Changes in intention to use an interprofessional approach to decision-making following training: a cluster before-and-after study.

BACKGROUND: Health professionals in home care work in interprofessional teams. Yet most training in decision support assumes a one-on-one relationship with patients. We assessed the impact of an in-person training session in interprofessional shared decision-making (IP-SDM) on home care professionals' intention to adopt this approach. METHODS: We conducted a secondary analysis of a cluster stepped-wedge trial using a before-and-after study design. We collected data among home care professionals from November 2016 to February 2018 in 9 health and social services centers in Quebec, Canada. The intervention was an in-person IP-SDM training session. Intention to engage in IP-SDM pre- and post-session (dependent variable) was compared using a continuing professional development evaluation scale (CPD-Reaction) informed by the Godin's Integrated Behavioral Model for health professionals. We also assessed socio-demographic and psychosocial variables (beliefs about capabilities, beliefs about consequences, social influence and moral norm). We performed bivariate and multivariate analysis to identify factors influencing post-intervention intention. We used the STROBE reporting guidelines for observational studies to report our results. RESULTS: Of 134 respondents who provided complete pairs of questionnaires (pre- and post-), most were female (90.9%), mean age was 42 (± 9.3) years and 66.9% were social workers. Mean intention scores decreased from 5.84 (± 1.19) to 5.54 (± 1.35) (Mean difference = -0.30 ± 1.16; p = 0.02). Factors associated with higher intention post-intervention were social influence (ß = 0.34, p = 0.01) and belief about capabilities (ß = 0.49, p < 0.01). CONCLUSION: After in-person IP-SDM training, healthcare professionals' intention to engage in IP-SDM decreased. However, the scope of this decrease is probably not clinically significant. Due to their association with intention, beliefs about capabilities, which translate into having a sense of self-competency in the new clinical behavior, and social influences, which translate into what important others think one should be doing, could be targets for future research aiming to implement IP-SDM in home care settings.

Evaluating the impact of continuing professional development courses on physician behavioral intention: a pre-post study with follow-up at six months.

BACKGROUND: Continuing professional development (CPD) for health professionals includes educational activities to maintain or improve skills. We evaluated the impact of a series of CPD courses by identifying factors influencing physicians' intention to adopt targeted behaviors and assessing self-reported behavior adoption six months later. METHODS: In this pre-post study, eligible participants attended at least one in-person course at the Fédération des Médecins Spécialistes du Québec annual meeting in November 2019. Before and afterwards, participants completed CPD-REACTION, a validated questionnaire based on Godin's integrated model for health professional behavior change that measures intention and psychosocial factors influencing intention. We used Wilcoxon signed-rank test to compare pre- and post-course intention scores and linear regression analyses to identify factors influencing intention. We also compared the post-course intention scores of participants reporting a behavior change six months later with the scores of those reporting no behavior change six months later. Qualitative data was collected only six months after courses and responses to open-ended questions were analyzed using the Theoretical Domains Framework. RESULTS: A total of 205/329 course attendees completed CPD-REACTION (response rate 62.3%). Among these participants, 158/329 (48%) completed the questionnaire before CPD courses, 129/329 (39.2%) only after courses and 47/329 (14.3%) at 6 months. Study population included 192 physicians of whom 78/192(40.6%) were female; 59/192(30.7%) were between 50 and 59 years old; and 72/192 (37.5%) were surgical specialist physicians. Mean intention scores before (n = 158) and after (n = 129) courses were 5.74(SD = 1.52) and 6.35(SD = 0.93) respectively. Differences in mean (DM) intention before and afterwards ranged from - 0.31(p = 0.17) to 2.25(p = 0.50). Multivariate analysis showed that beliefs about capabilities (ß = 0.15, p = 0.001), moral norm (ß = 0.75, p < 0.0001), and beliefs about consequences (ß = 0.11, p = 0.04) influenced post-course intention. Post-course intention was correlated with behavior six months later (DM = 0.63; p = 0.02). Qualitative analysis showed that facilitators to behavior adoption after six months were most often related to the TDF domains of beliefs about capabilities. Most frequent barriers to adoption related to lack of resources. CONCLUSIONS: Overall, scores for intention to adopt targeted behaviors increased after the courses. CPD providers could increase participants' intention by including interventions that emphasize beliefs about capabilities, moral norm and beliefs about consequences.

La santé sexuelle des hommes trans : entre problèmes de catégorisation et invisibilisation.

INTRODUCTION: Sexual minorities have been disproportionally impacted by the HIV-Aids epidemic. Their high prevalence motivated sexual health research that first focused on gay men, then trans women. Trans men have been considered at very low risk of exposition, Hence the scarce number of research about them. However, an emerging literature is showing diversified and surprising results regarding the reasons for their initial exclusion. PURPOSE OF RESEARCH: This article seeks to establish the state of knowledge on trans men's sexual health through a French and international literature review. RESULTS: Trans men have a variety of partners, sexual and non-sexual practices (IDU) that leads to categorize them at high risk of HIV exposure. The proportion of trans men who are HIV positive still is difficult to assess. It is estimated to be high in the USA, and close to zero in France. Low screening rates, difficulties accessing health care, and identification problems in the very classification of people suggest that they might be more of them. Trans men also report discriminations in access to health care services, and specific health vulnerabilities. Gynecology and reproductive health are rarely even mentioned. CONCLUSIONS: Rethinking the categories used in research would produce a more accurate representation of the varied realities of trans people.

Learning how a tree branches out: A statistical modeling approach.

The increasingly large size of the graphical and numerical data sets collected with modern technologies requires constant update and upgrade of the statistical models, methods and procedures to be used for their analysis in order to optimize learning and maximize knowledge and understanding. This is the case for plant CT scanning (CT: computed tomography), including applications aimed at studying leaf canopies and the structural complexity of the branching patterns that support them in trees. Therefore, we first show after a brief review, how the CT scanning data can be leveraged by constructing an analytical representation of a tree branching structure where each branch is represented by a line segment in 3D and classified in a level of a hierarchy, starting with the trunk (level 1). Each segment, or branch, is characterized by four variables: (i) the position on its parent, (ii) its orientation, a unit vector in 3D, (iii) its length, and (iv) the number of offspring that it bears. The branching structure of a tree can then be investigated by calculating descriptive statistics on these four variables. A deeper analysis, based on statistical models aiming to explain how the characteristics of a branch are associated with those of its parents, is also presented. The branching patterns of three miniature trees that were CT scanned are used to showcase the statistical modeling framework, and the differences in their structural complexity are reflected in the results. Overall, the most important determinant of a tree structure appears to be the length of the branches attached to the trunk. This variable impacts the characteristics of all the other branches of the tree.

Predictors of Decision Regret among Caregivers of Older Canadians Receiving Home Care: A Cross-Sectional Online Survey.

Background. In Canada, caregivers of older adults receiving home care face difficult decisions that may lead to decision regret. We assessed difficult decisions and decision regret among caregivers of older adults receiving home care services and factors associated with decision regret. Methods. From March 13 to 30, 2020, at the outbreak of the COVID-19 pandemic, we conducted an online survey with caregivers of older adults receiving home care in the 10 Canadian provinces. We distributed a self-administered questionnaire through Canada's largest and most representative private online panel. We identified types of difficult health-related decisions faced in the past year and their frequency and evaluated decision regret using the Decision Regret Scale (DRS), scored from 0 to 100. We performed descriptive statistics as well as bivariable and multivariable linear regression to identify factors predicting decision regret. Results. Among 932 participants, the mean age was 42.2 y (SD = 15.6 y), and 58.4% were male. The most frequently reported difficult decisions were regarding housing and safety (75.1%). The mean DRS score was 28.8/100 (SD = 8.6). Factors associated with less decision regret included higher caregiver age, involvement of other family members in the decision-making process, wanting to receive information about the options, and considering organizations interested in the decision topic and health care professionals as trustworthy sources of information (all P < 0.001). Factors associated with more decision regret included mismatch between the caregiver's preferred option and the decision made, the involvement of spouses in the decision-making process, higher decisional conflict, and higher burden of care (all P < 0.001). Discussion. Decisions about housing and safety were the difficult decisions most frequently encountered by caregivers of older adults in this survey. Our results will inform future decision support interventions. Highlights: This is one of the first studies to assess decision regret among caregivers of older adults receiving home and community care services and to identify their most frequent difficult decisions.Difficult decisions were most frequently about housing and safety. Most caregivers of older adults in all 10 provinces of Canada experienced decision regret.Factors associated with less decision regret included higher caregiver age, the involvement of other family members in the decision-making process, wanting to receive information about the options, considering organizations interested in the decision topic, and health care professionals as trustworthy sources of information. Factors associated with more decision regret included mismatch between the caregiver's preferred option and the decision made, the involvement of spouses in the decision-making process, higher decisional conflict, and higher burden of care.

Shared Decision-Making Training for Home Care Teams to Engage Frail Older Adults and Caregivers in Housing Decisions: Stepped-Wedge Cluster Randomized Trial.

BACKGROUND: Frail older adults and caregivers need support from their home care teams in making difficult housing decisions, such as whether to remain at home, with or without assistance, or move into residential care. However, home care teams are often understaffed and busy, and shared decision-making training is costly. Nevertheless, overall awareness of shared decision-making is increasing. We hypothesized that distributing a decision aid could be sufficient for providing decision support without the addition of shared decision-making training for home care teams. OBJECTIVE: We evaluated the effectiveness of adding web-based training and workshops for care teams in interprofessional shared decision-making to passive dissemination of a decision guide on the proportion of frail older adults or caregivers of cognitively-impaired frail older adults reporting active roles in housing decision-making. METHODS: We conducted a stepped-wedge cluster randomized trial with home care teams in 9 health centers in Quebec, Canada. Participants were frail older adults or caregivers of cognitively impaired frail older adults facing housing decisions and receiving care from the home care team at one of the participating health centers. The intervention consisted of a 1.5-hour web-based tutorial for the home care teams plus a 3.5-hour interactive workshop in interprofessional shared decision-making using a decision guide that was designed to support frail older adults and caregivers in making housing decisions. The control was passive dissemination of the decision guide. The primary outcome was an active role in decision-making among frail older adults and caregivers, measured using the Control Preferences Scale. Secondary outcomes included decisional conflict and perceptions of how much care teams involved frail older adults and caregivers in decision-making. We performed an intention-to-treat analysis. RESULTS: A total of 311 frail older adults were included in the analysis, including 208 (66.9%) women, with a mean age of 81.2 (SD 7.5) years. Among 339 caregivers of cognitively-impaired frail older adults, 239 (70.5%) were female and their mean age was 66.4 (SD 11.7) years. The intervention increased the proportion of frail older adults reporting an active role in decision-making by 3.3% (95% CI -5.8% to 12.4%, P=.47) and the proportion of caregivers of cognitively-impaired frail older adults by 6.1% (95% CI -11.2% to 23.4%, P=.49). There was no significant impact on the secondary outcomes. However, the mean score for the frail older adults' perception of how much health professionals involved them in decision-making increased by 5.4 (95% CI -0.6 to 11.4, P=.07) and the proportion of caregivers who reported decisional conflict decreased by 7.5% (95% CI -16.5% to 1.6%, P=.10). CONCLUSIONS: Although it slightly reduced decisional conflict for caregivers, shared decision-making training did not equip home care teams significantly better than provision of a decision aid for involving frail older adults and their caregivers in decision-making. TRIAL REGISTRATION: ClinicalTrials.gov NCT02592525; https://clinicaltrials.gov/show/NCT02592525.

Factors Associated With Specialists' Intention to Adopt New Behaviors After Taking Web-Based Continuing Professional Development Courses: Cross-sectional Study.

BACKGROUND: Web-based continuing professional development (CPD) is a convenient and low-cost way for physicians to update their knowledge. However, little is known about the factors that influence their intention to put this new knowledge into practice. OBJECTIVE: We aimed to identify sociocognitive factors associated with physicians' intention to adopt new behaviors as well as indications of Bloom's learning levels following their participation in 5 web-based CPD courses. METHODS: We performed a cross-sectional study of specialist physicians who had completed 1 of 5 web-based CPD courses offered by the Federation of Medical Specialists of Quebec. The participants then completed CPD-Reaction, a questionnaire based on Godin's integrated model for health professional behavior change and with evidence of validity that measures behavioral intention (dependent variable) and psychosocial factors influencing intention (n=4). We also assessed variables related to sociodemographics (n=5), course content (n=9), and course format (eg, graphic features and duration) (n=8). Content variables were derived from CanMEDS competencies, Bloom's learning levels, and Godin's integrated model. We conducted ANOVA single-factor analysis, calculated the intraclass correlation coefficient (ICC), and performed bivariate and multivariate analyses. RESULTS: A total of 400 physicians participated in the courses (range: 38-135 physicians per course). Average age was 50 (SD 12) years; 56% (n=223) were female, and 44% (n=177) were male. Among the 259 who completed CPD-Reaction, behavioral intention scores ranged from 5.37 (SD 1.17) to 6.60 (SD 0.88) out of 7 and differed significantly from one course to another (P<.001). The ICC indicated that 17% of the total variation in the outcome of interest, the behavioral intention of physicians, could be explained at the level of the CPD course (ICC=0.17). In bivariate analyses, social influences (P<.001), beliefs about capabilities (P<.001), moral norm (P<.001), beliefs about consequences (P<.001), and psychomotor learning (P=.04) were significantly correlated with physicians' intention to adopt new behaviors. Multivariate analysis showed the same factors, except for social influences and psychomotor learning, as significantly correlated with intention. CONCLUSIONS: We observed average to high behavioral intention scores after all 5 web-based courses, with some variations by course taken. Factors affecting physicians' intention were beliefs about their capabilities and about the consequences of adopting new clinical behaviors, as well as doubts about whether the new behavior aligned with their moral values. Our results will inform design of future web-based CPD courses to ensure they contribute to clinical behavior change.

Variations in factors associated with healthcare providers' intention to engage in interprofessional shared decision making in home care: results of two cross-sectional surveys.

BACKGROUND: DOLCE (Improving Decision making On Location of Care with the frail Elderly and their caregivers) was a post-intervention clustered randomised trial (cRT) to assess the effect of training home care teams on interprofessional shared decision-making (IP-SDM). Alongside the cRT, we sought to monitor healthcare providers' level of behavioural intention to engage in an IP-SDM approach and to identify factors associated with this intention. METHODS: We conducted two cross-sectional surveys in the province of Quebec, Canada, one each at cRT entry and exit. Healthcare providers (e.g. nurses, occupational therapists and social workers) in the 16 participating intervention and control sites self-completed an identical paper-based questionnaire at entry and exit. Informed by the Integrated model for explaining healthcare professionals' clinical behaviour by Godin et al. (2008), we assessed their behavioural intention to engage in IP-SDM to support older adults and caregivers of older adults with cognitive impairment to make health-related housing decisions. We also assessed psychosocial variables underlying their behavioural intention and collected sociodemographic data. We used descriptive statistics and linear mixed models to account for clustering. RESULTS: Between 2014 and 2016, 271 healthcare providers participated at study entry and 171 at exit. At entry, median intention level was 6 in a range of 1 (low) to 7 (high) (Interquartile range (IQR): 5-6.5) and factors associated with intention were social influence (ß = 0.27, P <  0.0001), beliefs about one's capabilities (ß = 0.43, P <  0.0001), moral norm (ß = 0.31, P <  0.0001) and beliefs about consequences (ß = 0.21, P <  0.0001). At exit, median intention level was 5.5 (IQR: 4.5-6.5). Factors associated with intention were the same but did not include moral norm. However, at exit new factors were kept in the model: working in rehabilitation (ß = - 0.39, P = 0.018) and working as a technician (ß = - 0.41, P = 0.069) (compared to as a social worker). CONCLUSION: Intention levels were high but decreased from entry to exit. Factors associated with intention also changed from study entry to study exit. These findings may be explained by the major restructuring of the health and social care system that took place during the 2 years of the study, leading to rapid staff turnover and organisational disturbance in home care teams. Future research should give more attention to contextual factors and design implementation interventions to withstand the disruption of system- and organisational-level disturbances. TRIAL REGISTRATION: Clinicaltrials.gov (NCT02244359). Registered on September 19th, 2014.

Engaging Caregivers in Health-Related Housing Decisions for Older Adults With Cognitive Impairment: A Cluster Randomized Trial.

BACKGROUND AND OBJECTIVES: Informal caregivers are rarely as involved as they want to be in the housing decisions of cognitively impaired older adults. Lack of awareness of available options and their benefits and risks may lead to decisions that do not reflect older adults' preferences, and to guilt and regret. We assessed the effect of training home care teams in interprofessional shared decision-making (SDM) on the proportion of caregivers who report being active in this decision. RESEARCH DESIGN AND METHODS: In a two-arm pragmatic cluster randomized trial with home care teams working in health centers in the Province of Quebec, we randomized health centers to receive training in interprofessional SDM (intervention) or not (control). Eligible caregivers had made a housing decision for a cognitively impaired adult aged 65 years or older who was receiving services from a home care team. The primary outcome was the proportion of caregivers reporting an active role in decision making. We performed intention-to-treat multilevel analysis. RESULTS: We consecutively enrolled a random group of 16 health centers and recruited 309 caregivers, among whom 296 were included in the analysis. In the intervention arm, the proportion of caregivers reporting an active role in decision making increased by 12% (95% CI -2% to 27%; p = .10). After removal of an influential cluster outlier, the proportion increased to 18% (95% CI: 7%-29%; p < .01). DISCUSSION AND IMPLICATIONS: Training home care teams in interprofessional SDM increased caregiver involvement in health-related housing decisions for cognitively impaired older adults.

Implementing shared decision-making in interprofessional home care teams (the IPSDM-SW study): protocol for a stepped wedge cluster randomised trial.

INTRODUCTION: The frail elderly in Canada face a tough decision when they start to lose autonomy: whether to stay at home or move to another location. This study seeks to scale up and evaluate the implementation of shared decision-making (SDM) in interprofessional (IP) home care teams caring for elderly clients or their caregivers facing a decision about staying at home or moving elsewhere. METHODS: A stepped wedge cluster randomised trial involving 8 Health and Social Service Centers (HSSCs) will be conducted with IP home care teams. HSSCs are the unit of randomisation. A decision guide will be passively distributed to all of the participating HSSCs at the beginning of the project. The participating HSSCs will then be randomised to 1 of 4 intervention start times, separated by 7-month intervals. The primary outcome is whether or not clients and caregivers assumed an active role in decision-making, assessed with a modified version of the Control Preferences Scale. The intervention, targeted at IP home care teams, consists of a 1.5 hour online tutorial and a 3.5 hour skills building workshop in IP SDM. Clients will be eligible for outcome assessment if they (1) are aged ≥65; (2) are receiving care from the IP home care team of the enrolled HSSCs; (3) have made a decision about whether to stay at home or move to another location during the recruitment periods; (4) are able to read, understand and write French or English; (5) can give informed consent. If clients are not able to provide informed consent, their primary caregiver will become the eligible participant. ETHICS AND DISSEMINATION: Ethics committee review approval has been obtained from the Multicenter Ethics Committee of CISSS-Laval. Results will be disseminated at conferences, on websites of team members and in peer-reviewed and professional journals intended for policymakers and managers. TRIAL REGISTRATION NUMBER: NCT02592525, Pre-results.

Mixture regression models for closed population capture-recapture data.

In capture-recapture studies, the use of individual covariates has been recommended to get stable population estimates. However, some residual heterogeneity might still exist and ignoring such heterogeneity could lead to underestimating the population size (N). In this work, we explore two new models with capture probabilities depending on both covariates and unobserved random effects, to estimate the size of a population. Inference techniques including Horvitz-Thompson estimate and confidence intervals for the population size, are derived. The selection of a particular model is carried out using the Akaike information criterion (AIC). First, we extend the random effect model of Darroch et al. (1993, Journal of American Statistical Association 88, 1137-1148) to handle unit level covariates and discuss its limitations. The second approach is a generalization of the traditional zero-truncated binomial model that includes a random effect to account for an unobserved heterogeneity. This approach provides useful tools for inference about N, since key quantities such as moments, likelihood functions and estimates of N and their standard errors have closed form expressions. Several models for the unobserved heterogeneity are available and the marginal capture probability is expressed using the Logit and the complementary Log-Log link functions. The sensitivity of the inference to the specification of a model is also investigated through simulations. A numerical example is presented. We compare the performance of the proposed estimator with that obtained under model Mh of Huggins (1989 Biometrika 76, 130-140).

Dyadic validity of the Decisional Conflict Scale: common patient/physician measures of patient uncertainty were identified.

OBJECTIVES: We aimed to assess the dyadic validity of the Decisional Conflict Scale (DCS) for assessing shared decision making in clinical consultations. We applied dyadic criteria, which consider the patient and physician as an interactive dyad instead of as independent individuals, to identify common patient/physician measures of patient uncertainty. STUDY DESIGN AND SETTING: Patients and their physicians, participating in a randomized clustered trial, completed separately an adapted version of the DCS with five subscales. We performed factor analysis on the full DCS and each subscale independently. We defined a measure as dyadic when measurement invariance across patients and physicians was supported. RESULTS: We analyzed 332 paired responses (physicians with adults or with parents and children) at study entry and 339 at exit. Factor analysis showed that the full DCS is not a valid dyadic measure. However, independent analysis of each subscale showed measurement invariance for values clarity, support, and effective decision (comparative fit index range, 0.93-1; root mean square error of approximation range, 0-0.07; and P-value > 0.05). CONCLUSION: Application of our dyadic validation criterion indicated that the full DCS cannot be considered a dyadic measure. However, three of its subscales, values clarity, support and effective decision, are valid dyadic measures.

Equivalence between Step Selection Functions and Biased Correlated Random Walks for Statistical Inference on Animal Movement.

Animal movement has a fundamental impact on population and community structure and dynamics. Biased correlated random walks (BCRW) and step selection functions (SSF) are commonly used to study movements. Because no studies have contrasted the parameters and the statistical properties of their estimators for models constructed under these two Lagrangian approaches, it remains unclear whether or not they allow for similar inference. First, we used the Weak Law of Large Numbers to demonstrate that the log-likelihood function for estimating the parameters of BCRW models can be approximated by the log-likelihood of SSFs. Second, we illustrated the link between the two approaches by fitting BCRW with maximum likelihood and with SSF to simulated movement data in virtual environments and to the trajectory of bison (Bison bison L.) trails in natural landscapes. Using simulated and empirical data, we found that the parameters of a BCRW estimated directly from maximum likelihood and by fitting an SSF were remarkably similar. Movement analysis is increasingly used as a tool for understanding the influence of landscape properties on animal distribution. In the rapidly developing field of movement ecology, management and conservation biologists must decide which method they should implement to accurately assess the determinants of animal movement. We showed that BCRW and SSF can provide similar insights into the environmental features influencing animal movements. Both techniques have advantages. BCRW has already been extended to allow for multi-state modeling. Unlike BCRW, however, SSF can be estimated using most statistical packages, it can simultaneously evaluate habitat selection and movement biases, and can easily integrate a large number of movement taxes at multiple scales. SSF thus offers a simple, yet effective, statistical technique to identify movement taxis.

Improving Decision making On Location of Care with the frail Elderly and their caregivers (the DOLCE study): study protocol for a cluster randomized controlled trial.

BACKGROUND: One of the toughest decisions faced by elderly people is whether to stay at home or move to a care facility. This study seeks to evaluate the impact of training interprofessional home-care teams in shared decision making combined with a decision aid on the proportion of elderly people who report being active in the decision-making process regarding whether to stay at home or move to a care facility. METHODS/DESIGN: We propose a multicenter cluster randomized trial conducted with home-care interprofessional teams in the Province of Quebec with 2 data collection phases: before and after the intervention. Units of randomization will be centers for primary healthcare and social services. We will enroll 16 of these and ask each to provide one home-care interprofessional team involved in decisions and care planning with eligible clients. Clients will be included if they i) are aged ≥65; ii) are receiving care from the participating home-care interprofessional team; iii) have faced the decision about staying at home or moving to a care facility in the past 3 to 6 months; iv) are able to read, understand and write French or English; and v) are able to give informed consent. If clients are unable to provide informed consent, their primary caregiver who was involved in the decision-making process will be eligible to participate. The intervention arm will receive training in shared decision making and use of a decision aid. The control arm will receive 'usual care'. The primary outcome of interest is the assumed role in the decision-making process as assessed in clients or caregivers with a modified version of the Control Preferences Scale. Multilevel modeling will be used to take the hierarchical structure of the data into account. The study has obtained full ethical approval. The trial will comply with CONSORT guidelines adapted for cluster randomized trials. DISCUSSION: Home care is a rapidly growing sector and this study will lay the foundations of a national strategy to ensure that IP home-care teams provide the highest quality of care for seriously ill elderly people and support for their families. TRIAL REGISTRATION: ClinicalTrials.gov NCT02244359 (registered 18 September 2014).

A stochastic Pella Tomlinson model and its maximum sustainable yield.

This paper investigates the biological reference points, such as the maximum sustainable yield (MSY), for the Pella Tomlinson and the Fox surplus production models (SPM) in the presence of a multiplicative environmental noise. These models are used in fisheries stock assessment as a firsthand tool for the elaboration of harvesting strategies. We derive conditions on the environmental noise distribution that insure that the biomass process for an SPM has a stationary distribution, so that extinction is avoided. Explicit results about the stationary behavior of the biomass distribution are provided for a particular specification of the noise. The consideration of random noise in the MSY calculations leads to more conservative harvesting target than deterministic models. The derivations account for a possible noise autocorrelation that represents the occurrence of spells of good and bad years. The impact of the noise is found to be more severe on Pella Tomlinson model for which the asymmetry parameter p is large while it is less important for Fox model.

Shared decision making does not influence physicians against clinical practice guidelines.

BACKGROUND: While shared decision making (SDM) and adherence to clinical practice guidelines (CPGs) are important, some believe they are incompatible. This study explored the mutual influence between physicians' intention to engage in SDM and their intention to follow CPGs. METHODS: Embedded within a clustered randomized trial to assess the impact of training physicians in SDM about using antibiotics to treat acute respiratory tract infections, this study evaluated physicians' intentions to both engage in SDM and follow CPGs. A self-administered questionnaire based on the theory of planned behavior evaluated both behavioral intentions and their respective determinants (attitude, subjective norm and perceived behavioral control) at study entry and exit. We used path analysis to explore the relationships between the intentions. We conducted statistical analyses using the maximum likelihood method and the variance-covariance matrix. Goodness of fit indices encompassed the chi-square statistic, the comparative fit index and the root mean square error of approximation. RESULTS: We analyzed 244 responses at entry and 236 at exit. In the control group, at entry we observed that physicians' intention to engage in SDM (r = 0, t = 0.03) did not affect their intention to follow CPGs; however, their intention to follow CPGs (r = -0.31 t = -2.82) did negatively influence their intention to engage in SDM. At exit, neither behavioral intention influenced the other. In the experimental group, at entry neither behavioral intention influenced the other; at exit, the intention to engage in SDM still did not influence the intention to use CPGs, although the intention to follow CPGs (r = -0.15 t = -2.02) slightly negatively influenced the intention to engage in SDM, but this was not clinically significant. CONCLUSION: Physicians' intention to engage in SDM does not affect their intention to adopt CPGs even after SDM training. Physicians' intention to adopt CPGs had no clinically significant influence on intention to engage in SDM. TRIAL REGISTRATION: ClinicalTrials.gov NCT01116076.

A study of the association between characteristics of CLSCs and the risk of small for gestational age births among term and preterm births in Quebec, Canada.

OBJECTIVES: The objective of this study was to describe whether the social environment of the territory of residence is associated with indicators of foetal growth retardation. METHODS: All newborns (n = 667,254) from 143 Centres locaux de services communautaires (CLSC) territories of Quebec, Canada, 2000-2008 were included in this study. Small for gestational age (SGA), very small for gestational age (VSGA) and SGA-preterm births were identified. Social characteristics and access to medical services of the population in the CLSCs were obtained from the Canadian Community Health Survey. Data on material deprivation, racial diversity and social isolation were obtained from the 2001 and 2006 Canadian censuses. A compromise between two methods, stepwise and best subset, was used to select variables for multivariate logistic modelling. The model was fitted on each studied outcome: SGA, VSGA and SGA among preterm births. RESULTS: When investigating material deprivation, racial diversity, social isolation, proportion of sedentary residents and proportion with fair or poor availability of health care services in the CLSC territories, material deprivation, racial diversity, social isolation and sedentary residents showed increased adjusted risk of SGA. Results of the model fit on VSGA birth and on SGA among preterm births were similar. CONCLUSION: CLSC characteristics of material deprivation, racial diversity, social isolation as well as the contextual variable of sedentary lifestyle were associated with indicators of foetal growth retardation. Further work on features of the CLSCs could help understand how the outcome of SGA is associated with contextual factors and identify groups for intervention.

Score tests for independence in semiparametric competing risks models.

A popular model for competing risks postulates the existence of a latent unobserved failure time for each risk. Assuming that these underlying failure times are independent is attractive since it allows standard statistical tools for right-censored lifetime data to be used in the analysis. This paper proposes simple independence score tests for the validity of this assumption when the individual risks are modeled using semiparametric proportional hazards regressions. It assumes that covariates are available, making the model identifiable. The score tests are derived for alternatives that specify that copulas are responsible for a possible dependency between the competing risks. The test statistics are constructed by adding to the partial likelihoods for the individual risks an explanatory variable for the dependency between the risks. A variance estimator is derived by writing the score function and the Fisher information matrix for the marginal models as stochastic integrals. Pitman efficiencies are used to compare test statistics. A simulation study and a numerical example illustrate the methodology proposed in this paper.

Redefining the maximum sustainable yield for the Schaefer population model including multiplicative environmental noise.

The focus of this article is to investigate the biological reference points, such as the maximum sustainable yield (MSY), in a common Schaefer (logistic) surplus production model in the presence of a multiplicative environmental noise. This type of model is used in fisheries stock assessment as a first-hand tool for biomass modelling. Under the assumption that catches are proportional to the biomass, we derive new conditions on the environmental noise distribution such that stationarity exists and extinction is avoided. We then get new explicit results about the stationary behavior of the biomass distribution for a particular specification of the noise, namely the biomass distribution itself and a redefinition of the MSY and related quantities that now depend on the value of the variance of the noise. Consequently, we obtain a more precise vision of how less optimistic the stochastic version of the MSY can be than the traditionally used (deterministic) MSY. In addition, we give empirical conditions on the error variance to approximate our specific noise by a lognormal noise, the latter being more natural and leading to easier inference in this context. These conditions are mild enough to make the explicit results of this paper valid in a number of practical applications. The outcomes of two case-studies about northwest Atlantic haddock [Spencer, P.D., Collie, J.S., 1997. Effect of nonlinear predation rates on rebuilding the Georges Bank haddock (Melanogrammus aeglefinus) stock. Can. J. Fish. Aquat. Sci. 54, 2920-2929] and South Atlantic albacore tuna [Millar, R.B., Meyer, R., 2000. Non-linear state space modelling of fisheries biomass dynamics by using Metropolis-Hastings within-Gibbs sampling. Appl. Stat. 49, 327-342] are used to illustrate the impact of our results in bioeconomic terms.