Patient-specific predictions for clinical decision-making

There are many ways in which clinicians make decisions regarding therapy for an individual patient. Invariably, the decision is supplemented by collateral information which is obtained from clinical trials. Prospective and retrospective clinical studies take an unnecessary adversarial position but each method has its place. Parametric survival analysis can produce patient-specific predictions of an event of interest for an individual patient based on the risk factor profile of that patient, and these methods are just as applicable to prospective clinical studies as they are to retrospective clinical studies. Parametric survival analysis can estimate the distribution of time to an event, estimate the phases of hazard (instantaneous risk of the event), determine risk factors associated with the event in each of the identified phases of risk, predict the time-related probability of an event for a specific patient based on his or her risk factor profile, and by risk adjustment compare the effectiveness of different therapies.     

Changing predictors of map use in wayfinding.

Differential predictors of route map use in wayfinding by 48 48–63-month-olds vs 46 64–79-month-olds were tested. Predictors of map use should shift from landmark to array encoding, from mental rotation of 1 element to array rotation, and from direct perception of an array to recall. Landmark and array encoding and array rotation were measured by duplication of placements on an array when 2 arrays were aligned or 1 was rotated 180°. Matching a rotated letterlike form to a standard gauged single-element rotation; recall of landmark locations after their removal from an array indexed memory. Each rotation task and landmark placements predicted the younger children's map scores; array encoding, single-element rotation, and recall predicted older children's map errors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ecological predictors of substance use in middle school students.

The current study examined important predictors of substance use during early adolescence. The authors hypothesized that adolescents' relationships with key adults (i.e., teachers and parents) influence their choices to use substances indirectly through links with their decisions regarding peer groups. A total of 461 middle school students from an affluent suburban community completed self-report measures of authoritative parenting, perceived social support from teachers, affiliation with rule-breaking and substance-using peers, and frequency of alcohol, cigarette, and drug use. Results of structural equation modeling supported the hypothesized model. Authoritative parenting and teacher support accounted for 31% of the variance in affiliation with deviant peers which, in turn, accounted for 27% of the variance in adolescent substance use; direct paths from parenting and teacher support to substance use were not indicated. Implications for school psychologists' involvement in substance use prevention and intervention are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Illicit substance use among adolescents: a matrix of prospective predictors

This paper reviews findings from 58 prospective studies of illicit substance use (ISU) among adolescents. It arranges 384 findings according to three types of influence (viz., social, attitudinal, and intrapersonal) and four levels of influence (viz., ultimate, distal, proximal, and immediate). The bulk of evidence reconfirms the importance of several predictors of ISU (e.g., intentions and prior substance-related behavior, friendship patterns and peer behaviors, absence of supportive parents, psychological temperament), reveals that a few variables thought to be well-established predictors may not be (e.g., parental behaviors, parental permissiveness, depression, low self-esteem), and uncovers several variables where findings were either sparse or inconsistent (e.g., the role of public policies concerning ISU, mass media depictions of ISU, certain parenting styles, affective states, perceptions of parental disapproval for ISU, and substance-specific refusal skills). Directions for future research are discussed.     

Economic regulation of ambulance services in California

OBJECTIVE: This study was intended to identify economic regulatory programs used by California counties (including ambulance franchising and rate setting), to inventory their foci and application, and to identify differences around the state. By studying the variety of programs used in one state, this study establishes a framework for evaluation of state and local regulatory programs elsewhere. METHODS: This study surveyed all California local EMS agencies (LEMSAs); these are California's equivalent of regional EMS organizations. The survey achieved a 100% response rate, and all data involve population parameters obviating the need for inferential statistics. RESULTS: Seventy-three percent of California counties use economic regulations. Large-population counties and those that operate their own LEMSAs are more likely to use economic regulations than are small counties and those that participate in multicounty EMS agencies. Despite a preference for competition in the authorizing statute, most franchises were granted without competition to existing providers. The majority of franchises in the state were granted to public services. Most ambulance rate setting occurs outside of a competitive process. CONCLUSIONS: Economic regulations that were intended to provide a structured marketplace are often being used to protect existing providers, particularly public services, from competition. The growing interest by fire departments in entering the market for emergency ambulance service, along with the existing bias toward them in granting of franchises, does not bode well for use of the competitive process. The growth of managed care may change or eliminate the need for economic regulations but, if they are to continue, more state oversight should be considered.     

Memory activation and expectancy as prospective predictors of alcohol and marijuana use.

This study examined whether indicators of drug-related memory associations predicted drug use prospectively. The predictive effects of outcome expectancies, sensation seeking, and other variables also were investigated. The results revealed that the memory association measures significantly predicted subsequent drug use. Outcome expectancies and sensation seeking predicted alcohol use, but not marijuana use. The findings suggest 2 possibly different aspects of cognition involved in drug use motivation: (a) a memory activation or implicit cognition component, representing the effects of memory associations that are prompted relatively spontaneously by the prevailing motivational and situational circumstances and (b) an outcome expectancy component, which is more likely to reflect explicit cognitions involved in introspection and deliberate decision-making processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A two-year study of patterns and predictors of substance use among Mexican American youth

This study investigated the incidence and patterns of substance use in a school-age population, as well as predictive risk factors that may play an important role in understanding its initiation. Low socioeconomic status Mexican American fourth-, fifth-, and sixth-grade students were surveyed for two consecutive years in order to obtain information on their substance use and its relationship to specific demographic, environmental, and psychological risk factors. Results capture patterns of substance use among this population over the two years, as well as the relationship between reported risk factors in year one and the use of minor and major substances in year two.     

Using systems performance data for ambulance management

The ambulance service is an important component in the emergency medical system of a community. The availability of performance information on several aspects of the ambulance system may improve ambulance management. The location of new ambulance stations, selection of the destination hospital for urgent cases, scheduling of crew changes, and evaluation of crew performance can be approached through an examination of existing data. Management use of such an information system by the Victorian Civil Ambulance Service in Melbourne, Australia is included in the discussion.     

Memory association and personality as predictors of alcohol use: mediation and moderator effects

We investigated the nature of the effects of memory associations on alcohol use and abuse. First, we determined if effects of memory associations on drinking problems are mediated entirely through the frequency of alcohol consumption or, alternatively, if such effects are more direct. Second, personality traits were assessed to evaluate whether they were confounded with memory association in their effects or whether they might moderate the effects of memory associations on alcohol use and abuse. The results showed that memory association measures directly and independently predicted alcohol consumption; these measures indirectly predicted problems from drinking, including drunk driving. None of the assessed personality variables moderated the predictive effects of memory association. The results are consistent with the view that memory associations influence behavior through cognitive processes that are not affected by personality traits or by cognitions emanating from such traits.     

Psychological and social predictors of motorcycle use by young adult males in New Zealand

Motorcycle riding is a significant cause of serious injuries to young males. Little is known about the psychological and social characteristics of these riders, despite such knowledge being potentially important for the targeting of appropriate injury prevention interventions. Using problem-behaviour theory to broadly guide and structure the research, the present study focused on identifying predictors of motorcycle riding. Previous research investigating differences between riders and non-riders has tended to be inconclusive, methodologically limited, and lacking in explicit theoretical foundations. The present research was based on the birth cohort enrolled in the Dunedin Multidisciplinary Health and Development Study (DMHDS), a comprehensive New Zealand longitudinal study of health, development, attitudes, and behaviours. Logistic regression models were built using prior measures of health risk behaviour, other psychological and social factors, and motorcycle riding history as potential predictors of any motorcycle use at the age of 18 years. The strongest predictors were early motorcycle riding, including illegal on-road driving at age 13 (OR 4.0; 95% CI 1.7, 9.1), below average reading skills (OR 2.4; 95% CI 1.3, 4.6) and fighting in a public place at age 15 (OR 2.9; 95% CI 1.2, 6.9). It was of particular interest that this profile tended to fit less well those subgroups of riders with greatest exposure to on-road motorcycle driving. Although based on small numbers, this finding was consistent with earlier cross-sectional research that linked casual and unlicensed driving with less protective motorcycling opinions and behaviours. Some implications for injury prevention and public policies regarding motorcycling are discussed. In particular, stricter enforcement of present licensing regulations and stronger penalties for their violation could help to reduce the number of less responsible riders.     

Comparison of indirect assessments of association as predictors of marijuana use among at-risk adolescents.

In this study, the authors compared indirect measures that attempt to quantify the level of marijuana associations among adolescents. They also evaluated whether these various methods overlap or tap different aspects of associative processes that may act in concert to influence marijuana use. Automatic drug-relevant associations were assessed in 121 at-risk youth in continuation high schools in California with the use of a word association index and computer-based, reaction time measures (i.e., Implicit Association Test [IAT] and Extrinsic Affective Simon Task [EAST]). Measures of working memory capacity, sensation seeking, and explicit cognitions also were included in analyses as potential confounders. The word association index and the marijuana IAT excited D measure were significant predictors of marijuana use. The word association index accounted for more variance in marijuana use than did the IAT or EAST measures. Further, confirmatory factor analytic models of the indirect measures of marijuana use revealed a significant moderate correlation between the EAST Excitement and Word Association factors but no significant correlations between the Word Association and IAT factors. These findings suggest that there is some convergence among the different indirect measures, but these assessments also appear to tap different aspects of associative processes. The types of indirect measures evaluated in this work provide information about spontaneous cognitions related to substance use, capturing influences on behavior that are not evaluated with traditional explicit assessments of behavior. Findings from this work add to a growing body of research that implicates the importance of implicit associative processes in risk and health behaviors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Childhood predictors of adolescent substance use in a longitudinal study of children with ADHD.

Children diagnosed with attention-deficit hyperactivity disorder (ADHD; n=142) were prospectively monitored into adolescence (13-18 years old) to evaluate their risk for elevated substance use relative to same-aged adolescents without ADHD (n=100). Probands reported higher levels of alcohol, tobacco, and illicit drug use than did controls. Group differences were apparent for alcohol symptom scores but not for alcohol or marijuana disorder diagnoses. Within probands, severity of childhood inattention symptoms predicted multiple substance use outcomes; childhood oppositional defiant disorder/conduct disorder (ODD/CD) symptoms predicted illicit drug use and CD symptoms. Persistence of ADHD and adolescent CD were each associated with elevated substance use behaviors relative to controls. Further study of the mediating mechanisms that explain risk for early substance use and abuse in children with ADHD is warranted. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive motivations for drug use among adolescents: Longitudinal tests of gender differences and predictors of change in drug use.

Four factors were found to reflect 15 reasons for drug use, Enhance Positive Affect and Creativity, Reduce Negative Affect, Social Cohesion, and Addiction. These factors were found to reflect second-order latent factors of Alcohol Motivations as well as Cannabis Motivations and to be invariant by sex. All Alcohol and Cannabis Motivation scales were significantly correlated with actual use of alcohol, cannabis, cocaine, and hard drugs. In both bivariate and latent variable longitudinal analyses over a 1-yr period, motivations for alcohol use increased actual use of alcohol, whereas motivations for cannabis use increased all types of drug use. Very similar patterns of effects were noted for boys and girls. We conclude that self-acknowledged cognitive motivations or reasons for drug use are important etiological factors in understanding actual drug-use behavior and discuss the counseling and prevention implications of these results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stages and processes of change as predictors of drug use among methadone maintenance patients.

In this study the authors evaluated the predictive validity of stages-of-change and processes-of-change measures among methadone maintenance patients. One month after treatment entry, participants completed questionnaires providing stage and process scale scores regarding readiness to discontinue polydrug use. Participants also completed an algorithm assigning them to a stage category on the basis of their stated intentions regarding quitting. The algorithm predicted urinalysis results during a 12-week posttest period; however, only 1 stage scale (contemplation) and no process scales correlated significantly with outcome. In a hierarchical regression, stage and process scale scores significantly improved prediction of posttest abstinence beyond that afforded by baseline drug-free urine rates, but this effect was attributable to the contemplation scale alone. Despite their widespread use, stage and process scales have yet to demonstrate clearly predictive validity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Personality, social environment, and past behavior as predictors of late adolescent alcohol use

Personality, as measured by subscales of the Sensation Seeking Scale (Zuckerman, 1979), social environmental exposure to alcohol use measured by parental and peer alcohol use, and past alcohol use were examined as predictors of late adolescent alcohol use in a sample of 575 1st-year college students. Efficacious predictors, in order of importance, include peer alcohol use, disinhibition, and age of first intoxication. The results support the relative importance of peer networks over parental models in determining late adolescent alcohol use. Our combinatorial model of personality, social environment, and past behavior is one such model in a growing trend toward the use of interactional models for predicting behavior.