Factorial Cluster Research Articles

English

Istrian dairy sheep is a local breed essential for the identity and development of the NorthernAdriatic karstic region through high-quality products, primarily the hard sheep artisanal cheese. Border changes fragmented the initial Istrian dairy sheep population in three genetically isolated subpopulations in Italy (1000 animals), Slovenia (1150 animals) and Croatia (2500 animals). Due to the drastic reduction of their population sizes and fragmentation, the populations in Croatia and Slovenia are included in governmentally supported conservation programs. The initial subpopulation in Italy was restored after near extinction with stock from Slovenia, and is used today in meat production. The aim of this study was to provide an initial understanding of the current genetic structure and distribution of the genetic variability that exists in Istrian sheep by analysing individuals sampled in two regional groups of Istrian sheep from Croatia and Slovenia. Cres island sheep and Lika pramenka sheep were used as out-groups for comparison. Genetic differentiation was analysed using factorial correspondence analysis and structure clustering over 26 microsatellite loci for a total of 104 sheep belonging to three breeds from Croatia and Slovenia. Factorial correspondence analysis and clustering-based structure analysis both showed three distinct populations: Lika pramenka sheep, Cres island sheep and Istrian sheep. We did not find a marked genetic divergence of the regional groups of Istrian sheep. Istrian sheep regional group from Slovenia showed lower genetic variability compared to the one from Croatia. Variability and structure information obtained in this study considered alongside with socio-cultural-contexts and economic goals for the Istrian sheep reared in Croatia and Slovenia indicate that the cross-border exchange of genetic material of animals carrying private alleles among populations would maintain these alleles at low frequencies and minimize the inbreeding rate.

Printed educational messages aimed at family practitioners fail to increase retinal screening among their patients with diabetes: a pragmatic cluster randomized controlled trial [ISRCTN72772651

BackgroundEvidence of the effectiveness of printed educational messages in narrowing the gap between guideline recommendations and practice is contradictory. Failure to screen for retinopathy exposes primary care patients with diabetes to risk of eye complications. Screening is initiated by referral from family practitioners but adherence to guidelines is suboptimal. We aimed to evaluate the ability of printed educational messages aimed at family doctors to increase retinal screening of primary care patients with diabetes.MethodsDesign: Pragmatic 2×3 factorial cluster trial randomized by physician practice, involving 5,048 general practitioners (with 179,833 patients with diabetes). Setting: Ontario family practitioners. Interventions: Reminders (that retinal screening helps prevent diabetes-related vision loss and is covered by provincial health insurance for patients with diabetes) with prompts to encourage screening were mailed to each physician in conjunction with a widely-read professional newsletter. Alternative printed materials formats were an ‘outsert’ (short, directive message stapled to the outside of the newsletter), and/or a two-page, evidence-based article (‘insert’) and a pre-printed sticky note reminder for patients. Main outcome measure: A successful outcome was an eye examination (which includes retinal screening) provided to a patient with diabetes, not screened in the previous 12 months, within 90 days after visiting a family practitioner. Analysis accounted for clustering of doctors within practice groups.ResultsNo intervention effect was detected (eye exam rates were 31.6% for patients of control physicians, 31.3% for the insert, 32.8% for the outsert, 32.3% for those who received both, and 31.2% for those who received both plus the patient reminder with the largest 95% confidence interval around any effect extending from −1.3% to 1.1%).ConclusionsThis large trial conclusively failed to demonstrate any impact of printed educational messages on screening uptake. Despite their low cost, printed educational messages should not be routinely used in attempting to close evidence-practice gaps relating to diabetic retinopathy screening.Trial registrationISRCTN72772651Electronic supplementary materialThe online version of this article (doi:10.1186/1748-5908-9-87) contains supplementary material, which is available to authorized users.

Perceived Strategies Under the Focus of Strategic Positioning Theory, Resource Based-View, Strategic Mission and Organizational Typology: a Study of Companies in Southern Brazil

This paper examines the subject of organizational strategy of companies in southern Brazil. Our aim is to propose a tool that allows the identification of strategic approaches of organizations. From theoretical viewpoint of strategic positioning, resource-based view, strategic mission and strategic typology, an integrating framework is proposed. We conducted a survey using a questionnaire with closed questions and applied it to medium and large firms in southern Brazil. Using the factorial analysis technique and cluster analysis, we analyzed the identified strategies in each cluster, comparing them with the perceived performance. The results suggest that the more strategies are aligned with the theoretical model, considering the four approaches used, the better the performance perceived by managers is.

Alcohol screening and brief interventions for offenders in the probation setting (SIPS Trial): a pragmatic multicentre cluster randomized controlled trial.

To evaluate the effectiveness of different brief intervention strategies at reducing hazardous or harmful drinking in the probation setting. Offender managers were randomized to three interventions, each of which built on the previous one: feedback on screening outcome and a client information leaflet control group, 5 min of structured brief advice and 20 min of brief lifestyle counselling. A pragmatic multicentre factorial cluster randomized controlled trial. The primary outcome was self-reported hazardous or harmful drinking status measured by Alcohol Use Disorders Identification Test (AUDIT) at 6 months (negative status was a score of <8). Secondary outcomes were AUDIT status at 12 months, experience of alcohol-related problems, health utility, service utilization, readiness to change and reduction in conviction rates. Follow-up rates were 68% at 6 months and 60% at 12 months. At both time points, there was no significant advantage of more intensive interventions compared with the control group in terms of AUDIT status. Those in the brief advice and brief lifestyle counselling intervention groups were statistically significantly less likely to reoffend (36 and 38%, respectively) than those in the client information leaflet group (50%) in the year following intervention. Brief advice or brief lifestyle counselling provided no additional benefit in reducing hazardous or harmful drinking compared with feedback on screening outcome and a client information leaflet. The impact of more intensive brief intervention on reoffending warrants further research.

Evaluating an audit and feedback intervention for reducing antibiotic prescribing behaviour in general dental practice (the RAPiD trial): a partial factorial cluster randomised trial protocol

BackgroundAntibiotic prescribing in dentistry accounts for 9% of total antibiotic prescriptions in Scottish primary care. The Scottish Dental Clinical Effectiveness Programme (SDCEP) published guidance in April 2008 (2nd edition, August 2011) for Drug Prescribing in Dentistry, which aims to assist dentists to make evidence-based antibiotic prescribing decisions. However, wide variation in prescribing persists and the overall use of antibiotics is increasing.MethodsRAPiD is a 12-month partial factorial cluster randomised trial conducted in NHS General Dental Practices across Scotland. Its aim is to compare the effectiveness of individualised audit and feedback (A&F) strategies for the translation into practice of SDCEP recommendations on antibiotic prescribing. The trial uses routinely collected electronic healthcare data in five aspects of its design in order to: identify the study population; apply eligibility criteria; carry out stratified randomisation; generate the trial intervention; analyse trial outcomes.Eligibility was determined on contract status and a minimum level of recent NHS treatment provision. All eligible dental practices in Scotland were simultaneously randomised at baseline either to current audit practice or to an intervention group. Randomisation was stratified by single-handed/multi-handed practices. General dental practitioners (GDPs) working at intervention practices will receive individualised graphical representations of their antibiotic prescribing rate from the previous 14 months at baseline and an update at six months. GDPs could not be blinded to their practice allocation. Intervention practices were further randomised using a factorial design to receive feedback with or without: a health board comparator; a supplementary text-based intervention; additional feedback at nine months. The primary outcome is the total antibiotic prescribing rate per 100 courses of treatment over the year following delivery of the baseline intervention.A concurrent qualitative process evaluation will apply theory-based approaches using the Consolidated Framework for Implementation Research to explore the acceptability of the interventions and the Theoretical Domains Framework to identify barriers and enablers to evidence-based antibiotic prescribing behaviour by GDPs.DiscussionRAPiD will provide a robust evaluation of A&F in dentistry in Scotland. It also demonstrates that linked administrative datasets have the potential to be used efficiently and effectively across all stages of an randomised controlled trial.Trial registrationCurrent Controlled Trials ISRCTN49204710

Evaluation of Gold Geochemical Anomalies in the Liaodong Paleorift

89 Au geochemical anomalies are delineated by using 1/200000 regional geochemical exploration data. By researching regional geochemical characteristics and the relationship with the geological background, the author points out that: the main factors causing high background of Au geochemical anomalies are Gaixian and Dashiqiao formation of Liaohe group, intrusions of Mesozoic intermediate-acid intrusive rocks. The elements combination types of typical anomalies are determined by using factorial analysis,cluster analysis and other mathematical methods with the combination of elements association in typical anomalies:the composite anomaly of Baiyun gold deposits is Au-As-Sb, Maoling gold deposit is Au-As-Bi-Mo, Wulong gold deposits is Au-As-Bi-W, Xiaotongjiapuzi gold deposit is Au-As-Bi-Mo-Sb. By using multivariate statistical analysis method,62 ore-caused anomaly are preferred in 89 Au geochemical anomalies delineated. On this basis, the 62 anomalies are divided into 4 kinds of anomaly types reference to elements combination types of typical anomalies,the classification results of ore-caused anomalies are: 4 geochemical anomalies of Baiyun type,36 geochemical anomalies of Maoling type,11 geochemical anomalies of Wulong type, 11 geochemical anomalies of Xiaotongjapuzi type. According to the results, the prospecting direction is provided for the future of gold exploration.

Improving chronic disease prevention and screening in primary care: results of the BETTER pragmatic cluster randomized controlled trial.

BackgroundPrimary care provides most of the evidence-based chronic disease prevention and screening services offered by the healthcare system. However, there remains a gap between recommended preventive services and actual practice. This trial (the BETTER Trial) aimed to improve preventive care of heart disease, diabetes, colorectal, breast and cervical cancers, and relevant lifestyle factors through a practice facilitation intervention set in primary care.MethodsPragmatic two-way factorial cluster RCT with Primary Care Physicians’ practices as the unit of allocation and individual patients as the unit of analysis. The setting was urban Primary Care Team practices in two Canadian provinces. Eight Primary Care Team practices were randomly assigned to receive the practice-level intervention or wait-list control; 4 physicians in each team (32 physicians) were randomly assigned to receive the patient-level intervention or wait-list control. Patients randomly selected from physicians’ rosters were stratified into two groups: 1) general and 2) moderate mental illness. The interventions involved a multifaceted, evidence-based, tailored practice-level intervention with a Practice Facilitator, and a patient-level intervention involving a one-hour visit with a Prevention Practitioner where patients received a tailored ‘prevention prescription’. The primary outcome was a composite Summary Quality Index of 28 evidence-based chronic disease prevention and screening actions with pre-defined targets, expressed as the ratio of eligible actions at baseline that were met at follow-up. A cost-effectiveness analysis was conducted.Results789 of 1,260 (63%) eligible patients participated. On average, patients were eligible for 8.96 (SD 3.2) actions at baseline. In the adjusted analysis, control patients met 23.1% (95% CI: 19.2% to 27.1%) of target actions, compared to 28.5% (95% CI: 20.9% to 36.0%) receiving the practice-level intervention, 55.6% (95% CI: 49.0% to 62.1%) receiving the patient-level intervention, and 58.9% (95% CI: 54.7% to 63.1%) receiving both practice- and patient-level interventions (patient-level intervention versus control, P < 0.001). The benefit of the patient-level intervention was seen in both strata. The extra cost of the intervention was $26.43CAN (95% CI: $16 to $44) per additional action met.ConclusionsA Prevention Practitioner can improve the implementation of clinically important prevention and screening for chronic diseases in a cost-effective manner.

Fruit morphological descriptors as a tool for discrimination of Daucus L. germplasm

Fruits present major morphological characters used to define genera and species within the Apiaceae. Northern Africa represents a major center of diversity of Daucus, with Tunisia containing at least 12 species and six subspecies. We assessed 14 mature fruit characters from the Daucus L. germplasm collection at the National Gene Bank of Tunisia. Quantification of variability for each character was investigated using the standardized Shannon–Weaver diversity index (H′). Diversity was established by factorial analysis of correspondence and cluster analysis. The computing H′ index ranged from 0.31 for stylopodium shape to a maximum of 0.81 for spine shape. A mean diversity index for all traits recorded across all populations averaged 0.58 indicating existence of an important genetic diversity within the collection. Multivariate analysis of factorial correspondence and cluster analysis on morphological descriptors permitted the subdivision of the Daucus collection into five distinct groups including one single accession group, two groups with six accessions, one group of nine accessions and one large group with 81 accessions corresponding each one to a species among Daucus except the large group corresponding to D. carota and D. capillifolius. The grouping of populations did not reflect bioclimatic and geographic patterns, suggesting adaptation of populations to local environments. Of equal importance, our study shows the effectiveness of fruit characters alone to identify species in this collection of Daucus.

Effects of quality improvement in health facilities and community mobilization through women's groups on maternal, neonatal and perinatal mortality in three districts of Malawi: MaiKhanda, a cluster randomized controlled effectiveness trial

BackgroundMaternal, perinatal and neonatal mortality remains high in low-income countries. We evaluated community and facility-based interventions to reduce deaths in three districts of Malawi.MethodsWe evaluated a rural participatory women’s group community intervention (CI) and a quality improvement intervention at health centres (FI) via a two-by-two factorial cluster randomized controlled trial. Consenting pregnant women were followed-up to 2 months after birth using key informants. Primary outcomes were maternal, perinatal and neonatal mortality. Clusters were health centre catchment areas assigned using stratified computer-generated randomization. Following exclusions, including non-birthing facilities, 61 clusters were analysed: control (17 clusters, 4912 births), FI (15, 5335), CI (15, 5080) and FI + CI (14, 5249). This trial was registered as International Standard Randomised Controlled Trial [ISRCTN18073903]. Outcomes for 14 576 and 20 576 births were recorded during baseline (June 2007–September 2008) and intervention (October 2008–December 2010) periods.ResultsFor control, FI, CI and FI + CI clusters neonatal mortality rates were 34.0, 28.3, 29.9 and 27.0 neonatal deaths per 1000 live births and perinatal mortality rates were 56.2, 55.1, 48.0 and 48.4 per 1000 births, during the intervention period. Adjusting for clustering and stratification, the neonatal mortality rate was 22% lower in FI + CI than control clusters (OR = 0.78, 95% CI 0.60–1.01), and the perinatal mortality rate was 16% lower in CI clusters (OR = 0.84, 95% CI 0.72–0.97). We did not observe any intervention effects on maternal mortality.ConclusionsDespite implementation problems, a combined community and facility approach using participatory women’s groups and quality improvement at health centres reduced newborn mortality in rural Malawi.

Avaliação da modernização da produção agrícola nas microrregiões do Nordeste brasileiro: classificação e agrupamento de indicadores

The Brazilian agriculture modernization process began in the mid 1960s. However, this process occurred differently in regions of the country, marked by profound transformation of the Mid-South region to which received most of the agricultural credit for producing of the main commodities of the agricultural export sector, and due to the concentration of subsistence and low added value of agriculture in the North and Northeast regions. In this context, this study aimed to verify what is the agriculture modernization level in Northeast microregions. For so, were selected 21 variables to analyze the modernization of agriculture in the 188 microregions of the Northeast and were held a factorial analyses and cluster. Broadly, the results indicated a large homogeneity of the region, characterized by a low technological intensity, calling attention to the need to formulation of policies that enhance the formulation of incentive projects that foster agricultural development, human capital training, use of production technology, creation and better use of rural credit, in order to definitely incorporate the Northeast to domestic production.

Factorial cluster algebras

We show that cluster algebras do not contain non-trivial units and that all cluster variables are irreducible elements. Both statements follow from Fomin and Zelevinsky's Laurent phenomenon. As an application we give a criterion for a cluster algebra to be a factorial algebra. This can be used to construct cluster algebras, which are isomorphic to polynomial rings. We also study various kinds of upper bounds for cluster algebras, and we prove that factorial cluster algebras coincide with their upper bounds.

Effect of gender on the association between weight status and health-related quality of life in adolescents

BackgroundSome studies have investigated the association between body mass index (BMI) and health-related quality of life (HRQoL) among adolescents, but their results have been discrepant and few paid attention to the role of gender. The present investigation aimed to assess the relationship between weight status and HRQoL in adolescents and to verify whether it was similar in boys and girls.MethodsFive thousand two hundred and twenty six adolescents aged 14 to 18 years were included in the PRomotion de l’ALIMentation et de l’Activité Physique (PRALIMAP) trial, a 2x2x2 factorial cluster randomized trial performed in 24 high schools in France. Sociodemographic, anthropometric and HRQoL data were collected. BMI was categorized in four classes (thin, normal-weight, overweight, obese). Linear regression models were used to estimate the association between weight status and HRQoL, adjusting for confounders.ResultsThe mean age of adolescents was 15.7±0.6 years and their mean BMI was 21.6 ±3.5 kg/m2; 55% were girls. Boys were more often overweight and obese than were girls (overweight: 15.6% vs 14.2%, obese: 4.8% vs 3.3%), and girls were more likely to be thin (5.5% vs 4.5%, p=0.0042). All HRQoL scores were higher for boys (p=<0.0001). Weight status was not associated with physical and social scores neither in boys nor in girls. Conversely, it was associated with mental score, but differently in girls than boys. As compared with normal-weight girls, thin girls had better mental HRQoL (β=+6.17, p=0.0010), and overweight and obese girls had lower mental HRQoL (β=−3.89 and β=−5.90, respectively, p<0.001). Mental HRQoL was lower for thin, overweight and obese boys than for normal-weight boys (β= −4.97, β= −1.68 and β= −3.17, respectively, p<0.0001).ConclusionsGender can modify the association between weight status and HRQoL in adolescents. Body image could be an important target of public health programs to improve subjective health during adolescence.

Delivery Strategies to Optimize Resource Utilization and Performance Status for Patients With Advanced Life-Limiting Illness: Results From the “Palliative Care Trial” [ISRCTN 81117481

ContextEvidence-based approaches are needed to improve the delivery of specialized palliative care. ObjectivesThe aim of this trial was to improve on current models of service provision. MethodsThis 2×2×2 factorial cluster randomized controlled trial was conducted at an Australian community-based palliative care service, allowing three simultaneous comparative effectiveness studies. Participating patients were newly referred adults, experiencing pain, and who were expected to live >48 hours. Patients enrolled with their general practitioners (GPs) and were randomized three times: 1) individualized interdisciplinary case conference including their GP vs. control, 2) educational outreach visiting for GPs about pain management vs. control, and 3) structured educational visiting for patients/caregivers about pain management vs. control. The control condition was current palliative care. Outcomes included Australia-modified Karnofsky Performance Status (AKPS) and pain from 60 days after randomization and hospitalizations. ResultsThere were 461 participants: mean age 71 years, 50% male, 91% with cancer, median survival 179 days, and median baseline AKPS 60. Only 47% of individuals randomized to the case conferencing intervention received it; based on a priori-defined analyses, 32% of participants were included in final analyses. Case conferencing reduced hospitalizations by 26% (least squares means hospitalizations per patient: case conference 1.26 [SE 0.10] vs. control 1.70 [SE 0.13], P=0.0069) and better maintained performance status (AKPS case conferences 57.3 [SE 1.5] vs. control 51.7 [SE 2.3], P=0.0368). Among patients with declining function (AKPS <70), case conferencing and patient/caregiver education better maintained performance status (AKPS case conferences 55.0 [SE 2.1] vs. control 46.5 [SE 2.9], P=0.0143; patient/caregiver education 54.7 [SE 2.8] vs. control 46.8 [SE 2.1], P=0.0206). Pain was unchanged. GP education did not change outcomes. ConclusionA single case conference added to current specialized community-based palliative care reduced hospitalizations and better maintained performance status. Comparatively, patient/caregiver education was less effective; GP education was not effective.

Diarrhea and dengue control in rural primary schools in Colombia: study protocol for a randomized controlled trial.

BackgroundDiarrheal diseases and dengue fever are major global health problems. Where provision of clean water is inadequate, water storage is crucial. Fecal contamination of stored water is a common source of diarrheal illness, but stored water also provides breeding sites for dengue vector mosquitoes. Poor household water management and sanitation are therefore potential determinants of both diseases. Little is known of the role of stored water for the combined risk of diarrhea and dengue, yet a joint role would be important for developing integrated control and management efforts. Even less is known of the effect of integrating control of these diseases in school settings. The objective of this trial was to investigate whether interventions against diarrhea and dengue will significantly reduce diarrheal disease and dengue entomological risk factors in rural primary schools.Methods/designThis is a 2×2 factorial cluster randomized controlled trial. Eligible schools were rural primary schools in La Mesa and Anapoima municipalities, Cundinamarca, Colombia. Eligible pupils were school children in grades 0 to 5. Schools were randomized to one of four study arms: diarrhea interventions (DIA); dengue interventions (DEN); combined diarrhea and dengue interventions (DIADEN); and control (C). Schools were allocated publicly in each municipality (strata) at the start of the trial, obviating the need for allocation concealment. The primary outcome for diarrhea is incidence rate of diarrhea in school children and for dengue it is density of adult female Aedes aegypti per school. Approximately 800 pupils from 34 schools were enrolled in the trial with eight schools in the DIA arm, nine in the DEN, eight in the DIADEN, and nine in the control arms. The trial status as of June 2012 was: completed baseline data collections; enrollment, randomization, and allocation of schools. The trial was funded by the Research Council of Norway and the Lazos de Calandaima Foundation.DiscussionThis is the first trial investigating the effect of a set of integrated interventions to control both dengue and diarrhea. This is also the first trial to study the combination of diarrhea-dengue disease control in school settings.Trial registrationCurrent Controlled Trials ISRCTN40195031

Effect of a nutrition supplement and physical activity program on pneumonia and walking capacity in Chilean older people: a factorial cluster randomized trial.

Ageing is associated with increased risk of poor health and functional decline. Uncertainties about the health-related benefits of nutrition and physical activity for older people have precluded their widespread implementation. We investigated the effectiveness and cost-effectiveness of a national nutritional supplementation program and/or a physical activity intervention among older people in Chile. We conducted a cluster randomized factorial trial among low to middle socioeconomic status adults aged 65-67.9 years living in Santiago, Chile. We randomized 28 clusters (health centers) into the study and recruited 2,799 individuals in 2005 (~100 per cluster). The interventions were a daily micronutrient-rich nutritional supplement, or two 1-hour physical activity classes per week, or both interventions, or neither, for 24 months. The primary outcomes, assessed blind to allocation, were incidence of pneumonia over 24 months, and physical function assessed by walking capacity 24 months after enrollment. Adherence was good for the nutritional supplement (~75%), and moderate for the physical activity intervention (~43%). Over 24 months the incidence rate of pneumonia did not differ between intervention and control clusters (32.5 versus 32.6 per 1,000 person years respectively; risk ratio = 1.00; 95% confidence interval 0.61-1.63; p = 0.99). In intention-to-treat analysis, after 24 months there was a significant difference in walking capacity between the intervention and control clusters (mean difference 33.8 meters; 95% confidence interval 13.9-53.8; p = 0.001). The overall cost of the physical activity intervention over 24 months was US$164/participant; equivalent to US$4.84/extra meter walked. The number of falls and fractures was balanced across physical activity intervention arms and no serious adverse events were reported for either intervention. Chile's nutritional supplementation program for older people is not effective in reducing the incidence of pneumonia. This trial suggests that the provision of locally accessible physical activity classes in a transition economy population can be a cost-effective means of enhancing physical function in later life. Current Controlled Trials ISRCTN 48153354.

Population structure in three Albanian sheep breeds using 36 single nucleotide polymorphisms

Local sheep breeds are important species for the Albanian livestock farmers. Nienty three unrelated individuals belonging to three local sheep breeds were analyzed for 36 single nucleotide polymorphisms. Results were used to assess population parameters. This study was carried out within the framework of ECONOGENE project, intended to help molecular characterization of Albanian local sheep breeds. Population structure analysis and the assignment of individuals to their reference population were carried out. Almost all of the genetic variations were due to differences between individuals. Mean percentage of individuals was correctly assigned using the Bayesian approach at 45.16%. Factorial component analysis and model-based clustering did not differentiate sheep breeds but displayed a high level of breed admixture. These statements were in concordance with small genetic distance between breeds. We were able to identify individuals purely corresponding to their reference population, who might be used in the breeding programs in the near future, for conserving these valuable breeds.

PRALIMAP: study protocol for a high school-based, factorial cluster randomised interventional trial of three overweight and obesity prevention strategies

BackgroundGiven the increase in overweight and obesity prevalence in adolescents in the last decade, effective prevention strategies for these conditions in adolescents are urgently needed. The PRALIMAP (Promotion de l'ALImentation et de l'Activité Physique) trial aims to evaluate the effectiveness for these conditions of 3 health promotion strategies -- educational, screening and environmental -- applied singly or in combination in high schools over a 2-year intervention period.MethodsPRALIMAP is a stratified 2 × 2 × 2 factorial cluster randomised controlled trial including 24 state high schools in Lorraine, northeastern France, in 2 waves: 8 schools in 2006 (wave 1) and 16 in 2007 (wave 2). Students entering the selected high schools in the 4 academic years from 2006 to 2009 are eligible for data collection. Interventional strategies are organized over 2 academic years. The follow-up consists of 3 visits: at the entry of grade 10 (T0), grade 11 (T1) and grade 12 (T2). At T0, 5,458 (85.7%) adolescents participated. The educational strategy consists of nutritional lessons, working groups and a final party. The screening strategy consists in detecting overweight/obesity and eating disorders in adolescents and proposing, if necessary, an adapted care management program of 7 group educational sessions. The environmental strategy consists in improving dietary and physical activity offerings in high schools and facilities, especially catering. The main outcomes are body size evolution over time, nutritional behaviour and knowledge, health and quality of life. An evaluation process documents how each intervention strategy is implemented in the schools and estimates the dose of the intervention, allowing for a per protocol analysis after the main intention-to-treat analysis.DiscussionPRALIMAP aims at improving the prevention and management of overweight and obesity in adolescents by translating current evidence into public health practice. Particular attention is paid to clustering, multiple factorials and long-term duration to address common pitfalls in health promotion trials. The results should inform how best to implement, in a school environment, effective nutrition prevention programs targeting adolescents who are at a point their lives when they develop responsibilities and empowerment for health attitude behaviours.Trial registrationThis trial is registered at ClinicalTrials.gov under NCT00814554.

Effectiveness of earlier antenatal screening for sickle cell disease and thalassaemia in primary care: cluster randomised trial

Objective To evaluate the effectiveness of offering antenatal screening for sickle cell disease and thalassaemia in primary care as a way of facilitating earlier uptake of screening.Design Partial factorial cluster...

Screening and brief interventions for hazardous and harmful alcohol use in probation services: a cluster randomised controlled trial protocol.

BackgroundA large number of randomised controlled trials in health settings have consistently reported positive effects of brief intervention in terms of reductions in alcohol use. However, although alcohol misuse is common amongst offenders, there is limited evidence of alcohol brief interventions in the criminal justice field. This factorial pragmatic cluster randomised controlled trial with Offender Managers (OMs) as the unit of randomisation will evaluate the effectiveness and cost-effectiveness of different models of screening to identify hazardous and harmful drinkers in probation and different intensities of brief intervention to reduce excessive drinking in probation clients.Methods and designNinety-six OMs from 9 probation areas across 3 English regions (the North East Region (n = 4) and London and the South East Regions (n = 5)) will be recruited. OMs will be randomly allocated to one of three intervention conditions: a client information leaflet control condition (n = 32 OMs); 5-minute simple structured advice (n = 32 OMs) and 20-minute brief lifestyle counselling delivered by an Alcohol Health Worker (n = 32 OMs). Randomisation will be stratified by probation area. To test the relative effectiveness of different screening methods all OMs will be randomised to either the Modified Single Item Screening Questionnaire (M-SASQ) or the Fast Alcohol Screening Test (FAST). There will be a minimum of 480 clients recruited into the trial. There will be an intention to treat analysis of study outcomes at 6 and 12 months post intervention. Analysis will include client measures (screening result, weekly alcohol consumption, alcohol-related problems, re-offending, public service use and quality of life) and implementation measures from OMs (the extent of screening and brief intervention beyond the minimum recruitment threshold will provide data on acceptability and feasibility of different models of brief intervention). We will also examine the practitioner and organisational factors associated with successful implementation.DiscussionThe trial will evaluate the impact of screening and brief alcohol intervention in routine probation work and therefore its findings will be highly relevant to probation teams and thus the criminal justice system in the UK.Ethical approval was given by Northern & Yorkshire RECTrial Registration numberISRCTN 19160244

Restricted randomization of ZAMSTAR: a 2 × 2 factorial cluster randomized trial

A small number of clusters and substantial variation between clusters increase the chance of unbalanced randomization in cluster randomized trials. Baseline imbalances between groups may distort intervention effects. When adjusting for imbalances in the cluster-level analysis, this results in loss of degrees of freedom. Variance reduction that can be achieved through stratification and blocking is limited. Restricted randomization is an alternative approach that ensures balanced allocation. We present the randomization scheme used in the ZAMSTAR trial of tuberculosis control interventions in Southern Africa. We used stratification and restriction to randomize 24 clusters (16 Zambian, 8 South African) into four intervention groups in a 2 x 2 factorial design. Stratification was by country and tuberculous infection prevalence and restriction by tuberculous infection prevalence, HIV prevalence, urban/rural, social context, and geographical location. Balance was defined in terms of covariate-specific tolerance thresholds for the measure of imbalance. For binary (0/1) covariates we defined imbalance = max(S(i)) - min(S(i)), where, S(i) was the number of 1s in group i = 1,2,3,4. For continuous covariates we defined imbalance = (max(M(i)) - min(M(i)))/ min(M(i) ), where, M( i) was the average in group i = 1,2,3,4.We used simulation to estimate the restriction factor (proportion of unacceptable allocations) both for individual covariates and overall. Simulation was also used to investigate the validity of the restricted randomization design, with the use of the validity matrix, by monitoring the probability that any given pair of clusters is allocated to the same intervention group. There were 3 657 930 400 possible ways of allocating the 24 clusters to the four groups after stratification. With a combined restriction factor of 0.998 this still left 7 million acceptable allocations. The final allocation was selected at a public ceremony from a randomly-generated list of acceptable allocations. The design of the allocation process was observed to be valid. The restricted randomization scheme significantly decreased the total number of available allocations of clusters into intervention groups. Our restricted randomization was successful in that it achieved good balance while preserving the impartiality and validity of the trial.