Russell C. Callaghan

Increased risk of Parkinson's disease in individuals hospitalized with conditions related to the use of methamphetamine or other amphetamine-type drugs

BACKGROUND Since methamphetamine and other amphetamine-type stimulants (meth/amphetamine) can damage dopaminergic neurons, researchers have long speculated that these drugs may predispose users to develop Parkinsons disease (PD), a dopamine deficiency neurological disorder. METHODS We employed a retrospective population-based cohort study using all linked statewide California inpatient hospital episodes and death records from January 1, 1990 through December 31, 2005. Patients at least 30 years of age were followed for up to 16 years. Competing risks analysis was used to determine whether the meth/amphetamine cohort had elevated risk of developing PD (ICD-9 332.0; ICD-10 G20) in comparison to a matched population-proxy appendicitis group and a matched cocaine drug control group. Individuals admitted to hospital with meth/amphetamine-related conditions (n=40,472; ICD-9 codes 304.4, 305.7, 969.7, E854.2) were matched on age, race, sex, date of index admission, and patterns of hospital admission with patients with appendicitis conditions (n=207,831; ICD-9 codes 540-542) and also individuals with cocaine-use disorders (n=35,335; ICD-9 codes 304.2, 305.6, 968.5). RESULTS The meth/amphetamine cohort showed increased risk of PD compared to both that of the matched appendicitis group [hazard ratio (HR)=1.76, 95% CI: 1.12-2.75, p=0.017] and the matched cocaine group [HR=2.44, 95% CI: 1.32-4.41, p=0.004]. The cocaine group did not show elevated hazard of PD compared to the matched appendicitis group [HR=1.04, 95% CI: 0.56-1.93, p=0.80]. CONCLUSION These data provide evidence that meth/amphetamine users have above-normal risk for developing PD.

Methamphetamine Use and Schizophrenia: A Population-Based Cohort Study in California

OBJECTIVE Clinical investigators in Japan have long suggested that exposure to methamphetamine might cause a persistent schizophrenia-like psychosis. This possibility is discounted in the Western literature. To investigate the relationship between drug use and later schizophrenia, the authors conducted a large-scale cohort study of drug users initially free of persistent psychosis. METHOD A population-based cohort study was conducted using data from California inpatient hospital discharge records from 1990 through 2000. Patients with methamphetamine-related conditions (N=42,412) and those with other drug use disorders (cannabis, cocaine, alcohol, and opioids) were propensity score-matched to individuals with primary appendicitis who served as a population proxy comparison group; the methamphetamine cohort was also matched to the other drug cohorts. Cox modeling was used to estimate differences between matched groups in the rates of subsequent admission with schizophrenia diagnoses. RESULTS The methamphetamine cohort had a significantly higher risk of schizophrenia than the appendicitis group (hazard ratio=9.37) and the cocaine, opioid, and alcohol groups (hazard ratios ranging from 1.46 to 2.81), but not significantly different from that of the cannabis group. The risk of schizophrenia was higher in all drug cohorts than in the appendicitis group. CONCLUSIONS Study limitations include difficulty in confirming schizophrenia diagnoses independent of drug intoxication and the possibility of undetected schizophrenia predating drug exposure. The studys findings suggest that individuals with methamphetamine-related disorders have a higher risk of schizophrenia than those with other drug use disorders, with the exception of cannabis use disorders. The elevated risk in methamphetamine users may be explained by shared etiological mechanisms involved in the development of schizophrenia.

Incidence of Parkinson's disease among hospital patients with methamphetamine-use disorders.

Because methamphetamine exposure to experimental animals can damage brain dopamine neurones, we examined whether hospital patients diagnosed with methamphetamine‐related disorders might have greater risk of subsequent admission with a Parkinsons disease diagnosis. This was a population‐based cohort study using all statewide inpatient hospital discharge records from July 1, 1990, through June 30, 2000, in California, USA, in which subjects aged at least 50 years were followed for up to 10 years. Individuals with reported methamphetamine‐related conditions (n = 1,863; ICD‐9 codes 304.4, 305.7, 969.7, and E854.2) were matched on demographic variables and follow‐up time with those with primary appendicitis conditions (n = 9,315). The appendicitis group had a Parkinsons disease incidence rate no different than the rate found among members of a large health maintenance organization in California. Cox regression procedures were used to estimate group differences in the rates of receiving a subsequent inpatient diagnosis of Parkinsons disease (ICD‐9 332.0). The methamphetamine group showed increased risk of a subsequent admission with Parkinsons disease compared with that of the matched appendicitis group (adjusted hazard ratio = 2.65, 95% CI, 1.17–5.98, P= 0.019). Study limitations include a population limited to hospital admissions, an uncertainty regarding diagnostic validity of the ICD‐9 code 332.0 (Parkinsons disease), and a small number of incident cases with suspected Parkinsons disease. We strongly emphasize the preliminary nature of the findings. Nevertheless, these data, requiring replication, provide some evidence that methamphetamine users might be at greater than normal risk for developing Parkinsons disease.

Gender differences in detoxification: predictors of completion and re-admission.

This study examined the medical records of 2595 consecutive admissions over a 3-year period to an inpatient mixed-gender, hospital-based alcohol and drug detoxification unit. Women reported a significantly different pattern of primary drug use, a younger age, a different pattern of referral sources, and higher rates of parenting status and unemployment. In addition, females were administered prescription medication and medical evaluation tests at a significantly higher rate than males. Multiple regression analyses demonstrated that an opiate as a primary drug of choice was a significant risk factor for dropout. Risk factors for re-admission to inpatient detoxification included: alcohol as a primary drug of choice, residential instability, multiple drug use, single marital status, unemployment, an older age (> 37 years), and treatment dropout at Time 1 in the study. For both the final prediction models, gender was not a significant factor. The treatment implications of these findings are discussed.

The incidence of cardiovascular morbidity among patients with bipolar disorder: A population-based longitudinal study in Ontario, Canada

BACKGROUND Despite the high rates of cardiovascular risk factors among people with bipolar disorder, little is known about the incidence of cardiovascular morbidity in this population. METHODS Based upon Ontario, Canada hospital discharge records from April 1, 2002 to March 31, 2006, we constructed a population-based cohort study to assess whether individuals diagnosed with bipolar disorder (n=5999) would have a significantly greater risk of subsequent readmission with a cardiovascular condition in comparison to a matched population-proxy group of individuals receiving an appendicitis primary diagnosis. A Cox regression procedure was used to estimate group differences in time-to-readmission with a cardiovascular-related diagnosis. Patients were followed for a period up to 4 years. RESULTS The bipolar disorder group had a significantly greater adjusted risk of readmission for a cardiovascular event in comparison to individuals in the appendicitis group [adjusted hazard ratio (AHR)=1.66, 95% CI, 1.37-2.07, p<0.001). LIMITATIONS Current research has not confirmed the accuracy of ICD-10 bipolar diagnoses in population-based administrative files with a gold-standard diagnostic reference. Also, our study did not have access to mortality files which, given the elevated rate of mortality among patients with bipolar disorder, may have led to an underestimation of link between bipolar disorder and cardiovascular morbidity. CONCLUSIONS In light of the elevated risk of cardiovascular morbidity among persons with bipolar disorder, our findings add to the importance of screening and intervention programs for metabolic disorders and known cardiovascular risk factors among patients with bipolar disorder.

Alcohol- or drug-use disorders and motor vehicle accident mortality: A retrospective cohort study

A large body of research has linked alcohol consumption and motor vehicle accidents (MVAs), but far fewer studies have estimated the risk of MVA fatality among drug users. Our study addresses this gap. We identified cohorts of individuals hospitalized in California from 1990 to 2005 with ICD-9 diagnoses of methamphetamine- (n=74,170), alcohol- (n=592,406), opioids- (n=68,066), cannabis- (n=47,048), cocaine- (n=48,949), or polydrug-related disorders (n=411,175), and these groups were followed for up to 16 years. Age-, sex-, and race-adjusted standardized mortality rates (SMRs) for deaths due to MVAs were generated in relation to the California general population. Standardized MVA mortality ratios were elevated across all drug cohorts: alcohol (4.5, 95% CI, 4.1-4.9), cocaine (3.8, 95% CI, 2.3-5.3), opioids (2.8, 95% CI, 2.1-3.5), methamphetamine (2.6, 95% CI, 2-3.1), cannabis (2.3, 95% CI, 1.5-3.2) and polydrug (2.6, 95% CI, 2.4-2.9). Males and females had similar MVA SMRs. Our large, population-based study found elevated risk of MVA mortality across all cohorts of individuals with alcohol- or drug-use disorders. Given that illicit drug users are often unaware of or misperceive the impacts of drug use on safe driving, it may be important for health-service or public-health interventions to address such biases and improve road safety.

Prevalence of unassisted quit attempts in population-based studies: a systematic review of the literature.

AIMS The idea that most smokers quit without formal assistance is widely accepted, however, few studies have been referenced as evidence. The purpose of this study is to systematically review the literature to determine what proportion of adult smokers report attempting to quit unassisted in population-based studies. METHODS A four stage strategy was used to conduct a search of the literature including searching 9 electronic databases (PUBMED, MEDLINE (OVID) (1948-), EMBASE (1947-), CINAHL, ISI Web of Science with conference proceedings, PsycINFO (1806-), Scopus, Conference Papers Index, and Digital Dissertations), the gray literature, online forums and hand searches. RESULTS A total of 26 population-based prevalence studies of unassisted quitting were identified, which presented data collected from 1986 through 2010, in 9 countries. Unassisted quit attempts ranged from a high of 95.3% in a study in Christchurch, New Zealand, between 1998 and 1999, to a low of 40.6% in a national Australian study conducted between 2008 and 2009. In 24 of the 26 studies reviewed, a majority of quit attempts were unassisted. CONCLUSIONS This systematic review demonstrates that a majority of quit attempts in population-based studies to date are unassisted. However, across and within countries over time, it appears that there is a trend toward lower prevalence of making quit attempts without reported assistance or intervention.

Schizophrenia and the incidence of cardiovascular morbidity: A population-based longitudinal study in Ontario, Canada

OBJECTIVE Despite the high rates of cardiovascular mortality among people with schizophrenia, little is known about the incidence of cardiovascular morbidity in this population. We assessed whether individuals diagnosed with schizophrenia, in comparison to a population-proxy comparison group (comprised of individuals receiving an appendicitis-related primary diagnosis), would have a significantly greater risk of subsequent readmission to an inpatient or Emergency Department setting with a cardiovascular condition. DESIGN Using inpatient hospital discharge records from April 1, 2002 to March 31, 2006 in Ontario, Canada, we constructed a population-based cohort study of patients who were followed for a period up to 4 years. Individuals with a primary ICD-10 (F20) schizophrenia diagnosis (n=9815) were matched with persons with a primary ICD-10 appendicitis-related diagnosis (K35-37) on sex, age, average neighbourhood income level, and amount of follow-up time available. We used a Cox regression procedure to estimate group differences in time-to-readmission with a cardiovascular-related diagnosis. RESULTS Individuals in the Schizophrenia group had a significantly greater adjusted risk of readmission for a cardiovascular event in comparison to individuals in the Appendicitis group [adjusted hazard ratio (AHR)=1.43, 95% CI, 1.22-1.69]. CONCLUSIONS Given the elevated risk of cardiovascular morbidity among individuals with schizophrenia, our findings add to the importance of screening and intervention programs for metabolic disorders and known cardiovascular risk factors among patients with schizophrenia.

All-cause mortality among individuals with disorders related to the use of methamphetamine: A comparative cohort study

BACKGROUND Understanding the mortality rate of methamphetamine users, especially in relation to other drug users, is a core component of any evaluation of methamphetamine-related harms. Although methamphetamine abuse has had a major impact on United States (U.S.) drug policy and substance-abuse treatment utilization, large-scale cohort studies assessing methamphetamine-related mortality are lacking. METHODS The current study identified cohorts of individuals hospitalized in California from 1990 to 2005 with ICD-9 diagnoses of methamphetamine- (n=74,139), alcohol- (n=582,771), opioid- (n=67,104), cannabis- (n=46,548), or cocaine-related disorders (n=48,927), and these groups were followed for up to 16 years. Age-, sex-, and race-adjusted standardized mortality rates (SMRs) were generated. RESULTS The methamphetamine cohort had a higher SMR (4.67, 95% CI 4.53, 4.82) than did users of cocaine (2.96, 95% CI 2.87, 3.05), alcohol (3.83, 95% CI 3.81, 3.85), and cannabis (3.85, 95% CI 3.67, 4.03), but lower than opioid users (5.71, 95% CI 5.60, 5.81). CONCLUSIONS Our study demonstrates that individuals with methamphetamine-use disorders have a higher mortality risk than those with diagnoses related to cannabis, cocaine, or alcohol, but lower mortality risk than persons with opioid-related disorders. Given the lack of long-term cohort studies of mortality risk among individuals with methamphetamine-related disorders, as well as among those with cocaine- or cannabis-related conditions, the current study provides important information for the assessment of the comparative drug-related burden associated with methamphetamine use.

Use of contraband cigarettes among adolescent daily smokers in Canada

Current tobacco-control strategies seek to inhibit and reduce smoking among adolescents. However, such strategies are probably undermined by the contraband tobacco market. Using data from Canada’s 2006/2007 Youth Smoking Survey, we found that 13.1% of respondents who were daily smokers reported that contraband cigarettes were their usual brand. They consumed significantly more cigarettes than respondents who smoked other brands. Contraband cigarettes accounted for about 17.5% of all cigarettes smoked by adolescent daily smokers in Canada overall, and for more than 25% in the provinces of Ontario and Quebec.