A comparison of self-reported risk and protective factors and the death implicit association test in the prediction of future suicide attempts in adolescent emergency department patients

BACKGROUND

Concerns have been raised about the utility of self-report assessments in predicting future suicide attempts. Clinicians in pediatric emergency departments (EDs) often are required to assess suicidal risk. The Death Implicit Association Test (IAT) is an alternative to self-report assessment of suicidal risk that may have utility in ED settings.

METHODS

A total of 1679 adolescents recruited from 13 pediatric emergency rooms in the Pediatric Emergency Care Applied Research Network were assessed using a self-report survey of risk and protective factors for a suicide attempt, and the IAT, and then followed up 3 months later to determine if an attempt had occurred. The accuracy of prediction was compared between self-reports and the IAT using the area under the curve (AUC) with respect to receiver operator characteristics.

RESULTS

A few self-report variables, namely, current and past suicide ideation, past suicidal behavior, total negative life events, and school or social connectedness, predicted an attempt at 3 months with an AUC of 0.87 [95% confidence interval (CI), 0.84-0.90] in the entire sample, and AUC = 0.91, (95% CI 0.85-0.95) for those who presented without reported suicidal ideation. The IAT did not add significantly to the predictive power of selected self-report variables. The IAT alone was modestly predictive of 3-month attempts in the overall sample ((AUC = 0.59, 95% CI 0.52-0.65) and was a better predictor in patients who were non-suicidal at baseline (AUC = 0.67, 95% CI 0.55-0.79).

CONCLUSIONS

In pediatric EDs, a small set of self-reported items predicted suicide attempts within 3 months more accurately than did the IAT.

A risk algorithm that predicts alcohol use disorders among college students

The first year of college may carry especially high risk for onset of alcohol use disorders. We assessed the one-year incidence of alcohol use disorders (AUD) among incoming first-year students, predictors of AUD-incidence, prediction accuracy and population impact. A prospective cohort study of first-year college students (baseline: N = 5843; response rate = 51.8%; 1-year follow-up: n = 1959; conditional response rate = 41.6%) at a large university in Belgium was conducted. AUD were evaluated with the AUDIT and baseline predictors with the Composite International Diagnostic Interview Screening Scales (CIDI-SC). The one-year incidence of AUD was 3.9% (SE = 0.4). The most important individual-level baseline predictors of AUD incidence were being male (OR = 1.53; 95% CI = 1.12-2.10), a break-up with a romantic partner (OR = 1.67; 95% CI = 1.08-2.59), hazardous drinking (OR = 3.36; 95% CI = 1.31-8.63), and alcohol use characteristics at baseline (ORs between 1.29 and 1.38). Multivariate cross-validated prediction (cross-validated AUC = 0.887) shows that 55.5% of incident AUD cases occurred among the 10% of students at highest predicted risk (20.1% predicted incidence in this highest-risk subgroup). Four out of five students with incident AUD would hypothetically be preventable if baseline hazardous drinking was to be eliminated along with a reduction of one standard deviation in alcohol use characteristics scores, and another 15.0% would potentially be preventable if all 12-month stressful events were eliminated. Screening at college entrance is a promising strategy to identify students at risk of transitioning to more problematic drinking and AUD, thus improving the development and deployment of targeted preventive interventions.

[Major depressive episode in college freshmen: prevalence, academic functioning and receipt of treatment]

Background Little is known about the epidemiology of Major Depressive Episode (mde) in university students. Aim To investigate the prevalence of mde, psychiatric comorbidity, and the association with academic performance among first-year university students, and to investigate to what extent these students use professional mental health services. Method All first-year students at the ku Leuven (Leuven, Belgium) were invited to complete a computer-assisted survey with a weighted cross-sectional design (N=5,460; response rate corrected for drop-out=51.8%). mde was assessed using the Composite International Diagnostic Interview - Screening Scales (cidi-sc) with dsm-iv criteria. Results We found that 13.6% of first-year students met criteria for a cidi-sc mde in the past year. mde was associated with a wide range of other comorbid disorders (such as generalized anxiety disorder or hypo[mania]) and suicidal thoughts and behaviors. mde was associated with significantly lower academic year percentage (-3.6 to -6.4%) and elevated odds of academic year failure (ors=1.5-2.0). Professional service use was estimated at 21.5%. Conclusion mde is common among first-year university students and is associated with a high degree of psychiatric comorbidity and poor academic performance. It is therefore surprising that so few students actually receive treatment for their psychiatric and emotional problems. Tijdschrift voor Psychiatrie 63(2021)1, 24-31.

The associations between non-suicidal self-injury and first onset suicidal thoughts and behaviors

BACKGROUND

Theoretical and empirical literature suggests that non-suicidal self-injury (NSSI) is an important correlate of suicide risk. The present study was designed to evaluate: (a) whether NSSI is associated with increased odds of subsequent onsets of suicidal thoughts and behaviors (STB) independent of common mental disorders, (b) whether NSSI is associated with increased risk of transitioning from suicide ideation to attempt, and (c) which NSSI characteristics are associated with STB after NSSI.

METHOD

Using discrete-time survival models, based on retrospective age of onset reports from college students (n = 6,393, 56.8% female), we examined associations of temporally prior NSSI with subsequent STB (i.e., suicide ideation, plan, and attempt) controlling mental disorders (i.e., MDD, Broad Mania, GAD, Panic Disorder, and risk for Alcohol Dependence). NSSI characteristics associated with subsequent STB were examined using logistic regressions.

RESULTS

NSSI was associated with increased odds of subsequent suicide ideation (OR = 2.8), plan (OR = 3.0), and attempt (OR = 5.5) in models that controlled for the distribution of mental disorders. Further analyses revealed that NSSI was associated with increased risk of transitioning to a plan among those with ideation, as well as attempt among those with a plan (ORs = 1.7-2.1). Several NSSI characteristics (e.g., automatic positive reinforcement, earlier onset NSSI) were associated with increased odds of experiencing STB.

LIMITATIONS

Surveys relied on self-report, and thus, there is the potential for recall bias.

CONCLUSIONS

This study provides support for the conceptualization of NSSI as a risk factor for STB. Investigation of the underlying pathways accounting for these time-ordered associations is an important avenue for future research.

The prevalence of suicidal thoughts and behaviours among college students: a meta-analysis

BACKGROUND

Adolescence and young adulthood carry risk for suicidal thoughts and behaviours (STB). An increasing subpopulation of young people consists of college students. STB prevalence estimates among college students vary widely, precluding a validated point of reference. In addition, little is known on predictors for between-study heterogeneity in STB prevalence.

METHODS

A systematic literature search identified 36 college student samples that were assessed for STB outcomes, representing a total of 634 662 students [median sample size = 2082 (IQR 353-5200); median response rate = 74% (IQR 37-89%)]. We used random-effects meta-analyses to obtain pooled STB prevalence estimates, and multivariate meta-regression models to identify predictors of between-study heterogeneity.

RESULTS

Pooled prevalence estimates of lifetime suicidal ideation, plans, and attempts were 22.3% [95% confidence interval (CI) 19.5-25.3%], 6.1% (95% CI 4.8-7.7%), and 3.2% (95% CI 2.2-4.5%), respectively. For 12-month prevalence, this was 10.6% (95% CI 9.1-12.3%), 3.0% (95% CI 2.1-4.0%), and 1.2% (95% CI 0.8-1.6%), respectively. Measures of heterogeneity were high for all outcomes (I 2 = 93.2-99.9%), indicating substantial between-study heterogeneity not due to sampling error. Pooled estimates were generally higher for females, as compared with males (risk ratios in the range 1.12-1.67). Higher STB estimates were also found in samples with lower response rates, when using broad definitions of suicidality, and in samples from Asia.

CONCLUSIONS

Based on the currently available evidence, STB seem to be common among college students. Future studies should: (1) incorporate refusal conversion strategies to obtain adequate response rates, and (2) use more fine-grained measures to assess suicidal ideation.

First onset of suicidal thoughts and behaviours in college

BACKGROUND

College students are a worldwide increasing group of young people at risk for suicidal thoughts and behaviours (STB). However, no previous studies have prospectively investigated the first onset of STB during the college period.

METHODS

Using longitudinal data from the Leuven College Surveys, 2337 (response rate [RR]=66.6%) incoming freshmen provided baseline data on STB, parental psychopathology, childhood-adolescent traumatic experiences, 12-month risk for mental disorders, and 12-month stressful experiences. A total of 1253 baseline respondents provided data on 12-month STB in a two-year annual follow-up survey (conditional RR=53.6%; college dropout adjusted conditional RR=70.2%).

RESULTS

One-year incidence of first-onset STB was 4.8-6.4%. Effect sizes of the included risk factors varied considerably whether viewed from individual-level (ORs=1.91-17.58) or population-level perspective (PARPs=3.4-34.3%). Dating violence prior to the age of 17, physical abuse prior to the age of 17, and 12-month betrayal by someone else than the partner were most strong predictors for first-onset suicidal ideation (ORs=4.23-12.25; PARPs=8.7-27.1%) and plans (ORs=6.57-17.58; PARPs=15.2-34.3%). Multivariate prediction (AUC=0.84-0.91) revealed that 50.7-65.7% of first-onset STB cases were concentrated in the 10% at highest predicted risk.

LIMITATIONS

As this is a first investigation of STB onset in college, future studies should use validation samples to test the accuracy of our multivariate prediction model.

CONCLUSIONS

The first onset of STB in college appears to be higher than in the general population. Screening at college entrance is a promising strategy to identify those students at highest prospective risk, enabling the cost-efficient clinical assessment of young adults in college.

Mental disorders among college students in the World Health Organization World Mental Health Surveys

BACKGROUND

Although mental disorders are significant predictors of educational attainment throughout the entire educational career, most research on mental disorders among students has focused on the primary and secondary school years.

METHOD

The World Health Organization World Mental Health Surveys were used to examine the associations of mental disorders with college entry and attrition by comparing college students (n = 1572) and non-students in the same age range (18-22 years; n = 4178), including non-students who recently left college without graduating (n = 702) based on surveys in 21 countries (four low/lower-middle income, five upper-middle-income, one lower-middle or upper-middle at the times of two different surveys, and 11 high income). Lifetime and 12-month prevalence and age-of-onset of DSM-IV anxiety, mood, behavioral and substance disorders were assessed with the Composite International Diagnostic Interview (CIDI).

RESULTS

One-fifth (20.3%) of college students had 12-month DSM-IV/CIDI disorders; 83.1% of these cases had pre-matriculation onsets. Disorders with pre-matriculation onsets were more important than those with post-matriculation onsets in predicting subsequent college attrition, with substance disorders and, among women, major depression the most important such disorders. Only 16.4% of students with 12-month disorders received any 12-month healthcare treatment for their mental disorders.

CONCLUSIONS

Mental disorders are common among college students, have onsets that mostly occur prior to college entry, in the case of pre-matriculation disorders are associated with college attrition, and are typically untreated. Detection and effective treatment of these disorders early in the college career might reduce attrition and improve educational and psychosocial functioning.

Self-injurious thoughts and behaviors as risk factors for future suicide ideation, attempts, and death: a meta-analysis of longitudinal studies

BACKGROUND

A history of self-injurious thoughts and behaviors (SITBs) is consistently cited as one of the strongest predictors of future suicidal behavior. However, stark discrepancies in the literature raise questions about the true magnitude of these associations. The objective of this study is to examine the magnitude and clinical utility of the associations between SITBs and subsequent suicide ideation, attempts, and death.

METHOD

We searched PubMed, PsycInfo, and Google Scholar for papers published through December 2014. Inclusion required that studies include at least one longitudinal analysis predicting suicide ideation, attempts, or death using any SITB variable. We identified 2179 longitudinal studies; 172 met inclusion criteria.

RESULTS

The most common outcome was suicide attempt (47.80%), followed by death (40.50%) and ideation (11.60%). Median follow-up was 52 months (mean = 82.52, s.d. = 102.29). Overall prediction was weak, with weighted mean odds ratios (ORs) of 2.07 [95% confidence interval (CI) 1.76-2.43] for ideation, 2.14 (95% CI 2.00-2.30) for attempts, and 1.54 (95% CI 1.39-1.71) for death. Adjusting for publication bias further reduced estimates. Diagnostic accuracy analyses indicated acceptable specificity (86-87%) and poor sensitivity (10-26%), with areas under the curve marginally above chance (0.60-0.62). Most risk factors generated OR estimates of <2.0 and no risk factor exceeded 4.5. Effects were consistent regardless of sample severity, sample age groups, or follow-up length.

CONCLUSIONS

Prior SITBs confer risk for later suicidal thoughts and behaviors. However, they only provide a marginal improvement in diagnostic accuracy above chance. Addressing gaps in study design, assessment, and underlying mechanisms may prove useful in improving prediction and prevention of suicidal thoughts and behaviors.

Occupational differences in US Army suicide rates

BACKGROUND

Civilian suicide rates vary by occupation in ways related to occupational stress exposure. Comparable military research finds suicide rates elevated in combat arms occupations. However, no research has evaluated variation in this pattern by deployment history, the indicator of occupation stress widely considered responsible for the recent rise in the military suicide rate.

METHOD

The joint associations of Army occupation and deployment history in predicting suicides were analysed in an administrative dataset for the 729 337 male enlisted Regular Army soldiers in the US Army between 2004 and 2009.

RESULTS

There were 496 suicides over the study period (22.4/100 000 person-years). Only two occupational categories, both in combat arms, had significantly elevated suicide rates: infantrymen (37.2/100 000 person-years) and combat engineers (38.2/100 000 person-years). However, the suicide rates in these two categories were significantly lower when currently deployed (30.6/100 000 person-years) than never deployed or previously deployed (41.2-39.1/100 000 person-years), whereas the suicide rate of other soldiers was significantly higher when currently deployed and previously deployed (20.2-22.4/100 000 person-years) than never deployed (14.5/100 000 person-years), resulting in the adjusted suicide rate of infantrymen and combat engineers being most elevated when never deployed [odds ratio (OR) 2.9, 95% confidence interval (CI) 2.1-4.1], less so when previously deployed (OR 1.6, 95% CI 1.1-2.1), and not at all when currently deployed (OR 1.2, 95% CI 0.8-1.8). Adjustment for a differential 'healthy warrior effect' cannot explain this variation in the relative suicide rates of never-deployed infantrymen and combat engineers by deployment status.

CONCLUSIONS

Efforts are needed to elucidate the causal mechanisms underlying this interaction to guide preventive interventions for soldiers at high suicide risk.

Understanding the elevated suicide risk of female soldiers during deployments

BACKGROUND

The Army Study to Assess Risk and Resilience in Servicemembers (Army STARRS) has found that the proportional elevation in the US Army enlisted soldier suicide rate during deployment (compared with the never-deployed or previously deployed) is significantly higher among women than men, raising the possibility of gender differences in the adverse psychological effects of deployment.

METHOD

Person-month survival models based on a consolidated administrative database for active duty enlisted Regular Army soldiers in 2004-2009 (n = 975,057) were used to characterize the gender × deployment interaction predicting suicide. Four explanatory hypotheses were explored involving the proportion of females in each soldier's occupation, the proportion of same-gender soldiers in each soldier's unit, whether the soldier reported sexual assault victimization in the previous 12 months, and the soldier's pre-deployment history of treated mental/behavioral disorders.

RESULTS

The suicide rate of currently deployed women (14.0/100,000 person-years) was 3.1-3.5 times the rates of other (i.e. never-deployed/previously deployed) women. The suicide rate of currently deployed men (22.6/100,000 person-years) was 0.9-1.2 times the rates of other men. The adjusted (for time trends, sociodemographics, and Army career variables) female:male odds ratio comparing the suicide rates of currently deployed v. other women v. men was 2.8 (95% confidence interval 1.1-6.8), became 2.4 after excluding soldiers with Direct Combat Arms occupations, and remained elevated (in the range 1.9-2.8) after adjusting for the hypothesized explanatory variables.

CONCLUSIONS

These results are valuable in excluding otherwise plausible hypotheses for the elevated suicide rate of deployed women and point to the importance of expanding future research on the psychological challenges of deployment for women.

[The epidemiology of ADHD in first-year university students]

BACKGROUND

Little is known about the epidemiology of attention-deficit/hyperactivity disorder (ADHD) in university students.

AIM

To investigate the prevalence of adult ADHD and comorbid psychiatric symptoms and their effect on the academic performance of first-year university students, and to find out to what extent these students make use of the mental health services of the university.

METHOD

All first-year students at the University of Leuven in Belgium were asked to complete a computer-assisted survey with a weighted cross-sectional design (n=4,921, response rate=65.4%). The ADHD of these students was measured with the help of the ADHD Self-Report Scale (ASRS-6).

RESULTS

On the basis of the threshold used, we found that between 1.4 and 8.3% of the entire population of first-year students met the criteria for ADHD. Even after controlling for sociodemographic variables, we found that ADHD was associated with a wide range of emotional problems including suicide attempts (OR=9.10; Cohen's d=0.53), binge eating (OR=5.87; Cohen's d=0.42), or psychotic symptoms (ORS 4.44-4.69; Cohen's d=0.36-0.37). Students with ADHD were 2.46-3.84 times more likely to have a total grading percentage below 50 at the end of the academic year. Current use and lifetime use of the professional mental health services were estimated in the 7.6-15.5% and 26.5-41.5% range, respectively.

CONCLUSION

Adult ADHD is common among first-year university students and is associated with comorbid psychiatric symptoms and poor academic performance. It is therefore surprising that so few students actually receive treatment for their psychiatric and emotional problems.

Sociodemographic and career history predictors of suicide mortality in the United States Army 2004-2009

BACKGROUND

The US Army suicide rate has increased sharply in recent years. Identifying significant predictors of Army suicides in Army and Department of Defense (DoD) administrative records might help focus prevention efforts and guide intervention content. Previous studies of administrative data, although documenting significant predictors, were based on limited samples and models. A career history perspective is used here to develop more textured models.

METHOD

The analysis was carried out as part of the Historical Administrative Data Study (HADS) of the Army Study to Assess Risk and Resilience in Servicemembers (Army STARRS). De-identified data were combined across numerous Army and DoD administrative data systems for all Regular Army soldiers on active duty in 2004-2009. Multivariate associations of sociodemographics and Army career variables with suicide were examined in subgroups defined by time in service, rank and deployment history.

RESULTS

Several novel results were found that could have intervention implications. The most notable of these were significantly elevated suicide rates (69.6-80.0 suicides per 100 000 person-years compared with 18.5 suicides per 100 000 person-years in the total Army) among enlisted soldiers deployed either during their first year of service or with less than expected (based on time in service) junior enlisted rank; a substantially greater rise in suicide among women than men during deployment; and a protective effect of marriage against suicide only during deployment.

CONCLUSIONS

A career history approach produces several actionable insights missed in less textured analyses of administrative data predictors. Expansion of analyses to a richer set of predictors might help refine understanding of intervention implications.

War and first onset of suicidality: the role of mental disorders

BACKGROUND

Suicide rates increase following periods of war; however, the mechanism through which this occurs is not known. The aim of this paper is to shed some light on the associations of war exposure, mental disorders, and subsequent suicidal behavior.

METHOD

A national sample of Lebanese adults was administered the Composite International Diagnostic Interview to collect data on lifetime prevalence and age of onset of suicide ideation, plan, and attempt, and mental disorders, in addition to information about exposure to stressors associated with the 1975-1989 Lebanon war.

RESULTS

The onset of suicide ideation, plan, and attempt was associated with female gender, younger age, post-war period, major depression, impulse-control disorders, and social phobia. The effect of post-war period on each type of suicide outcome was largely explained by the post-war onset of mental disorders. Finally, the conjunction of having a prior impulse-control disorder and either being a civilian in a terror region or witnessing war-related stressors was associated with especially high risk of suicide attempt.

CONCLUSIONS

The association of war with increased risk of suicidality appears to be partially explained by the emergence of mental disorders in the context of war. Exposure to war may exacerbate disinhibition among those who have prior impulse-control disorders, thus magnifying the association of mental disorders with suicidality.

Lifetime prevalence of suicide ideation, plan, and attempt in metropolitan China

OBJECTIVE

This is the first community-based epidemiological study examining the prevalence of suicidal behaviors, their transitional pathways, and their relationship with mental disorders in metropolitan China.

METHOD

Suicidal behaviors, including ideation, plans, and attempts were assessed by face-to-face household interviews among 5201 respondents in Beijing and Shanghai in 2001-2002. Lifetime prevalence and risk factors were examined using multivariate discrete-time survival models.

RESULTS

The lifetime prevalence estimates of suicidal ideation, plans, and attempts were 3.1%, 0.9%, and 1.0% respectively. Among suicide ideators, the conditional probability of ever making a plan and an attempt was 29.5% and 32.3% respectively. Progression from ideation to plan and attempt was the highest during the first year after onset. Suicide attempt was predicted by young adulthood, being unmarried, recent onset of ideation and plan, and the presence of mental disorders, especially mood disorder.

CONCLUSION

Suicidal behaviors in metropolitan China exhibit a low prevalence and an epidemiological profile resembling that found in Western countries.

Examination of predictors of severe violence in combat-exposed Vietnam veterans

This study examined several proposed predictors of severe wartime violence in a randomly selected, nationally representative sample of 1,125 Vietnam veterans. Participation in severe acts of violence during wartime was reported by 7.6% of the sample. Disruptive behavior before the age of 15 and increased combat exposure were both significant predictors of severe wartime violence. Childhood contextual factors were indirectly related to severe wartime violence via prewar disruptive behavior. The classification rate of perpetrators of severe violence was comparable to rates from studies of less severe forms of violence. The implications of these results and suggestions for future research in this area are discussed.

Multimethod assessment of suicidality in adolescent psychiatric inpatients: preliminary results

OBJECTIVE

To examine agreement among multiple assessments of adolescent suicidal ideation and suicidal behavior for adolescent psychiatric inpatients, including pencil/paper checklists; structured and unstructured interviews; and adolescent, clinician, and parent reports, and to provide suggestions for the accurate and reliable assessment of suicidality in adolescence.

METHOD

Participants included 153 adolescent psychiatric inpatients (54 boys, 99 girls) between the ages of 12 and 17 years. Measurement of suicidal ideation and behavior included common assessment instruments and standard clinical practices, including the Suicidal Ideation Questionnaire, NIMH Diagnostic Interview Schedule for Children, clinician interview, and parent report (Behavior Assessment Scale for Children).

RESULTS

Results revealed significantly different rates of suicidality across each instrument and poor to moderate agreement between similar measures of adolescent suicidal ideation and suicidal behavior. Agreement between measures was generally best for boys, for older adolescents, and for assessments relying on a single informant. Reporters were most likely to agree on the presence of suicidality for more severely suicidal adolescents; this finding suggests that agreement in itself may be a useful marker for adolescent suicide.

CONCLUSIONS

Results of this preliminary study supported the use of multiple measurement approaches when examining adolescent suicidality, particularly those that rely on clinician judgment and adolescents' own reports. Implications for future research and for clinical practice are also discussed.

Ambient temperature and mortality from unintentional cocaine overdose

CONTEXT

Hot weather taxes cardiovascular function and is associated with increased deaths from heart disease. Cocaine can cause hypertension, tachycardia, coronary vasospasm, arrhythmias, and increased core temperature.

OBJECTIVE

To determine the association between mortality from cocaine overdose and hot weather.

SETTING

New York, NY.

DESIGN

Retrospective review of medical examiner cases from 1990 through 1995.

SUBJECTS

All fatal unintentional cocaine overdoses from 1990 through 1992 (n = 1382) and all hyperthermia deaths of cocaine users (n = 10) were used to identify a maximum daily temperature threshold above which mortality from cocaine intoxication increased. The study population consisted of all fatal unintentional cocaine overdoses from 1993 through 1995 (n = 2008) and 4 contemporaneous comparison groups that included fatal unintentional opiate overdoses (n = 793), all other fatal unintentional overdoses (n = 85), and a subset of homicides (n = 4638) and fatalities from motor vehicle crashes (n = 815).

MAIN OUTCOME MEASURES

The number of overdose deaths and the proportion of homicides and traffic fatalities with a positive cocaine toxicology test result on days with a maximum temperature above or below the temperature threshold.

RESULTS

A threshold temperature of 31.1 degrees C (88 degrees F) was identified, above which the mean daily number of fatal cocaine overdoses increased steadily. On days with a maximum daily temperature of 31.1 degrees C (88 degrees F) or higher ("hot days"), the mean daily number of cocaine overdose deaths was 2.34 (SD = 1.68), which was 33% higher than the mean on days with a maximum temperature of less than 31.1 degrees C (88 degrees F) (mean = 1.76 [SD=1.37] (P<.001). In contrast, the mean number of opiate overdose deaths per day was 0.81 (SD = 0.94) on hot days and 0.71 (SD = 0.86) on other days (P=.28). For other drug overdose deaths, the mean number of deaths per day was 0.08 (SD = 0.28) on hot days and 0.08 (SD = 0.28) on other days (P=.69). Among homicides, the proportion with a positive cocaine toxicology test result was 18.9% on hot days and 19.5% on other days (P=.69), and among traffic fatalities, the proportions with positive cocaine toxicology test results were 9.5% on hot days and 10.3% on other days (P=.91).

CONCLUSIONS

High ambient temperature is associated with a significant increase in mortality from cocaine overdose. Based on our comparison groups, the increase is not explained by changes in cocaine use among the general population. Although cocaine use is dangerous on all days, it appears to be even more dangerous on hot days.