributable direct costs.

DIAG: A computer-assisted dermatologic diagnostic system—clinical experience and insight

Purpose. Lifelong, self-directed learning (SDL) has been identified as an important ability for medical graduates. To evaluate the effect of the University of Toronto Faculty of Medicine’s revised undergraduate medical curriculum on students’ SDL, a cross-sectional study was conducted. Method. A questionnaire package was mailed to 280 randomly selected students, 70 from each of the four years of the curriculum. The package contained the two most widely recognized, extensively used, and validated instruments of SDL (Guglielmino’s 58-item Self-Directed Learning Readiness Scale and Oddi’s 24-item Continuous Learning Inventory) and Ryan’s two-part Self-Assessment Questionnaire. An identification number and sociodemographic questions were included with the questionnaires. Data analysis was completed using chi-square for differences of proportions, analysis of variance for differences between means, and linear regression for trends. Results. A total of 250 (89.3%) complete questionnaire packages were returned. No significant trend in SDL was evident by curriculum year, and similar SDL levels were observed for women and men. However, a significant positive trend in SDL was found with the highest level of premedical education achieved (undergraduate only, masters, or doctoral). Further, students’ perceptions concerning the importance of SDL decreased according to year in the curriculum. Conclusion. This study found no evidence that students’ self-reported SDL is positively influenced by the current undergraduate medical curriculum at the University of Toronto Faculty of Medicine.

Canadian medical students' perceptions of public health education in the undergraduate medical curriculum.

BackgroundImprovements in the quality of health care services are often measured using data present in medical records. Electronic Medical Records (EMRs) contain potentially valuable new sources of health data. However, data quality in EMRs may not be optimal and should be assessed. Data reliability (are the same data elements being measured over time?) is a prerequisite for data validity (are the data accurate?). Our objective was to measure the reliability of data for preventive services in primary care EMRs during the transition to EMR.MethodsOur data sources were randomly selected eligible patients’ medical records and data obtained from provincial administrative datasets. Eighteen community-based family physicians in Toronto, Ontario that implemented EMRs starting in 2006 participated in this study. We measured the proportion of patients eligible for a service (Pap smear, screening mammogram or influenza vaccination) that received the service. We compared the change in rates of selected preventive services calculated from the medical record audits with the change in administrative datasets.ResultsIn the first year of EMR use (2006) services decreased by 8.7% more (95% CI −11.0%– − 6.4%, p < 0.0001) when measured through medical record audits as compared with administrative datasets. Services increased by 2.4% more (95% CI 0%–4.9%, p = 0.05) in the medical record audits during the second year of EMR use (2007).ConclusionThere were differences between the change measured through medical record audits and administrative datasets. Problems could include difficulties with organizing new data entry processes as well as continued use of both paper and EMRs. Data extracted from EMRs had limited reliability during the initial phase of EMR implementation. Unreliable data interferes with the ability to measure and improve health care quality

Hypothesis Testing, Study Power, and Sample Size

Over the past few decades, the computer has been utilized in various ways to assist physicians in formulating their differential diagnoses, usually on an experimental basis. Following a review of the three major technics employed in computer-assisted diagnosis, statistical pattern classification, production rules, and cognitive models, a new system (DIAG) is described. The sole function of DIAG is to assist in the formulation of the differential diagnosis of skin diseases. At the beginning of the fourth year of development, the accuracy of the program in reaching diagnoses has been shown, on many occasions, to be comparable to its expert counterparts. However, it has been demonstrated that the system is not utilized within the dermatology clinic routinely. In response to this, aspects of DIAG have been modified in order to improve its clinical acceptability. Until this acceptance is achieved, these tools will not fulfill their potential to affect patient care.

Predictors of competing mortality to invasive breast cancer incidence in the Canadian National Breast Screening study

Purpose To understand the perceptions and attitudes of Canadian medical students toward their undergraduate medical public health curriculum and to identify student suggestions and priorities for curriculum change. Method Five focus groups of 11 or 12 medical students from all years of medical school were recruited at McMaster University Faculty of Health Sciences, Université de Sherbrooke Faculty of Medicine and Health Sciences, University of Toronto Faculty of Medicine, University of Manitoba Faculty of Medicine, and University of British Columbia Faculty of Medicine between February and April 2006. A professional facilitator was hired to conduct the focus groups using a unique, computer-based facilitation system. Questions in both the focus group and an accompanying survey sought to determine medical students’ understanding and exposure to public health and how this impacted their attitudes and choices toward careers in the public health medical specialty of community medicine. The transcripts were independently reviewed and analyzed by each of the authors to identify themes. Results Four major themes related to students’ desired curriculum change were identified: (1) poor educational experiences in public health courses, (2) lack of positive role models, especially exposure to community medicine specialists, (3) emphasis on statistics and epidemiology, and (4) negative attitudes toward public health topics. Conclusions Students are disillusioned, disengaged, and disappointed with the public health curriculum currently being provided at the Canadian medical schools studied. Many medical students would prefer a public health curriculum that is more challenging and has more applied field experience and exposure to public health physician role models.

Preventing texting while driving: a statement of the American College of Preventive Medicine.

T earlier articles in this Medical Writing Tips series presented several guidelines for reporting important statistical information in scientifi c articles, including hypothesis testing. 1 , 2 In this article, we briefl y review hypothesis testing to set the stage for discussing two additional statistical procedures used for planning and interpreting scientifi c studies: estimating sample size and calculating study power.