Biomedical subjects

Valerie L Durkalski

Publications and source records attributed to Valerie L Durkalski.

8 recordsLinked to original sources

PubMed2006

Therapeutic inertia is an impediment to achieving the Healthy People 2010 blood pressure control goals.

Therapeutic inertia (TI), defined as the providers' failure to increase therapy when treatment goals are unmet, contributes to the high prevalence of uncontrolled hypertension (> or =140/90 mm Hg), but the quantitative impact is unknown. To address this gap, a retrospective cohort study was conducted on 7253 hypertensives that had > or =4 visits and > or =1 elevated blood pressure (BP) in 2003. A 1-year TI score was calculated for each patient as the difference between expected and observed medication change rates with higher scores reflecting greater TI. Antihypertensive therapy was increased on 13.1% of visits with uncontrolled BP. Systolic BP decreased in patients in the lowest quintile of the TI score but increased in those in the highest quintile (-6.8+/-0.5 versus +1.8+/-0.6 mm Hg; P<0.001). Individuals in the lowest TI quintile were &33 times more likely to have their BP controlled at the last visit than those in highest quintile (odds ratio, 32.7; 95% CI, 25.1 to 42.6; P<0.0001). By multivariable analysis, TI accounted for &19% of the variance in BP control. If TI scores were decreased &50%, that is, increasing medication dosages on &30% of visits, BP control would increase from the observed 45.1% to a projected 65.9% in 1 year. This study confirms the high rate of TI in uncontrolled hypertensive subjects. TI has a major impact on BP control in hypertensive subjects receiving regular care. Reducing TI is critical in attaining the Healthy People 2010 goal of controlling hypertension in 50% of all patients.

Antihypertensive Agents↗

PubMed2006

Evaluation of treatment with direct thrombin inhibitors in patients with heparin-induced thrombocytopenia.

STUDY OBJECTIVE: To evaluate the efficacy, safety, and associated costs of anticoagulation with argatroban, bivalirudin, and lepirudin for managing patients with heparin-induced thrombocytopenia (HIT) or presumed HIT. DESIGN: Retrospective medical record review. SETTING: University-affiliated teaching hospital. PATIENTS: Forty-two patients who were hospitalized between January 1 and December 31, 2004, and who were treated with bivalirudin, argatroban, or lepirudin for at least 24 hours. MEASUREMENTS AND MAIN RESULTS: The primary outcome was the time to reach the desired goal for activated partial thromboplastin time (aPTT). Secondary outcomes were the number of aPTT measurements within the therapeutic range, costs, treatment duration, clinical outcomes, and adverse events. Of the 42 patients who met the inclusion criteria, 24 received bivalirudin, 13 received argatroban, and 5 received lepirudin. Patients receiving bivalirudin who reached therapeutic aPTTs attained them sooner than those receiving either argatroban or lepirudin (8.5 vs 14 and 24 hrs, respectively, p=0.124). Average percentage of therapeutic aPTTs/patient was greatest in the argatroban group (62%), followed by the bivalirudin (57%) and lepirudin (29%) groups (p=0.062). Average drug cost/day/patient was greater in the lepirudin group than the other groups, whereas average laboratory costs were similar among groups. Treatment duration was longer with argatroban than with bivalirudin or lepirudin. Bleeding rates were similar in the argatroban and bivalirudin groups, but higher than in the lepirudin group. A composite of clinical outcomes (deep vein thrombosis, nonfatal myocardial infarction, nonfatal stroke, limb amputation, and all-cause mortality) were similar among the three groups. CONCLUSION: All three drugs were effective as anticoagulants for patients with HIT or presumed HIT. Based on average use and average wholesale price, bivalirudin cost less per day than the other two agents. Although not yet approved by the United States Food and Drug Administration for management of HIT, bivalirudin appears to be a viable treatment alternative for anticoagulation therapy.

Adult↗

PubMed2006

Open-label trial of escitalopram in the treatment of posttraumatic stress disorder.

BACKGROUND: Posttraumatic stress disorder (PTSD) is a highly prevalent, disabling illness. Selective serotonin reuptake inhibitors (SSRIs) are considered first-line medication treatment, with sertraline, paroxetine, and fluoxetine being the most studied. More limited but favorable data suggest that citalopram, an SSRI, may also have a role in the treatment of PTSD. Its S-enantiomer escitalopram, which may have faster onset and greater magnitude of effect than citalopram in other conditions, has not yet been investigated in PTSD. OBJECTIVE: To assess the efficacy, safety, and tolerability of escitalopram in the treatment of PTSD. METHOD: A 12-week, prospective, open-label trial of escitalopram was conducted from January 2003 through August 2004 in military veterans with PTSD. Escitalopram was initiated at 10 mg daily for 4 weeks, then increased to 20 mg daily for the remainder of the study. Concomitant psychiatric medications were discontinued at least 2 weeks prior to enrollment. The primary outcome variable was the change from baseline to endpoint in global Clinician-Administered PTSD Scale-Symptom version (CAPS-SX) score. Secondary efficacy measures included the Clinical Global Impressions-Severity of Illness (CGI-S) and -Improvement (CGI-I) scales, the Hamilton Rating Scale for Depression (HAM-D), and the Davidson Trauma Scale (DTS). Posttraumatic stress disorder and comorbid diagnoses were established using the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. RESULTS: Twenty-four of 25 patients were evaluated for efficacy. The mean global CAPS-SX score decreased from 79.4 (SD = 15.7) at baseline to 61.2 (SD = 24.7) at the end of the study (p = .0002). The CAPS-C avoidance/numbing and CAPS-D hyper-arousal subscale scores decreased significantly from baseline to endpoint (CAPS-C, p = .0171; CAPS-D, p = .0001), with trend-level reductions observed in CAPS-B reexperiencing subscale scores (p = .0593). Forty-five percent of patients (9/20) were much or very much improved at the end of the study (CGI-I of 1 or 2). The HAM-D and DTS also significantly improved (p = .0063 and p = .0004, respectively). Mild to moderate gastrointestinal disturbances were the most common side effects. Only 4 patients discontinued early because of adverse effects. CONCLUSIONS: This preliminary open-label study suggests that escitalopram is both efficacious and well tolerated in PTSD patients. However, randomized controlled studies are needed to confirm these results and to further define its potential role in the treatment of PTSD.

Citalopram↗

PubMed2005

Analysis of trichotomous pharmaceutical endpoints.

Many important clinical trial endpoints are measured on an ordered categorical scale. These include objective tumor response in oncology trials, the Thombolysis in Myocardial Infarction (TIMI) flow in cardiovascular trials, and the American College of Radiology (A CR) criterion in rheumatology trials. A common tendency among researchers is to simplify the ordered outcomes and collapse the data into a 2 x 2 contingency table in order to perform simpler statistical tests, such as the chi-square test or Fisher's exact test. Recently, more appropriate approaches, such as adaptive tests, have been developed for the analysis of ordered categorical endpoints. Each test in the adaptive class of tests is exact and balances good global power with nearly optimal power to detect a specific alternative of most interest. Prior knowledge of the direction of the treatment effect and the level of confidence in this prior information can be used to select a specific test from this class. However, little guidance has been offered regarding the selection of adaptive parameters when prior information is available. The purpose of this paper is to fill this gap by offering an objective approach for parameter selection, and to provide real data examples to illustrate the use of this objective approach.

Algorithms↗

PubMed2004

Computed tomographic colonography (virtual colonoscopy): a multicenter comparison with standard colonoscopy for detection of colorectal neoplasia.

CONTEXT: Conventional colonoscopy is the best available method for detection of colorectal cancer; however, it is invasive and not without risk. Computed tomographic colonography (CTC), also known as virtual colonoscopy, has been reported to be reasonably accurate in the diagnosis of colorectal neoplasia in studies performed at expert centers. OBJECTIVE: To assess the accuracy of CTC in a large number of participants across multiple centers. DESIGN, SETTING, AND PARTICIPANTS: A nonrandomized, evaluator-blinded, noninferiority study design of 615 participants aged 50 years or older who were referred for routine, clinically indicated colonoscopy in 9 major hospital centers between April 17, 2000, and October 3, 2001. The CTC was performed by using multislice scanners immediately before standard colonoscopy; findings at colonoscopy were reported before and after segmental unblinding to the CTC results. MAIN OUTCOME MEASURES: The sensitivity and specificity of CTC and conventional colonoscopy in detecting participants with lesions sized at least 6 mm. Secondary outcomes included detection of all lesions, detection of advanced lesions, possible technical confounders, participant preferences, and evidence for increasing accuracy with experience. RESULTS: A total of 827 lesions were detected in 308 of 600 participants who underwent both procedures; 104 participants had lesions sized at least 6 mm. The sensitivity of CTC for detecting participants with 1 or more lesions sized at least 6 mm was 39.0% (95% confidence interval [CI], 29.6%-48.4%) and for lesions sized at least 10 mm, it was 55.0% (95% CI, 39.9%-70.0%). These results were significantly lower than those for conventional colonoscopy, with sensitivities of 99.0% (95% CI, 97.1%->99.9%) and 100%, respectively. A total of 496 participants were without any lesion sized at least 6 mm. The specificity of CTC and conventional colonoscopy for detecting participants without any lesion sized at least 6 mm was 90.5% (95% CI, 87.9%-93.1%) and 100%, respectively, and without lesions sized at least 10 mm, 96.0% (95% CI, 94.3%-97.6%) and 100%, respectively. Computed tomographic colonography missed 2 of 8 cancers. The accuracy of CTC varied considerably between centers and did not improve as the study progressed. Participants expressed no clear preference for either technique. CONCLUSIONS: Computed tomographic colonography by these methods is not yet ready for widespread clinical application. Techniques and training need to be improved.

Colonography, Computed Tomographic↗

PubMed2003

Analysis of clustered matched-pair data.

Evaluation of the performance of a new diagnostic procedure with respect to a standard procedure arises frequently in practice. The response of interest, often in a dichotomous form, is measured twice, once with each procedure. The two procedures are administered to either two matched individuals, or when practical, to the same individual. A large sample test for matched-pair data is the McNemar test. The main assumption of this test is independent paired responses; however, when more than one outcome from an individual is measured by each procedure, the data are clustered. Examples of such cases can be seen in dental and ophthalmology studies. Variance adjustment methods for the analysis of clustered matched-pair data have been proposed; however, because of unequal cluster sizes, variability of correlation structures within a cluster (within paired responses in a cluster as well as between paired responses in a cluster), and unequal success probabilities among the clusters, the performances of some available methods are not consistent. This research proposes a simple adjustment to the McNemar test for the analysis of clustered matched-pair data. Method of moments is used to calculate a consistent variance estimator. Using Monte Carlo simulation, the size and power of the proposed test are compared to those of two currently available methods. To illustrate practical application, clustered matched-pair data from two clinical studies are analysed.

Clinical Trials as Topic↗

PubMed2003

Analysis of clustered matched-pair data for a non-inferiority study design.

Hypothesis testing of matched-pair data has been adapted for equivalence (one- and two-sided) study designs; however, a statistical problem arises when more than one measurement is recorded for each study subject. Ignoring the correlation between the repeated measurements per subject may underestimate the standard error of the parameter estimate. A method of testing for non-inferiority or equivalence of clustered matched-pair data is not yet available. This paper proposes a Wald-type test statistic for a non-inferiority hypothesis and applies it to the comparison of two diagnostic procedures.

Computer Simulation↗

PubMed2002

The virtual colonoscopy study: a large multicenter clinical trial designed to compare two diagnostic screening procedures.

This paper reviews the design of a large multicenter clinical trial currently being conducted to test the equivalence of two screening procedures for colorectal polyps. The primary outcome is the sensitivity and specificity of the new and standard procedures for detecting subjects with and without polyps of a size > or =6 mm, respectively. An important secondary outcome is the accuracy of these procedures in detecting individual polyps. A total of 619 participants underwent virtual colonoscopy, the new procedure, followed by conventional colonoscopy, the standard procedure. Strategies for the design and implementation of the study are shared as well as the challenges encountered.

Bias↗