Biomedical subjects

James Rochon

Publications and source records attributed to James Rochon.

18 recordsLinked to original sources

PubMed2005

The Study of the Effects of Diet on Metabolism and Nutrition (STEDMAN) weight loss project: Rationale and design.

This paper outlines the rationale and design of the Study of the Effects of Diet on Metabolism and Nutrition (STEDMAN) weight loss project, in which detailed biologic profiling of three hundred and fifty obese individuals (body mass index (BMI): 30-50 kg/m(2)) will be conducted as they lose weight via seven distinct interventions. These profiles will be compared to those of fifty normal, healthy, control participants (BMI: 18.5-24.9 kg/m(2)). The interventions include the following: Roux-en-Y gastric bypass surgery, dietary interventions of differing macronutrient composition and diverse pharmacologic interventions. Outcome variables include eight conventional metabolites and CRP measured by standard clinical chemistry techniques, twenty hormones of energy balance and fuel homeostasis measured by radioimmunoassay (RIA) or by enzyme-linked Immunosorbent assay (ELISA), ten pro- and anti-inflammatory cytokines measured using Luminex xMAP technology, one hundred and one intermediary metabolites measured by targeted mass-spectrometry-based methods, and physiologic variables such as body composition measured by dual energy X-ray absorptiometry (DEXA), air displacement plethysmography, and abdominal computerized tomography (CT), insulin sensitivity measured by intravenous glucose tolerance test (IV-GTT) and metabolic rate measured by indirect calorimetry. Results from this study will expand our knowledge of the biology of obesity and weight regulation and may lead to targeted strategies for its treatment and control.

Adolescent↗

PubMed2005

Pain, stiffness, and fatigue in juvenile polyarticular arthritis: contemporaneous stressful events and mood as predictors.

OBJECTIVE: To analyze patterns of stress, mood, disease symptoms, and activity reduction in children with polyarticular arthritis, using a prospective daily diary method. METHODS: For a 2-month period, 51 children with polyarticular arthritis (mean age 12.4 years, 65% female) completed daily diaries that included measures of symptoms of pain, stiffness, and fatigue, as well as stress, mood, and activity reduction. Functional status and disease activity were assessed at the initial and followup evaluations with use of the Childhood Health Assessment Questionnaire, physician global assessment, joint count, and laboratory testing. RESULTS: Children reported having pain, stiffness, and fatigue on >70% of days, with significant variability in symptom levels. Results revealed significant same-day relationships between stress, mood, and disease symptoms, after controlling for covariates. Specifically, daily fluctuations in both stress and mood were predictive of increased pain, stiffness, and fatigue. Increases in daily stress, mood, and disease symptoms were also significantly related to decreased participation in social activities on a day-to-day basis. Only mood and stiffness were predictors of a cutback in school attendance. CONCLUSION: Stress and mood are important predictors of daily disease symptoms in children with polyarticular arthritis. Moreover, daily fluctuations in stress, mood, and disease symptoms are predictive of aspects of daily function, including participation in school and social activities. Thus, health care providers should solicit daily symptom reports when making decisions regarding clinical management. Nonpharmacologic interventions such as cognitive-behavioral therapy and stress management may be useful adjuvant therapy when treating the disease symptoms of children with polyarticular arthritis.

Adolescent↗

PubMed2004

Physical activity self-report and accelerometry measures from the Girls health Enrichment Multi-site Studies.

BACKGROUND: Valid and reliable physical activity checklists are needed to assess effectiveness of interventions. This study tested the validity and reliability of the Girls health Enrichment Multi-site Studies (GEMS) Activity Questionnaire. METHODS: Two-hundred and ten African-American girls completed the GEMS Activity Questionnaire (GAQ), a checklist of 28 physical and 7 sedentary activities, including TV viewing, inquiring whether performed on the previous day ("yesterday"), and whether usually performed ("usual"). The girls wore an accelerometer (used as the criterion for validity) for three consecutive days at baseline and after a 12-week pilot intervention. Data from 172 girls at baseline and follow-up were usable for this report. RESULTS: Girls were (mean +/- SD) 8.8 +/- 0.8 years old with a BMI of 22.3 +/- 5.9 kg/m2. The intraclass correlation (ICC) examining reliability for the accelerometer across 3 days at baseline for the combined group was fair (ICC = 0.33, P < 0.21). The test-retest reliability coefficient for the 18-item MET-weighted GAQ yesterday scores for the comparison group of girls was 0.57 (P < 0.001). At baseline and follow-up, nonsignificant correlations were observed between 3-day accelerometer counts/minute and GAQ 18-item usual score for both comparison and intervention groups. A significant correlation was found between change in accelerometer minutes of moderate-to-vigorous activity (MVPA) between 12 noon and 6 PM and change in GAQ physical activities in the comparison girls (R = 0.35, P < 0.01). The TV-usual score was correlated with 3-day accelerometer counts/minute (R = -0.19, P = 0.02) at baseline for the total sample. CONCLUSIONS: Correlations between the GAQ and accelerometer were low, indicating low validity. Although the GAQ may be helpful in describing types of physical activities performed, it needs further development to improve its psychometric properties.

Black or African American↗

PubMed2004

Validity and reliability of a behavior-based food coding system for measuring fruit, 100% fruit juice, vegetable, and sweetened beverage consumption: results from the Girls Health Enrichment Multisite Studies.

BACKGROUND: This paper presents the rationale, reliability, and validity of a behavior-based food coding system for measuring fruit (F), juice (J), vegetable (V), sweetened beverage, and water consumption in children. METHODS: Coding algorithms for FJV, sweetened beverages, and water were developed for use with the Nutrition Data System for Research (NDS-R). Two hundred and ten 8- to 10-year-old African American girls at four field centers completed two 24-h dietary recalls at baseline and at 12 weeks follow-up after a weight gain prevention intervention. Differences in mean baseline consumption of selected food variables and other selected nutrients across the four field centers were analyzed. Intraclass correlation coefficients (ICCs) for reliability across 2 days of food recalls and 12-week test-retest reliability correlations were calculated. For the purposes of this paper, nutrient intake estimates were considered construct validators of food intake, and validity was assessed by correlating the coded food variable servings with nutrient intake. RESULTS: ICCs varied from zero (0.001 for beta carotene equivalents) to moderate (0.44 for sucrose), indicating substantial instability in consumption or reporting. Twelve-week test-retest correlations were slight to moderate (0.09 for lycopene to 0.49 for folate). FJV consumption was negatively related to percent energy from fat (r = -0.28; P = 0.001) and positively related to other nutrients. Sweetened beverage consumption was positively related to energy, sucrose, fructose, and vitamin C consumption. CONCLUSIONS: This behavior-based food coding system demonstrated construct validity among 8- to 10-year-old African American girls and can measure the desired food groups.

Black or African American↗

PubMed2004

Measurement characteristics of diet-related psychosocial questionnaires among African-American parents and their 8- to 10-year-old daughters: results from the Girls' health Enrichment Multi-site Studies.

OBJECTIVE: This paper presents the reliability and validity of several diet-related psychosocial questionnaires. METHODS: At baseline and 12 weeks follow-up, parents/caregivers of one hundred fifty 8- to 10-year-old African-American completed questionnaires on food preparation habits for their daughter, perceived home barriers to healthy eating, and fruit, juice, vegetable (FJV), low-fat and high-fat food availability. Girls completed a sweetened beverage preferences questionnaire and two 24-h dietary recalls to assess intake. Principal components analyses were conducted for two newly designed measures. Internal consistency was calculated and construct validity was assessed between the psychosocial scales and obesity-related dietary variables. RESULTS: Low-fat and high-fat food preparation for daughters, and perceived home barriers to eating low-fat food and FJV subscales were derived from the new questionnaires. Internal consistency reliabilities were moderate (0.58) to substantial (0.80) across all new and existing scales. Test-retest reliabilities were moderate (0.44) to substantial (0.79). Girls' intake of fat as a percentage of energy was positively related to parental high-fat food preparation for daughters (P < 0.01) and negatively related to parental low-fat food preparation practices for daughters (P < 0.05). CONCLUSIONS: Measures of family influences on FJV, fat, and sweetened beverage consumption were internally consistent with moderate to substantial stability. Scales for low-fat and high-fat food preparation practices for daughters achieved construct validity with fat consumption in the hypothesized direction. Family food preparation habits appear to be important targets for future interventions.

Black or African American↗

PubMed2004

Evaluation of quality control procedures for 24-h dietary recalls: results from the Girls Health Enrichment Multisite Studies.

BACKGROUND: Quality control methods are key components of dietary assessment, but have rarely been evaluated. METHODS: One hundred forty-four 8-10-year-old African-American girls at three field centers completed two 24-h dietary recalls at baseline before a pilot weight gain prevention intervention (one recall collected in-person and one by telephone). The dietary recall data were initially reviewed by the dietary interviewer (Phase 1), then by a local lead nutritionist at the field center (Phase 2), and then by the Nutrition Coordinating Center (NCC) (Phase 3); any differences identified by NCC were reconciled (Phase 4). Bland-Altman and generalizability theory methods were used to assess agreement of consumption for selected food variables and nutrients between phases. RESULTS: Only small differences occurred. Quality control procedures primarily reduced the variances of nutrients rather than caused the means to shift. Most of the variability among phases was due to individual level variability in dietary intake. CONCLUSIONS: Decisions to review dietary recall data beyond local review should be based on the level of precision and accuracy required for the study outcomes and the availability of financial resources.

Black or African American↗

PubMed2004

Early sexual maturation, body composition, and obesity in African-American girls.

OBJECTIVE: To describe associations between sexual maturation and body composition in a sample of African-American girls who were participants in phase 1 pilot interventions of the Girls Health Enrichment Multisite Studies. RESEARCH METHODS AND PROCEDURES: Stature, weight, and waist circumference were measured. Pubic hair and breast development were assessed, and body composition was measured by DXA for 147 African-American girls who were 8 to 10 years of age from three field centers. Participants had BMI > or =25th percentile for age (one site) or BMI > or =50th percentile for age. RESULTS: Girls Health Enrichment Multisite Studies girls had greater BMI, fat mass, and percentage body fat than national norms and relatively earlier initiation of breast development and pubic hair. Increasing stages of breast development, but not stages of pubic hair, were related to increased stature, waist circumference, BMI, lean mass, fat mass, and percentage of body fat. Pubescent girls (breast stage > or = 2) were greater than six times as likely to be classified as at risk of overweight (BMI > or = 85th percentile) and greater than eight times as likely to be classified as overweight (BMI > or = 95th percentile) as prepubescent counterparts. Adjusted odds ratios for advanced breast development [breast stage > or = 2 (8 years) or > or = 3 (9 and 10 years)] were 3.6 for risk of overweight and for overweight compared to girls with average or less than average breast development. DISCUSSION: Sexual maturation is important to consider in understanding the classification of overweight and the development of obesity during adolescence. Breast development and pubic hair development should be considered separately for their associations with growth and body composition.

Black or African American↗

PubMed2004

Using a serial marker to predict a repeated measures outcome in a cohort design--results of a simulation study.

Consider the cohort design and suppose that the outcome of primary interest is a continuous random variable observed repeatedly over time. Suppose that there is a second variable of clinical relevance which is also observed repeatedly. We are interested in assessing whether the "serial marker" is in some sense predictive of the primary outcome. We would also like to predict the trend for the primary outcome assuming that the clinical marker follows a profile of specific clinical interest. In series of earlier papers, we have addressed these issues by applying a bivariate repeated measures model. One regression model was prescribed to relate the primary outcome to important explanatory variables, while a second regression model was prescribed for the serial marker. In this paper, we perform a series of simulation studies to investigate the empirical properties of this approach. Bivariate repeated measures data were generated at random, and basic study parameters including the sample size, the number of time points, the degree of serial correlation within the clinical marker, and type of association between the serial marker and the primary outcome were varied. The ability of the methodology to capture the underlying relationship between the two set of repeated measures was assessed. The ability to predicting the primary outcome corresponding to a known marker profile of specific interest was examined.

Algorithms↗

PubMed2003

Using a serial marker to predict a repeated measures outcome in a cohort study.

Consider the cohort design and suppose that the outcome of primary interest is a continuous random variable observed repeatedly over time. Suppose that the value of a "clinical marker," which is thought to be predictive of the primary outcome, is also recorded. We would like to determine whether there is an association between the two variables as they evolve over time. We might also want to predict the pattern for the primary outcome conditionally on a specific profile of clinical interest for the serial marker. A model is developed to address these issues. One regression model is created for the primary outcome while a second regression model is developed for the clinical marker. The vector autoregressive model, i.e., VAR(1), is used to characterize the covariance structure between the two sets of repeated observations. Hypotheses of interest are described and procedures for testing them are elaborated. The Diabetes Control and Complications Trial is used to illustrate the procedures.

Biomarkers↗

PubMed2003

Mixed-effect models to assess consistency and reliability across multiple evaluations.

The issue of consistency and reliability arises frequently in applied clinical trials, and there is a considerable amount of literature on this topic. For a continuous random variable, we describe a process to assess whether the mean and variance are the same from one evaluation to the other and we derive the intraclass correlation (ICC) for evaluating consistency in the distributions of paired data. Mixed-effects linear models are applied, and these procedures are illustrated using dietary recall data from the Girls health Enrichment Multi-site Studies (GEMS). The SAS program code for performing the statistical analysis is provided. The models can be generalized to account for more design factors and other applicable covariates.

Clinical Trials as Topic↗

PubMed2003

Validity and reliability of activity measures in African-American girls for GEMS.

PURPOSE: To determine the reliability and validity of physical activity monitors and self-report instruments suitable for young African-American girls. METHODS: A validation study was conducted by the Girls health Enrichment Multi-site Studies (GEMS) research team to compare an accelerometer with a pedometer and two self-report instruments for assessing physical activity in African-American girls, age 8-9 yr. Girls (N= 68) attended two clinic visits spaced 4 d apart. Each girl wore a MTI/CSA accelerometer (used as the criterion standard for validity) and a pedometer simultaneously for four consecutive days. Girls completed on two occasions a 24-h physical activity checklist of yesterday and usual activities, including sedentary activities (GEMS Activity Questionnaire, GAQ), and a 3-d computerized self-report instrument (Activitygram). RESULTS: Girls were (mean +/- SD) 9.0 +/- 0.6 yr old and had a body mass index of 19.4 kg x m. Reliability measured by intraclass correlations (ICC) and Pearson correlation coefficients (r) were calculated for the MTI/CSA (ICC = 0.37, P< 0.0001), pedometer (ICC = 0.08, = 0.094), Activitygram (ICC = 0.24) (P = 0.005), and GAQ for physical (r = 0.80, P< 0.0001) and sedentary (r = 0.3-0.5, P< 0.005) activities. Significant Pearson correlations between the MTI/CSA and the other instruments, as a measure of validity, were observed for the 4-d average pedometer score (r = 0.47, P< 0.0001), 3-d average Activitygram score (r = 0.37, P= 0.002), and the average of the two yesterday and two usual GAQ activity scores for a subset of 18 physical activities questions (r = 0.27, = 0.03; and r = 0.29,P = 0.02, respectively). The MTI/CSA was uncorrelated with single day scores from the three other instruments. CONCLUSION: The reliability of the instruments tested was acceptable, except the pedometer. Validity correlations were significant when more than one day was used. Self-report instruments need further development for improved reliability and validity.

Activities of Daily Living↗

PubMed2003

Common design elements of the Girls health Enrichment Multi-site Studies (GEMS).

The Girls health Enrichment Multi-site Studies (GEMS) was a multi-center research program created for the purpose of testing interventions designed to prevent excess weight gain by African-American girls, as they enter and proceed through puberty. However, GEMS was not a "multi-center clinical trial" in the usual sense. Although these studies applied similar eligibility criteria, observed a similar follow-up schedule, and followed a similar measurement protocol, important differences existed, as well. Each field center developed its own intervention(s) and corresponding control, and tailored its study to the specific hypothesis being tested. Therefore, the study populations were somewhat different, with recruitment strategies that varied accordingly, and supplemental evaluations appropriate to the specific interventions were conducted on a site-specific basis. The purpose of this paper is to describe the common design elements of the GEMS Phase 1 pilot studies. This report presents the basic study design, a brief overview of the interventions, the measurements taken and their rationale, and procedures both for compiling the collaborative database, and performing site-specific analyses.

Adolescent↗

PubMed2003

The Fun, Food, and Fitness Project (FFFP): the Baylor GEMS pilot study.

OBJECTIVE: The Girls health Enrichment Multisite Studies (GEMS) Fun, Food, and Fitness Project (FFFP) was designed to prevent obesity among 8-year-old African-American girls. DESIGN: Twelve-week, two-arm parallel group randomized controlled pilot study. SETTING: Summer day camp and homes in Houston, Texas. PARTICIPANTS: Thirty-five girls and their parents or caregivers were randomly assigned to treatment (N=19) or control groups (N=16). INTERVENTION: Girls in the intervention group attended a special 4-week summer day camp, followed by a special 8-week home Internet intervention for the girls and their parents. Control group girls attended a different 4-week summer day camp, followed by a monthly home Internet intervention, neither of which components included the GEMS-FFFP enhancements. MAIN OUTCOME MEASURES: Body mass index (BMI), consumption of fruit, 100% fruit juice, and vegetables (FJV), physical activity. RESULTS: After adjusting for baseline BMI, there were no significant differences in BMI between treatment and control group girls, either at the end of the 4-week summer day camp, or after the full 12-week intervention. By the end of the summer camp, the subgroup of treatment group girls heavier at baseline exhibited a trend (P<.08) toward lower BMI, compared to their heavier counterparts in the control group. Overall results at the end of the 12-week program demonstrated substantial, although not significant, differences between treatment and control groups in the hypothesized directions. On average, less than half the treatment sample logged onto the Website, which limited intervention dose. CONCLUSIONS: Summer day camp appears to offer promise for initiating health behavior change. Effective methods must be developed and tested to enhance log-on rates among healthy children and their parents before Internet programs can achieve their potential.

Black or African American↗

PubMed2003

Child- and parent-targeted interventions: the Memphis GEMS pilot study.

OBJECTIVE: To assess the feasibility, acceptability, and outcomes of 2 versions of a culturally relevant, family-based intervention to prevent excess weight gain in pre-adolescent African-American girls. DESIGN: Three-arm, 12-week parallel group randomized controlled pilot trial. SETTING: Community centers in Memphis, Tennessee. PARTICIPANTS: Sixty African-American girls, aged 8 to 10 years, with a body mass index (BMI) > or = 25th percentile of the CDC growth charts, along with their parents/caregivers. INTERVENTIONS: The active interventions involved highly interactive weekly group sessions with either girls (child-targeted program) or parents/caregivers (parent-targeted program). Content focused on knowledge and behavior change skills to promote healthy eating and increased physical activity. The comparison intervention focused on global self-esteem. MAIN OUTCOME MEASURES: Given the lack of power and the limited time frame of the pilot study, outcomes were evaluated on the basis of implementation measures and changes in physical activity (accelerometer data), and in consumption of sweetened beverages and water, as estimated from questionnaires. Changes in body mass index, waist circumference, and body composition were also examined. RESULTS: The Memphis GEMS pilot intervention met all recruitment, retention, implementation, and participation goals, and was given high rating by both participants and interventionists. With respect to the comparison intervention, girls in both the child-targeted and parent-targeted interventions demonstrated a trend toward reduced body mass index and waist circumference. In addition, girls in the active intervention groups reduced their consumption of sweetened beverages by 34%, increased their level of moderate-to-vigorous activity by 12%, and increased their serving; of water by 1.5%. CONCLUSIONS: The findings from this pilot study demonstrated the feasibility, perceived acceptability, and efficacy of culturally relevant, obesity prevention interventions for pre-adolescent African-American girls and their parents/caregivers.

Adult↗

PubMed2003

An after-school obesity prevention program for African-American girls: the Minnesota GEMS pilot study.

OBJECTIVE: This paper describes the development of an after-school obesity-prevention program for African-American girls, and presents findings from a 12-week pilot trial conducted by the University of Minnesota. This study was part of the GEMS project, created to test interventions designed to reduce excess weight gain in African-American girls. DESIGN: Two-arm parallel group, randomized controlled trial. Measures were taken at baseline and at 12 weeks follow up. SETTING: An after-school community program. PARTICIPANTS: Fifty-four African-American girls, 8- to 10-years of age, and their parents/caregivers. INTERVENTION: The after-school intervention was conducted twice a week for 12 weeks, and focused on increasing physical activity and healthy eating. A family component was also included. Girls in the control group received a program over 12 weeks unrelated to nutrition and physical activity. OUTCOMES: Measures included height and weight (body mass index), percent body fat (DEXA), physical activity, assessed using a CSA accelerometer and self-report, two 24-hour dietary recalls, and psycho-social and demographic variables. Parental data included demographic and psycho-social characteristics, and dietary measures. Additionally, process evaluation data on the intervention were collected. RESULTS: Recruitment goals were met. After adjustment for baseline level, follow-up BMI did not differ between the treatment groups, an expected finding, given that this was a pilot study. At 12 weeks follow up, differences between the intervention and control groups were in the hypothesized direction of change for most variables, among both the girls and their parents. Process evaluation results demonstrated that the program was well attended, and well received, by girls and parents. CONCLUSIONS: An after-school obesity prevention program for low-income African-American girls is a promising model for future efforts.

Adult↗

PubMed2003

Dance and reducing television viewing to prevent weight gain in African-American girls: the Stanford GEMS pilot study.

OBJECTIVE: To test the feasibility, acceptability, and potential efficacy of after-school dance classes and a family-based intervention to reduce television viewing, thereby reducing weight gain, among African-American girls. DESIGN: Twelve-week, 2-arm parallel group, randomized controlled trial. SETTING: Low-income neighborhoods. PARTICIPANTS: Sixty-one 8-10-year-old African-American girls and their parents/guardians. INTERVENTIONS: The treatment intervention consisted of after-school dance classes at 3 community centers, and a 5-lesson intervention, delivered in participants' homes, and designed to reduce television, videotape, and video game use. The active control intervention consisted of disseminating newsletters and delivering health education lectures. MAIN OUTCOME MEASURES: Implementation and process measures, body mass index, waist circumference, physical activity measured by accelerometry, self-reported media use, and meals eaten with TV. RESULTS: Recruitment and retention goals were exceeded. High rates of participation were achieved for assessments and intervention activities, except where transportation was lacking. All interventions received high satisfaction ratings. At follow up, girls in the treatment group, as compared to the control group, exhibited trends toward lower body mass index (adjusted difference = -.32 kg/m2, 95% confidence interval [CI] -.77, .12; Cohen's d = .38 standard deviation units) and waist circumference (adjusted difference = -.63 cm, 95% CI -1.92, .67; d = .25); increased after-school physical activity (adjusted difference = 55.1 counts/minute, 95% CI -115.6, 225.8; d = .21); and reduced television, videotape, and video game use (adjusted difference = -4.96 hours/week, 95% CI -11.41, 1.49; d = .40). The treatment group reported significantly reduced household television viewing (d = .73, P = .007) and fewer dinners eaten while watching TV (adjusted difference = -1.60 meals/week, 95% CI -2.99, -.21; d = .59; P = .03). Treatment group girls also reported less concern about weight (d = .60; P = .03), and a trend toward improved school grades (d = .51; P = .07). CONCLUSIONS: This study confirmed the feasibility, acceptability, and potential efficacy of using dance classes and a family-based intervention to reduce television viewing, thereby reducing weight gain, in African-American girls.

Black or African American↗

PubMed2003

Recruitment of African-American pre-adolescent girls into an obesity prevention trial: the GEMS pilot studies.

OBJECTIVE: The objective of this report is to describe the methods used to recruit 8- to 10-year-old African-American girls into four 12-week randomized controlled pilot studies on obesity prevention. DESIGN: The Girls health Enrichment Multi-site Study (GEMS) involved 4 field centers which independently developed and tested interventions designed to prevent excess weight gain in African-American girls. Each field center developed its own recruitment plan, but used a standardized recruitment reporting form. The goal was to recruit 40-60 girls, depending on the center. MEASURES: Recruitment yields were computed at each site. Socio-demographic data and weight status were collected for 210 African-American girls who were randomized into the study, as well as for their parents/caregivers. Data were collected on the sources from which participants heard about the study, and the reasons for their interest in the project. RESULTS: The 4 field centers used multiple, but different, recruitment strategies. The most commonly used approaches were mailings, flyers, radio announcements, and group presentations. Caregivers were most likely to hear about the program from the radio (29%), a flyer from the school (23%), or from their child (18%). Among caregivers, the most common reasons for participating were: interest in health (56%), interest in diet/health (51%), and believing the program would be fun for their child (46%). The most frequent reason given by girls was that the program sounded like fun (70%). Three of the 4 field centers met their recruitment target goals. CONCLUSIONS: The GEMS experience demonstrates the feasibility of recruiting and enrolling African-American girls in short-term intervention studies of behavior change. The multiple recruitment strategies, which included developing trusting relationships in the respective communities, were considered critical to the success of recruitment.

Advertising↗

PubMed2002

Interaction and intervention modeling: predicting and extrapolating the impact of multiple interventions.

PURPOSE: Methods called interaction and intervention modeling are presented. Interaction modeling examines the interactions between variables as the basis for predicting the impact of multiple variables on a target population and on populations with difference distributions of risk factors. Intervention modeling incorporates these interactions and aims to extrapolate the impact of multiple interventions to new populations. The aim is to develop methods that will be useful for modeling and comparing intervention strategies using existing data and standard statistical methods. METHODS: Traditional hypothesis testing methods used for randomized clinical trials and cohort studies and extrapolating the results to new populations are compared with interaction and intervention modeling methods. Interaction and intervention modeling utilizes the same data as the traditional approach but examines the impact of multiple simultaneous interactions and allows extrapolation of the results to populations with different prevalences and distributions of risk factors. An example using real data demonstrates the potential of interaction and intervention modeling to predict the impact of multiple interacting variables and to compare the impact of alternative interventions. RESULTS: The methods outlined take into account the impact of the magnitude of the relative risks, prevalence of risk factors, and interaction of risk variables when predicting the impact on a new population or extrapolating the results of one or more interventions on a new population. Traditional methods that do not take into account interactions are shown to produce different conclusions from the intervention modeling approach that incorporates interactions. The impact of the intervention modeling approach compared with the traditional approach will be quite variable depending on the prevalence of the risk factors and their extent of interaction. CONCLUSIONS: Studies designed to test a hypothesis treat most variables as potential confounding variables adjusting for their impact and their interactions as part of the analysis using traditional regression methods. Interaction and intervention modeling focuses on the interactions themselves and allows comparison of the effectiveness of alternative interventions.

Clinical Trials as Topic↗