Biomedical subjects

Richard Clayton

Publications and source records attributed to Richard Clayton.

8 recordsLinked to original sources

PubMed2005

The proximal association between smoking and alcohol use among first year college students.

OBJECTIVE: This study was undertaken to evaluate the association between patterns of day-to-day smoking and drinking among first year college students. METHOD: Using 210 days of weekly time-line follow-back diary data, the authors examined the within-person relationships between smoking and drinking. Bivariate time series procedures were utilized. RESULTS: Findings revealed a high degree of significant cross-correlations between smoking and drinking in which the amount of use of one substance could be predicted by current, as well as past and future use of the other. For the majority of participants, smoking and drinking were positively associated with the alternate behavior. The most common pattern of prediction for individuals was within day (i.e. synchronous correlations). When examining rates of individuals showing significant cross-correlations according to their level of either smoking or drinking, those smoking less than one cigarette on average per day were found to be less likely to demonstrate a synchronous cross-correlation between the two behaviors than those smoking at higher rates. No significant association was found between level of drinking and the rate of significant synchronous cross-correlations between smoking and drinking. CONCLUSIONS: Reports of daily behavior over long periods of time have the potential to provide insight into the more proximal influences of smoking and alcohol use on one another. Future research is needed to establish the specific factors (i.e. third variables) and related mechanisms that may drive both behaviors.

Adolescent↗

PubMed2004

The eVALuate study: two parallel randomised trials, one comparing laparoscopic with abdominal hysterectomy, the other comparing laparoscopic with vaginal hysterectomy.

OBJECTIVE: To compare the effects of laparoscopic hysterectomy and abdominal hysterectomy in the abdominal trial, and laparoscopic hysterectomy and vaginal hysterectomy in the vaginal trial. DESIGN: Two parallel, multicentre, randomised trials. SETTING: 28 UK centres and two South African centres. PARTICIPANTS: 1380 women were recruited; 1346 had surgery; 937 were followed up at one year. Primary outcome Rate of major complications. RESULTS: In the abdominal trial laparoscopic hysterectomy was associated with a higher rate of major complications than abdominal hysterectomy (11.1% v 6.2%, P = 0.02; difference 4.9%, 95% confidence interval 0.9% to 9.1%) and the number needed to treat to harm was 20. Laparoscopic hysterectomy also took longer to perform (84 minutes v 50 minutes) but was less painful (visual analogue scale 3.51 v 3.88, P = 0.01) and resulted in a shorter stay in hospital after the operation (3 days v 4 days). Six weeks after the operation, laparoscopic hysterectomy was associated with less pain and better quality of life than abdominal hysterectomy (SF-12, body image scale, and sexual activity questionnaires). In the vaginal trial we found no evidence of a difference in major complication rates between laparoscopic hysterectomy and vaginal hysterectomy (9.8% v 9.5%, P = 0.92; difference 0.3%, -5.2% to 5.8%), and the number needed to treat to harm was 333. We found no evidence of other differences between laparoscopic hysterectomy and vaginal hysterectomy except that laparoscopic hysterectomy took longer to perform (72 minutes v 39 minutes) and was associated with a higher rate of detecting unexpected pathology (16.4% v 4.8%, P = < 0.01). However, this trial was underpowered. CONCLUSIONS: Laparoscopic hysterectomy was associated with a significantly higher rate of major complications than abdominal hysterectomy. It also took longer to perform but was associated with less pain, quicker recovery, and better short term quality of life. The trial comparing vaginal hysterectomy with laparoscopic hysterectomy was underpowered and is inconclusive on the rate of major complications; however, vaginal hysterectomy took less time.

Adult↗

PubMed2004

Early adolescent through young adult alcohol and marijuana use trajectories: early predictors, young adult outcomes, and predictive utility.

The present study takes a developmental approach to subgrouping and examines the trajectories of substance use from early adolescence through young adulthood among a community sample of 481 individuals. The patterns of use were examined, subgroups were identified separately for men and women and for alcohol and marijuana, and psychosocial predictors and psychopathology outcomes that differentiated the groups were identified. The results revealed three substantially overlapping subgroups for both alcohol and marijuana: early onset, late onset, and nonuser. Although the general patterns of which dependent variables were related to group were similar for alcohol and marijuana, a closer examination revealed important subgroup differences. For alcohol use, the early-onset group was more dysfunctional in terms of predictors and outcomes whereas the late-onset and nonuser groups were better adjusted. In contrast, for marijuana, the early- and late-onset groups were both more dysfunctional than the nonuser group. In a final analysis, we examined the predictive utility of our developmental approach to subgrouping compared to a traditional, static approach.

Adolescent↗

PubMed2003

Development of a new application apparatus for entomopathogenic nematodes.

This paper describes the assessment of nematode spray application methods and details the redesign of a spinning disc applicator for the improved application of the infective juveniles of entomopathogenic nematodes to foliage. The assessment highlighted fundamental design features that prevent efficient and accurate nematode application and these are dealt with in turn specifically to enable improved nematode application. The redesigned or prototype spinning disc was shown to improve nematode carriage in droplets, leading to greater deposition of nematodes per unit area. There is a trade-off between spray droplet coverage of the target surface and the production of a suitable droplet spectrum for nematode carriage.

Animals↗

PubMed2003

Relation between childhood disruptive behavior disorders and substance use and dependence symptoms in young adulthood: individuals with symptoms of attention-deficit/hyperactivity disorder and conduct disorder are uniquely at risk.

Most prior literature examining the relations among attention-deficit/hyperactivity disorder (ADHD), conduct disorder (CD), and substance use and abuse suggests that CD fully account for the ADHD-substance abuse relation. This study sought to test an alternate theory that individuals with symptoms of both ADHD and CD are at a special risk for substance abuse. Relations between childhood ADHD and CD symptoms, and young adult tobacco, alcohol, marijuana, and hard drug use and dependence symptoms, were examined in a sample of 481 young adults. ADHD and CD symptoms interacted to predict marijuana dependence symptoms and hard drug use and dependence symptoms, such that individuals with high levels of both ADHD and CD had the highest levels of these outcomes.

Adult↗

PubMed2003

Prices, policies and youth smoking, May 2001.

Youth smoking continues to be an important public health problem. Many policy tools designed to reduce youth smoking are based on economic principles. This paper describes the economic and policy context of tobacco use aiming at reducing youth smoking and explains the economic rationale for tobacco control tools such as excise tax and price, clean indoor air laws, youth access laws and the broad provision of health information to the public. An overview of economic models of addiction provides the framework for empirical analysis of the impact of these policies. This is followed by a summary of the empirical evidence of the effectiveness of various tobacco control tools that are primarily economic in nature. The most consistent finding in this literature is that higher cigarette prices discourage youth smoking. Compared to the effects of cigarette taxation and price on youth smoking, the evidence on the effectiveness of the youth access laws and clean indoor air laws are still mixed and inconclusive. More research is needed to address issues such as: (1) the effects of gender, age, race and socio-economic status on the relationship between tobacco control policies and youth smoking; (2) better measurement of the outcome variables to account for the multi-dimensional nature of dependence; and (3) the effects of excise taxes and other tobacco control policies with regard to a host of dimensions of smoking such as initiation, cessation, and more generally the trajectories of tobacco use that would include patterns of progression, maintenance, regression, cessation, and relapse. More frequently collected longitudinal data than those currently available are needed to address the above issues. Understanding smoking behavior cannot be achieved without incorporating familial and other social contexts.

Adolescent↗

PubMed2002

The relations among personality, symptoms of alcohol and marijuana abuse, and symptoms of comorbid psychopathology: results from a community sample.

This study examined the relation of the Five-Factor Model (FFM) of personality to symptoms of alcohol and marijuana abuse before and after controlling for symptoms of antisocial personality disorder (APD) and internalizing psychopathology. The 481 participants completed a well-validated measure of the FFM and a structured diagnostic interview at age 21 years. Hierarchical regression analyses indicated that unique constellations of personality characteristics were associated with symptoms of alcohol abuse, marijuana abuse, APD, and internalizing disorders. For example, symptoms of alcohol abuse were associated with high Extraversion and low Conscientiousness, whereas symptoms of marijuana abuse were characterized by low Extraversion and high Openness to Experience. Findings have implications for models of the etiology and treatment of substance use and abuse.

Adult↗

PubMedDate not supplied

Drug use and AIDS: estimating injection prevalence in a rural state.

This paper presents approaches used in one rural U.S. state to describe the level of injecting drug use and to estimate the number of injectors not receiving drug-user treatment. The focus is on two broad areas of estimation that were used to present the prevalence of injecting drug use in Kentucky. The first estimation approach uses available data from secondary data sources. The second approach involves three small community studies.

Acquired Immunodeficiency Syndrome↗