Finite Element-Derived Surrogate Models of Locked Plate Fracture Fixation Biomechanics

Internal fixation of bone fractures using plates and screws involves many choices-implant type, material, sizes, and geometric configuration-made by the surgeon. These decisions can be important for providing adequate stability to promote healing and prevent implant mechanical failure. The purpose of this study was to develop mathematical models of the relationships between fracture fixation construct parameters and resulting 3D biomechanics, based on parametric computer simulations. Finite element models of hundreds of different locked plate fixation constructs for midshaft diaphyseal fractures were systematically assembled using custom algorithms, and axial, torsional, and bending loadings were simulated. Multivariate regression was used to fit response surface polynomial equations relating fixation design parameters to outputs including maximum implant stresses, axial and shear strain at the fracture site, and construct stiffness. Surrogate models with as little as three regressors showed good fitting (R ² = 0.62-0.97). Inner working length was the strongest predictor of maximum plate and screw stresses, and a variety of quadratic and interaction terms influenced resulting biomechanics. The framework presented in this study can be applied to additional types of bone fractures to provide clinicians and implant designers with clinical insight, surgical optimization, and a comprehensive mathematical description of biomechanics.

Circulating microRNAs as biomarkers in patients with allergic rhinitis and asthma

BACKGROUND

MicroRNAs (miRNAs) are emerging as important regulatory molecules that might be involved in the pathogenesis of various diseases. Circulating miRNAs might be noninvasive biomarkers to diagnose and characterize asthma and allergic rhinitis (AR).

OBJECTIVE

We sought to determine whether miRNAs are differentially expressed in the blood of asthmatic patients compared with those in the blood of nonasthmatic patients with AR and nonallergic nonasthmatic subjects. Furthermore, we sought to establish whether miRNAs could be used to characterize or subtype asthmatic patients.

METHODS

Expression of plasma miRNAs was measured by using real-time quantitative PCR in 35 asthmatic patients, 25 nonasthmatic patients with AR, and 19 nonallergic nonasthmatic subjects. Differentially expressed miRNAs were identified by using Kruskal-Wallis 1-way ANOVA with Bonferroni P value adjustment to correct for multiple comparisons. A random forest classification algorithm combined with a leave-one-out cross-validation approach was implemented to assess the predictive capacities of the profiled miRNAs.

RESULTS

We identified 30 miRNAs that were differentially expressed among healthy, allergic, and asthmatic subjects. These miRNAs fit into 5 different expression pattern groups. Among asthmatic patients, miRNA expression profiles identified 2 subtypes that differed by high or low peripheral eosinophil levels. Circulating miR-125b, miR-16, miR-299-5p, miR-126, miR-206, and miR-133b levels were most predictive of allergic and asthmatic status.

CONCLUSIONS

Subsets of circulating miRNAs are uniquely expressed in patients with AR and asthmatic patients and have potential for use as noninvasive biomarkers to diagnose and characterize these diseases.

Single-cell analysis reveals differential regulation of the alveolar macrophage actin cytoskeleton by surfactant proteins A1 and A2: implications of sex and aging

Background

Surfactant protein A (SP-A) contributes to lung immunity by regulating inflammation and responses to microorganisms invading the lung. The huge genetic variability of SP-A in humans implies that this protein is highly important in tightly regulating the lung immune response. Proteomic studies have demonstrated that there are differential responses of the macrophages to SP-A1 and SP-A2 and that there are sex differences implicated in these responses.

Methods

Purified SP-A variants were used for administration to alveolar macrophages from SP-A knockout (KO) mice for in vitro studies, and alveolar macrophages from humanized SP-A transgenic mice were isolated for ex vivo studies. The actin cytoskeleton was examined by fluorescence and confocal microscopy, and the macrophages were categorized according to the distribution of polymerized actin.

Results

In accordance with previous data, we report that there are sex differences in the response of alveolar macrophages to SP-A1 and SP-A2. The cell size and F-actin content of the alveolar macrophages are sex- and age-dependent. Importantly, there are different subpopulations of cells with differential distribution of polymerized actin. In vitro, SP-A2 destabilizes actin in female, but not male, mice, and the same tendency is observed by SP-A1 in cells from male mice. Similarly, there are differences in the distribution of AM subpopulations isolated from SP-A transgenic mice depending on sex and age.

Conclusions

There are marked sex- and age-related differences in the alveolar macrophage phenotype as illustrated by F-actin staining between SP-A1 and SP-A2. Importantly, the phenotypic switch caused by the different SP-A variants is subtle, and pertains to the frequency of the observed subpopulations, demonstrating the need for single-cell analysis approaches. The differential responses of alveolar macrophages to SP-A1 and SP-A2 highlight the importance of genotype in immune regulation and the susceptibility to lung disease and the need for development of individualized treatment options.

Dyspnoea as a predictor of cause-specific heart/lung disease mortality in Bangladesh: a prospective cohort study

BACKGROUND

The spectrum of mortality outcomes by cause in populations with/without dyspnoea has not been determined. The study aimed to evaluate whether dyspnoea, a symptom, predicts cause-specific mortality differences between groups. The hypothesis was that diseases that result in chronic dyspnoea, those originating from the heart and lungs, would preferentially result in heart and lung disease mortality in those with baseline dyspnoea (relative to no dyspnoea) when followed over time.

METHODS

A population-based sample of 11 533 Bangladeshis was recruited and followed for 11-12 years and cause-specific mortality evaluated in those with and without baseline dyspnoea. Dyspnoea was ascertained by trained physicians. The cause of death was determined by verbal autopsy. Kaplan-Meier survival curves, the Fine-Gray competing risk hazards model and logistic regression models were used to determine group differences in cause-specific mortality.

RESULTS

Compared to those not reporting dyspnoea at baseline, the adjusted HRs were 6.4 (3.8 to 10.7), 9.3 (3.9 to 22.3), 1.8 (1.2 to 2.8), 2.2 (1.0 to 5.1) and 2.8 (1.3 to 6.2) for greater risk of dying from chronic obstructive pulmonary disease (COPD), asthma, heart disease, tuberculosis and lung cancer, respectively. In contrast, there was a similar risk of dying from stroke, cancer (excluding lung), liver disease, accidents and other (miscellaneous causes) between the dyspnoeic and non-dyspnoeic groups. In addition, the HR was 2.1 (1.7 to 2.5) for greater all-cause mortality in those with baseline dyspnoea versus no dyspnoea.

CONCLUSIONS

Dyspnoea, ascertained by a single question with binary response, predicts heart and lung disease mortality. Individuals reporting dyspnoea were twofold to ninefold more likely to die of diseases that involve the heart and/or lungs relative to the non-dyspnoeic individuals. Therefore, in those with chronic dyspnoea, workup to look for the five common dyspnoeic diseases resulting in increased mortality (COPD, asthma, heart disease, tuberculosis and lung cancer), all treatable, should reduce mortality and improve the public health.

Medication safety curriculum: enhancing skills and changing behaviors

BACKGROUND

Adverse drug reactions are a leading cause of death in the United States. Safe and effective management of complex medication regimens is a skill for which recent medical school graduates may be unprepared when they transition to residency. We wished to assess the impact of a medication safety curriculum on student competency when evaluating medication therapeutic appropriateness as well as evaluate students' ability to transfer curricular material to management of patients in clinical settings.

METHODS

To prepare 3rd and 4th year medical students to critically evaluate medication safety and appropriateness, we developed a medication reconciliation/optimization curriculum and embedded it within a Patient-Centered Medical Home longitudinal elective. This curriculum is comprised of a medication reconciliation workshop, in-class and individual case-based assignments, and authentic patient encounters in which medication management skills are practiced and refined. Pre- and post-course competency and skills with medication reconciliation/optimization are evaluated by assessing student ability to identify and resolve medication-related problems (MRPs) in case-based assignments using paired difference tests. A group of students who had wished to enroll in the elective but whose schedule did not permit it, served as a comparison group.

RESULTS

Students completing the curriculum (n = 45) identified 75 % more MRPs in case assignments compared to baseline. No changes from baseline were apparent in the comparison group. Enrolled students were able to transfer their skills to the care of authentic patients; these students identified an average of 2.5 MRPs per patient from a panel of individuals that had recently transitioned from hospital to home. Moreover, patient questionnaires (before and several months following the medication encounters with assigned students) indicated that patients felt more knowledgeable about several medication parameters as a result of the student-led medication encounter. Patients also indicated that students helped them overcome barriers to medication adherence (e.g. cost, transportation, side effects).

CONCLUSIONS

Novice learners may have difficulty transitioning from knowledge of basic pharmacology facts to application of that information in clinical practice. Our curriculum appears to bridge that gap in ways that may positively impact patient care.

Impact of Age and Sex on Response to Asthma Therapy

RATIONALE

Age and sex are associated with differences in asthma prevalence and morbidity.

OBJECTIVES

To determine if age and sex associate with distinct phenotypes and a variable response to therapy in subjects with mild to moderate asthma.

METHODS

We used Asthma Clinical Research Network data to determine the impact of age and sex on phenotypes and treatment failures among subjects participating in 10 trials from 1993 to 2003.

MEASUREMENTS AND MAIN RESULTS

A total of 1,200 subjects were identified (median age, 30.4 yr; male, 520 [43.3%]; female, 680 [56.7%]) and analyzed. A higher proportion of subjects greater than or equal to 30 years old experienced treatment failures (17.3% vs. 10.3%; odds ratio [OR], 1.82; confidence interval [CI], 1.30-2.54; P < 0.001), and rates increased proportionally with increasing age older than 30 across the cohort (OR per yr, 1.02 [CI, 1.01-1.04]; OR per 5 yr, 1.13 [CI, 1.04-1.22]; P < 0.001). Lower lung function and longer duration of asthma were associated with a higher risk of treatment failures. A higher proportion of subjects greater than or equal to 30 years old receiving controller therapy experienced treatment failures. When stratified by specific therapy, treatment failures increased consistently for every year older than age 30 in subjects on inhaled corticosteroids (OR per year, 1.03; CI, 1.01-1.07). Females had a slightly higher FEV1 % predicted (84.5% vs. 81.1%; P < 0.001) but similar asthma control measures. There was not a statistically significant difference in treatment failures between females and males (15.2% vs. 11.7%; P = 0.088).

CONCLUSIONS

Older age is associated with an increased risk of treatment failure, particularly in subjects taking inhaled corticosteroids. There was no significant difference in treatment failures between sexes.

Dipstick proteinuria as a predictor of all-cause and cardiovascular disease mortality in Bangladesh: A prospective cohort study

OBJECTIVE

Baseline, persistent, incident, and remittent dipstick proteinuria have never been tested as predictors of mortality in an undeveloped country. The goal of this study was to determine which of these four types of proteinuria (if any) predict mortality.

METHODS

Baseline data was collected from 2000 to 2002 in Bangladesh from 11,121 adults. Vital status was ascertained over 11-12years. Cox models were used to evaluate proteinuria in relation to all-cause and cardiovascular disease (CVD) mortality. CVD mortality was evaluated only in those with baseline proteinuria. Persistent, remittent, and incident proteinuria were determined at the 2-year exam.

RESULTS

Baseline proteinuria of 1+ or greater was significantly associated with all-cause (hazard ratio (HR) 2.87; 95% C.I., 1.71-4.80) and CVD mortality (HR: 3.55; 95% C.I., 1.81-6.95) compared to no proteinuria, adjusted for age, gender, arsenic well water concentration, education, hypertension, BMI, smoking, and diabetes mellitus. Persistent 1+ proteinuria had a stronger risk of death, 3.49 (1.64-7.41)-fold greater, than no proteinuria. Incident 1+ proteinuria had a 1.87 (0.92-3.78)-fold greater mortality over 9-10years. Remittent proteinuria revealed no increased mortality.

CONCLUSIONS

Baseline, persistent, and incident dipstick proteinuria were predictors of all-cause mortality with persistent proteinuria having the greatest risk. In developing countries, those with 1+ dipstick proteinuria, particularly if persistent, should be targeted for definitive diagnosis and treatment. The two most common causes of proteinuria to search for are diabetes mellitus and hypertension.

Reducing Unintended Pregnancies Through Web-Based Reproductive Life Planning and Contraceptive Action Planning among Privately Insured Women: Study Protocol for the MyNewOptions Randomized, Controlled Trial

BACKGROUND

The Affordable Care Act mandates that most women of reproductive age with private health insurance have full contraceptive coverage with no out-of-pocket costs, creating an actionable time for women to evaluate their contraceptive choices without cost considerations. The MyNewOptions study is a three-arm, randomized, controlled trial testing web-based interventions aimed at assisting privately insured women with making contraceptive choices that are consistent with their reproductive goals.

METHODS

Privately insured women between the ages of 18 and 40 not intending pregnancy were randomly assigned to one of three groups: 1) a reproductive life planning (RLP) intervention, 2) a reproductive life planning enriched with contraceptive action planning (RLP+) intervention, or 3) an information only control group. Both the RLP and RLP+ guide women to identify their individualized reproductive goals and contraceptive method requirements. The RLP+ additionally includes a contraceptive action planning component, which uses if-then scenarios that allow the user to problem solve situations that make it difficult to be adherent to their contraceptive method. All three groups have access to a reproductive options library containing information about their contraceptive coverage and the attributes of alternative contraceptive methods. Women completed a baseline survey with follow-up surveys every 6 months for 2 years concurrent with intervention boosters. Study outcomes include contraceptive use and adherence. ClinicalTrials.gov identifier: NCT02100124.

DISCUSSION

Results from the MyNewOptions study will demonstrate whether web-based reproductive life planning, with or without contraceptive action planning, helps insured women make patient-centered contraceptive choices compared with an information-only control condition.

Markers of Differential Response to Inhaled Corticosteroid Treatment Among Children with Mild Persistent Asthma

BACKGROUND

Inhaled corticosteroids are recommended as first-line therapy for children with mild persistent asthma; however, specific patient characteristics may modify the treatment response.

OBJECTIVE

Identify demographic, clinical, and atopic characteristics that may modify the inhaled corticosteroid treatment response among children enrolled in the Treating Children to Prevent Exacerbations of Asthma trial.

METHODS

Children aged 6 to 18 years with mild persistent asthma were randomized to 44 weeks of combined, daily, rescue, or placebo treatment. Daily treatment consisted of 40 μg of beclomethasone twice daily. Rescue treatment consisted of 40 μg of beclomethasone accompanying each symptom-driven albuterol actuation. Combined treatment consisted of both. Outcomes included time to first exacerbation and proportion of asthma control days. Fourteen baseline characteristics were selected for interaction testing on the basis of their clinical relevance.

RESULTS

Two hundred eighty-eight children were randomized. Seventy-five percent were white, and 55% were male. As measured by time to first exacerbation, 4 characteristics identified children who received greater benefit from treatment: non-Hispanic ethnicity, positive aeroallergen skin test result, serum immunoglobulin E level of 350 K/μL or more, and history of oral corticosteroid use in the year before enrollment. As measured by asthma control days, 4 characteristics identified children who received greater benefit from treatment: male sex, positive aeroallergen skin test result, serum immunoglobulin E level of 350 K/μL or more, and incomplete run-in asthma control.

CONCLUSIONS

Children with mild persistent asthma who have markers of atopic asthma or who have greater asthma burden may obtain greater benefit from beclomethasone therapy. Additional study is needed to confirm whether these markers can guide individualized therapy.

Genetic and environmental influences on plasma vitamin D binding protein concentrations

Recent studies suggest that low vitamin D-binding protein (VDBP aka group-specific complement or Gc) concentrations may be linked with inflammatory-mediated conditions, including asthma, chronic obstructive pulmonary disease, and cancer. However, these studies may be confounded by substantial racial and ethnic or genetic differences. The purpose of this study was to test the hypothesis that circulating VDBP concentrations are significantly associated with genetic ancestry. We used a validated high-performance liquid chromatography tandem mass spectrometry assay of 25-hydroxyvitamin D3 and its downstream metabolite 24,25-dihydroxyvitamin D3. VDBP concentrations (milligrams per liter) were measured in duplicate using a commercial enzyme-linked immunosorbent assay among healthy African American (n = 56) and Caucasian American (n = 60) participants. Ancestry informative markers across the genome were used to estimate individual genetic ancestry proportions, designed to robustly distinguish between West African and European ancestry. Genotype-defined Gc isoforms were defined using rs7041 and rs4588 combination groups. VDBP concentration was correlated with both Gc isoform (r = 0.93, P < 0.001) and West African genetic ancestry (r = -0.66, P < 0.001). In the final model, Gc isoform, the catabolic ratio of serum vitamin D, oral contraceptive use, and body mass index remained significantly associated with VDBP concentration, after adjustment for genetic ancestry. Failure to adjust for Gc isoform may lead to spurious associations in studies of VDBP concentration and disease risk, particularly when the condition of interest may also be associated with genetic ancestry. The higher circulating VDBP concentrations and higher vitamin D catabolic rate among Caucasian Americans observed here appear to be consistent with lower bone mineral density and racial and ethnic differences in vitamin D-inducing cytokines.

Genome-wide association study of short-acting β2-agonists. A novel genome-wide significant locus on chromosome 2 near ASB3

RATIONALE

β2-Agonists are the most common form of treatment of asthma, but there is significant variability in response to these medications. A significant proportion of this responsiveness may be heritable.

OBJECTIVES

To investigate whether a genome-wide association study (GWAS) could identify novel pharmacogenetic loci in asthma.

METHODS

We performed a GWAS of acute bronchodilator response (BDR) to inhaled β2-agonists. A total of 444,088 single-nucleotide polymorphisms (SNPs) were examined in 724 individuals from the SNP Health Association Resource (SHARe) Asthma Resource Project (SHARP). The top 50 SNPs were carried forward to replication in a population of 444 individuals.

MEASUREMENTS AND MAIN RESULTS

The combined P value for four SNPs reached statistical genome-wide significance aftercorrecting for multiple comparisons. Combined P values for rs350729, rs1840321, rs1384918, and rs1319797 were 2.21 × 10(-10), 5.75 × 10(-8), 9.3 × 10(-8), and 3.95 × 10(-8), respectively. The significant variants all map to a novel genetic region on chromosome 2 near the ASB3 gene, a region associated with smooth muscle proliferation. As compared with the wild type, the presence of the minor alleles reduced the degree of BDR by 20% in the original population and by a similar percentage in the confirmatory population.

CONCLUSIONS

These GWAS findings for BDR in subjects with asthma suggest that a gene associated with smooth muscle proliferation may influence a proportion of the smooth muscle relaxation that occurs in asthma.

Validation of an indirect calorimeter using n-of-1 methodology

BACKGROUND

Validation data for currently available indirect calorimeters is limited. The purpose of this investigation was to validate a newer indirect calorimeter system (Vmax Encore) against a criterion device (Deltatrac Metabolic Monitor) in spontaneously breathing mode.

MATERIALS AND METHODS

An n-of-1 methodology was used in which both indirect calorimeters were employed in the same subject repeatedly until 15 measurement pairs were generated for oxygen consumption (VO2), carbon dioxide production (VCO2), resting metabolic rate (RMR), and respiratory quotient (RQ). Bias was defined as a 95% confidence interval of differences between devices that excluded zero. A set of intradevice measurement pairs was also obtained to analyze the precision of the Vmax and Deltatrac (precision defined as not more than 5% of measurements being ≥5% different).

RESULTS

Both Vmax and Deltatrac precisely measured VO2 and RMR. The largest intradevice difference for RMR in the Deltatrac was 4.7% (one of 20 pairs) and in the Vmax 4.8%. On the other hand, VCO2 and RQ were not measured precisely by either device, with 10% or more of the measurement pairs differing by ≥ 5%. The Vmax was biased toward low measurement of VO2 and RMR relative to the Deltatrac. Oxygen consumption was on average 4.5 ± 2.4% lower for the Vmax device compared to Deltatrac while RMR was lower by an average of 4.1 ± 2.2%.

CONCLUSIONS

The Vmax Encore indirect calorimeter is a precise instrument for measuring VO2 and RMR in spontaneously breathing individuals, but it is biased toward lower values compared to the Deltatrac.

Assessing the agreement of biomarker data in the presence of left-censoring

BACKGROUND

In many clinical biomarker studies, Lin's concordance correlation coefficient (CCC) is commonly used to assess the level of agreement of a biomarker measured under two different conditions. However, measurement of a specific biomarker typically cannot provide accurate numerical values below the lower limit of detection (LLD) of the assay, which results in left-censored data. Most researchers discard the data below the LLD or apply simple data imputation methods in the presence of left-censored data, such as replacing values below the LLD with a fixed number less than or equal to the LLD. This is not statistically optimal, because it often leads to biased estimates and overestimates the precision.

METHODS

We describe a simple method using a bivariate normal distribution in this situation and apply SAS statistical software to arrive at the maximum likelihood (ML) estimate of the parameters and construct the estimate of the CCC. We conduct a computer simulation study to investigate the statistical properties of the ML method versus the data deletion and simple data imputation method. We also contrast the methods with real data using two urine biomarkers, Interleukin 18 and Cystatin C.

RESULTS

The computer simulation studies confirm that the ML procedure is superior to the data deletion and simple data imputation procedures. In all of the simulated scenarios, the ML method yields the smallest relative bias and the highest percentage of the 95% confidence intervals that include the true value of the CCC. In the first simulation scenario (sample size of 100 paired data points, 25% left-censoring for both members of the pair, true CCC of 0.238), the relative bias is -1.43% for the ML method, -40.97% for the data deletion method, and it ranges between -12.94% and -21.72% for the simple data imputation methods. Similarly, when the left-censoring for one of the members of the data pairs increases from 25% to 40%, the relative bias displays the same pattern for all methods.

CONCLUSIONS

When estimating the CCC from paired biomarker data in the presence of left-censored values, the ML method works better than data deletion and simple data imputation methods.

Impact of TimeSlips creative expression program on behavioral symptoms and psychotropic medication use in persons with dementia in long-term care: a cluster-randomized pilot study

OBJECTIVES

To evaluate whether involvement in TimeSlips, a creative storytelling program, reduced mood and behavioral symptoms as well as psychotropic medication use in persons with dementia.

METHODS

A cluster-randomized pilot study compared two discrete dementia care units in one nursing home. The control cohort (N = 10) received standard-of-care activity programming, and the intervention cohort (N = 10) received standard-of-care plus two one-hour TimeSlips sessions per week for six weeks. Data on mood and behavioral symptoms and psychotropic drug prescriptions were collected, and within-group and between-group comparisons were performed.

RESULTS

Between-group comparisons did not reveal statistically significant differences in mood and behavioral symptoms. No differences in psychotropic drug prescriptions were found.

CONCLUSIONS

Larger trials of longer duration are needed to determine whether involvement in TimeSlips reduces mood and behavioral symptoms that compromise quality of life for persons with dementia.

Personality as a moderator of cognitive stimulation in older adults at high risk for cognitive decline

This exploratory study examined the moderating effects of personality traits on cognitive function following a cognitively stimulating individualized activity intervention delivered to individuals at high risk for cognitive decline: those with delirium superimposed on dementia. Data were taken from an ongoing randomized clinical trial with the addition of a personality measure. The results for 71 participants randomized to intervention or control groups are reported. Significant moderating effects of personality traits were found such that participants with higher agreeableness were more likely to have improved delayed recall and those with lower extraversion were more likely to have improved executive function, as a result of the intervention. Lower openness, higher agreeableness, and lower conscientiousness were associated with greater engagement in the intervention. A cognitive stimulation intervention for older adults at high risk for further cognitive decline may be differentially effective based on certain personality traits.

Effects of inhaled fluticasone on upper airway during sleep and wakefulness in asthma: a pilot study

STUDY OBJECTIVE

Obstructive sleep apnea is prevalent among people with asthma, but underlying mechanisms remain unknown. Inhaled corticosteroids may contribute. We tested the effects of orally inhaled fluticasone propionate (FP) on upper airway (UAW) during sleep and wakefulness.

STUDY DESIGN

16-week single-arm study.

PARTICIPANTS

18 (14 females, mean [ ± SD] age 26 ± 6 years) corticosteroid-naïve subjects with mild asthma (FEV1 89 ± 8% predicted).

INTERVENTIONS

High dose (1,760 mcg/day) inhaled FP.

MEASUREMENTS

(1) UAW collapsibility (passive critical closing pressure [Pcrit]); (2) tongue strength (maximum isometric pressure-Pmax, in KPa) and endurance-time (in seconds) able to maintain 50% Pmax across 3 trials (Ttot)-at anterior and posterior locations; (3) fat fraction and volume around UAW, measured by magnetic resonance imaging in three subjects.

RESULTS

Pcrit overall improved (became more negative) (mean ± SE) (-8.2 ± 1.1 vs. -12.2 ± 2.2 cm H2O, p = 0.04); the response was dependent upon baseline characteristics, with older, male gender, and worse asthma control predicting Pcrit deterioration (less negative). Overall, Pmax increased (anterior p = 0.02; posterior p = 0.002), but Ttot generally subsided (anterior p = 0.0007; posterior p = 0.06), unrelated to Pcrit response. In subjects studied with MRI, fat fraction and volume increased by 20.6% and 15.4%, respectively, without Pcrit changes, while asthma control appeared improved.

CONCLUSIONS

In this study of young, predominantly female, otherwise healthy subjects with well-controlled asthma and stiff upper airways, 16-week high dose FP treatment elicited Pcrit changes which may be dependent upon baseline characteristics, and determined by synchronous and reciprocally counteracting local and lower airway effects. The long-term implications of these changes on sleep disordered breathing severity remain to be determined.

Abstract T P295: Identifying Unmet Needs 30-days Following Ischemic Stroke: The Post Stroke Checklist

Background: Stroke care often focuses on acute intervention and treatment, but important long-term sequelae are sometimes overlooked and may not be captured in standard outcome measures.

The Post Stroke Checklist (PSC) is a simple tool recently developed by a global panel of stroke experts to identify the unmet needs of stroke survivors. It consists of 11 items addressing a variety of important medical, functional and social issues. The intent is to improve stroke survivor follow-up and ensure that treatable complications are identified and referred for treatment.

Methods: The PSC was administered at 30 days post ischemic stroke in 126 recently hospitalized patients in the outpatient clinic of a Comprehensive Stroke Center. Items were originally scored by a nurse and reviewed with a stroke physician. Age range (median) was 31-97 (68) years. All patients were also scored with Barthel Index (BI), NIH Stroke Scale (NIHSS), and modified Rankin Scale (mRS) during the clinic visit. Actionable items were identified by positive responses to any question on the PSC. The number of patients with actionable items was tabulated.

Results: The median (range) BI was 100 (10-100), NIHSS was 1 (0-28), and mRS was 1 (0-4). The PSC identified actionable items in 79/124 (64%) patients. In 39/79 (49%) patients, more than one actionable item was identified. The most common items were depression/anxiety 32 (26%), cognitive dysfunction 28 (23%), decreased ability to perform instrumental ADL’s 18 (15%), and any new pain 13 (10%). All other items were scored positively in less than 10% of patients. The PSC was judged acceptable by both stroke professionals and patients, who felt the items on the PSC identified important issues that otherwise, may have been overlooked in a clinic setting.

Conclusions: The PSC proved to be a useful tool at 30 days to identify important unmet needs in stroke survivors with mild deficits. The next step in this research is to evaluate patients at 90 days post stroke, when a larger range of deficits is expected.

A genome-wide association study of bronchodilator response in asthmatics

Reversibility of airway obstruction in response to β2-agonists is highly variable among asthmatics, which is partially attributed to genetic factors. In a genome-wide association study of acute bronchodilator response (BDR) to inhaled albuterol, 534 290 single-nucleotide polymorphisms (SNPs) were tested in 403 white trios from the Childhood Asthma Management Program using five statistical models to determine the most robust genetic associations. The primary replication phase included 1397 polymorphisms in three asthma trials (pooled n=764). The second replication phase tested 13 SNPs in three additional asthma populations (n=241, n=215 and n=592). An intergenic SNP on chromosome 10, rs11252394, proximal to several excellent biological candidates, significantly replicated (P=1.98 × 10(-7)) in the primary replication trials. An intronic SNP (rs6988229) in the collagen (COL22A1) locus also provided strong replication signals (P=8.51 × 10(-6)). This study applied a robust approach for testing the genetic basis of BDR and identified novel loci associated with this drug response in asthmatics.

Abstract T P312: The Addition of the Post Stroke Checklist to Standard Outcome Measures Provides Unique Information Relevant to Stroke Recovery

Background: The Post Stroke Checklist (PSC) is an easily administered, recently developed clinical tool to identify unmet needs in stroke patients. The relative value of the PSC compared to other outcome measures has yet to be determined.

Method: We evaluated 126 ischemic stroke patients (median age 68, range 31-97) 30 days following discharge in the outpatient clinic of our Comprehensive Stroke Center. Items were originally scored by a nurse and reviewed with a stroke physician. The PSC was administered to all patients as well as the Barthel Index (BI) and modified Rankin Scale (mRS). We stratified each scale according to severity and identified actionable PSC items in each severity group. Using Fisher’s Exact Test we searched for correlation between the total number of PSC items scored positively and the total score of other outcome measures. We also looked for correlations between individual PSC items and other outcome scores.

Results: The median (range) BI was 100 (10-100) and mRS was 1 (0-4). We stratified each outcome measure into 2 groups: BI-S (more severe) 0-89 (n=23) and BI-L (less severe) 90-100 (n=103); mRS-S (more severe) 3-5 (n=23) and mRS-L (less severe) 0-2 (n=103). 79 patients responded positively to one or more items in the PSC. There was no difference in total positive scores for any of the stratified groups, mRS (p=0.69) and BI (p=0.28). The frequency of positive responses for individual patients ranged from 1 to 6. The most common items identified are listed in the table below. No significant differences were noted.

Conclusion: The PSC is simple to administer and was well accepted by clinicians and patients. Depression/Anxiety, Cognitive Dysfunction, Instrumental ADL’s, and New Onset Pain are not included in the BI and mRS but are easily identified using the PSC. Our results suggest that the PSC provides important information about these unmet needs in stroke patients independent of stroke severity.

Evaluation of a Novel Method for Determining Transverse Plane Pelvic Obliquity

STUDY DESIGN

This was a retrospective review of neuromuscular scoliosis radiographs evaluating interobserver and intra-observer error for a novel method of transverse plane pelvic obliquity.

OBJECTIVES

To evaluate the utility of a previously described method by Lucas et al. of determining transverse plane pelvic obliquity using standard radiographs in patients with cerebral palsy and neuromuscular scoliosis.

SUMMARY OF BACKGROUND DATA

Evaluation of pelvic obliquity in the transverse plane has not been thoroughly studied. The pelvis has been noted to function as intercalary vertebra in neuromuscular scoliosis, resulting in marked obliquity in all 3 planes.

METHODS

Forty radiographs were chosen from 10 patients with cerebral palsy and neuromuscular scoliosis who had had a posterior spine arthrodesis and Galveston spino-pelvic fixation. Four observers independently examined the radiographs at different levels of training on 2 dates 1 week apart. Measurements recorded by each observer were described by Lucas et al.: E (the distance measured on lateral radiographs between the ilium at the inferior part of the sacro-iliac joint and the lateral edge of the anterior superior iliac spine), F_R and F_L (the coronal plane linear distance between the same 2 landmarks, measured from a posteroanterior radiograph, where F was measured for both the left (F_L) and right (F_R) sides of the pelvis, respectively), and β (the transverse plane rotation of the pelvis). Reproducibility of the measurements were analyzed using the concordance correlation coefficient (CCC). A CCC of 0.80 or higher was considered excellent agreement.

RESULTS

The CCC between the first and second sets of measurements was lowest for E and highest for the calculated β, although none of the CCC calculations was statistically significant, demonstrating poor agreement.

CONCLUSIONS

The ability to reliably measure and calculate the degree of transverse plane rotation by radiographs in cerebral palsy patients with spino-pelvic deformity by the method described by Lucas et al. is poor, likely because of difficulty in consistently identify pelvic landmarks.

Urine stability studies for novel biomarkers of acute kidney injury

BACKGROUND

The study of novel urinary biomarkers of acute kidney injury has expanded exponentially. Effective interpretation of data and meaningful comparisons between studies require awareness of factors that can adversely affect measurement. We examined how variations in short-term storage and processing might affect the measurement of urine biomarkers.

STUDY DESIGN

Cross-sectional prospective.

SETTING & PARTICIPANTS

Hospitalized patients from 2 sites: Yale New Haven Hospital (n=50) and University of California, San Francisco Medical Center (n=36).

PREDICTORS

We tested the impact of 3 urine processing conditions on these biomarkers: (1) centrifugation and storage at 4°C for 48 hours before freezing at -80°C, (2) centrifugation and storage at 25°C for 48 hours before freezing at -80°C, and (3) uncentrifuged samples immediately frozen at -80°C.

OUTCOMES

Urine concentrations of 5 biomarkers: neutrophil gelatinase-associated lipocalin (NGAL), interleukin 18 (IL-18), kidney injury molecule 1 (KIM-1), liver-type fatty acid-binding protein (L-FABP), and cystatin C.

MEASUREMENTS

We measured urine biomarkers by established enzyme-linked immunosorbent assay methods. Biomarker values were log-transformed, and agreement with a reference standard of immediate centrifugation and storage at -80°C was compared using concordance correlation coefficients (CCCs).

RESULTS

Neither storing samples at 4°C for 48 hours nor centrifugation had a significant effect on measured levels, with CCCs higher than 0.9 for all biomarkers tested. For samples stored at 25°C for 48 hours, excellent CCC values (>0.9) also were noted between the test sample and the reference standard for NGAL, cystatin C, L-FABP and KIM-1. However, the CCC for IL-18 between samples stored at 25°C for 48 hours and the reference standard was 0.81 (95% CI, 0.66-0.96).

LIMITATIONS

No comparisons to fresh, unfrozen samples; no evaluation of the effect of protease inhibitors.

CONCLUSIONS

All candidate markers tested using the specified assays showed high stability with both short-term storage at 4°C and without centrifugation prior to freezing. For optimal fidelity, urine for IL-18 measurement should not be stored at 25°C before long-term storage or analysis.