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1.  A Comprehensive Assessment of Health Care Utilization among Homeless Adults under a System of Universal Health Insurance 
American journal of public health  2013;103(0 2):S294-S301.
To comprehensively assess health care utilization in a population-based sample of homeless adults compared to matched controls under a system of universal health insurance.
Health care utilization was assessed for 1,165 homeless single adult men, single adult women, and adults in families and their age- and sex-matched low-income controls in Toronto, Canada from 2005-2009. Repeated measures general linear models (GLM) were used to calculate risk ratios and 95% confidence intervals.
Homeless participants had mean rates of 9.1 ambulatory care encounters (maximum=141.1), 2.0 emergency department encounters (maximum=104.9), 0.2 medical/surgical hospitalizations (maximum=14.9), and 0.1 psychiatric hospitalizations per person-year (maximum=4.8). Rate ratios comparing homeless participants to matched controls were 1.76 (95% CI: 1.58-1.96) for ambulatory care encounters, 8.48 (95% CI: 6.72-10.70) for emergency department encounters, 4.22 (95% CI: 2.99-5.94) for medical/surgical hospitalizations, and 9.27 (95% CI: 4.42-19.43) for psychiatric hospitalizations.
Within a system of universal health insurance, homeless people have substantially higher rates of emergency department and hospital use compared to general population controls. These differences are largely driven by the subset of homeless persons who are extremely high-intensity users of health services.
PMCID: PMC3969141  PMID: 24148051
Health care utilization; Homeless persons; Matched controls; Ambulatory care; Hospitalization
2.  Predictors of Medical/surgical and Psychiatric Hospitalizations among a Population-based Cohort of Homeless Adults 
American journal of public health  2013;103(0 2):S380-S388.
To identify factors associated with inpatient hospitalizations among a population-based cohort of homeless adults in Toronto, Canada.
Participants were linked to administrative databases to capture hospital admissions during the study period (2005–2009). Logistic regression was used to identify predictors of medical/surgical and psychiatric hospitalizations.
Among 1,165 homeless adults, 20% had a medical/surgical hospitalization and 12% had a psychiatric hospitalization during the study period. These individuals contributed a total of 921 hospitalizations, of which 548 were medical/surgical and 373 were psychiatric. Independent predictors of medical/surgical hospitalization included birth in Canada, having a primary care provider, higher perceived external health locus of control, and lower health status. Independent predictors of psychiatric hospitalization included being a current smoker, having a recent mental health problem, and having a lower perceived internal health locus of control. Being accompanied by a partner or dependent children was protective for hospitalization.
Health care need was a strong predictor of medical/surgical and psychiatric hospitalizations. Some hospitalizations among homeless adults are potentially avoidable, while others represent an unavoidable use of health services.
PMCID: PMC3969145  PMID: 24148040
Hospitalization; Homeless persons; Health care utilization
3.  High Utilizers of Emergency Health Services in a Population-based Cohort of Homeless Adults 
American journal of public health  2013;103(0 2):S302-S310.
To identify predictors of emergency department (ED) use among a population-based prospective cohort of homeless adults in Toronto, Canada.
ED visit rates were assessed using administrative data (2005-2009). Logistic regression was used to identify predictors of ED use. Frequent users were defined as participants with rates in the top decile (≥4.7 visits per person-year).
Among 1,165 homeless adults, 892 (77%) had at least one ED visit during the study period. The average rate of ED visits was 2.0 visits/person-year, while frequent users averaged 12.1 visits/person-year. Frequent users accounted for 10% of the sample but contributed over 60% of visits. Predictors of frequent use in adjusted analyses included birth in Canada, higher monthly income, lower health status, perceived unmet mental health needs, and perceived external health locus of control from powerful others; being accompanied by a partner and/or dependent children had a protective effect on frequent use.
Among homeless adults with universal health insurance, a small subgroup accounts for the majority of visits to emergency services. Frequent use was driven by multiple predisposing, enabling, and need factors.
PMCID: PMC3969147  PMID: 24148033
Health care utilization; Emergency department; Homeless persons
4.  Pitfalls with Smartphones in Medicine 
Journal of General Internal Medicine  2013;28(10):1260-1263.
PMCID: PMC3785658  PMID: 23625267
information exchange; smartphones; healthcare communication; medical decision-making; mobile technology; clinical efficiency
5.  Risk of Cerebral Palsy among the Offspring of Immigrants 
PLoS ONE  2014;9(7):e102275.
Cerebral palsy (CP) has a multifactorial etiology, and placental vascular disease may be one major risk factor. The risk of placental vascular disease may be lower among some immigrant groups. We studied the association between immigrant status and the risk of CP.
We conducted a population-based retrospective cohort study of all singleton and twin livebirths in Ontario between 2002–2008, and who survived ≥28 days after birth. Each child was assessed for CP up to age 4 years, based on either a single inpatient or ≥2 outpatient pediatric diagnoses of CP. Relative to non-immigrants (n = 566,668), the risk of CP was assessed for all immigrants (n = 177,390), and further evaluated by World region of origin. Cox proportional hazard ratios (aHR) were adjusted for maternal age, income, diabetes mellitus, obesity, tobacco use, Caesarean delivery, year of delivery, physician visits, twin pregnancy, preterm delivery, as well as small- and large-for-gestational age birthweight.
There were 1346 cases of CP, with a lower rate among immigrants (1.45 per 1000) than non-immigrants (1.92 per 1000) (aHR 0.77, 95% confidence interval [CI] 0.67 to 0.88). Mothers from East Asia and the Pacific (aHR 0.54, 95% CI 0.39 to 0.77) and the Caribbean (aHR 0.58, 95% CI 0.37 to 0.93) were at a significantly lower risk of having a child with CP. Whether further adjusting for preeclampsia, gestational hypertension, placental abruption or placental infraction, or upon using a competing risk analysis that further accounted for stillbirth and neonatal death, these results did not change.
Immigration and ethnicity appear to attenuate the risk of CP, and this effect is not fully explained by known risk factors.
PMCID: PMC4096602  PMID: 25019202
6.  Pregnancy and the risk of a traffic crash 
Pregnancy causes diverse physiologic and lifestyle changes that may contribute to increased driving and driving error. We compared the risk of a serious motor vehicle crash during the second trimester to the baseline risk before pregnancy.
We conducted a population-based self-matched longitudinal cohort analysis of women who gave birth in Ontario between April 1, 2006, and March 31, 2011. We excluded women less than age 18 years, those living outside Ontario, those who lacked a valid health card identifier under universal insurance, and those under the care of a midwife. The primary outcome was a motor vehicle crash resulting in a visit to an emergency department.
A total of 507 262 women gave birth during the study period. These women accounted for 6922 motor vehicle crashes as drivers during the 3-year baseline interval (177 per mo) and 757 motor vehicle crashes as drivers during the second trimester (252 per mo), equivalent to a 42% relative increase (95% confidence interval 32%–53%; p < 0.001). The increased risk extended to diverse populations, varied obstetrical cases and different crash characteristics. The increased risk was largest in the early second trimester and compensated for by the third trimester. No similar increase was observed in crashes as passengers or pedestrians, cases of intentional injury or inadvertent falls, or self-reported risky behaviours.
Pregnancy is associated with a substantial risk of a serious motor vehicle crash during the second trimester. This risk merits attention for prenatal care.
PMCID: PMC4081196  PMID: 24821870
7.  Elevator buttons as unrecognized sources of bacterial colonization in hospitals 
Open Medicine  2014;8(3):e81-e86.
Elevators are ubiquitous and active inside hospitals, potentially facilitating bacterial transmission. The objective of this study was to estimate the prevalence of bacterial colonization on elevator buttons in large urban teaching hospitals.
A total of 120 elevator buttons and 96 toilet surfaces were swabbed over separate intervals at 3 tertiary care hospitals on weekdays and weekends in Toronto, Ontario. For the elevators, swabs were taken from 2 interior buttons (buttons for the ground floor and one randomly selected upper-level floor) and 2 exterior buttons (the "up" button from the ground floor and the "down" button from the upper-level floor). For the toilet surfaces, swabs were taken from the exterior and interior handles of the entry door, the privacy latch, and the toilet flusher. Samples were obtained using standard bacterial collection techniques, followed by plating, culture, and species identification by a technician blind to sample source.
The prevalence of colonization of elevator buttons was 61% (95% confidence interval 52%–70%). No significant differences in colonization prevalence were apparent in relation to location of the buttons, day of the week, or panel position within the elevator. Coagulase-negative staphylococci were the most common organisms cultured, whereas Enterococcus and Pseudomonas species were infrequent. Elevator buttons had a higher prevalence of colonization than toilet surfaces (61% v. 43%, p = 0.008).
Hospital elevator buttons were commonly colonized by bacteria, although most pathogens were not clinically relevant. The risk of pathogen transmission might be reduced by simple countermeasures.
PMCID: PMC4242253  PMID: 25426176
8.  Site of hospital readmission and mortality: a population-based retrospective cohort study 
CMAJ Open  2014;2(2):E77-E85.
Unplanned hospital readmission is a complex process, particularly if the patient is readmitted to an acute care institution other than the original hospital. This study tested the hypothesis that readmission to an alternative hospital is associated with increased mortality compared with readmission to the original hospital.
We performed a population-based retrospective cohort analysis set between 1995 and 2010 for all 21 acute care adult general hospitals in the Greater Toronto and Hamilton Area. Participants were consecutive adults (age ≥ 18 yr) readmitted through the emergency department within 30 days after hospital discharge. The primary outcome measure was all-cause mortality within 30 days after readmission.
Of the 198 149 patients included in the study, 38 134 (19.2%) died within 30 days after readmission. Patients readmitted to an alternative hospital were more likely than those readmitted to the original hospital to be older, reside in a chronic-care facility and arrive by ambulance. Alternative-hospital readmission was associated with a higher risk of death within 30 days (22.3% v. 18.6%, p < 0.001; odds ratio [OR] 1.26, 95% confidence interval [CI] 1.23–1.30). The increased risk was substantially less after adjustment for patient- and hospital-level covariables (adjusted OR 1.06, 95% CI 1.02–1.10). Unadjusted Kaplan–Meier survival curves separated early and the absolute difference in mortality continued throughout the entire 1-year follow-up period, but no difference between groups was observed based on adjusted survival analyses.
Among patients readmitted within 30 days after discharge, readmission to an alternative hospital was associated with a higher risk of death than readmission to the original hospital. Whether this adverse prognosis reflects a true causal relation or residual confounding is unknown.
PMCID: PMC4084742  PMID: 25077133
9.  JURaSSiC 
Neurology  2013;81(5):448-455.
We compared the accuracy of clinicians and a risk score (iScore) to predict observed outcomes following an acute ischemic stroke.
The JURaSSiC (Clinician JUdgment vs Risk Score to predict Stroke outComes) study assigned 111 clinicians with expertise in acute stroke care to predict the probability of outcomes of 5 ischemic stroke case scenarios. Cases (n = 1,415) were selected as being representative of the 10 most common clinical presentations from a pool of more than 12,000 stroke patients admitted to 12 stroke centers. The primary outcome was prediction of death or disability (modified Rankin Scale [mRS] ≥3) at discharge within the 95% confidence interval (CI) of observed outcomes. Secondary outcomes included 30-day mortality and death or institutionalization at discharge.
Clinicians made 1,661 predictions with overall accuracy of 16.9% for death or disability at discharge, 46.9% for 30-day mortality, and 33.1% for death or institutionalization at discharge. In contrast, 90% of the iScore-based estimates were within the 95% CI of observed outcomes. Nearly half (n = 53 of 111; 48%) of participants were unable to accurately predict the probability of the primary outcome in any of the 5 rated cases. Less than 1% (n = 1) provided accurate predictions in 4 of the 5 cases and none accurately predicted all 5 case outcomes. In multivariable analyses, the presence of patient characteristics associated with poor outcomes (mRS ≥3 or death) in previous studies (older age, high NIH Stroke Scale score, and nonlacunar subtype) were associated with more accurate clinician predictions of death at 30 days (odds ratio [OR] 2.40, 95% CI 1.57–3.67) and with a trend for more accurate predictions of death or disability at discharge (OR 1.85, 95% CI 0.99–3.46).
Clinicians with expertise in stroke performed poorly compared to a validated tool in predicting the outcomes of patients with an acute ischemic stroke. Use of the risk stroke outcome tool may be superior for decision-making following an acute ischemic stroke.
PMCID: PMC3776534  PMID: 23897872
10.  Judging Whether a Patient is Actually Improving: More Pitfalls from the Science of Human Perception 
Journal of General Internal Medicine  2012;27(9):1195-1199.
Fallible human judgment may lead clinicians to make mistakes when assessing whether a patient is improving following treatment. This article provides a narrative review of selected studies in psychology that describe errors that potentially apply when a physician assesses a patient's response to treatment. Comprehension may be distorted by subjective preconceptions (lack of double blinding). Recall may fail through memory lapses (unwanted forgetfulness) and tacit assumptions (automatic imputation). Evaluations may be further compromised due to the effects of random chance (regression to the mean). Expression may be swayed by unjustified overconfidence following conformist groupthink (group polarization). An awareness of these five pitfalls may help clinicians avoid some errors in medical care when determining whether a patient is improving.
PMCID: PMC3515001  PMID: 22592355
medical error; fallible reasoning; judgement and decisions; human psychology; patient outcomes; symptom changes
11.  Validity of Physician Billing Claims to Identify Deceased Organ Donors in Large Healthcare Databases 
PLoS ONE  2013;8(8):e70825.
We evaluated the validity of physician billing claims to identify deceased organ donors in large provincial healthcare databases.
We conducted a population-based retrospective validation study of all deceased donors in Ontario, Canada from 2006 to 2011 (n = 988). We included all registered deaths during the same period (n = 458,074). Our main outcome measures included sensitivity, specificity, positive predictive value, and negative predictive value of various algorithms consisting of physician billing claims to identify deceased organ donors and organ-specific donors compared to a reference standard of medical chart abstraction.
The best performing algorithm consisted of any one of 10 different physician billing claims. This algorithm had a sensitivity of 75.4% (95% CI: 72.6% to 78.0%) and a positive predictive value of 77.4% (95% CI: 74.7% to 80.0%) for the identification of deceased organ donors. As expected, specificity and negative predictive value were near 100%. The number of organ donors identified by the algorithm each year was similar to the expected value, and this included the pre-validation period (1991 to 2005). Algorithms to identify organ–specific donors performed poorly (e.g. sensitivity ranged from 0% for small intestine to 67% for heart; positive predictive values ranged from 0% for small intestine to 37% for heart).
Primary data abstraction to identify deceased organ donors should be used whenever possible, particularly for the detection of organ-specific donations. The limitations of physician billing claims should be considered whenever they are used.
PMCID: PMC3743842  PMID: 23967114
12.  Drowning and the Influence of Hot Weather 
PLoS ONE  2013;8(8):e71689.
Drowning deaths are devastating and preventable. Public perception does not regard hot weather as a common scenario for drowning deaths. The objective of our study was to test the association between hot weather and drowning risk.
Materials and Methods
We conducted a retrospective case-crossover analysis of all unintentional drowning deaths in Ontario, Canada from 1999 to 2009. Demographic data were obtained from the Office of the Chief Coroner. Weather data were obtained from Environment Canada. We used the pair-matched analytic approach for the case-crossover design to contrast the weather on the date of the drowning with the weather at the same location one week prior (control period).
We identified 1243 drowning deaths. The mean age was 40 years, 82% were male, and most events (71%) occurred in open water. The pair-matched analytic approach indicated that temperatures exceeding 30°C were associated with a 69% increase in the risk of outdoor drowning (OR = 1.69, 95% CI 1.23–2.25, p = 0.001). For indoor drowning, however, temperatures exceeding 30°C were not associated with a statistically significant increase in the risk of drowning (OR = 1.50, 95% CI 0.53–4.21, p = 0.442). Adult men were specifically prone to drown in hot weather (OR 1.67, 95% CI 1.19–2.34, p = 0.003) yet an apparent increase in risk extended to both genders and all age groups.
Contrary to popular belief, hot weather rather than cold stormy weather increases the risk of drowning. An awareness of this risk might encourage greater use of drowning prevention strategies known to save lives.
PMCID: PMC3743751  PMID: 23977112
13.  Modern Medicine Is Neglecting Road Traffic Crashes 
PLoS Medicine  2013;10(6):e1001463.
Don Redelmeier and Barry McLellan admonish the medical community for failure to act on the vast problem of road traffic crashes.
Please see later in the article for the Editors' Summary
PMCID: PMC3678998  PMID: 23776413
14.  Organ donation after death in Ontario: a population-based cohort study 
Shortfalls in deceased organ donation lead to shortages of solid organs available for transplantation. We assessed rates of deceased organ donation and compared hospitals that had clinical services for transplant recipients (transplant hospitals) to those that did not (general hospitals).
We conducted a population-based cohort analysis involving patients who died from traumatic brain injury, subarachnoid hemorrhage, intracerebral hemorrhage or other catastrophic neurologic conditions in Ontario, Canada, between Apr. 1, 1994, and Mar. 31, 2011. We distinguished between acute care hospitals with and without transplant services. The primary outcome was actual organ donation determined through the physician database for organ procurement procedures.
Overall, 87 129 patients died from catastrophic neurologic conditions during the study period, of whom 1930 became actual donors. Our primary analysis excluded patients from small hospitals, reducing the total to 79 746 patients, of whom 1898 became actual donors. Patients who died in transplant hospitals had a distribution of demographic characteristics similar to that of patients who died in other large general hospitals. Transplant hospitals had an actual donor rate per 100 deaths that was about 4 times the donor rate at large general hospitals (5.0 v. 1.4, p < 0.001). The relative reduction in donations at general hospitals was accentuated among older patients, persisted among patients who were the most eligible candidates and amounted to about 121 fewer actual donors per year (adjusted odds ratio 0.58, 95% confidence interval 0.36–0.92). Hospital volumes were only weakly correlated with actual organ donation rates.
Optimizing organ donation requires greater attention to large general hospitals. These hospitals account for most of the potential donors and missed opportunities for deceased organ donation.
PMCID: PMC3652962  PMID: 23549970
15.  Determining Whether a Patient is Feeling Better: Pitfalls from the Science of Human Perception 
Human perception is fallible and may lead patients to be inaccurate when judging whether their symptoms are improving with treatment. This article provides a narrative review of studies in psychology that describe misconceptions related to a patient's comprehension, recall, evaluation and expression. The specific misconceptions include the power of suggestion (placebo effects), desire for peace-of-mind (cognitive dissonance reduction), inconsistent standards (loss aversion), a flawed sense of time (duration neglect), limited perception (measurement error), declining sensitivity (Weber's law), an eagerness to please (social desirability bias), and subtle affirmation (personal control). An awareness of specific pitfalls might help clinicians avoid some mistakes when providing follow-up and interpreting changes in patient symptoms.
PMCID: PMC3138972  PMID: 21336670
symptomatic changes; patient follow-up; fallible judgment; medical error; human psychology; eliciting the history
16.  Social benefit payments and acute injury among low-income mothers 
Open Medicine  2012;6(3):e101-e108.
Human error due to risky behaviour is a common and important contributor to acute injury related to poverty. We studied whether social benefit payments mitigate or exacerbate risky behaviours that lead to emergency visits for acute injury among low-income mothers with dependent children.
We analyzed total emergency department visits throughout Ontario to identify women between 15 and 55 years of age who were mothers of children younger than 18 years, who were living in the lowest socio-economic quintile and who presented with acute injury. We used universal health care databases to evaluate emergency department visits during specific days on which social benefit payments were made (child benefit distribution) relative to visits on control days over a 7-year interval (1 April 2003 to 31 March 2010).
A total of 153 377 emergency department visits met the inclusion criteria. We observed fewer emergencies per day on child benefit payment days than on control days (56.4 v. 60.1, p = 0.008). The difference was primarily explained by lower values among mothers age 35 years or younger (relative reduction 7.29%, 95% confidence interval [CI] 1.69% to 12.88%), those living in urban areas (relative reduction 7.07%, 95% CI 3.05% to 11.10%) and those treated at community hospitals (relative reduction 6.83%, 95% CI 2.46% to 11.19%). No significant differences were observed for the 7 days immediately before or the 7 days immediately after the child benefit payment.
Contrary to political commentary, we found that small reductions in relative poverty mitigated, rather than exacerbated, risky behaviours that contribute to acute injury among low-income mothers with dependent children.
PMCID: PMC3654504  PMID: 23687523
18.  Emergency department visits during an Olympic gold medal television broadcast 
Open Medicine  2011;5(2):e112-e119.
Practice pattern variations are often attributed to physician decision-making with no accounting for patient preferences.
To test whether a mass media television broadcast unrelated to health was associated with changes in the rate and characteristics of visits for acute emergency care.
Time-series analysis of emergency department visits for any reason.
Population-based sample of all patients seeking emergency care in Ontario, Canada.
The broadcast day was defined as the Olympic men’s gold medal ice hockey game final. The control days were defined as the 6 Sundays before and after the broadcast day.
A total of 99 447 visits occurred over the 7 Sundays, of which 13 990 occurred on the broadcast day. Comparing the broadcast day with control days, we found no significant difference in the hourly rate of visits before the broadcast (544 vs 537, p = 0.41) or after the broadcast (647 vs 639, p = 0.55). In contrast, we observed a significant reduction in hourly rate of visits during the broadcast (647 vs 783, p < 0.001), equal to an absolute decrease of 409 patients, a relative decrease of 17% (95% confidence interval 13–21), or about 136 fewer patients per hour. The relative decrease during the broadcast was particularly large for adult men with low triage severity. The greatest reductions were for patients with abdominal, musculoskeletal or traumatic disorders.
Mass media television broadcasts can influence patient preferences and thereby lead to a decrease in emergency department visits.
PMCID: PMC3148000  PMID: 21915235
19.  On the Psychology of Pharmaceutical Industry Gifts to Physicians 
PMCID: PMC2811604  PMID: 19894080
20.  Competing risks of mortality with marathons: retrospective analysis 
BMJ : British Medical Journal  2007;335(7633):1275-1277.
Objective To determine from a societal perspective the risk of sudden cardiac death associated with running in an organised marathon compared with the risk of dying from a motor vehicle crash that might otherwise have taken place if the roads had not been closed.
Design Population based retrospective analysis with linked ecological comparisons of sudden death.
Setting Marathons with at least 1000 participants that had two decades of history and were on public roads in the United States, 1975-2004.
Main outcome measures Sudden death attributed to cardiac causes or to motor vehicle trauma.
Results The marathons provided results for 3 292 268 runners on 750 separate days encompassing about 14 million hours of exercise. There were 26 sudden cardiac deaths observed, equivalent to a rate of 0.8 per 100 000 participants (95% confidence interval 0.5 to 1.1). Because of road closure, an estimated 46 motor vehicle fatalities were prevented, equivalent to a relative risk reduction of 35% (95% confidence interval 17% to 49%). The net reduction in sudden death during marathons amounted to a ratio of about 1.8 crash deaths saved for each case of sudden cardiac death observed (95% confidence interval: 0.7 to 3.8). The net reduction in total deaths could not be explained by re-routing traffic to other regions or days and was consistent across different parts of the country, decades of the century, seasons of the year, days of the week, degree of competition, and course difficulty.
Conclusion Organised marathons are not associated with an increase in sudden deaths from a societal perspective, contrary to anecdotal impressions fostered by news media.
PMCID: PMC2151171  PMID: 18156224
21.  Road Trauma in Teenage Male Youth with Childhood Disruptive Behavior Disorders: A Population Based Analysis 
PLoS Medicine  2010;7(11):e1000369.
Donald Redelmeier and colleagues conducted a population-based case-control study of 16-19-year-old males hospitalized for road trauma or appendicitis and showed that disruptive behavior disorders explained a significant amount of road trauma in this group.
Teenage male drivers contribute to a large number of serious road crashes despite low rates of driving and excellent physical health. We examined the amount of road trauma involving teenage male youth that might be explained by prior disruptive behavior disorders (attention deficit hyperactivity disorder, conduct disorder, oppositional defiant disorder).
Methods and Findings
We conducted a population-based case-control study of consecutive male youth between age 16 and 19 years hospitalized for road trauma (cases) or appendicitis (controls) in Ontario, Canada over 7 years (April 1, 2002 through March 31, 2009). Using universal health care databases, we identified prior psychiatric diagnoses for each individual during the decade before admission. Overall, a total of 3,421 patients were admitted for road trauma (cases) and 3,812 for appendicitis (controls). A history of disruptive behavior disorders was significantly more frequent among trauma patients than controls (767 of 3,421 versus 664 of 3,812), equal to a one-third increase in the relative risk of road trauma (odds ratio  =  1.37, 95% confidence interval 1.22–1.54, p<0.001). The risk was evident over a range of settings and after adjustment for measured confounders (odds ratio 1.38, 95% confidence interval 1.21–1.56, p<0.001). The risk explained about one-in-20 crashes, was apparent years before the event, extended to those who died, and persisted among those involved as pedestrians.
Disruptive behavior disorders explain a significant amount of road trauma in teenage male youth. Programs addressing such disorders should be considered to prevent injuries.
Please see later in the article for the Editors' Summary
Editors' Summary
In the latest World Health Organization (WHO) global burden of disease list, road traffic crashes are currently ranked eighth but are predicted to take fourth place by 2030 (by which time, road traffic deaths are likely to increase by more than 80% in developing countries and to decrease by nearly 30% in industrialized countries.) Every year, road traffic crashes kill an estimated 1.2 million people world-wide and injure or disable a further 20–60 million. Furthermore, the economic consequences of road traffic crashes account for about 2% of the gross national product of the entire global economy.
90% of road traffic deaths occur in developing countries where pedestrians, cyclists, and users of two-wheel vehicles (scooters, motorbikes) are the most vulnerable. In industrialized countries, teenage male drivers are the single most risky demographic group, with an incidence of road traffic crashes of twice that of the population average. Also, male teenagers are sometimes a hazard to other road users and contribute to more fatalities in older pedestrians than older drivers. Furthermore, teenage male drivers involved in serious crashes can have ongoing health care needs but are often resistant to standard road safety advice.
Why Was This Study Done?
Previous studies have suggested that disruptive behavior disorders might contribute to the risk of road traffic crashes in male teenagers but methodological problems with these studies make these results unclear. Given the importance of this topic, authorities have called for more research into the full range of behavioral disorders and relevant populations. This study attempted to avoid the methodological problems of previous studies and to rigorously assess whether disruptive behavior disorders predispose male teenagers to road traffic crashes.
What Did the Researchers Do and Find?
The researchers conducted a 7-year population-based case-control study in Ontario, Canada of consecutive male teenagers aged between 16 and 19 years who were admitted to a hospital due to a road traffic crash, including those who were pedestrians. For the controls, the researchers used consecutive males in the same age range who were admitted to the same hospitals during the same time interval for acute appendicitis (which is common and generally unrelated to traumatic injury). For each participant in the study, the authors used universal health care databases in Canada's single-payer health care system to identify relevant psychiatric diagnoses (attention deficit hyperactivity disorder, conduct disorder, and oppositional defiant disorder) during the decade before admission.
During the study period, 3,421 male teenagers were admitted to hospital as the result of a road traffic crash and 3,812 male teenagers were admitted to hospital for appendicitis. A history of disruptive behavior disorders was significantly more frequent among male teenagers admitted for road traffic crashes than controls (767 of 3,421 versus 664 of 3,812) giving an odds ratio 1.37. This higher risk was still present after the researchers adjusted for possible confounding factors (such as age, social status, and home location) and accounted for about one-in-20 road traffic crashes, including male teenagers who had died and those involved as pedestrians.
What Do These Findings Mean?
The results of this study suggest that disruptive behavior disorders explain a significant amount of road traffic crashes experienced in male teenagers. Overall, attention deficit hyperactivity disorder, conduct disorder, and oppositional defiant disorder are associated with about a one-third increase in the risk of a road traffic crash (which is similar to the relative risk among individuals treated for epilepsy.) As in previous studies in this area, some methodological problems may affect the interpretation of these findings. As this study did not document who was “at fault,” an alternative interpretation might be that behavioral disorders impair a teenager's ability to avoid a mishap initiated by someone else. Most importantly, the observed increase in risk as pedestrians indicates that male teenagers who abstain from driving do not escape the danger of road traffic crashes.
The researchers stress that any increased risk of road traffic crashes associated with disruptive behavior disorders in male teenagers does not justify withholding a driver's license, especially as many such disorders can be effectively treated or, indeed, because it does not address the issue of the increased risk for those teenagers who were pedestrians. Instead, they suggest that disruptive behavior disorders could be considered as contributors to road traffic crashes—analogous to seizure disorders and some other medical diseases. Therefore, greater attention by primary care physicians, psychiatrists, and community health workers might be helpful since interventions can perhaps reduce the risk including medical treatments and avoidance of distractions.
Additional Information
Please access these Web sites via the online version of this summary at
The World Health Organization has information on road traffic crashes
The US National Institutes of Health has information about behavior disorders in children as well as UK-based Kids Development
The Ontarion Ministry of Transportation has information on annual roadway collisions in Ontario
PMCID: PMC2981585  PMID: 21125017
22.  The health of homeless immigrants 
This study examined the association between immigrant status and current health in a representative sample of 1,189 homeless people in Toronto, Canada.
Multivariate regression analyses were performed to examine the relationship between immigrant status and current health status (assessed using the SF-12) among homeless recent immigrants (≤10 years since immigration), non-recent immigrants (>10 years since immigration), and Canadian-born individuals recruited at shelters and meal programs (response rate 73%).
After adjusting for demographic characteristics and lifetime duration of homelessness, recent immigrants were significantly less likely to have chronic conditions (RR 0.7, 95% CI 0.5 to 0.9), mental health problems (OR 0.4, 95% CI 0.2 to 0.7), alcohol problems (OR 0.2, 95% CI 0.1 to 0.5), and drug problems (OR 0.2, 95% CI 0.1 to 0.4) compared to non-recent immigrants and Canadian-born individuals. Recent immigrants were also more likely to have better mental health status (+3.4 points, SE ±1.6) and physical health status (+2.2 points, SE ±1.3) on scales with a mean of 50 and a standard deviation of 10 in the general population.
Homeless recent immigrants are a distinct group who are generally healthier and may have very different service needs compared to other homeless people.
PMCID: PMC2773541  PMID: 19654122
homelessness; migration and health
23.  Drug problems among homeless individuals in Toronto, Canada: prevalence, drugs of choice, and relation to health status 
BMC Public Health  2010;10:94.
Drug use is believed to be an important factor contributing to the poor health and increased mortality risk that has been widely observed among homeless individuals. The objective of this study was to determine the prevalence and characteristics of drug use among a representative sample of homeless individuals and to examine the association between drug problems and physical and mental health status.
Recruitment of 603 single men, 304 single women, and 284 adults with dependent children occurred at homeless shelters and meal programs in Toronto, Canada. Information was collected on demographic characteristics and patterns of drug use. The Addiction Severity Index was used to assess whether participants suffered from drug problems. Associations of drug problems with physical and mental health status (measured by the SF-12 scale) were examined using regression analyses.
Forty percent of the study sample had drug problems in the last 30 days. These individuals were more likely to be single men and less educated than those without drug problems. They were also more likely to have become homeless at a younger age (mean 24.8 vs. 30.9 years) and for a longer duration (mean 4.8 vs. 2.9 years). Marijuana and cocaine were the most frequently used drugs in the past two years (40% and 27%, respectively). Drug problems within the last 30 days were associated with significantly poorer mental health status (-4.9 points, 95% CI -6.5 to -3.2) but not with poorer physical health status (-0.03 points, 95% CI -1.3 to 1.3)).
Drug use is common among homeless individuals in Toronto. Current drug problems are associated with poorer mental health status but not with poorer physical health status.
PMCID: PMC2841106  PMID: 20181248
24.  Motor Vehicle Crashes in Diabetic Patients with Tight Glycemic Control: A Population-based Case Control Analysis 
PLoS Medicine  2009;6(12):e1000192.
Using a population-based case control analysis, Donald Redelmeier and colleagues found that tighter glycemic control, as measured by the HbA1c, is associated with an increased risk of a motor vehicle crash.
Complications from diabetes mellitus can compromise a driver's ability to safely operate a motor vehicle, yet little is known about whether euglycemia predicts normal driving risks among adults with diabetes. We studied the association between glycosylated hemoglobin (HbA1c) and the risk of a motor vehicle crash using a population-based case control analysis.
Methods and Findings
We identified consecutive drivers reported to vehicle licensing authorities between January 1, 2005 to January 1, 2007 who had a diagnosis of diabetes mellitus and a HbA1c documented. The risk of a crash was calculated taking into account potential confounders including blood glucose monitoring, complications, and treatments. A total of 57 patients were involved in a crash and 738 were not involved in a crash. The mean HbA1c was lower for those in a crash than controls (7.4% versus 7.9%, unpaired t-test, p = 0.019), equal to a 26% increase in the relative risk of a crash for each 1% reduction in HbA1c (odds ratio = 1.26, 95% confidence interval 1.03–1.54). The trend was evident across the range of HbA1c values and persisted after adjustment for measured confounders (odds ratio = 1.25, 95% confidence interval 1.02–1.55). The two other significant risk factors for a crash were a history of severe hypoglycemia requiring outside assistance (odds ratio = 4.07, 95% confidence interval 2.35–7.04) and later age at diabetes diagnosis (odds ratio per decade = 1.29, 95% confidence interval 1.07–1.57).
In this selected population, tighter glycemic control, as measured by the HbA1c, is associated with an increased risk of a motor vehicle crash.
Please see later in the article for the Editors' Summary
Editors' Summary
Around 8% of the US population has diabetes, a group of diseases in which the body cannot control levels of glucose (sugar) in the blood. It can lead to serious complications and premature death, but suitable treatment can control the disease and lower the risk of complications.
Type 1 diabetes occurs when the body's immune system prevents the production of insulin, the hormone that controls blood glucose. It accounts for 5%–10% of diabetes cases in adults and the vast majority of cases in childhood. Patients with type 1 diabetes need to inject insulin to survive. Type 2 diabetes is associated with older age, obesity, family history of diabetes, lack of physical activity, and race/ethnicity. As obesity rates rise worldwide, it is expected that the prevalence of type 2 diabetes will increase.
Why Was This Study Done?
Some complications of diabetes affect the ability to drive safely. Prolonged periods of high blood sugar levels can damage eyesight and nerves throughout the body, resulting in pain, tingling, and reduction of feeling or muscle control. Over time, some diabetics may become unaware of the early symptoms of an abnormally low blood sugar level (hypoglycemia) that can cause confusion, clumsiness, or fainting. Severe hypoglycemia can result in seizures or a coma.
It is common for driver licensing authorities to require evidence that a diabetic person's condition is well controlled before they issue a driving license. One measure of this is the percentage of hemoglobin in their blood that has joined up with glucose, known as HbA1c. This provides a measure of average blood glucose levels over the previous 8–12 weeks. A lower reading is considered an indicator of good diabetic control, but conversely, a blood glucose level that is too low can cause hypoglycemia. Normal nondiabetic HbA1c is between 3.5% and 5.5%, but 6.5% is considered good for people with diabetes.
In this study the researchers tested whether blood glucose levels, as measured by levels of HbA1c, were statistically associated with the risk of a motor vehicle crash.
What Did the Researchers Do and Find?
The authors studied 795 diabetic adults who had been in contact with the driver licensing authority in Ontario, Canada between January 1, 2005 and January 1, 2007 and for whom HbA1c levels were recorded. HbA1c levels varied between 4.4% and 14.7%.
Of the drivers considered, 57 were involved in a car crash and 738 were not. The authors found that lower HbA1c levels were associated with an increased risk of a motor vehicle crash, even when they took into account other factors such as time since diagnosis, treatment, age, age when diagnosed, and, if taking insulin, age insulin started.
The authors also found that the risk of a crash quadrupled when a driver had a history of severe hypoglycemia that required outside help and that there was an increase in risk when diabetes had first been diagnosed at an older age.
What Do These Findings Mean?
The authors conclude by emphasizing the difficulty in knowing whether someone with diabetes is fit to drive. They suggest that a patient's HbA1c level is neither necessary nor sufficient to determine whether a diabetic person is fit to drive and these results, which agree with some other studies, call into question the current legal framework of the US, UK, Canada, Germany, Holland, and Australia, which single out diabetic drivers for medical review.
The finding that lower HbA1c levels are associated with an increased risk of a crash is surprising, as it suggests that a driver is less safe if they control their diabetes well. However, a statistical link does not prove that one event causes another. Unknown social or medical factors might explain the results. In this case, the authors point out that a major drawback of their study is that it is not randomized and drivers have free will in choosing how tightly to control their diabetes and also how carefully they drive. The authors considered whether time spent driving might explain the results, but discounted this for several reasons. One more plausible explanation is that intensive treatment to attain a lower HbA1c level for better general health raises the risk of hypoglycemic episodes.
Additional Information
Please access these Web sites via the online version of this summary at
Wikipedia includes an article on diabetes (note that Wikipedia is a free online encyclopedia that anyone can edit; available in several languages)
The American Diabetes Association publishes information on diabetes in English and Spanish
The American Diabetes Association also publishes information on US states regulation of drivers with diabetes
The World Health Organization of the United Nations Diabetes Programme works to prevent diabetes, minimize complications, and maximize quality of life
PMCID: PMC2780354  PMID: 19997624
25.  Rainy weather and medical school admission interviews 
Mood can influence behaviour and consumer choice in diverse settings. We found that such cognitive influences extend to candidate admission interviews at a Canadian medical school. We suggest that an awareness of this fallibility might lead to more reasonable medical school admission practices.
PMCID: PMC2789141  PMID: 19969588

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