How to use structural equation modeling in medical education research: a brief guide

BACKGROUND

Structural equationmodeling (SEM) is a family of statistical techniques used for the analysis of multivariate data to measure latent variables and their interrelationships. SEM has potential to advance theory and research in medical education.

PURPOSE

The purpose of this article is to introduce SEM to medical education researchers and provide procedural information for applying SEM.

METHODS

We outline the basic tenets of SEM, principles of model creation, identification, estimation, and model fit to data, and the use of SEM in medical education research.

RESULTS

Although it is a powerful statistical research tool, SEM has had only limited use in medical education research. We explicate a five-step procedure for applying SEM to research problems and summarize an example of SEM to test a hypothetical model.

CONCLUSIONS

Notwithstanding some pitfalls, SEM does provide promise for testing complex, integrated theoretical models and advance research in medical education.

Predictors of quality of life in old age: A cross-validation study

A replication study was undertaken to validate a model of quality of life (QOL) generated in an earlier study on a random sample of 202 older adults. Pathways found to be significant were retested using QOL data from a convenience sample of 420 older adults. Using path analysis, we found that financial resources, health, and meaning in life directly and positively influenced QOL. Health, emotional support, and the physical environment indirectly affected QOL through purpose in life. All but one pathway were replicated, explaining 50.5% of the variance in QOL. Further explorations of the influence of spirituality, emotionally close ties, and opportunities for active engagement on QOL in older age are warranted.

Multiple imputation using an iterative hot-deck with distance-based donor selection

Hot-deck imputation offers advantages in reflecting salient features of data distributions in missing-data problems, but previous implementations have lacked the appeal associated with modern Bayesian statistical-computing techniques. We outline a strategy of iterative hot-deck multiple imputation with distance-based donor selection. With distance defined as a monotonic function of the difference in predictive means between cases, donors are chosen with probability inversely proportional to their distance from the donee. This method retains the implementation ease of ad hoc techniques, while incorporating the desirable features of Bayesian approaches. Special cases of our method include nearest-neighbor imputation and a simple random hot-deck. Iterating the procedure provides an analogy to Markov Chain Monte Carlo methods and is intended to mitigate dependence on starting values. Results from imputing missing values in a longitudinal depression treatment trial as well as a simulation study are presented. We evaluate how different definitions of distance, choices of starting values, the order in which variables are chosen for imputation, and the number of iterations impact inferences. We show that our measure of distance controls the tradeoff between bias and variance of our estimates. We find that inferences from the depression treatment trial are not sensitive to most definitions of distance. In addition, while differences exist between 1 iteration and 10 iterations, there are no meaningful differences between inferences based on 10 iterations and those based on 500 iterations. The choice of starting value did not have an impact on inferences but the order in which the variables were chosen for imputation was significant even after iteration.

Neuropsychological performance following staged bilateral pallidal or subthalamic nucleus deep brain stimulation for Parkinson's disease

Deep brain stimulation (DBS) has the potential to significantly reduce motor symptoms in advanced Parkinson's disease (PD). Controversy remains about non-motor effects of DBS and the relative advantages of treatment at two brain targets, the globus pallidus internus (GPi) and the subthalamic nucleus (STN). We investigated effects of DBS on neuropsychological functioning in 42 patients with advanced PD randomly assigned to receive staged bilateral DBS surgery of either the GPi or STN. Patients underwent neuropsychological assessment prior to and 6 months after unilateral surgery. Twenty-nine subsequently underwent surgery to the contralateral side and completed a second follow-up neuropsychological evaluation 15 months later. Unilateral treatment resulted in small but statistically significant reductions in performance on several measures, including verbal fluency and working memory. A similar pattern was observed after bilateral treatment. Reductions in verbal associative fluency were significant only after left-sided treatment. There were few significant differences related to treatment at the two surgical targets. Supplementary analyses suggested that decrements in select neuropsychological domains following DBS are unrelated to age or post-surgical reduction in dopaminergic medication dose. Findings are discussed with reference to possible causes of neuropsychological decline and the need for further controlled studies of specific neuropsychological effects of DBS.

A randomized clinical trial of a population- and transtheoretical model-based stress-management intervention

Stress has been associated with a variety of chronic and acute conditions and with higher use of health care services. This research reports on 18-month outcomes of a randomized clinical trial of a stress-management program based on the transtheoretical model (TTM; J. O. Prochaska & C. C. DiClemente, 1986). A national sample of 1,085 individuals participated (age range = 18-91 years, M = 55.33; 68.9% female, 31.1% male; 84.8% Caucasian; 15.2% non-Caucasian). Both the treatment and control groups received assessments at 0, 6, 12, and 18 months. In addition to the assessments, the treatment group received 3 individualized reports (0, 3, 6 months) and a manual. The 18-month assessment was completed by 778 individuals (72%). A random effects model indicated that participants completing the study in the treatment group had significantly more individuals reporting effective stress management at follow-up time points than did completers in the control group. Results also indicate that the intervention had significant effects on stress, depression, and specific stress-management behaviors. Results provide evidence for the effectiveness of this TTM population-based stress-management intervention.

Visual Fixation Patterns during Reciprocal Social Interaction Distinguish a Subgroup of 6-Month-Old Infants At-Risk for Autism from Comparison Infants

Thirty-one infant siblings of children with autism and 24 comparison infants were tested at 6 months of age during social interaction with a caregiver, using a modified Still Face paradigm conducted via a closed-circuit TV-video system. In the Still Face paradigm, the mother interacts with the infant, then freezes and displays a neutral, expressionless face, then resumes interaction. Eye tracking data on infant visual fixation patterns were recorded during the three episodes of the experiment. Using a hierarchical cluster analysis, we identified a subgroup of infants demonstrating diminished gaze to the mother's eyes relative to her mouth during the Still Face episode. Ten out of the 11 infants in this subgroup had an older sibling with autism.

Relation of emotion-related regulation to children's social competence: a longitudinal study

The differential relations of children's emotion-related regulation (i.e., effortful control and impulsivity) to their personality resiliency, adult-rated popularity, and social competence were examined in children who were 4.5-7.9 years old and who were remeasured 2 years later. Parents and teachers reported on all constructs, and children's attentional persistence was observed. Structural equation modeling was used to test the mediating role of resiliency on the relations between regulation/control and popularity using two-wave longitudinal data. The results provide some evidence of the mediating role of resiliency in the relations between effortful control and popularity, provide some evidence of bidirectional effects, and also buttress the view that emotional regulation should be differentiated into effortful and reactive forms of control.

Usability of a barcode scanning system as a means of data entry on a PDA for self-report health outcome questionnaires: a pilot study in individuals over 60 years of age

Background

Throughout the medical and paramedical professions, self-report health status questionnaires are used to gather patient-reported outcome measures. The objective of this pilot study was to evaluate in individuals over 60 years of age the usability of a PDA-based barcode scanning system with a text-to-speech synthesizer to collect data electronically from self-report health outcome questionnaires.

Methods

Usability of the system was tested on a sample of 24 community-living older adults (7 men, 17 women) ranging in age from 63 to 93 years. After receiving a brief demonstration on the use of the barcode scanner, participants were randomly assigned to complete two sets of 16 questions using the bar code wand scanner for one set and a pen for the other. Usability was assessed using directed interviews with a usability questionnaire and performance-based metrics (task times, errors, sources of errors).

Results

Overall, participants found barcode scanning easy to learn, easy to use, and pleasant. Participants were marginally faster in completing the 16 survey questions when using pen entry (20/24 participants). The mean response time with the barcode scanner was 31 seconds longer than traditional pen entry for a subset of 16 questions (p = 0.001). The responsiveness of the scanning system, expressed as first scan success rate, was less than perfect, with approximately one-third of first scans requiring a rescan to successfully capture the data entry. The responsiveness of the system can be explained by a combination of factors such as the location of the scanning errors, the type of barcode used as an answer field in the paper version, and the optical characteristics of the barcode scanner.

Conclusion

The results presented in this study offer insights regarding the feasibility, usability and effectiveness of using a barcode scanner with older adults as an electronic data entry method on a PDA. While participants in this study found their experience with the barcode scanning system enjoyable and learned to become proficient in its use, the responsiveness of the system constitutes a barrier to wide-scale use of such a system. Optimizing the graphical presentation of the information on paper should significantly increase the system's responsiveness.

Posterior parahippocampal gyrus lesions in the human impair egocentric learning in a virtual environment

Functional imaging studies have shown that the posterior parahippocampal gyrus (PHG) is involved in allocentric (world-centered) object and scene recognition. However, the putative role of the posterior PHG in egocentric (body-centered) spatial memory has received only limited systematic investigation. Thirty-one subjects with pharmacoresistant medial temporal lobe epilepsy (TLE) and temporal lobe removal were compared with 19 matched healthy control subjects on a virtual reality task affording the navigation in a virtual maze (egocentric memory). Lesions of the hippocampus and PHG of TLE subjects were determined by three-dimensional magnetic resonance imaging volumetric assessment. The results indicate that TLE subjects with right-sided posterior PHG lesions were impaired on virtual maze acquisition when compared with controls and TLE subjects with anterior PHG lesions. Larger posterior PHG lesions were significantly related to stronger impairments in virtual maze performance. Our results point to a role of the right-sided posterior PHG for the representation and storage of egocentric information. Moreover, access to both allocentric and egocentric streams of spatial information may enable the posterior PHG to construct a global and comprehensive representation of spatial environments.

Mending metacognitive illusions: a comparison of mnemonic-based and theory-based procedures

Previous research indicated that learners experience an illusion of competence during learning (termed foresight bias) because judgments of learning (JOLs) are made in the presence of information that will be absent at test. The authors examined the following 2 procedures for alleviating foresight bias: enhancing learners' sensitivity to mnemonic cues pertaining to ease of retrieval and inducing learners to resort to theory-based judgments as a basis for JOLs. Both procedures proved effective in mending metacognitive illusions-as reflected in JOLs and self-regulation of study time-but only theory-based debiasing yielded transfer to new items. The results support the notion that improved metacognition is 1 key to optimizing transfer but also that educating subjective experience does not guarantee generalization to new situations.

Predictors of resident outcome improvement in nursing homes

The effects of contextual characteristics and nursing-related factors on the overall quality improvement of resident outcomes, measured by a weighted index in incidents of pressure ulcers, physical restraints, and catheter use in nursing homes, were investigated by autoregressive latent trajectory modeling of panel data (1997-2003). Findings show that in the initial study period, nursing homes with a smaller bed size, being for-profit, caring for more Medicare residents, having residents with lower acuity levels, being located elsewhere than the South, having a high level of nurse staffing, and certified with lower frequencies of nursing care deficiencies had better quality. The intercept factor, representing the baseline of quality, was well predicted by six of the eight contextual and facility characteristics variables, and the slope trajectory of quality was only weakly predicted by them. The improved quality in resident outcomes was associated with facilities having fewer nursing care deficiency citations than their counterparts.

Demographic risk factors, mediators, and moderators in youths' diabetes metabolic control

BACKGROUND

Socioeconomic status (SES) is one of the most frequently identified and potent predictors of disease morbidity and mortality. It also predicts diabetes care and metabolic control, yet it is often confounded with parental marital status and ethnicity in pediatric samples.

PURPOSE

Key demographic risk factors for poorer metabolic control in adolescents with type I diabetes are examined to distinguish their relative effects, along with disease care mediators and family environment moderators.

METHODS AND RESULTS

When SES, ethnicity, and marital status are considered simultaneously with path analysis, living with married biological parents is the sole predictor of better metabolic control in a predominantly middle-class sample. Specifically, adolescents who lived with their biologic parents had glycosylated hemoglobin levels that were approximately .5% lower on average than those who lived in alternative family arrangements (i.e., blended and single-parent families). More frequent meals and snacks and more blood glucose monitoring mediates this effect. Under favorable conditions of greater familial harmony, children from married biologic families experience a stronger beneficial health effect, with average glycohemoglobin levels that are approximately .81% lower in less conflicted families and .62% lower in more cohesive families.

CONCLUSIONS

In toto, marital status eclipsed the well known effects of SES in the prediction of metabolic control in a primarily middle-class sample of children with diabetes. The 8.0% average glycohemoglobin level of youths from married biologic families is similar to that of intensively treated adolescents in the Diabetes Control and Complications Trial and, if maintained, should be associated with clinically significant reductions in disease complications.

Brief report: relative effectiveness of different home-based behavioral approaches to early teaching intervention

The effectiveness of home-based early behavioral interventions for children (2:6-4:0 years old) with autistic spectrum disorders was studied over 9-10 months. Measures of autistic severity, intellectual, educational, and adaptive behavioral functioning were taken. There was no evidence of recovery from autism. High-intensity behavioral approaches (mean 30 h/week) produced greater gains than low-intensity programs (mean 12 h/week). Lovaas- and complete application of behavior analysis to schools approach-type interventions produced largest gains [similar to gains produced by longer-term clinic-based applied behavior analysis (ABA) programs]. Within the high-intensity groups, increased temporal input on the program was not associated with increased gains in the children. The results from clinic-based ABA trials were partially replicated on a home-based sample, using children with greater autistic and intellectual impairments.

Are there demonstrable effects of distant intercessory prayer? A meta-analytic review

BACKGROUND

The use of alternative treatments for illness is common in the United States. Practitioners of these interventions find them compatible with personal philosophies. Consequently, distant intercessory prayer (IP) for healing is one of the most commonly practiced alternative interventions and has recently become the topic of scientific scrutiny.

PURPOSE

This study was designed to provide a current meta-analytic review of the effects of IP and to assess the impact of potential moderator variables.

METHODS

A random effects model was adopted. Outcomes across dependent measures within each study were pooled to arrive at one omnibus effect size. These were combined to generate the overall effect size. A test of homogeneity and examination of several potential moderator variables was conducted.

RESULTS

Fourteen studies were included in the meta-analysis yielding an overall effect size of g = .100 that did not differ from zero. When one controversial study was removed, the effect size reduced to g = .012. No moderator variables significantly influenced results.

CONCLUSIONS

There is no scientifically discernable effect for IP as assessed in controlled studies. Given that the IP literature lacks a theoretical or theological base and has failed to produce significant findings in controlled trials, we recommend that further resources not be allocated to this line of research.

The evolutionary significance of depressive symptoms: different adverse situations lead to different depressive symptom patterns

Although much depression may be dysfunctional, the capacity to experience normal depressive symptoms in response to certain adverse situations appears to have been shaped by natural selection. If this is true, then different kinds of situations may evoke different patterns of depressive symptoms that are well suited to solving the adaptive challenges specific to each situation. The authors called this the situation-symptom congruence hypothesis. They tested this hypothesis by asking 445 participants to identify depressive symptoms that followed a recent adverse situation. Guilt, rumination, fatigue, and pessimism were prominent following failed efforts; crying, sadness, and desire for social support were prominent following social losses. These significant differences were replicated in an experiment in which 113 students were randomly assigned to visualize a major failure or the death of a loved one.

Studies reporting ROC curves of diagnostic and prediction data can be incorporated into meta-analyses using corresponding odds ratios

OBJECTIVE

To develop an approach by which studies describing the accuracy of diagnostic tests or clinical predictions can be combined in a meta-analysis, even though studies may report their results using different summary measures.

STUDY DESIGN

A method is proposed to allow algebraic and numerical conversion of values of the Receiver Operating Characteristic Area Under the Curve (AUC) summary statistic into corresponding odds ratios (OR). A similar conversion is demonstrated for the standard errors (SEs) of these summary statistics.

RESULTS

The conversion of the AUC values into OR values was achieved using a logit-threshold model. The delta method was used to convert the associated SEs. An example concerning predictions of mortality in the intensive care unit illustrates the calculations.

CONCLUSION

This paper provides an accessible method that permits the meta-analyst to overcome some of the difficulties implied by incomplete and inconsistent reporting of research studies in this area. It allows all studies to be included on the same metric, which in turn more easily permits exploration of issues such as heterogeneity. The method can readily be used for meta-analyses of diagnostic or screening tests, or for prediction data.

A cross-lagged analysis of the relationship between symptoms of PTSD and retrospective reports of exposure

As part of a larger longitudinal investigation, 522 U.S. peacekeepers who served in Somalia were administered a comprehensive psychosocial questionnaire. The questionnaire included the PTSD Checklist [PCL; Weathers, F. W., Litz, B. T., Herman, D. S., Huska, J. A., & Keane, T. M. (1993, November). The PTSD Checklist (PCL): reliability, validity, and diagnostic utility. Paper presented at the annual meeting of the International Society for Traumatic Stress Studies, San Antonio, TX], the Mississippi Scale [Keane, T. M., Caddell, J. M., & Taylor, K. L. (1988). Mississippi Scale for combat-related posttraumatic stress disorder: three studies in reliability and validity. Journal of Consulting and Clinical Psychology, 56, 85-90], the War-Zone Exposure Scale [WZES; Litz, B. T., Orsillo, S. M, Freidman, M., Ehlich, P., & Batres, A. (1997). Posttraumatic stress disorder associated with peacekeeping duty in Somalia for US military personnel. American Journal of Psychiatry, 154(2), 178-184], and the Other Stressors Associated with Peacekeeping Scale [Litz, B. T., King, L. A., King, D. W., Orsillo, S. M., & Friedman, M. J. (1997). Warriors as peacekeepers: features of the Somalia experience and PTSD. Journal of Consulting and Clinical Psychology, 65, 1001-1010]. These measures were administered approximately 15 weeks postdeployment and roughly a year and a half later. Using a cross-lagged panel design, PTSD symptom severity was associated with increases in reports of exposure at Time 2. However, this finding was modest and was not specific to the recall of traumatic events.

Development of scales measuring the capacity of community-based initiatives

This article describes the development of two measures for the capacity of local public health initiatives. Data obtained from a qualitative study of eight community-based initiatives served as the basis for the development of a survey instrument. It was administered to a national sample of both leaders and nonleaders of 291 such initiatives. Because survey results for leaders and nonleaders differed, results could not be combined into a single data set for analysis. Results for each data set were analyzed by employing exploratory principal components and factor analyses. A 44-item, six-factor scale resulted for leaders and a 38-item, five-factor scale resulted for nonleaders. The high degree of overlap (22 items) between the two scales resulted in a combined 60-item instrument that can be administered to both leaders and nonleaders but analyzed separately.

Hostility, Anger, and Marital Adjustment: Concurrent and Prospective Associations with Psychosocial Vulnerability

Hostility may contribute to risk for disease through psychosocial vulnerability, including the erosion of the quality of close relationships. This study examined hostility, anger, concurrent ratings of the relationship, and change in marital adjustment over 18 months in 122 married couples. Wives' and husbands' hostility and anger were related to concurrent ratings of marital adjustment and conflict. In prospective analyses, wives' but not husbands' hostility and anger were related to change in marital adjustment. In hierarchical regression and SEM models wives' anger was a unique predictor of both wives' and husbands' change in marital adjustment. The association between wives' anger and change in husbands' marital satisfaction was mediated by husbands' ratings of conflict in the marriage. These results support the role of hostility and anger in the development of psychosocial vulnerability, but also suggest an asymmetry in the effects of wives' and husbands' trait anger and hostility on marital adjustment.

Panic and phobic anxiety: associations among neuroticism, physiological hyperarousal, anxiety sensitivity, and three phobias

A dimensional and psychometrically informed taxonomy of anxiety is emerging, but the specific and nonspecific dimensions of panic and phobic anxiety require greater clarification. In this study, confirmatory factor analyses of data from a sample of 438 college students were used to validate a model of panic and phobic anxiety with six content factors; multiple scales from self-report measures were indicators of each model component. The model included a nonspecific component of (1) neuroticism and two specific components of panic attack, (2) physiological hyperarousal, and (3) anxiety sensitivity. The model also included three phobia components of (4) classically defined agoraphobia, (5) social phobia, and (6) blood-injection phobia. In these data, agoraphobia correlated more strongly with both the social phobia and blood phobia components than with either the physiological hyperarousal or the anxiety sensitivity components. These findings suggest that the association between panic attacks and agoraphobia warrants greater attention.

The factor structure of The Fear Survey Schedule for Children--II in Trinidadian children and adolescents

Part of understanding normal and abnormal fear in children and adolescents is having knowledge of how they acquire fears and of how fears change across development. One way to examine the relative contributions of heredity and environment to the experience of fear is to study fear across cultures. The Fear Survey Schedule for Children-II (FSSC-II; Gullone, E., & King, N. J. (1992). Psychometric evaluation of a revised fear survey schedule for children and adolescents. Journal of Child Psychology and Psychiatry, 33, 987-998) is one measure that has some evidence for cross-cultural validity. The present analysis examined the factor structure of the FSSC-II scores of 884 Trinidadian children and adolescents. Factor consistency across age, sex, and nationality (Trinidadian and American) was examined by calculating the coefficients of congruence for each pair of conceptually similar factors. Results indicated a five-factor structure for the overall sample. Although the solution was conceptually similar to those reported in other studies that used versions of the FSSC, the obtained structure was not congruent across age, sex, or nationality.

Neighborhood Environment Walkability Scale: validity and development of a short form

PURPOSE

The aim of this study was to examine the factorial and criterion validity of the Neighborhood Environment Walkability Scale (NEWS) and to develop an abbreviated version (NEWS-A).

METHODS

A stratified two-stage cluster sample design was used to recruit 1286 adults. The sample was drawn from residential addresses within eight high- and eight low-walkable neighborhoods matched for socioeconomic status. Subjects completed the NEWS and reported weekly minutes of walking for transport and recreation using items from the International Physical Activity Questionnaire.

RESULTS

Multilevel confirmatory factor analysis was used to develop measurement models of the NEWS and NEWS-A. Six individual-level and five blockgroup-level factors were identified. Factors/scales gauging presence of diversity of destinations, residential density, walking infrastructure, aesthetics, traffic safety, and crime were positively related to walking for transport. Aesthetics, mixed destinations, and residential density were associated with walking for recreation.

CONCLUSIONS

The NEWS and NEWS-A possess adequate levels of factorial and criterion validity. Alternative methods of scoring for different purposes are presented.

A taxometric investigation of the latent structure of social anxiety disorder in outpatients with anxiety and mood disorders

The latent structure of social phobia was examined in a sample of 2,035 outpatients with anxiety and mood disorders to determine whether the disorder operates in a categorical or dimensional fashion. We performed three mathematically distinct taxometric procedures-MAMBAC, MAXEIG, and L-Mode-using five indicators constructed from clinical interview ratings and questionnaire measures of social anxiety symptoms. Results from screening analyses and simulated comparison data consistently indicated that the data were suitable for taxometric analysis. The collective results across procedures, consistency tests, and analysis of simulated comparison data produced converging evidence in support of the conclusion that the latent structure of social phobia is dimensional.

Work-to-relationship conflict: crossover effects in dual-earner couples

To better understand the outcomes for couples whose work interferes with their relationships, with an emphasis on the crossover effects that can occur in close relationships, we examined experienced work-to-relationship conflict and perceptions of partner's work-to-relationship conflict for both members of 113 dual-earner couples. Outcomes of interests included relationship tension, health symptoms, and relationship satisfaction. Results indicate that personal work-to-relationship conflict and perceptions of partner's work-to-family conflict were related to personal as well as partner outcomes; a variety of direct crossover effects were demonstrated. The actor-partner interdependence model was incorporated to account for issues of interdependent data that naturally occur in relationship dyads, a methodological issue not typically addressed and accounted for in the dyadic work-family interface literature.

Why extraverts are happier than introverts: the role of mood regulation

Three studies tested the hypotheses that extraverts demonstrate better mood maintenance abilities than introverts and that these mood regulation abilities can account for the higher habitual happiness of extraverts. Using self- and peer-rated trait measures, Study 1 provided multimethod evidence that mood maintenance, but not mood repair, accounted for the link between extraversion and pleasant-unpleasant trait mood. Study 2 replicated this finding in a different sample of self-reports. Using a within-subjects design, Study 3 demonstrated that when confronted with an affectively ambivalent situation, extraverts maintained a more positive affect balance than introverts. Habitual mood maintenance mediated the effect of extraversion on pleasant-unpleasant affect change. Taken together, the findings support a self-regulation explanation of the extraversion-pleasant affect link.

Sensitivity of a computer adaptive assessment for measuring functional mobility changes in children enrolled in a community fitness programme

OBJECTIVE

To examine the relative sensitivity to detect functional mobility changes with a full-length parent questionnaire compared with a computerized adaptive testing version of the questionnaire after a 16-week group fitness programme.

DESIGN

Prospective, pre- and posttest study with a 16-week group fitness intervention.

SETTING

Three community-based fitness centres.

SUBJECTS

Convenience sample of children (n = 28) with physical or developmental disabilities.

INTERVENTIONS

A 16-week group exercise programme held twice a week in a community setting.

MAIN MEASURES

A full-length (161 items) paper version of a mobility parent questionnaire based on the Pediatric Evaluation of Disability Inventory, but expanded to include expected skills of children up to 15 years old was compared with a 15-item computer adaptive testing version. Both measures were administered at pre- and posttest intervals.

RESULTS

Both the full-length Pediatric Evaluation of Disability Inventory and the 15-item computer adaptive testing version detected significant changes between pre- and posttest scores, had large effect sizes, and standardized response means, with a modest decrease in the computer adaptive test as compared with the 161-item paper version. Correlations between the computer adaptive and paper formats across pre- and posttest scores ranged from r = 0.76 to 0.86.

CONCLUSIONS

Both functional mobility test versions were able to detect positive functional changes at the end of the intervention period. Greater variability in score estimates was generated by the computerized adaptive testing version, which led to a relative reduction in sensitivity as defined by the standardized response mean. Extreme scores were generally more difficult for the computer adaptive format to estimate with as much accuracy as scores in the mid-range of the scale. However, the reduction in accuracy and sensitivity, which did not influence the group effect results in this study, is counterbalanced by the large reduction in testing burden.

Is cataract surgery cost-effective among older patients with a low predicted probability for improvement in reported visual functioning?

INTRODUCTION

Although cataract surgery has been demonstrated to be effective and cost-effective, 5% to 20% of patients do not benefit functionally from the procedure. This study examines the cost-effectiveness of cataract surgery versus watchful waiting in a subgroup of patients who had less than a 30% predicted probability of reporting improvements in visual function after surgery.

METHODS

Randomized trial (first eye surgery vs. watchful waiting) of 250 patients who based on a cataract surgery index (CSI) were felt to have less than a 30% probability of reporting improvements in visual functioning after surgery. Cost was estimated using monthly resource utilization surveys and Medicare billing and payment data. Effectiveness was evaluated at 6 months using the Activities of Daily Vision Scale (ADVS) and the Health Utilities Index, Mark 3 (HUI3).

RESULTS

In terms of overall utility, the incremental cost-effectiveness of surgery was Dollars 38,288/QALY. In the subgroup of patients with a CSI score > 11 (< 20% probability of improvement), the cost-effectiveness of cataract surgery was Dollars 53,500/QALY. Sensitivity analysis demonstrated that often this population of patients may not derive a utility benefit with surgery.

CONCLUSION

Cataract surgery is cost-effective even in a subpopulation of patient with a lower, < 30%, predicted probability of reporting improved visual functioning after surgery. There may be a subgroup of patients, CSI > 11, for whom a strategy of watchful waiting may be equally effective and considerably less expensive.

Improving the use of research evidence in guideline development: 12. Incorporating considerations of equity

BACKGROUND

The World Health Organization (WHO), like many other organisations around the world, has recognised the need to use more rigorous processes to ensure that health care recommendations are informed by the best available research evidence. This is the 12th of a series of 16 reviews that have been prepared as background for advice from the WHO Advisory Committee on Health Research to WHO on how to achieve this.

OBJECTIVES

We reviewed the literature on incorporating considerations of equity in guidelines and recommendations.

METHODS

We searched PubMed and three databases of methodological studies for existing systematic reviews and relevant methodological research. We did not conduct systematic reviews ourselves. Our conclusions are based on the available evidence, consideration of what WHO and other organisations are doing and logical arguments.

KEY QUESTIONS AND ANSWERS

We found few directly relevant empirical methodological studies. These answers are based largely on logical arguments. When and how should inequities be addressed in systematic reviews that are used as background documents for recommendations? The following question should routinely be considered: Are there plausible reasons for anticipating differential relative effects across disadvantaged and advantaged populations? If there are plausible reasons for anticipating differential effects, additional evidence should be included in a review to inform judgments about the likelihood of differential effects. What questions about equity should routinely be addressed by those making recommendations on behalf of WHO? The following additional questions should routinely be considered: How likely is it that the results of available research are applicable to disadvantaged populations and settings? How likely are differences in baseline risk that would result in differential absolute effects across disadvantaged and advantaged populations? How likely is it that there are important differences in trade-offs between the expected benefits and harms across disadvantaged and advantaged populations? Are there different implications for disadvantaged and advantaged populations, or implications for addressing inequities? What context specific information is needed to inform adaptation and decision making in a specific setting with regard to impacts on equity? Those making recommendations on behalf of WHO should routinely consider and offer advice about the importance of the following types of context specific data that might be needed to inform adaptation and decision making in a specific setting: Effect modifiers for disadvantaged populations and for the likelihood of differential effects. Baseline risk in relationship to social and economic status. Utilization and access to care in relationship to social and economic status. Costs in relationship to social and economic status. Ethics and laws that may impact on strategies for addressing inequities. Availability of resources to address inequities. What implementation strategies are likely be needed to ensure that recommendations are implemented equitably? Organisational changes are likely to be important to address inequities. While it may only be possible to consider these in relationship to specific settings, consideration should be given to how best to provide support for identifying and addressing needs for organisational changes. In countries with pervasive inequities institutional, cultural and political changes may first be needed. Appropriate indicators of social and economic status should be used to monitor the effects of implementing recommendations on disadvantaged populations and on changes in social and economic status.

Examination of mediating variables in a partner assistance intervention designed to increase performance of skin self-examination

OBJECTIVE

We sought to identify mediating variables that may explain the increased effectiveness of a partner-learning skin self-examination (SSE) skills training program over a solo-learning SSE skills training program in a sample of patients at risk for melanoma.

METHODS

We conducted a randomized control design with pretest, immediate posttest, and 4-month follow-up measures in a clinical ambulatory care office of a hospital. In all, 130 participants were drawn from a melanoma hospital registry and randomly assigned to a solo-learning control group (n = 65) or a partner-learning group (n = 65). Participants either received the skills training individually in the solo-learning control group or in the partner-learning group in which a partner was actively involved in the training. The intervention consisted of a 10-minute educational presentation and skills training session about the ABCDE rule of early melanoma detection. The main outcome measure was SSE performance as measured by use of a body map. The mediators measured included attitudes toward SSE, self-efficacy/confidence in the ability to effectively perform SSE, comfort with having a partner help with SSE, perceived melanoma/skin cancer risk, concern about developing skin cancer/skin damage, and melanoma/skin cancer knowledge.

RESULTS

Attitudes toward SSE, self-efficacy, comfort with having someone help with SSE, and concern about developing sun-damaged skin were found to be significant mediators.

LIMITATIONS

Study limitations include sample size, the evaluation of short-term program effects, and partner relationship variables that could influence the effectiveness of partner learning.

CONCLUSIONS

Involvement of a partner in the SSE skills training was more effective than solo learning because of the changes in the above-mentioned mediators. Future SSE skills training programs could benefit through using approaches that produce changes in key variables such as increasing attitudes toward SSE, increasing self-efficacy beliefs in the ability to perform SSE, and making participants feel confident in their ability to examine their skin.

Does Effort Suppress Cognition After Traumatic Brain Injury? A Re-Examination of the Evidence for the Word Memory Test

Green, Rohling, Lees-Haley, and Allen (2001) suggested that scores on a test of "effort," the Word Memory Test (WMT), explains more variance in outcome after brain injury than does injury severity. As a consequence, Green and colleagues recommend using the WMT to control for sub-optimal effort in neuropsychological evaluations and group research. We re-examine the evidence for their conclusions and argue that identifying a larger proportion of explained variance is not in itself evidence of validity unless the premise to be proven is already assumed, namely, that the test is a valid measure of effort. Instead, the crux of Green and colleagues claim for the validity of the WMT implies an interaction between effort and injury severity on outcome scores, although the specific interaction has not been tested in their previous research. We failed to find any evidence for this interaction in a sample of 100 Australian litigants. We conclude that our data do not support the view that effort, as measured by the WMT, interacts with injury severity to suppress cognition after brain injury.

The role of imagery in the maintenance and treatment of snake fear

Two studies assessed the role of mental imagery in the maintenance of fear of common phobic stimuli. Study 1 asked participants who were afraid of a wide range of phobic stimuli to report their visual and somatic imagery. Blind ratings of the imagery on horror and vividness were positively correlated with participant's self-reported fear and avoidance. Study 2 tested the efficacy of modifying imagery using cognitive restructuring compared to in vivo exposure and a minimal exposure, relaxation control in snake fearful participants. Both active treatment groups improved significantly more than the control group in self-reported snake fearfulness and behavioral approach. Condition also interacted with initial severity. Highly fearful subjects responded better to the cognitive imagery modification than to the in vivo exposure, and found the cognitive intervention significantly less aversive. These results are seen as supporting a cognitive model of the maintenance of specific phobia.

A retrospective study of childhood gender-atypical behavior in Samoan fa'afafine

Retrospective studies, mostly conducted in Western cultures, indicate that childhood cross-gender behaviors are strongly predictive of androphilia in adult men. To test the cross-cultural validity of these findings, we conducted a study of fa'afafine in Independent Samoa. Fa'afafine are a heterogeneous group of androphilic males, some of whom are unremarkably masculine, but most of whom behave in a feminine manner in adulthood. A total of 53 fa'afafine, 27 control men, and 24 control women participated. Participants were asked how often they engaged in female- and male-typical behaviors in childhood. Results demonstrated that fa'afafine and women recalled engaging in significantly more female-typical behaviors and significantly fewer male-typical behaviors in childhood compared to the men. Fa'afafine's recalled female-typical and male-typical behaviors did not differ significantly from those of women. These results suggest that the relationship in males between gender-atypical behavior in childhood and adult androphilia is not unique to Western societies and may be a cross-culturally universal pattern of psychosexual development shared by most males who are predominantly androphilic.

Latent difference score approach to longitudinal trauma research

In this article, the authors introduce a latent difference score (LDS) approach to analyzing longitudinal data in trauma research. The LDS approach accounts for internal sources of change in an outcome variable, including the influence of prior status on subsequent levels of that variable and the tendency for individuals to experience natural change (e.g., a natural decrease in posttraumatic stress disorder [PTSD] symptoms over time). Under traditional model assumptions, the LDSs are maximally reliable and therefore less likely to introduce biases into model testing. The authors illustrate the method using a sample of children who experienced significant burns or other injuries to examine potential influences (i.e., age of child-adolescent at time of trauma and ongoing family strains) on PTSD symptom severity over time.

Conditions of Contact, Common In-Group Identity, and In-Group Bias Toward Contingent Workers

In a survey-based field study of 111 permanent Finnish restaurant employees, the authors investigated intergroup relations between permanent and contingent workers. On the basis of the common in-group identity model, the authors hypothesized that the conditions of contact (supportive norms and perceived intergroup competition) would be related to common in-group identity, which in turn would be negatively related to intergroup bias. The present results indicated that perceived competition and institutional support were related to in-group bias only through their influence on the common in-group identity, as the model predicted.

The selective effect of antipsychotics on the different dimensions of the experience of psychosis in schizophrenia spectrum disorders

While most standard symptom scales regard the 'psychotic' or 'positive' dimension of schizophrenia as a single factor, several lines of evidence suggest that psychosis itself is a multidimensional phenomenon. The foregoing literature suggested at least five distinct dimensions to psychosis; to test this, we developed, validated and applied an instrument to measure these dimensions and then applied it to examine the effect of antipsychotics on the different dimensions of the psychotic experience. The Dimensions of Psychosis Instrument (DIPI) was administered to 91 psychotic patients with schizophrenia spectrum disorders and a confirmatory factor analyses (CFA) was carried out to examine the five dimensions: cognitive preoccupation (CP) with the psychotic experience; emotional involvement (EM); behavioural impact (BI) of the experience; conviction (CO) in it; emotional; and external perspective (EP) about the experience. In a separate cohort of 17 prospectively treated patients, the impact of antipsychotics on these dimensions was assessed. BI showed the greatest improvement (32%) at 2 weeks, while CP and emotional improved somewhat less (22% and 14%, respectively). Improvement in CO was limited (6%) while EP showed no change. These results suggest that over the first few weeks of treatment, antipsychotics rapidly reduce the behavioural impact of the principal psychotic symptom and decrease cognitive and emotional preoccupation with it, without greatly altering the patients' conviction in or perspective about their psychotic experience.

Relationships at school and stage-environment fit as resources for adolescent engagement and achievement

Guided by Self-Determination and associated theories, we examined whether adolescent (N=324, Mage=15, 52% female) competence (academic engagement and achievement) were supported by relationships at school and school fit. Aspects of relationships and school fit that were measured included adolescents' perceptions of each context as promoting autonomy, relatedness and competence. Within a latent-variable structural equation model, direct and indirect path estimates, standard errors and confidence intervals were produced using maximum likelihood and bootstrapping. Results supported the hypothesized model. As predicted, school fit partially mediated the association between teacher-student relationships and engagement, but fully mediated the association between peer relationships and engagement. Engagement fully mediated the path from school fit to achievement. The use of SEM and bootstrapping are encouraged as the combination of these techniques can increase power to detect direct and indirect effects, and can be a better choice for data that do not conform to normal theory assumptions. Overall, these techniques allowed for more firm conclusions about the importance of a hierarchy of multidimensional contextual experiences for adolescent competence.

Thurstonian-Based Analyses: Past, Present, and Future Utilities

Current psychometric models of choice behavior are strongly influenced by Thurstone's (1927, 1931) experimental and statistical work on measuring and scaling preferences. Aided by advances in computational techniques, choice models can now accommodate a wide range of different data types and sources of preference variability among respondents induced by such diverse factors as person-specific choice sets or different functional forms for the underlying utility representations. At the same time, these models are increasingly challenged by behavioral work demonstrating the prevalence of choice behavior that is not consistent with the underlying assumptions of these models. I discuss new modeling avenues that can account for such seemingly inconsistent choice behavior and conclude by emphasizing the interdisciplinary frontiers in the study of choice behavior and the resulting challenges for psychometricians.

The influence of difficult temperament on alcohol-related aggression: better accounted for by executive functioning?

The purpose of this investigation was to test the hypothesis that executive functioning (EF) would mediate the relation between difficult temperament (DT) and intoxicated aggression. Participants were 165 social drinking men and women between the ages of 21-35years old. DT was measured using the Dimension of Temperament Scale - Revised and EF was measured using seven well-established neuropsychological tests. Following consumption of an alcoholic beverage, participants were tested on a laboratory aggression measure in which electric shocks were received from and administered to a fictitious opponent under the guise of a competitive reaction time task. Aggression was operationalized as shock intensities administered to the fictitious opponent under conditions of low and high provocation. Results indicated that EF successfully mediated the relation between DT and intoxicated aggression for men but not for women. These findings are discussed with regard to how they influence current models of aggressive behavior as well as their implications for future violence prevention efforts.

Do health behaviors mediate the association between social capital and health?

INTRODUCTION

There is increasing evidence that social capital is important for people's health. However, there is still considerable disagreement about the specific pathways that links social capital to health. This study investigates the hypothesis that the association between social capital and health is mediated by people's health behaviors.

METHOD

Data from the 2002 Health Survey for England (n = 7394) were used and analyzed from a multilevel perspective. The association between social capital and self-rated health were examined before and after controlling for smoking, alcohol intake, and fruit/vegetable consumption.

RESULTS

Social capital was found to be associated with self-rated health, as well as with the different health behaviors. In addition, the health behaviors were significantly related to self-rated health. However, controlling for smoking, alcohol intake, and fruit/vegetable consumption did not substantially affect the association between social capital and self-rated health.

CONCLUSIONS

The results demonstrate that social capital and support are important determinants of self-rated health and health behaviors. But only limited support was found for the hypothesis that health behaviors mediate the association between social capital and health.

Examining equivalence of concepts and measures in diverse samples

While there is growing awareness for the need to examine the etiology of problem behaviors across cultural, racial, socioeconomic, and gender groups, much research tends to assume that constructs are equivalent and that the measures developed within one group equally assess constructs across groups. The meaning of constructs, however, may differ across groups or, if similar in meaning, measures developed for a given construct in one particular group may not be assessing the same construct or may not be assessing the construct in the same manner in other groups. The aims of this paper were to demonstrate a process of testing several forms of equivalence including conceptual, functional, item, and scalar using different methods. Data were from the Cross-Cultural Families Project, a study examining factors that promote the healthy development and adjustment of children among immigrant Cambodian and Vietnamese families. The process described in this paper can be implemented in other prevention studies interested in diverse groups. Demonstrating equivalence of constructs and measures prior to group comparisons is necessary in order to lend support of our interpretation of issues such as ethnic group differences and similarities.

An update on the role of psychotherapy in the management of bipolar disorder

Recent studies have examined the value of combining structured forms of psychotherapy with medication maintenance for patients with bipolar disorder. These studies have been influenced by the growing body of literature on stress in the elicitation of manic and depressive episodes. Randomized trials published within the past 5 years indicate positive benefits of cognitive-behavioral therapy, interpersonal and social rhythm therapy, family-focused therapy, and group psychoeducation as adjuncts to mood stabilizers in delaying recurrences, stabilizing symptoms, and improving medication adherence. Open trials of family interventions for pediatric-onset bipolar patients also have yielded promising results. Questions remain about the relative advantages of one psychosocial approach over the others, whether there are subgroups of patients who respond to each type of intervention, the impact of psychotherapy on role functioning, mediators of treatment effects, and the potential utility of early intervention as a means of delaying the onset and/or severity of the disorder.