Stephen Hillis

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Severe pain during wound care procedures: A cross-sectional study protocol

Journal of advanced nursing, Jan 7, 2018

The aim of this study is to: (a) develop and evaluate a model to predict severe pain during wound... more The aim of this study is to: (a) develop and evaluate a model to predict severe pain during wound care procedures (WCPs) so that high-risk patients can be targeted for specialized dressings and preventive pain control; and (b) identify biological factors associated with severe pain during WCPs so that novel pain control strategies can be developed. Wound care procedures such as dressing changes can cause moderate to severe pain in 74% of patients, with nearly half (36%) of all patients experiencing severe pain (rated as 8-10 on a 10-point numeric rating scale) during dressing change. Additionally, clinicians have little direction with current guidelines regarding pain control during WCPs including the selection of the appropriate advanced wound dressings and the appropriate use of analgesics. This is a cross-sectional study. The National Institute of Nursing Research approved and funded the study June of 2015 and the appropriate Institutional Review Board approved all study protocol...

Longitudinal associations between mental health conditions and overactive bladder in women veterans

American journal of obstetrics and gynecology, Jan 20, 2017

One in 5 recently deployed US women veterans report overactive bladder symptoms. Mental health co... more One in 5 recently deployed US women veterans report overactive bladder symptoms. Mental health conditions such as depression and anxiety commonly co-occur in women with overactive bladder, but temporal relationships between these outcomes have not been well studied, and the mechanism behind this association is unknown. The Women Veterans Urinary Health Study, a nationwide longitudinal study in recently deployed women veterans, was designed to better understand relationships between overactive bladder and mental health conditions. We sought to estimate the 1-year incidence and remission of overactive bladder and to identify the impact of depression, anxiety, posttraumatic stress disorder, and prior sexual assault on 1-year overactive bladder incidence and remission rates. Participants of this 1-year prospective cohort study were female veterans separated from military service who had returned from Iraq or Afghanistan deployment within the previous 2 years. Eligible women were identif...

ROC or FROC? It depends on the research question

Medical Physics, 2017

Temporal stability in chronic wound microbiota is associated with poor healing

Journal of Investigative Dermatology, 2016

Microbial burden of chronic wounds is believed to play an important role in impaired healing and ... more Microbial burden of chronic wounds is believed to play an important role in impaired healing and the development of infection-related complications. However, clinical cultures have little predictive value of wound outcomes, and culture-independent studies have been limited by cross-sectional design and small cohort size. We systematically evaluated the temporal dynamics of the microbiota colonizing diabetic foot ulcers, a common and costly complication of diabetes, and its association with healing and clinical complications. Dirichlet multinomial mixture modeling, Markov chain analysis, and mixed-effect models were used to investigate shifts in the microbiota over time and their associations with healing. Here we show, to our knowledge, previously unreported temporal dynamics of the chronic wound microbiome. Microbiota community instability was associated with faster healing and improved outcomes. Diabetic foot ulcer microbiota were found to exist in one of four community types that experienced frequent and nonrandom transitions. Transition patterns and frequencies were associated with healing time. Exposure to systemic antibiotics destabilized the wound microbiota, rather than altering overall diversity or relative abundance of specific taxa. This study provides evidence that the dynamic wound microbiome is indicative of clinical outcomes and may be a valuable guide for personalized management and treatment of chronic wounds.

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Extending M-estimation to include censored data via james's method

Http Dx Doi Org 10 1080 03610919108812943, Jun 27, 2007

Volume Measures Using a Digital Image Analysis System are Reliable in Diabetic Foot Ulcers

Wounds a Compendium of Clinical Research and Practice, 2012

Reliable measures of wound size are critical to wound healing research and clinical management. M... more Reliable measures of wound size are critical to wound healing research and clinical management. Measurement of full-thickness wounds is increasingly being done using digital images and photogrammetric software, such as VeVMD (Vista Medical, Winnipeg, Manitoba, Canada), to estimate wound volume. The reliability of VeVMD in determining wound volume is unknown. The present study sought to examine the reliability of wound volume measurements obtained using VeVMD. Methods-A cross-sectional study of adults with full-thickness, neuropathic, diabetic foot ulcers (DFU) at 2 sites in the US Midwest was undertaken. Ulcer images were obtained, stored, and used to obtain measures of wound volume using VeVMD. Four raters independently completed wound measures, and then repeated these measures 2 weeks after the first measurement. Raters were blinded to the comparison measurements. Inter-and intra-rater correlations were computed. Results-Thirty-three enrolled subjects with 33 DFU were included in the analyses. Inter-rater reliability was 0.745 and intra-rater reliability was 0.868. Four ulcers showed noticeably less agreement between raters; these ulcers had small, but deeply recessed areas, resulting in differences in defining the wound margin. When these 4 ulcers were removed, inter-and intrarater reliabilities were excellent (0.970 and 0.981, respectively). Conclusion-Reliabilities of volume measurements obtained with VeVMD were acceptable in DFU, even when raters had different definitions of the ulcer margin or changed their definition from time to time. However, conclusions cannot be drawn regarding the performance of VeVMD in other wound types.

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A heuristic generalization of smith's buckley james variance estimator

Commun Statist Simulat Comput, 1994

... observations. The Buckley-James and Weissfeld-Schneider variance estimators for p are given b... more

Diagnostic validity of three swab techniques for identifying chronic wound infection

Wound Repair and Regeneration Official Publication of the Wound Healing Society and the European Tissue Repair Society, Sep 1, 2006

This study examined the diagnostic validity of three different swab techniques in identifying chr... more This study examined the diagnostic validity of three different swab techniques in identifying chronic wound infection. Concurrent swab specimens of chronic wounds were obtained using wound exudate, the Z-technique, and the Levine technique, along with a specimen of viable wound tissue. Swab and tissue specimens were cultured using quantitative and qualitative laboratory procedures. Infected wounds were defined as those containing 1 x 10(6) or more organisms per gram of tissue. Accuracy was determined by associating the quantitative cultures of swab specimens with the cultures from tissue specimens using receiver operating characteristic curves. Of the 83 study wounds, 30 (36%) were infected. Accuracy was the highest for swab specimens obtained using Levine&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s technique at 0.80. Based on Levine&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s technique, a critical threshold of 37,000 organisms per swab provided a sensitivity of 90% and a specificity of 57%. The mean concordance between swab specimens obtained using Levine&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s technique and tissue specimens was 78%. The findings suggest that swab specimens collected using Levine&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s technique provide a reasonably accurate measure of wound bioburden, given that they are more widely applicable than tissue cultures. The diagnostic validity of Levine&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s technique needs further study using an alternative reference standard, such as the development of infection-related complications.

Diagnostic validity of semiquantitative swab cultures

Wounds a Compendium of Clinical Research and Practice, 2007

Swab cultures of wounds are noninvasive and most laboratories are capable of semiquantitatively p... more Swab cultures of wounds are noninvasive and most laboratories are capable of semiquantitatively processing these specimens. This study examined the diagnostic validity of semiquantitative swab cultures obtained using Levine&amp;amp;amp;amp;amp;amp;amp;amp;#39;s technique and compared semiquantitative and quantitative swab cultures. Two swab specimens were obtained from a sample of 44 chronic wounds using Levine&amp;amp;amp;amp;amp;amp;amp;amp;#39;s technique. One was processed using quantitative laboratory procedures and the other using semiquantitative laboratory procedures. The diagnostic validity of the findings from each swab culture process was determined by associating the culture findings of each with quantitative tissue cultures (reference standard) using receiver operating characteristic (ROC) curves and by evaluating concordance. The area under the curve (AUC) of the semiquantitative swab culture was 0.639, which was not significantly higher than the .50 diagonal chance (P = 0.0501), suggesting a non-informative test. The AUC for quantitative swab cultures was 0.821. The AUC of the quantitative swab culture was significantly higher than the diagonal chance line of 0.5 and was significantly higher than the AUC of the semiquantitative swab culture (P = 0.0128). The mean concordance of semiquantitative cultures in recovering all organisms was 57%. The mean concordance of quantitative swab cultures in recovering all organisms was 72%. The findings of this study suggest that swab specimens processed using semiquantitative processes do not provide culture findings that correlate well with culture findings from tissue specimens. More meaningful information can be obtained from swab specimens if they are quantitatively processed in the laboratory.

Health Beliefs toward Cardiovascular Risk Reduction in Patients Admitted to Chest Pain Observation Units

Academic Emergency Medicine, Apr 1, 2009

Objectives: Even after acute coronary syndrome (ACS) is ruled out, observational studies have sug... more Objectives: Even after acute coronary syndrome (ACS) is ruled out, observational studies have suggested that many patients with nonspecific chest pain have a high burden of cardiovascular risk factors (CRFs) and are at increased long-term risk of ischemic heart disease (IHD)-related mortality. The aim of this study was to evaluate the premise that evaluation in an observation unit for symptoms of possible ACS is a ''teachable moment'' with regard to modification of CRFs. Methods: The authors conducted a baseline face-to-face interview and a 3-month telephone interview of 83 adult patients with at least one modifiable CRF who presented with symptoms of possible ACS to an academic medical center. Existing questionnaires were adapted to measure Health Belief Model (HBM) constructs for IHD. Stage of change and self-reported CRF-related behaviors (diet, exercise, and smoking) were assessed using previously validated measures. The paired t-test or signed rank test was used to compare baseline and 3-month measures of health behavior within the analysis sample. Results: Of the 83 study patients, 45 and 40% reported having received clinician advice regarding diet and physical activity during the observation unit encounter, respectively; 69% of current smokers received advice to quit smoking. Patients reported lower susceptibility to IHD (13.3 vs. 14.0, p = 0.06) and greater perceived benefit of healthy lifestyles (27.5 vs. 26.4, p = 0.0003) at 3-month follow-up compared to baseline. Patients also reported greater readiness to change and improved self-reported behaviors at follow-up (vs. baseline): decreased intake of saturated fat (10.1% vs. 10.5% of total calories, p = 0.005), increased fruit and vegetable intake (4.0 servings ⁄ day vs. 3.6 servings ⁄ day, p = 0.01), and fewer cigarettes (13 vs. 18, p = 0.002). Conclusions: Observed changes in IHD health beliefs and CRF-related behaviors during follow-up support the idea that observation unit admission is a teachable moment. Patients with modifiable risk factors may benefit from systematic interventions to deliver CRF-related counseling during observation unit evaluation.

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The equivalence of two buckley-james variance estimators

Commun Statist Theor Method, 1993

Buckley and James’s (1979) procedure has been shown to be an effective method for estimating the ... more Buckley and James’s (1979) procedure has been shown to be an effective method for estimating the regression coefficients in a censored data linear regression model without requiring distributional assumptions. Three methods of estimating the covariance matrix of the Buckley-James estimator directly have been proposed. One method was proposed by Buckley and James and the other two methods were proposed by

Equivalence of binormal likelihood-ratio and bi-chi-squared ROC curve models

Statistics in Medicine, 2015

A basic assumption for a meaningful diagnostic decision variable is that there is a monotone rela... more A basic assumption for a meaningful diagnostic decision variable is that there is a monotone relationship between it and its likelihood ratio. This relationship, however, generally does not hold for a decision variable that results in a binormal receiver operating characteristic (ROC) curve. As a result, ROC curve estimation based on the assumption of a binormal ROC-curve model produces improper ROC curves, which have &amp;amp;amp;amp;#39;hooks&amp;amp;amp;amp;#39;, are not concave over the entire domain and cross the chance line. Although in practice this &amp;amp;amp;amp;#39;improperness&amp;amp;amp;amp;#39; is usually not noticeable, sometimes it is evident and problematic. To avoid this problem, Metz and Pan proposed basing ROC-curve estimation on the assumption of a binormal likelihood-ratio (binormal-LR) model, which states that the decision variable is an increasing transformation of the likelihood-ratio function of a random variable having normal conditional diseased and nondiseased distributions. However, their development is not easy to follow. I show that the binormal-LR model is equivalent to a bi-chi-squared model in the sense that the families of corresponding ROC curves are the same. The bi-chi-squared formulation provides an easier-to-follow development of the binormal-LR ROC curve and its properties in terms of well-known distributions. Copyright © 2015 John Wiley &amp;amp;amp;amp;amp; Sons, Ltd.

Prevalence and Correlates of Illness Worry in the General Population

Psychosomatics, 2005

The prevalence and correlates of illness worry in the general population were investigated in a r... more The prevalence and correlates of illness worry in the general population were investigated in a representative sample. The authors screened residents of the United States by telephone, and more detailed interviews were conducted with 123 respondents who reported at least 1 month of worry about serious illness in the past 12 months and an equal number of randomly selected persons without such worry. Data on demographic characteristics, medical and psychiatric conditions, functional impairment, and health care utilization were collected. At least 1 month of worry was endorsed by 13.1% of the screened population. Correlates of worry included a cluster of psychiatric conditions (major depressive episode, panic attacks, and generalized anxiety disorder) and three clusters of physical conditions (heart disease, cancer, and other diseases). Worry about serious illness was associated with functional impairment and health care utilization.

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Effect of a Behavioral Self-Regulation Intervention on Patient Adherence to Fluid-Intake Restrictions in Hemodialysis: a Randomized Controlled Trial

Annals of behavioral medicine : a publication of the Society of Behavioral Medicine, Jan 2, 2015

The purpose of this study is to evaluate the efficacy of a behavioral self-regulation interventio... more The purpose of this study is to evaluate the efficacy of a behavioral self-regulation intervention vs. active control condition using a parallel-group randomized clinical trial with a sample of center hemodialysis patients with chronic kidney disease. Participants were recruited from 8 hemodialysis treatment centers in the Midwest. Eligible patients were (a) fluid nonadherent as defined by an interdialytic weight gain >2.5 kg over a 4-week period, (b) >18 years of age, (c) English-speaking without severe cognitive impairment, (d) treated with center-based hemodialysis for >3 months, and (e) not living in a care facility in which meals were managed. Medical records were used to identify eligible patients. Patients were randomly assigned to either a behavioral self-regulation intervention or active control condition in which groups of 3-8 patients met for hour-long, weekly sessions for 7 weeks at their usual hemodialysis clinic. Primary analyses were intention-to-treat. Sixty...

Analysis of Categorized Data: Use of the Odds Ratio as a Measure of Association

Textbook in Psychiatric Epidemiology, 2002

DBM MRMC: Software to Perform Analysis of Variance for Multi-Reader Multi-Case Receiver Operating Characteristic Experiments Using Various Observer Models and Accuracy Parameters

ABSTRACT

Implementing Best Evidence in Smoking Cessation Treatment for Hospitalized Veterans: Results from the VA-BEST Trial

Joint Commission journal on quality and patient safety / Joint Commission Resources, 2014

Although the US Department of Veterans Affairs (VA) has promoted adherence to smoking cessation g... more Although the US Department of Veterans Affairs (VA) has promoted adherence to smoking cessation guidelines since 1997, hospitalized smokers do not consistently receive assistance in quitting. In a pre-post guideline implementation trial on the inpatient medicine units of four VA hospitals, the effectiveness of a multimodal intervention (enhanced academic detailing, modification of the nursing admission template, patient education materials and quitline referral, practice facilitation and staff feedback) changing practice behavior was evaluated. Peridischarge interviews were conducted with 824 patients to assess receipt of nurses' and physicians' delivery of the 5A's (Ask, Advise, Assess, Assist, Arrange) in hospitalized smokers. Subjects were significantly more likely to have received each of the…

Generalized Roe and Metz receiver operating characteristic model: analytic link between simulated decision scores and empirical AUC variances and covariances

Journal of Medical Imaging, 2014

Modeling and simulation are often used to understand and investigate random quantities and estima... more Modeling and simulation are often used to understand and investigate random quantities and estimators. In 1997, Roe and Metz introduced a simulation model to validate analysis methods for the popular endpoint in reader studies to evaluate medical imaging devices, the reader-averaged area under the receiver operating characteristic (ROC) curve. Here, we generalize the notation of the model to allow more flexibility in recognition that variances of ROC ratings depend on modality and truth state. We also derive and validate equations for computing population variances and covariances for reader-averaged empirical AUC estimates under the generalized model. The equations are one-dimensional integrals that can be calculated using standard numerical integration techniques. This work provides the theoretical foundation and validation for a Java application called iRoeMetz that can simulate multireader multicase ROC studies and numerically calculate the corresponding variances and covariances of the empirical AUC. The iRoeMetz application and source code can be found at the "iMRMC" project on the google code project hosting site. These results and the application can be used by investigators to investigate ROC endpoints, validate analysis methods, and plan future studies.

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$Research paper thumbnail of A novel impaction technique to create experimental articular fractures in large animal joints$

A novel impaction technique to create experimental articular fractures in large animal joints

Osteoarthritis and cartilage / OARS, Osteoarthritis Research Society, 2013

A novel impaction fracture insult technique, developed for modeling post-traumatic osteoarthritis... more A novel impaction fracture insult technique, developed for modeling post-traumatic osteoarthritis in porcine hocks in vivo, was tested to determine the extent to which it could replicate the cell-level cartilage pathology in human clinical intra-articular fractures. Eight fresh porcine hocks (whole-joint specimens with fully viable chondrocytes) were subjected to fracture insult. From the fractured distal tibial surfaces, osteoarticular fragments were immediately sampled and cultured in vitro for 48 h. These samples were analyzed for the distribution and progression of chondrocyte death, using the Live/Dead assay. Five control joints, in which "fractures" were simulated by means of surgical osteotomy, were also similarly analyzed. In the impaction-fractured joints, chondrocyte death was concentrated in regions adjacent to fracture lines (near-fracture regions), as evidenced by fractional cell death significantly higher (P < 0.0001) than in central non-fracture (control)...

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Laser fluorescence detection of occlusal caries

American journal of dentistry, 2002

This study compared six diagnostic methods with a histologic standard, including diode laser fluo... more This study compared six diagnostic methods with a histologic standard, including diode laser fluorescence, caries detection dye, and an operating microscope. Diagnosis groups included: visual only (VO); visual and bitewing radiograph (VX); visual, bitewing radiograph and explorer (VXE); Global Protege operating microscope at x10 (S); caries detection dye (CDD); diode laser fluorescence (DLF). Three examiners individually evaluated five independent sites on 29 extracted human molars using the above methods. Teeth were sectioned and evaluated histologically. Response Operating Characteristic (ROC) analysis was used to descriptively and inferentially assess the relationship between occlusal caries and the six diagnostic methods. In this in vitro study, the resulting AUCs (areas under the ROC curve) showed that the DLF method appeared to be superior, when compared to traditional methods (VO, VX, VXE) and caries detection dye. While caries detection with DLF ranked higher than use of an ...

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