Akaike's information criterion in generalized estimating equations

Rationale and design of the Sodium Lowering In Dialysate (SoLID) trial: a randomised controlled trial of low versus standard dialysate sodium concentration during hemodialysis for regression of left ventricular mass

BACKGROUND

The current literature recognises that left ventricular hypertrophy makes a key contribution to the high rate of premature cardiovascular mortality in dialysis patients. Determining how we might intervene to ameliorate left ventricular hypertrophy in dialysis populations has become a research priority. Reducing sodium exposure through lower dialysate sodium may be a promising intervention in this regard. However there is clinical equipoise around this intervention because the benefit has not yet been demonstrated in a robust prospective clinical trial, and several observational studies have suggested sodium lowering interventions may be deleterious in some dialysis patients.

METHODS/DESIGN

The Sodium Lowering in Dialysate (SoLID) study is funded by the Health Research Council of New Zealand. It is a multi-centre, prospective, randomised, single-blind (outcomes assessor), controlled parallel assignment 3-year clinical trial. The SoLID study is designed to study what impact low dialysate sodium has upon cardiovascular risk in dialysis patients. The study intends to enrol 118 home hemodialysis patients from 6 sites in New Zealand over 24 months and follow up each participant over 12 months. Key exclusion criteria are: patients who dialyse more frequently than 3.5 times per week, pre-dialysis serum sodium of <135 mM, and maintenance hemodiafiltration. In addition, some medical conditions, treatments or participation in other dialysis trials, which contraindicate the SoLID study intervention or confound its effects, will be exclusion criteria. The intervention and control groups will be dialysed using dialysate sodium 135 mM and 140 mM respectively, for 12 months. The primary outcome measure is left ventricular mass index, as measured by cardiac magnetic resonance imaging, after 12 months of intervention. Eleven or more secondary outcomes will be studied in an attempt to better understand the physiologic and clinical mechanisms by which lower dialysate sodium alters the primary end point.

DISCUSSION

The SoLID study is designed to clarify the effect of low dialysate sodium upon the cardiovascular outcomes of dialysis patients. The study results will provide much needed information about the efficacy of a cost effective, economically sustainable solution to a condition which is curtailing the lives of so many dialysis patients.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry number: ACTRN12611000975998.

Multilevel analysis of bacterial counts from chronic periodontitis after root planing/scaling, surgery, and systemic and local antibiotics: 2-year results

AIM

To follow changes (over 2 years) in subgingival bacterial counts of five microbial complexes including health-related Actinomyces spp. in deeper pockets (≥5 mm) after periodontal treatments.

METHODS

EIGHT DIFFERENT TREATMENTS WERE STUDIED: (1) scaling+root planing (SRP); (2) periodontal surgery (SURG)+systemic amoxicillin (AMOX)+systemic metronidazole (MET); (3) SURG+locally delivered tetracycline (TET); (4) SURG; (5) AMOX+MET+TET; (6) AMOX+MET; (7) TET; and (8) SURG+AMOX+MET+TET. Antibiotics were given immediately following SRP. Subgingival plaque was collected mesiobuccally from each tooth, except third molars, from 176 subjects, completing the study, at baseline, 3, 6, 12, 18, and 24 months post-treatment and analysed for 40 different bacteria using checkerboard hybridization. A negative binomial (NB) generalized estimating equation (NB GEE) model was used to analyze count data and a logistic GEE was used for proportions.

RESULTS

We observed short-term beneficial changes in the composition of the red complex of up to 3 months by treating subjects with AMOX+MET+TET. Similar short-term improvements with the same treatment were observed for Tannerella forsythia and Treponema denticola of the red complex. SURG had also short-term beneficial effect on Porphyromonas gingivalis. No periodontal treatments applied to severely affected sites promoted the growth of Actinomyces. Smoking elevated counts of both the red and orange complex while bleeding on probing (BOP) and gingival redness were also predictors of more red complex counts. Comparatively similar findings were obtained by analyzing counts and by analyzing proportions.

CONCLUSIONS

Although short-term reductions in the counts of the red complex were observed in sites that were treated with AMOX+MET+TET, long-term significant effects were not observed with any of the eight treatments. Poor oral hygiene in patients with severe chronic periodontitis diminished the beneficial effects of treatment.

Caffeine intake and risk of basal cell and squamous cell carcinomas of the skin in an 11-year prospective study

PURPOSE

Caffeine may repair skin damage induced by excessive exposure to ultraviolet light. The purpose of this study was to investigate the association between caffeine intake and incidence of basal cell (BCC) and squamous cell carcinoma (SCC). We also assessed the associations between coffee consumption and incidence of these skin cancers.

METHODS

Caffeine intake and consumption of coffee were estimated from food frequency questionnaires assessed in 1992, 1994, and 1996 among 1,325 randomly selected adult residents of a subtropical Australian community. All histologically confirmed tumours of BCC and SCC occurring between 1997 and 2007 were recorded. Associations with BCC and SCC were assessed using Poisson and negative binomial regression models and were adjusted for confounders including skin type and indicators of past sun exposure.

RESULTS

There was no association between total caffeine intake and incidence of BCC or SCC. Participants with prior skin cancers, however, had a 25% lower risk of BCC if they were in the highest tertile of total caffeine intake (equivalent to daily consumption of four cups of regular coffee) compared with the lowest tertile (multivariable RR 0.75; 95% CI 0.57-0.97, P trend = 0.025). There was no dose-response relationship with SCC. Consumption of neither caffeinated nor decaffeinated coffee was associated with BCC or SCC.

CONCLUSIONS

Among people with prior skin cancers, a relatively high caffeine intake may help prevent subsequent BCC development. However, caffeine intake appears not to influence the risk of SCC.

Parasite-induced and parasite development-dependent alteration of the swimming behavior of fish hosts

Parasites with complex life cycles have the ability to change the behavior of their intermediate host in a way that increases their transmission rate to the next host. However, the level of behavioral changes can vary considerably, depending on the stage of parasite development and parasite intensity. To investigate the influence of such parameters, we evaluated the locomotory activity of the fish Poecilia vivipara prior to experimental infections, 7 days post-infection (dpi) and 14dpi with cercariae of the digenean Ascocotyle (Phagicola) pindoramensis. The locomotory activity was monitored using an image system, Videomex(®), linked to with a video camera able to record the swimming behavior of the fishes. At the end of the experiments, fishes were dissected and all metacercariae from the gills and mesenteries, the specific sites utilized by A. (P.) pindoramensis, were recovered and counted. There was a significant decrease in the swimming behavior of fishes after 14dpi. Similarly, we found a significant correlation between the swimming behavior of the fishes and parasite intensity in both sites of infection. It is surmised that the decrease in locomotory activity of P. vivipara caused by A. (P.) pindoramensis can disturb its predator-prey relationship in natural environment.

To Dash or to Dawdle: Verb-Associated Speed of Motion Influences Eye Movements during Spoken Sentence Comprehension

In describing motion events verbs of manner provide information about the speed of agents or objects in those events. We used eye tracking to investigate how inferences about this verb-associated speed of motion would influence the time course of attention to a visual scene that matched an event described in language. Eye movements were recorded as participants heard spoken sentences with verbs that implied a fast ("dash") or slow ("dawdle") movement of an agent towards a goal. These sentences were heard whilst participants concurrently looked at scenes depicting the agent and a path which led to the goal object. Our results indicate a mapping of events onto the visual scene consistent with participants mentally simulating the movement of the agent along the path towards the goal: when the verb implies a slow manner of motion, participants look more often and longer along the path to the goal; when the verb implies a fast manner of motion, participants tend to look earlier at the goal and less on the path. These results reveal that event comprehension in the presence of a visual world involves establishing and dynamically updating the locations of entities in response to linguistic descriptions of events.

Too risky to settle: avian community structure changes in response to perceived predation risk on adults and offspring

Predation risk is widely hypothesized as an important force structuring communities, but this potential force is rarely tested experimentally, particularly in terrestrial vertebrate communities. How animals respond to predation risk is generally considered predictable from species life-history and natural-history traits, but rigorous tests of these predictions remain scarce. We report on a large-scale playback experiment with a forest bird community that addresses two questions: (i) does perceived predation risk shape the richness and composition of a breeding bird community? And (ii) can species life-history and natural-history traits predict prey community responses to different types of predation risk? On 9 ha plots, we manipulated cues of three avian predators that preferentially prey on either adult birds or offspring, or both, throughout the breeding season. We found that increased perception of predation risk led to generally negative responses in the abundance, occurrence and/or detection probability of most prey species, which in turn reduced the species richness and shifted the composition of the breeding bird community. Species-level responses were largely predicted from the key natural-history trait of body size, but we did not find support for the life-history theory prediction of the relationship between species' slow/fast life-history strategy and their response to predation risk.

Assessing pneumococcal meningitis association with viral respiratory infections and antibiotics: insights from statistical and mathematical models

Pneumococcus is an important human pathogen, highly antibiotic resistant and a major cause of bacterial meningitis worldwide. Better prevention requires understanding the drivers of pneumococcal infection incidence and antibiotic susceptibility. Although respiratory viruses (including influenza) have been suggested to influence pneumococcal infections, the underlying mechanisms are still unknown, and viruses are rarely considered when studying pneumococcus epidemiology. Here, we propose a novel mathematical model to examine hypothetical relationships between Streptococcus pneumoniae meningitis incidence (SPMI), acute viral respiratory infections (AVRIs) and antibiotic exposure. French time series of SPMI, AVRI and penicillin consumption over 2001-2004 are analysed and used to assess four distinct virus-bacteria interaction submodels, ascribing the interaction on pneumococcus transmissibility and/or pathogenicity. The statistical analysis reveals strong associations between time series: SPMI increases shortly after AVRI incidence and decreases overall as the antibiotic-prescription rate rises. Model simulations require a combined impact of AVRI on both pneumococcal transmissibility (up to 1.3-fold increase at the population level) and pathogenicity (up to threefold increase) to reproduce the data accurately, along with diminished epidemic fitness of resistant pneumococcal strains causing meningitis (0.97 (0.96-0.97)). Overall, our findings suggest that AVRI and antibiotics strongly influence SPMI trends. Consequently, vaccination protecting against respiratory virus could have unexpected benefits to limit invasive pneumococcal infections.

Parental psychological distress during pregnancy and wheezing in preschool children: the Generation R Study

BACKGROUND

Maternal psychological distress during pregnancy might affect fetal lung development and subsequently predispose children to childhood asthma.

OBJECTIVE

We sought to assess the associations of maternal psychological distress during pregnancy with early childhood wheezing.

METHODS

We performed a population-based prospective cohort study among 4848 children. We assessed maternal and paternal psychological distress at the second trimester of gestation and 3 years after delivery and maternal psychological distress at 2 and 6 months after delivery by using the Brief Symptom Inventory questionnaire. Wheezing in the children was annually examined by using questionnaires from 1 to 4 years. Physician-diagnosed ever asthma was reported at 6 years.

RESULTS

Mothers with psychological distress during pregnancy had increased odds of wheezing in their children from 1 to 4 years of life (overall distress: odds ratio [OR], 1.60 [95% CI, 1.32-1.93]; depression: OR, 1.46 [95% CI, 1.20-1.77]; and anxiety: OR, 1.39 [95% CI, 1.15-1.67]). We observed similar positive associations with the number of wheezing episodes, wheezing patterns, and physician-diagnosed asthma at 6 years. Paternal distress during pregnancy and maternal and paternal distress after delivery did not affect these results and were not associated with childhood wheezing.

CONCLUSION

Maternal psychological distress during pregnancy is associated with increased odds of wheezing in their children during the first 6 years of life independent of paternal psychological distress during pregnancy and maternal and paternal psychological distress after delivery. These results suggest a possible intrauterine programming effect of maternal psychological distress leading to respiratory morbidity.

Reductions in HIV/STI incidence and sharing of injection equipment among female sex workers who inject drugs: results from a randomized controlled trial

BACKGROUND

We evaluated brief combination interventions to simultaneously reduce sexual and injection risks among female sex workers who inject drugs (FSW-IDUs) in Tijuana and Ciudad Juarez, Mexico during 2008-2010, when harm reduction coverage was expanding rapidly in Tijuana, but less so in Juarez.

METHODS

FSW-IDUs ≥18 years reporting sharing injection equipment and unprotected sex with clients within the last month participated in a randomized factorial trial comparing four brief, single-session conditions combining either an interactive or didactic version of a sexual risk intervention to promote safer sex in the context of drug use, and an injection risk intervention to reduce sharing of needles/injection paraphernalia. Women underwent quarterly interviews and testing for HIV, syphilis, gonorrhea, Chlamydia and Trichomonas, blinding interviewers and assessors to assignment. Poisson regression with robust variance estimation and repeated measures ordinal logistic regression examined effects on combined HIV/STI incidence and receptive needle sharing frequency.

FINDINGS

Of 584 initially HIV-negative FSW-IDUs, retention was ≥90%. After 12 months, HIV/STI incidence decreased >50% in the interactive vs. didactic sex intervention (Tijuana:AdjRR:0.38,95% CI:0.16-0.89; Juarez: AdjRR:0.44,95% CI:0.19-0.99). In Juarez, women receiving interactive vs. didactic injection risk interventions decreased receptive needle-sharing by 85% vs. 71%, respectively (p = 0.04); in Tijuana, receptive needle sharing declined by 95%, but was similar in active versus didactic groups. Tijuana women reported significant increases in access to syringes and condoms, but Juarez women did not.

INTERPRETATION

After 12 months in both cities, the interactive sexual risk intervention significantly reduced HIV/STI incidence. Expanding free access to sterile syringes coupled with brief, didactic education on safer injection was necessary and sufficient for achieving robust, sustained injection risk reductions in Tijuana. In the absence of expanding syringe access in Juarez, the injection risk intervention achieved significant, albeit more modest reductions, suggesting that community-level interventions incorporating harm reduction are more powerful than individual-level interventions.

TRIAL REGISTRATION

clinicaltrials.gov NCT00840658.

Distinct functional domains of the Abelson tyrosine kinase control axon guidance responses to Netrin and Slit to regulate the assembly of neural circuits

To develop a functional nervous system, axons must initially navigate through a complex environment, directed by guidance ligands and receptors. These receptors must link to intracellular signaling cascades to direct axon pathfinding decisions. The Abelson tyrosine kinase (Abl) plays a crucial role in multiple Drosophila axon guidance pathways during development, though the mechanism by which Abl elicits a diverse set of guidance outputs is currently unknown. We identified Abl in a genetic screen for genes that contribute to Netrin-dependent axon guidance in midline-crossing (commissural) neurons. We find that Abl interacts both physically and genetically with the Netrin receptor Frazzled, and that disrupting this interaction prevents Abl from promoting midline axon crossing. Moreover, we find that Abl exerts its diverse activities through at least two different mechanisms: (1) a partly kinase-independent, structural function in midline attraction through its C-terminal F-actin binding domain (FABD) and (2) a kinase-dependent inhibition of repulsive guidance pathways that does not require the Abl C terminus. Abl also regulates motor axon pathfinding through a non-overlapping set of functional domains. These results highlight how a multifunctional kinase can trigger diverse axon guidance outcomes through the use of distinct structural motifs.

Age-specific probability of live birth with oocyte cryopreservation: an individual patient data meta-analysis

OBJECTIVE

To estimate age-specific probabilities of live birth with oocyte cryopreservation in nondonor (ND) egg cycles.

DESIGN

Individual patient data meta-analysis.

SETTING

Assisted reproduction centers.

PATIENT(S)

Infertile patients undergoing ND mature oocyte cryopreservation.

INTERVENTION(S)

PubMed was searched for clinical studies on oocyte cryopreservation from January 1996 through July 2011. Randomized and nonrandomized studies that used ND frozen-thawed mature oocytes with pregnancy outcomes were included. Authors of eligible studies were contacted to obtain individual patient data.

MAIN OUTCOME MEASURE(S)

Live birth probabilities based on age, cryopreservation method, and the number of oocytes thawed, injected, or embryos transferred.

RESULT(S)

Original data from 10 studies including 2,265 cycles from 1,805 patients were obtained. Live birth success rates declined with age regardless of the freezing technique. Despite this age-induced compromise, live births continued to occur as late as ages 42 and 44 years with slowly frozen and vitrified oocytes, respectively. Estimated probabilities of live birth for vitrified oocytes were higher than those for slowly frozen.

CONCLUSION(S)

The live birth probabilities we calculated would enable more accurate counseling and informed decisions for infertile women considering oocyte cryopreservation. Given the success probabilities, we suggest that policy makers should consider oocyte freezing as an integral part of prevention and treatment of infertility.

Overuse of preoperative cardiac stress testing in medicare patients undergoing elective noncardiac surgery

OBJECTIVE

To determine the frequency and predictors of cardiac stress testing before elective noncardiac surgery in Medicare patients with no indications for cardiovascular evaluation.

BACKGROUND

The American College of Cardiology/American Heart Association guidelines indicate that patients without class I (American Heart Association high risk) or class II cardiac conditions (clinical risk factors) should not undergo cardiac stress testing before elective noncardiac, nonvascular surgery.

METHODS

We used 5% Medicare inpatient claims data (1996-2008) to identify patients aged ≥ 66 years who underwent elective general surgical, urological, or orthopedic procedures (N = 211,202). We examined the use of preoperative stress testing in the subset of patients with no diagnoses consistent with cardiac disease (N = 74,785). Bivariate and multivariate analyses were used to identify predictors of preoperative cardiac stress testing.

RESULTS

Of the patients with no cardiac indications for preoperative stress testing, 3.75% (N = 2803) received stress testing in the 2 months before surgery. The rate of preoperative stress testing increased from 1.72% in 1996 to 6.44% in 2007 (P < 0.0001). A multivariate analysis adjusting for patient and hospital characteristics showed a significant increase in preoperative stress testing over time. Female sex [odds ratio (OR) 1.11; 95% CI: 1.02-1.21], presence of other comorbidities [OR 1.22; 95% confidence interval (CI): 1.09-1.35], high-risk procedure (OR 2.42; 95% CI: 2.04-2.89), and larger hospital size (OR 1.17; 95% CI: 1.03-1.32) were positive predictors of stress testing. Patients living in regions with greater Medicare expenditures (OR 1.24; 95% CI: 1.05-1.45) were also more likely to receive stress tests.

CONCLUSIONS

In a 5% sample of Medicare claims data, 2803 patients underwent preoperative stress testing without any indications. When these results were applied to the entire Medicare population, we estimated that there are over 56,000 patients who underwent unnecessary preoperative stress testing. The rate of testing in patients without cardiac indications has increased significantly over time.

Analysis of factors important for the occurrence of Campylobacter in Danish broiler flocks

For more than a decade human campylobacteriosis has been the leading zoonosis in many developed countries. Consumption of poultry or poultry products has been identified as the primary source of infection in humans. This study was conducted to identify risk factors for the occurrence of Campylobacter in Danish broiler flocks. The study was based on a large data set consisting of Campylobacter positive status for nearly 6000 broiler flocks and 43 explanatory variables. Data were obtained from the Danish Campylobacter surveillance programme in poultry and from the responses to a standardized questionnaire answered via interviews with broiler farm owners. Two hundred and forty broiler farms, comprising 539 broiler houses, were included in the study and their Campylobacter status was followed over a 2-year period (1999-2000). The large number of observations made it possible to carry out a multivariate analysis including all 43 variables. A multivariate analysis was conducted using a generalized linear model, and the correlations between the houses from the same farms were accounted for by adding a variance structure to the model. The procedures for analyses included backward elimination, forward selection and expanding of the number of observations used in the variance analysis along with the reduction of the number of parameters in the model. The unit of analysis was 'broiler house', meaning that all results from a broiler house were aggregated into one prevalence figure (number of positive flocks/total number of flocks delivered over the 2-year period). The following factors were found to be significantly associated with the occurrence of Campylobacter in the broiler flocks: old broiler houses, late introduction of whole wheat in the feed, relatively high broiler age at slaughter, improper rodent control, large number of chimneys on the broiler house, farm located in an area with a high density of cattle farms, having more than one broiler house on the farm, and improper storage of wheat. This large-scale study confirms several risk factors identified in previous studies. The results concerning chimneys may be explained by the easier access that flies have to the broiler houses, which seems in agreement with recent Danish studies on the significance of fly-screens to reduce Campylobacter in broiler flocks. The results of this study may be used in identification of effective interventions aimed at controlling Campylobacter in Danish broiler flocks.

Assessment of heterogeneity of efficacy of a three-dose regimen of a type III secreted protein vaccine for reducing STEC O157 in feces of feedlot cattle

Preharvest control of Escherichia coli O157:H7 (STEC O157) may prevent human illness by reducing the presence of STEC O157 throughout the beef production chain. Immunization of cattle with a type III secreted protein vaccine inhibits colonization of cattle with STEC O157 and reduces the probability of fecal shedding and hide contamination. Our objectives were to perform a meta-analysis to estimate efficacy of a three-dose regimen of TTSP vaccine at reducing the presence of STEC O157 in the feces of feedlot cattle and to test factors that might modify vaccine efficacy. Pen-level data (n=184 pens, 1462 cattle) from four randomized controlled vaccine trials conducted from 2002 to 2008 at the University of Nebraska-Lincoln were analyzed. Factors explaining a culture-positive fecal sample were tested in generalized estimating equations logistic regression and log-binomial models. An autoregressive correlation structure was defined to account for clustering of repeated test-periods within block. Clustering or potential confounding by study was accounted for by treating study as a fixed effect. STEC O157 was detected from 661 of 5451 postvaccination fecal samples. The probability to detect STEC O157 postvaccination was 8.4% and 15.8% in vaccinated and unvaccinated cattle, respectively. Interactions between vaccination and (1) study; (2) prevalence of control pens within each time-place cluster; and (3) days from vaccination were not significant or fit poorly with observed data. Adjusting for study, cattle in pens receiving three doses of vaccine were less likely to shed STEC O157 (odds ratio=0.46, p<0.0001). Model-adjusted vaccine efficacy was 48% (95% confidence interval: 0.37-0.57). We concluded that a three-dose regimen type III secreted protein vaccine was efficacious at reducing the probability of detecting STEC O157 in the feces of cattle and that vaccine efficacy was not modified by study or level of prevalence observed in control pens.

Adolescents' increasing stress response to social evaluation: pubertal effects on cortisol and alpha-amylase during public speaking

Stress responses to social evaluation are thought to increase during adolescence, which may be due to pubertal maturation. However, empirical evidence is scarce. This study is the first to investigate the relation between pubertal development and biological responses to a social-evaluative stressor longitudinally. Participants performed the Leiden Public Speaking Task twice, with a 2-year interval (N = 217; age at Time 1: 8-17 years). The results support an increase in sensitivity to social evaluation during adolescence. The overall cortisol and alpha-amylase responses increased-both between and within participants-and were more strongly related to self-reported pubertal development than to age. The cortisol response shifted from speech delivery toward anticipation. The alpha-amylase response increased in both phases.

Facial emotion expression recognition by children at familial risk for depression: high-risk boys are oversensitive to sadness

BACKGROUND

Offspring of depressed parents are at greatly increased risk for mood disorders. Among potential mechanisms of risk, recent studies have focused on information processing anomalies, such as attention and memory biases, in the offspring of depressed parents. In this study we examined another information processing domain, perceptual sensitivity to emotion cues in facial expressions, as a potential mechanism of risk that characterizes the offspring of depressed parents.

METHODS

The study included 64 children at familial-risk for depression and 40 low-risk peers between the ages 7 and 13(Mage = 9.51; SD = 2.27). Participants were presented with pictures of facial expressions that varied in emotional intensity from neutral to full-intensity sadness or anger (i.e., emotion recognition), or pictures of faces morphing from anger to sadness (emotion discrimination). After each picture was presented, children indicated whether the face showed a specific emotion (i.e., sadness, anger) or no emotion at all (neutral) using a forced choice paradigm. We examined group differences in the intensity of emotion that suggested greater sensitivity to specific emotions.

RESULTS

In the emotion recognition task, boys (but not girls) at familial-risk for depression identified sadness at significantly lower levels of emotional intensity than did their low-risk peers. The high and low-risk groups did not differ with regard to identification of anger. In the emotion discrimination task, both groups displayed over-identification of sadness in ambiguous mixed faces but high-risk youth were less likely to show this labeling bias than their peers.

CONCLUSION

Our findings are consistent with the hypothesis that enhanced perceptual sensitivity to subtle traces of sadness in facial expressions may be a potential mechanism of risk among boys at familial-risk for depression. This enhanced perceptual sensitivity does not appear to be due to biases in the labeling of ambiguous faces.

Do Workplace Wellness Programs Reduce Medical Costs? Evidence from a Fortune 500 Company

The recent passage of the Affordable Care Act has heightened the importance of workplace wellness programs. This paper used administrative data from 2002 to 2007 for PepsiCo’s self-insured plan members to evaluate the effect of its wellness program on medical costs and utilization. We used propensity score matching to identify a comparison group who were eligible for the program but did not participate. No significant changes were observed in inpatient admissions, emergency room visits, or per-member per-month (PMPM) costs. The discrepancy between our findings and those of prior studies may be due to the difference in intervention intensity or program implementation.

Risks and benefits of bladder antimuscarinics among elderly residents of Veterans Affairs Community Living Centers

OBJECTIVES

To evaluate risks and benefits of bladder antimuscarinics (BAMs) among elderly long term care nursing home residents.

DESIGN

Retrospective cohort study using a new user design and propensity score matching.

SETTING

Veterans Affairs (VA) Community Living Centers (Nursing Homes).

PARTICIPANTS

Older adults (65 and older) admitted for long term care between October 1, 2002, and September 30, 2009.

MEASUREMENTS

The study used multiple VA data sources (Minimum Data Set [MDS], inpatient, outpatient, and pharmacy prescriptions administrative files). The following outcomes were evaluated: (1) fractures (hip fracture and "any" fracture) identified from inpatient and/or outpatient data (ICD-9-CM codes) and from MDS; (2) cognitive performance measured using the validated MDS Cognitive Performance Scale; (3) improvement in urinary incontinence measured from MDS; (4) quality of life measured from MDS using 2 validated instruments: Index of Social Engagement and Health Status Index. Covariates included demographic characteristics, baseline continence status (bladder and bowel) and continence management, preexistent urinary tract infections, body mass index, comorbidities, other medication use, cognitive status, and mobility at baseline. These variables were used to calculate the predicted probability (propensity score) of being initiated on a BAM; the resulting propensity scores were used to match new users and nonusers. Outcomes were compared with Cox proportional hazards regression and generalized estimating equations methodology.

RESULTS

BAMs were used by 9.8% of the residents 65 years and older admitted for long term care; 44% (1195) were new users. Of these, all but 53 received nonselective immediate release preparations, predominantly oxybutynin chloride (75%). BAM initiation resulted in improved urinary continence status (odds ratio = 1.27, 95% confidence interval [CI] 1.07-1.5) and better social engagement (difference in mean index of social engagement score = 0.2074, 95% CI 0.055-0.3598). The risk of fractures was significantly increased in new users as compared to nonusers (hip fracture: hazard ratio [HR] = 3.67, 95% CI 1.46-9.34; "any" fracture: HR = 2.64, 95% CI 1.37-5.10). The number needed to treat (NNT) to obtain improvement in urinary incontinence after 90 days of treatment (NNT = 32, 95% CI 17-125) was similar to the number needed to harm (NNH) at 90 days in the hip fracture analysis (NNH = 36, 95% CI 12-209). There were no differences in cognitive performance or overall quality of life scores associated with BAM use.

CONCLUSION

These results question the continued use of BAMs, particularly immediate-release oxybutynin chloride in elderly nursing home residents.

Does the trematode Centrocestus formosanus affect the locomotory activity of the mollusc Melanoides tuberculatus?

Background

Melanoides tuberculatus (Müller, 1774) (Thiaridae), an introduced gastropod mollusc with a wide geographical distribution in the Neotropics, is the intermediate host of the trematode Centrocestus formosanus (Nishigori, 1924) (Heterophyidae). This parasite is considered to be pathogenic to humans. The aim of the present work was to evaluate the locomotory activity of uninfected M. tuberculatus compared with those naturally infected with C. formosanus.

Findings

The locomotory activity of each mollusc was recorded using an image analysis biomonitoring system, Videomex-V ®, to evaluate and quantify the parameters of ‘Stereotypic’ and ‘Resting time’. The Generalized Estimating Equation analysis of locomotory activity of M. tuberculatus infected with C. formosanus revealed significant differences compared with uninfected molluscs for the parameters ‘Stereotypic time’ and ‘Resting time’ with a reduction of movement. The variations in the values of the monitoring intervals recorded showed a significant difference for the infected molluscs in the case of Stereotypic time, with an irregular locomotory activity pattern, as compared to that of uninfected molluscs. The analysis of the standard length of all molluscs did not exhibit any correlation with locomotory activity, showing that C. formosanus is able to alter the locomotory activity of its snail host regardless of the standard length.

Conclusions

The trematode C. formosanus affects the locomotory activity of the mollusc M. tuberculatus by reducing its movement and causing it to exhibit an irregular pattern of activity, both of which are independent of the snail's standard length.

Spatiotemporal variations in resources affect activity and movement patterns of white-tailed deer (Odocoileus virginianus) at high density

Although activity budget, movements, and habitat use of herbivores have been extensively studied, few studies have simultaneously examined these behaviors at several temporal scales. We investigated the influence of spatiotemporal variations in forage and climate on the activity and movement patterns of white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) at high density, in a predator-free ecosystem impacted by long-term browsing. We used GPS telemetry and activity sensors to monitor seasonal activity budgets, movements, and patterns of habitat use within the home ranges of 24 female deer at three temporal scales: (1) season, (2) within season, and (3) daily. At large temporal scale, deer were less active and moved less during winter than during summer. Within each season, deer reduced their activity and movements in areas where forage resources were abundant and when climatic conditions were more difficult. On a daily scale, summer and winter movements peaked at dusk, but habitat selection neither changed with period of the day nor activity (foraging vs. resting). These results provide empirical evidence on how environmental constraints can modulate the trade-offs between forage acquisition and exposure to limiting factors.

Src inhibits midline axon crossing independent of Frazzled/Deleted in Colorectal Carcinoma (DCC) receptor tyrosine phosphorylation

The phylogenetically conserved Netrin family of chemoattractants signal outgrowth and attractive turning of commissural axons through the Deleted in Colorectal Carcinoma (DCC) family of receptors. Src family kinases are thought to be major signaling effectors of Netrin/DCC. In vertebrates, Src and the closely related Fyn kinases phosphorylate DCC and form a receptor-bound signaling complex leading to activation of downstream effectors. Here we show that, in the Drosophila embryonic CNS, Src kinases are dispensable for midline attraction of commissural axons. Consistent with this observation, tyrosine phosphorylation of the Netrin receptor DCC or its Drosophila ortholog, Frazzled, is not necessary for attraction to Netrin. Moreover, we uncover an unexpected function of Src kinases: inhibition of midline axon crossing through a novel mechanism. We propose that distinct signaling outputs must exist for midline axon crossing independent of Src kinases in commissural neurons.

Factors associated with hospitalisations for ambulatory care-sensitive conditions among persons with an intellectual disability: a publicly insured population perspective

BACKGROUND

Hospitalisations for ambulatory care-sensitive (ACS) conditions are used as an indicator of access to, and the quality of, primary care. The objective was to identify factors associated with hospitalisations for ACS conditions among adults with an intellectual disability (ID) in the context of a publicly insured healthcare system.

METHODS

This study examined adults with an ID living in a Canadian province between 1999 and 2003 identified from administrative databases. Using 5 years of data for the study population, characteristics of persons hospitalised or not hospitalised for ACS conditions were compared. Using a conceptual model, independent variables were selected and an analysis performed to identify which were associated with hospitalisations for ACS conditions. The correlated nature of the observations was accounted for statistically.

RESULTS

Living in a rural area [odds ratio (OR) 1.3; 95% confidence intervals (CI) = 1.0, 1.8], living in an area with a high proportion of First Nations people (OR 2.3; 95% CI = 1.3, 4.1), and experiencing higher levels of comorbidity (OR 25.2; 95% CI = 11.9, 53.0) were all associated with a higher likelihood of being hospitalised for an ACS condition. Residing in higher income areas had a protective effect (OR 0.56; 95% CI = 0.37, 0.85). None of the health service resource variables showed statistically significant associations.

CONCLUSIONS

Persons with an ID experience inequity in hospitalisations for ACS conditions according to rurality, income and proportion who are First Nations in a geographic area. This suggests that addressing the socio-economic problems of poorer areas and specifically areas densely populated by First Nations people may have an impact on the number of hospitalisations for ACS conditions. Study strengths and limitations and areas for potential future research are discussed.

Evaluation of an HIV prevention intervention designed for African American Women: results from the SISTA Community-Based Organization Behavioral Outcomes Project

One of the Centers for Disease Control and Prevention's strategies for addressing racial disparities within the HIV epidemic is to support the implementation of HIV prevention behavioral interventions designed for African Americans. One such intervention is Sisters Informing Sisters about Topics on AIDS (SISTA), a culturally relevant and gender-specific, five-session, group-level, HIV prevention intervention designed for African American women. In 2008, the Centers for Disease Control and Prevention funded five community-based organizations to conduct outcome monitoring of SISTA to assess the outcomes associated with implementation in the field. Using a 90-day recall, demographic and sexual risk data were collected from participants at baseline and at 90 and 180 days post-intervention. Findings reveal that women participating in SISTA (n = 432) demonstrated a significant reduction in sexual risk between baseline and both follow-up time points for each of the six outcomes being measured (e.g., any unprotected sex, all protected sex).

Proximity to a tobacco store and smoking cessation: a cohort study

BACKGROUND

It is not clear whether the availability of tobacco affects the likelihood of smoking cessation. We examined whether the proximity to a tobacco store and the number of stores were associated with smoking cessation, and compared results for proximity variables based on walking and straight-line (as the crow flies) distance.

METHODS

The study population consisted of 8751 baseline smokers from the Finnish Public Sector study in 1997-2005. Smoking intensity (cigarettes/day) was determined at baseline and smoking cessation was determined from a follow-up survey in 2008-2009. Proximity was measured using straight-line and walking distance from home to the nearest tobacco store, and another exposure variable was the number of stores within 0.50 km from home. We calculated associations with log-binomial regression models, adjusting for individual-level and area-level confounders.

RESULTS

Of the participants, 3482 (39.8%) quit smoking during the follow-up (mean follow-up 5.5 years, SD 2.3 years). Among men who were moderate/heavy smokers at baseline and lived <0.50 km walking distance from the nearest tobacco store, the likelihood of smoking cessation was 27% (95% CI 12% to 40%) lower compared with those living ≥0.50 km from a store. Having even one store within 0.50 km walking distance from home decreased cessation in men who were moderate/heavy smokers by 37% (95% CI 19% to 51%). No decrease was found for men who were light smokers at baseline or for women.

CONCLUSIONS

Living within walking distance of a tobacco store reduced the likelihood of smoking cessation among men who were moderate/heavy smokers.

Benefits Improvement and Protection Act's impact on transplantation rates among elderly MEDICARE beneficiaries with end-stage renal disease

BACKGROUND

The Benefits Improvement and Protection Act (BIPA) expanded Medicare coverage for posttransplantation immunosuppresants for elderly patients and others eligible for Medicare beyond their end-stage renal disease (ESRD) status yet retained the 3-year limit for patients eligible solely because of ESRD status. Our objective was to determine BIPA's impact on renal transplantation among elderly patients (age ≥65 years) affected by BIPA.

METHODS

Medicare claims and the U.S. Renal Data System Standard Analysis Files were used to analyze the likelihood of transplantation among elderly patients, all of whom were affected by BIPA, versus the nonelderly, many of whom were unaffected by BIPA. A difference-in-differences approach and generalized logistic regressions were used to estimate BIPA's impact.

RESULTS

Analysis of data for 632,904 ESRD Medicare beneficiaries who met inclusion/exclusion criteria suggests that BIPA made elderly patients more likely (relative likelihood, 1.36; 95% confidence interval, 1.32-1.41) to have a transplant. The likelihood for nonelderly patients decreased following BIPA (relative likelihood, 0.93; 95% confidence interval, 0.92-0.94).

CONCLUSION

Transplantation rates increased among those elderly patients, all of whom were affected by BIPA by extending immunosuppressant coverage under BIPA. These results suggest that removing financial barriers to posttransplantation care may positively impact transplantation rates yet raise questions regarding whether the law shifted transplants from younger to older patients.

Migration systems in Europe: evidence from harmonized flow data

Empirical tests of migration systems theory require consistent and complete data on international migration flows. Publicly available data, however, represent an inconsistent and incomplete set of measurements obtained from a variety of national data collection systems. We overcome these obstacles by standardizing the available migration reports of sending and receiving countries in the European Union and Norway each year from 2003-2007 and by estimating the remaining missing flows. The resulting harmonized estimates are then used to test migration systems theory. First, locating thresholds in the size of flows over time, we identify three migration systems within the European Union and Norway. Second, examining the key determinants of flows with respect to the predictions of migration systems theory, our results highlight the importance of shared experiences of nation-state formation, geography, and accession status in the European Union. Our findings lend support to migration systems theory and demonstrate that knowledge of migration systems may improve the accuracy of migration forecasts toward managing the impacts of migration as a source of social change in Europe.

Opioid overdose rates and implementation of overdose education and nasal naloxone distribution in Massachusetts: interrupted time series analysis

OBJECTIVE

To evaluate the impact of state supported overdose education and nasal naloxone distribution (OEND) programs on rates of opioid related death from overdose and acute care utilization in Massachusetts.

DESIGN

Interrupted time series analysis of opioid related overdose death and acute care utilization rates from 2002 to 2009 comparing community-year strata with high and low rates of OEND implementation to those with no implementation.

SETTING

19 Massachusetts communities (geographically distinct cities and towns) with at least five fatal opioid overdoses in each of the years 2004 to 2006.

PARTICIPANTS

OEND was implemented among opioid users at risk for overdose, social service agency staff, family, and friends of opioid users.

INTERVENTION

OEND programs equipped people at risk for overdose and bystanders with nasal naloxone rescue kits and trained them how to prevent, recognize, and respond to an overdose by engaging emergency medical services, providing rescue breathing, and delivering naloxone.

MAIN OUTCOME MEASURES

Adjusted rate ratios for annual deaths related to opioid overdose and utilization of acute care hospitals.

RESULTS

Among these communities, OEND programs trained 2912 potential bystanders who reported 327 rescues. Both community-year strata with 1-100 enrollments per 100,000 population (adjusted rate ratio 0.73, 95% confidence interval 0.57 to 0.91) and community-year strata with greater than 100 enrollments per 100,000 population (0.54, 0.39 to 0.76) had significantly reduced adjusted rate ratios compared with communities with no implementation. Differences in rates of acute care hospital utilization were not significant.

CONCLUSIONS

Opioid overdose death rates were reduced in communities where OEND was implemented. This study provides observational evidence that by training potential bystanders to prevent, recognize, and respond to opioid overdoses, OEND is an effective intervention.

Detecting selection along environmental gradients: analysis of eight methods and their effectiveness for outbreeding and selfing populations

Thanks to genome-scale diversity data, present-day studies can provide a detailed view of how natural and cultivated species adapt to their environment and particularly to environmental gradients. However, due to their sensitivity, up-to-date studies might be more sensitive to undocumented demographic effects such as the pattern of migration and the reproduction regime. In this study, we provide guidelines for the use of popular or recently developed statistical methods to detect footprints of selection. We simulated 100 populations along a selective gradient and explored different migration models, sampling schemes and rates of self-fertilization. We investigated the power and robustness of eight methods to detect loci potentially under selection: three designed to detect genotype-environment correlations and five designed to detect adaptive differentiation (based on F(ST) or similar measures). We show that genotype-environment correlation methods have substantially more power to detect selection than differentiation-based methods but that they generally suffer from high rates of false positives. This effect is exacerbated whenever allele frequencies are correlated, either between populations or within populations. Our results suggest that, when the underlying genetic structure of the data is unknown, a number of robust methods are preferable. Moreover, in the simulated scenario we used, sampling many populations led to better results than sampling many individuals per population. Finally, care should be taken when using methods to identify genotype-environment correlations without correcting for allele frequency autocorrelation because of the risk of spurious signals due to allele frequency correlations between populations.

Prevalence, risk factors and co-morbidities of diabetes among adults in rural Saskatchewan: the influence of farm residence and agriculture-related exposures

BACKGROUND

Although rural Canadians are reported to have higher rates of diabetes than others, little is known about the relative influence of known versus agriculture-related risk factors. The purpose of this research was to carry out a comprehensive study of prevalence, risk factors and co-morbidities of diabetes among adults in rural Saskatchewan and to determine possible differences between those living on and off farms.

METHODS

In 2010, we conducted a baseline mail-out survey (Saskatchewan Rural Health Study) of 11,982 households located in the province's four agricultural quadrants. In addition to self-reported physician-diagnosed diabetes, the questionnaire collected information from farm and small town cohorts on possible diabetes determinants including lifestyle, family history, early life factors and environmental/agricultural-related exposures. Clustering effect within households was adjusted using Generalized Estimating Equations approach.

RESULTS

Responses were obtained from 4624 (42%) households comprising 8208 males and females aged 18 years or older and 7847 self-described Caucasian participants (7708 with complete information). The overall age-standardized diabetes prevalence for the latter was 6.35% but people whose primary residence was on farms had significantly lower diabetes prevalence than those living in non-farm locations (5.11% versus 7.33% respectively; p<0.0001). Diabetes risk increased with age and affected almost 17% of those older than 65 (OR 2.57; CI' 1.63, 4.04 compared to those aged 18-45). Other known independent risk factors included family history of diabetes (OR 2.50 [CI's 1.94, 3.23] if father; OR 3.11 [CI's 2.44, 3.98] if mother), obesity (OR 2.66; CI's 1.86, 3.78), as well as lower socioeconomic status, minimal/no alcohol intake and smoking. The most original finding was that exposure to insecticides conferred an increased risk for diabetes among males (OR 1.83; CI's 1.15, 2.91). Finally, the co-morbidities with the strongest independent association with diabetes were heart disease and hypertension.

CONCLUSIONS

While known diabetes risk factors are important determinants of diabetes in the agricultural zones of Saskatchewan, on-farm residence is protective and appears related to increased outdoor activities. In contrast, we have now shown for the first time that exposure to insecticides is an independent risk factor for diabetes among men in rural Canada.

Prevention of alcohol-exposed pregnancies among nonpregnant American Indian women

PURPOSE

The goal of this project was to evaluate an intervention on reducing alcohol-exposed pregnancies with nonpregnant American Indian women, with a focus on risky drinking and ineffective contraception use.

DESIGN

This study had a descriptive longitudinal study design, with follow-up every 3 months for 1 year.

SETTING

Three American Indian tribes in the Northern Plains.

SUBJECTS

Participants were 231 nonpregnant American Indian women.

INTERVENTION

Participants responded to drinking and contraception questions through the telephone and then received intervention materials via mail. Follow-up telephone surveys occurred at 3, 6, 9, and 12 months after the baseline call, and participants were again mailed intervention materials.

MEASURES

Alcohol consumption and birth control measurements were modified from the Project CHOICES program. The intervention was based on motivational interviewing constructs.

ANALYSIS

Analysis techniques included covariate-adjusted generalized estimating equation methods and Bonferroni correction.

RESULTS

All of the alcohol consumption amount responses had significant decreases with each follow-up intervention session; the average change for the range of questions was  -26% to -17%. The proportion of those stating they did not use birth control decreased from 29% to 10% during the first 3 months.

CONCLUSIONS

The intervention was successful in modifying self-reported drinking and contraception behaviors. This project is the only one to date that has focused on preventing alcohol-exposed pregnancies in nonpregnant American Indian women.

Antipsychotic treatment patterns and aggressive behavior among adolescents in residential facilities

This study examined the association between acute aggressive behavior patterns of 145 adolescents in residential treatment facilities with use of and changes in antipsychotic medication for the chronic management of aggression. Seclusion/restraint (S/R) frequency over 12 months was used to categorize youth into none, low, moderate, and high S/R groups. Data were analyzed using longitudinal mixed effects logistic regression models that allowed for intra-subject variability over time. The high and moderate S/R groups were significantly more likely to receive antipsychotics, get higher doses, and have changes in medication compared with the none S/R group. Increases in antipsychotic dose were associated with a lower likelihood of changes in antipsychotic medication over time. Despite persistent antipsychotic use at higher doses, youth in the high and moderate S/R groups continued to be secluded/restrained frequently. The findings question the adequacy of these medications in managing aggressive behavior.

Long-term impact of environmental public health disaster on health system performance: experiences from the Graniteville, South Carolina chlorine spill

OBJECTIVES

In the aftermath of an environmental public health disaster (EPHD) a healthcare system may be the least equipped entity to respond. Preventable visits for ambulatory care-sensitive conditions (ACSCs) may be used as a population-based indicator to monitor health system access postdisaster. The objective of this study was to examine whether ACSC rates among vulnerable subpopulations are sensitive to the impact of a disaster.

METHODS

We conducted a retrospective analysis on the 2005 chlorine spill in Graniteville, South Carolina using a Medicaid claims database. Poisson regression was used to calculate change in monthly ACSC visits at the disaster site in the postdisaster period compared with the predisaster period after adjusting for parallel changes in a control group.

RESULTS

The adjusted rate of a predisaster ACSC hospital visit for the direct group was 1.68 times the rate for the control group (95% confidence interval [CI] 1.47-1.93), whereas the adjusted ACSC hospital rate postdisaster for the direct group was 3.10 times the rate for the control group (95% CI 1.97-5.18). For ED ACSC visits, the adjusted rate among those directly affected predisaster were 1.82 times the rate for the control group (95% CI 1.61-2.08), whereas the adjusted ACSC rate postdisaster was 2.81 times the rate for the control group (95% CI 1.92-5.17).

CONCLUSIONS

Results revealed that an increased demand on the health system altered health services delivery for vulnerable populations directly affected by a disaster. Preventable visits for ACSCs may advance public health practice by identifying healthcare disparities during disaster recovery.

Risk factors for exposure to influenza a viruses, including subtype H5 viruses, in Thai free-grazing ducks

Free-grazing ducks (FGD) have been associated with highly pathogenic avian influenza (HPAI) H5N1 outbreaks and may be a viral reservoir. In July-August 2010, we assessed influenza exposure of Thai FGD and risk factors thereof. Serum from 6254 ducks was analysed with enzyme-linked immunosorbent assay (ELISA) to detect antibodies to influenza A nucleoprotein (NP), and haemagglutinin H5 protein. Eighty-five per cent (5305 ducks) were seropositive for influenza A. Of the NP-seropositive sera tested with H5 assays (n = 1423), 553 (39%) were H5 ELISA positive and 57 (4%) suspect. Twelve per cent (74 of 610) of H5 ELISA-positive/suspect ducks had H5 titres ≥ 1 : 20 by haemagglutination inhibition. Risk factors for influenza A seropositivity include older age, poultry contact, flock visitors and older purchase age. Study flocks had H5 virus exposure as recently as March 2010, but no HPAI H5N1 outbreaks have been identified in Thailand since 2008, highlighting a need for rigorous FGD surveillance.

Geographic correlation between tapeworm carriers and heavily infected cysticercotic pigs

Background

Neurocysticercosis is a leading cause of preventable epilepsy in the developing world. Sustainable community-based interventions are urgently needed to control transmission of the causative parasite, Taenia solium. We examined the geospatial relationship between live pigs with visible cysticercotic cysts on their tongues and humans with adult intestinal tapeworm infection (taeniasis) in a rural village in northern Peru. The objective was to determine whether tongue-positive pigs could indicate high-risk geographic foci for taeniasis to guide targeted screening efforts. This approach could offer significant benefit compared to mass intervention.

Methods

We recorded geographic coordinates of all village houses, collected stool samples from all consenting villagers, and collected blood and examined tongues of all village pigs. Stool samples were processed by enzyme-linked immunosorbent assay (ELISA) for presence of Taenia sp. coproantigens indicative of active taeniasis; serum was processed by enzyme-linked immunoelectrotransfer blot for antibodies against T. solium cysticercosis (EITB LLGP) and T. solium taeniasis (EITB rES33).

Findings

Of 548 pigs, 256 (46.7%) were positive for antibodies against cysticercosis on EITB LLGP. Of 402 fecal samples, 6 (1.5%) were positive for the presence of Taenia sp. coproantigens. The proportion of coproantigen-positive individuals differed significantly between residents living within 100-meters of a tongue-positive pig (4/79, 5.1%) and residents living >100 meters from a tongue-positive pig (2/323, 0.6%) (p = 0.02). The prevalence of taeniasis was >8 times higher among residents living within 100 meters of a tongue-positive pig compared to residents living outside this range (adjusted PR 8.1, 95% CI 1.4–47.0).

Conclusions

Tongue-positive pigs in endemic communities can indicate geospatial foci in which the risk for taeniasis is increased. Targeted screening or presumptive treatment for taeniasis within these high-risk foci may be an effective and practical control intervention for rural endemic areas.

Taenia solium, aka the pork tapeworm, is an important cause of epilepsy in developing nations. People with intestinal tapeworms, a condition known as taeniasis, pass infectious eggs in their feces which contaminate the environment. These eggs can cause serious disease in both humans and pigs if they are ingested. Treating taeniasis is one way to potentially control transmission of the parasite in affected communities. However, this is difficult because people with taeniasis usually have no symptoms and therefore don't know they are infected. As a result, control programs may resort to offering treatment to entire communities in order to reach a few tapeworm carriers. Focusing detection and treatment on high-risk subgroups is another approach which might reduce unnecessary treatments. In this study, we found that people with taeniasis are more likely to be found living nearby pigs with visible signs of infection, specifically tapeworm cysts on their tongues. This suggests that routine tongue examination by pig owners and buyers could identify neighborhoods where detection and treatment of taeniasis may be more efficient.

Population pharmacokinetics and pharmacogenetics of alcohol in Chinese and Indians in Singapore

WHAT IS KNOWN AND OBJECTIVE

  Interindividual variability in alcohol pharmacokinetics is influenced by a number of factors, including polymorphisms in genes mediating alcohol pharmacology, ethnicity, sex and body size. Several studies have evaluated the population pharmacokinetics of alcohol from breath alcohol measures. None of these studies, however, have evaluated ethnicity and alcohol-metabolizing enzyme genotypes as covariates in their population pharmacokinetic modelling. We aimed to develop a population pharmacokinetic model using clinical and genetic factors and to identify covariates that influenced interindividual variability in alcohol clearance and volume of distribution.

METHODS

  Hundred and eighty healthy subjects (90 Chinese and 90 Indians; 45 males and 45 females from each ethnic group) ingested a vodka-orange juice mixture to simulate social drinking. Subjects were genotyped for the ADH1B (Arg48His), ALDH2 (Glu504Lys) and CYP2E1 (c.-1293G>C and c.-1053C>T) polymorphisms. A base pharmacokinetic model was developed using the nonmem software (NONMEM Project Group, University of California, San Francisco, San Francisco, CA, USA) to determine the alcohol clearance and volume of distribution. The model was extended to include covariates that influenced the between-subject variability.

RESULTS AND DISCUSSION

  Body weight and sex significantly influenced absorption rate and volume of distribution of alcohol. Body weight and ADH1B Arg48His polymorphism significantly influenced alcohol clearance. The Michaelis-Menten elimination rate (Vmax ) was decreased by 10% in homozygous ADH1B*1/*1 subjects. Ethnicity was not determined to be a significant covariate in the final population pharmacokinetic model.

WHAT IS NEW AND CONCLUSION

  Gender and body weight were covariates that contributed most to explaining the observed interindividual alcohol pharmacokinetic variability. Of the four SNPs examined in this study, only ADH1B Arg48His polymorphism had a significant, though modest, effect on the pharmacokinetics of alcohol.

Multilevel predictors of concurrent opioid use during methadone maintenance treatment among drug users with HIV/AIDS

Background

Ongoing drug use during methadone maintenance treatment (MMT) negatively affects outcomes of HIV/AIDS care and treatment for drug users. This study assessed changes in opioid use, and longitudinal predictors of continued opioid use during MMT among HIV-positive drug users in Vietnam, with the aim of identifying changes that might enhance program efficacy.

Methods

We analyze data of 370 HIV-positive drug users (mean age 29.5; 95.7% male) taking MMT at multi-sites. Opioid use was assessed at baseline, 3, 6, and 9 months using interviews and heroin confirmatory urine tests. A social ecological model was applied to explore multilevel predictors of continued opioid use, including individual, interpersonal, community and service influences. Generalized estimating equations (GEE) statistical models were constructed to adjust for intra-individual correlations.

Results

Over 9 month follow-up, self-reported opioid use and positive heroin urine test substantially decreased to 14.6% and 14.4%. MMT helped improve referrals and access to health care and social services. However, utilization of social integration services was small. GEE models determined that participants who were older (Adjusted Odd Ratio - AOR = 0.97 for 1 year increase), had economic dependents (AOR = 0.33), or were referred to TB treatment (AOR = 0.53) were less likely to continue opioid use. Significant positive predictors of ongoing opioid use included frequency of opioid use prior to MMT, peer pressure, living with sexual partners, taking antiretroviral treatment, other health concerns and TB treatment.

Conclusion

These findings show that MMT in the Vietnamese context can dramatically reduce opioid use, which is known to be associated with reduced antiretroviral (ART) adherence. Disease stage and drug interactions between antiretrovirals or TB drugs and MMT could explain some of the observed predictors of ongoing drug use; these findings could inform changes in MMT program design and implementation.

Despite variation in volume, Veterans Affairs hospitals show consistent outcomes among patients with non-postoperative mechanical ventilation

OBJECTIVE

To assess the relationship between volume of nonoperative mechanically ventilated patients receiving care in a specific Veterans Health Administration hospital and their mortality.

DESIGN

Retrospective cohort study.

SETTING

One-hundred nineteen Veterans Health Administration medical centers.

PATIENTS

We identified 5,131 hospitalizations involving mechanically ventilated patients in an intensive care unit during 2009, who did not receive surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We extracted demographic and clinical data from the VA Inpatient Evaluation Center. For each hospital, we defined volume as the total number of nonsurgical admissions receiving mechanical ventilation in an intensive care unit during 2009. We examined the hospital contribution to 30-day mortality using multilevel logistic regression models with a random intercept for each hospital. We quantified the extent of interhospital variation in 30-day mortality using the intraclass correlation coefficient and median odds ratio. We used generalized estimating equations to examine the relationship between volume and 30-day mortality and risk-adjusted all models using a patient-level prognostic score derived from clinical data representing the risk of death conditional on treatment at a high-volume hospital. Mean age for the sample was 65 (SD 11) yrs, 97% were men, and 60% were white. The median VA hospital cared for 40 (interquartile range 19-62) mechanically ventilated patients in 2009. Crude 30-day mortality for these patients was 36.9%. After reliability and risk adjustment to the median patient, adjusted hospital-level mortality varied from 33.5% to 40.6%. The intraclass correlation coefficient for the hospital-level variation was 0.6% (95% confidence interval 0.1, 3.4%), with a median odds ratio of 1.15 (95% confidence interval 1.06, 1.38). The relationship between hospital volume of mechanically ventilated and 30-day mortality was not statistically significant: each 50-patient increase in volume was associated with a nonsignificant 2% decrease in the odds of death within 30 days (odds ratio 0.98, 95% confidence interval 0.87-1.10).

CONCLUSIONS

Veterans Health Administration hospitals caring for lower volumes of mechanically ventilated patients do not have worse mortality. Mechanisms underlying this finding are unclear, but, if elucidated, may offer other integrated health systems ways to overcome the disadvantages of small-volume centers in achieving good outcomes.

Socio-economic- and sex-related disparities in rates of hospital admission among patients with HIV infection in Ontario: a population-based study

BACKGROUND

Among people living with HIV infection in the era of combination antiretroviral therapy (cART), admission to hospital may indicate inadequate community-based care. As such, population-based assessments of the utilization of inpatient services represent a necessary component of evaluating the quality of HIV-related care.

METHODS

We used a validated algorithm to search Ontario's administrative health care databases for all persons living with HIV infection aged 18 years or older between 1992/93 and 2008/09. We then conducted a population-based study using time-series and longitudinal analyses to first quantify the immediate effect of cART on hospital admission rates and then analyze recent trends (for 2002/03 to 2008/09) in rates of total and HIV-related admissions.

RESULTS

The introduction of cART in 1996/97 was associated with more pronounced reductions in the rate of hospital admissions among men than among women (for total admissions, -89.9 v. -60.5 per 1000 persons living with HIV infection, p = 0.003; for HIV-related admissions, -56.9 v. -36.3 per 1000 persons living with HIV infection, p < 0.001). Between 2002/03 and 2008/09, higher rates of total hospital admissions were associated with female sex (adjusted relative rate [RR] 1.15, 95% confidence interval [CI] 1.05-1.27) and low socio-economic status (adjusted RR 1.21, 95% CI 1.14-1.29). Higher rates of HIV-related hospital admission were associated with low socio-economic status (adjusted RR 1.30, 95% CI 1.17-1.45). Recent immigrants had lower rates of both total admissions (adjusted RR 0.70, 95% CI 0.61-0.80) and HIV-related admissions (adjusted RR 0.77, 95% CI 0.61-0.96).

INTERPRETATION

We observed important socio-economic- and sex-related disparities in rates of hospital admission among people with HIV living in Ontario, Canada.

Habitat selection and ranges of tolerance: how do species differ beyond critical thresholds?

Sensitivity to habitat fragmentation often has been examined in terms of thresholds in landscape composition at which a species is likely to occur. Observed thresholds often have been low or absent, however, leaving much unexplained about habitat selection beyond initial thresholds of occurrence, even for species with strong habitat preferences. We examined responses to varying amounts of tree cover, a widely influential measure of habitat loss, for 40 woodland bird species in a mixed woodland/grassland landscape in eastern North Dakota, USA. We used LOESS smoothing to describe incidence for each species at three scales: within 200, 400, and 1200 m around sample locations. For the 200-m scale, we also calculated the most-preferred range of tree cover (within which at least half of observations were predicted to occur) for each species. Only 10 of 40 species had occurrence thresholds greater than about 10% tree cover. After initial occurrence, species showed three general patterns: some increased monotonically with tree cover; some increased up to an asymptote; some peaked at intermediate amounts of tree cover and then declined. These patterns approximate selection for interior woodlands and for edge-rich environments, but incidence plots provide greater detail in landscape-scale selection than do those categories. For most species, patterns persisted at larger scales, but for some, larger scales had distinctly different patterns than local scales. Preferred ranges of tree cover varied from <20% tree cover (common grackle, Quiscalus quiscula) to >60% (veery, Catharus fuscescens). We conclude that incidence patterns provide more information on habitat selection than do threshold measures for most species: in particular, they differentiate species preferring concentrated woodlands from those preferring mixed landscapes, and they show contrasting degrees of selectiveness. [Correction added on 16 October 2012, after first online publication: the Abstract section has been reworded].