Biomedical subjects

Claudia Pedroza

Publications and source records attributed to Claudia Pedroza.

8 recordsLinked to original sources

PubMed2006

A Bayesian forecasting model: predicting U.S. male mortality.

This article presents a Bayesian approach to forecast mortality rates. This approach formalizes the Lee-Carter method as a statistical model accounting for all sources of variability. Markov chain Monte Carlo methods are used to fit the model and to sample from the posterior predictive distribution. This paper also shows how multiple imputations can be readily incorporated into the model to handle missing data and presents some possible extensions to the model. The methodology is applied to U.S. male mortality data. Mortality rate forecasts are formed for the period 1990-1999 based on data from 1959-1989. These forecasts are compared to the actual observed values. Results from the forecasts show the Bayesian prediction intervals to be appropriately wider than those obtained from the Lee-Carter method, correctly incorporating all known sources of variability. An extension to the model is also presented and the resulting forecast variability appears better suited to the observed data.

Bayes Theorem↗

PubMed2006

Confirmatory factor structure of the Center for Epidemiologic Studies-Depression scale (CES-D) in mild-to-moderate traumatic brain injury.

PRIMARY OBJECTIVE: The Center for Epidemiologic Studies Depression scale (CES-D) is a frequently-used self-report measure of depressive symptom severity. Brief depression screening measures can be important in the identification and prediction of depression following traumatic brain injury. The objective of this study was to investigate the validity of the CES-D in measuring depressive symptoms in patients with mild-to-moderate TBI as it has been rarely used in neurologically compromised populations. RESEARCH DESIGN: Inception cohort. METHODS AND PROCEDURES: The CES-D was administered to 340 participants with mild-to-moderate TBI at 3-months post-injury. MAIN OUTCOMES AND RESULTS: Confirmatory factor analysis of the CES-D indicated that the data are a reasonable fit similar to that of Radloff 's original 4-factor model. CONCLUSIONS: These findings suggest that the CES-D may be appropriate for use in patients with mild-to-moderate TBI.

Adult↗

PubMed2006

Post-traumatic amnesia predicts long-term cerebral atrophy in traumatic brain injury.

PRIMARY OBJECTIVE: To examine post-traumatic amnesia (PTA) and its relation to long-term cerebral atrophy in persons with traumatic brain injury (TBI) using objective indicators of PTA duration and Quantitative Magnetic Resonance Imaging (QMRI). It was hypothesized that longer PTA would predict later generalized atrophy (increased ventricle-to-brain ratio (VBR)). As a guide in assessing patients with TBI, this study determined the probability of developing chronic cerebral atrophy based on PTA duration. RESEARCH DESIGN: Probability model using 60 adult patients with mild-to-severe TBI. MAIN OUTCOMES AND RESULTS: A logistic regression model with a cut-off determined by normative QMRI data confirmed that longer PTA duration predicts increased VBR. A probability model demonstrated a 6% increase in the odds of developing later atrophy on neuroimaging with each additional day of PTA. CONCLUSIONS: PTA has previously proven to be a good indicator of later cognitive recovery and functional outcome and also predicts long-term parenchymal change.

Adolescent↗

PubMed2005

Frontal and temporal morphometric findings on MRI in children after moderate to severe traumatic brain injury.

In vivo MRI volumetric analysis enables investigators to evaluate the extent of tissue loss following traumatic brain injury (TBI). However, volumetric studies of pediatric TBI are sparse, and there have been no volumetric studies to date in children examining specific subregions of the prefrontal and temporal lobes. In this study, MRI volumetry was used to evaluate brain volume differences in the whole brain, and prefrontal, temporal, and posterior regions of children following moderate to severe TBI as compared to uninjured children of similar age and demographic characteristics. The TBI group had significantly reduced whole brain, and prefrontal and temporal regional tissue volumes as well as increased cerebrospinal fluid (CSF). Confidence interval testing further revealed group differences on gray matter (GM) and white matter (WM) in the superior medial and ventromedial prefrontal regions, WM in the lateral frontal region, and GM, WM, and CSF in the temporal region. Whole brain volume and total brain GM were reduced, and total ventricular volume, total CSF volume, and ventricle-to-brain ratio (VBR) were increased in the TBI group. Additional analyses comparing volumetric data from typically developing children and subgroups of TBI patients with and without regional focal lesions suggested that GM loss in the frontal areas was primarily attributable to focal injury, while WM loss in the frontal and temporal lobes was related to both diffuse and focal injury. Finally, volumetric measures of preserved frontotemporal tissue were related to functional recovery as measured by the Glasgow Outcome Scale (adapted for children) with greater tissue preservation predicting better recovery.

Adolescent↗

PubMed2005

Postconcussional disorder: Are the DSM-IV criteria an improvement over the ICD-10?

Little is known about the characteristics and outcomes of patients diagnosed with postconcussional disorder (PCD) under the provisionally proposed criteria in the DSM-IV and how they differ from patients diagnosed with postconcussional syndrome (PCS) under the International Classification of Diseases, 10th edition clinical (ICD-10) criteria. This study investigated differences in outcome based on a diagnosis of PCD (DSM-IV) versus PCS (ICD-10 clinical criteria) as to which criteria set might be preferred for clinical practice. A consecutive series of adult patients with mild (N = 319) to moderate (N = 21) traumatic brain injury was assessed at 3 months postinjury with a brief neuropsychological battery and measures of specific outcome domains. In two separate series of analyses, patients with PCD were compared with those without PCD, and those with PCS were compared with those without PCS. Although the two criteria sets resulted in markedly different incidence rates, there was no substantial pattern of differences between the DSM-IV and ICD-10 in the outcome domains of psychiatric symptoms and disorders, social and community integration, health-related quality of life, or global outcome as measured by the Glasgow Outcome Scale-Extended. In spite of significant differences between the two diagnostic criteria sets and different incidence rates for PCD/PCS, outcome in all measured domains was very similar at 3 months postinjury. There is no compelling evidence, based on these outcome domains, to suggest which of the two diagnostic criteria sets should be clinically preferred.

Adult↗

PubMed2005

Diagnostic criteria for postconcussional syndrome after mild to moderate traumatic brain injury.

This study evaluated the prevalence and specificity of diagnostic criteria for postconcussional syndrome (PCS) in 178 adults with mild to moderate traumatic brain injury (TBI) and 104 with extracranial trauma. Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) and International Classification of Diseases (ICD-10) criteria for PCS were evaluated 3 months after injury. The results showed that prevalence of PCS was higher using ICD-10 (64%) than DSM-IV criteria (11%). Specificity to TBI was limited because PCS criteria were often fulfilled by patients with extracranial trauma. The authors conclude that further refinement of the DSM-IV and ICD-10 criteria for PCS is needed before these criteria are routinely employed.

Adult↗

PubMed2005

Lost productive work time after mild to moderate traumatic brain injury with and without hospitalization.

OBJECTIVE: Lost productivity after mild traumatic brain injury (TBI) is a large component of the economic costs of brain trauma in the United States. This is the first prospective study of employment after mild TBI to include patients not admitted to a hospital. METHODS: Concurrent inception cohorts of 210 working-age adults with mild to moderate TBI and 122 patients who sustained general trauma not involving the brain were recruited at a trauma center and followed up to 6 months later. Outcomes were time from injury until first day worked and problems reported after resuming work. RESULTS: Most patients who worked after their injury remained employed 6 months later in a similar capacity as before the injury. No consistent differences were demonstrated between employment outcomes of patients with mild TBI and those with general trauma. The majority of nonhospitalized patients with mild TBI did not work for at least 1 month and did not begin working until 1 to 3 months after injury. Most patients with moderate TBI remained unemployed at 6 months postinjury. Patients with lower preinjury occupational status tended to have longer work absences. CONCLUSION: Lost productive work time after nonhospitalized TBI may cause significant economic costs because these injuries are frequent. Contrary to the theory that brain injury is more disabling to patients in cognitively demanding occupations, patients with higher job status tended to begin work earlier. A technique is needed to screen patients with mild TBI for risk of employment problems. Rehabilitation after moderate TBI may help to minimize lost productivity.

Adult↗

PubMed2004

Comparison of stochastic vs. conventional transcutaneous electrical stimulation for pain modulation in patients with electromyographically documented radiculopathy.

OBJECTIVE: To determine if a transcutaneous electrical stimulation (TENS) unit modified to deliver electrical impulses at random (R) or stochastic frequency, called TENS-R, provided better pain relief than conventional TENS. DESIGN: A prospective, randomized, double-blinded, placebo-controlled study at an urban teaching hospital. A total of 13 adult subjects with radiculopathy on electromyogram and chronic radicular pain rated pain before and after walking 100 feet with proximal (axial) placement of TENS leads with randomized settings on conventional TENS, placebo, or TENS-R and, subsequently, with distal (limb) placement of TENS leads with randomized settings, all on the same day. The pain measures used were the McGill Pain Questionnaire, parts 1 and 2, and the Visual Analog Scale. The functional measure was speed of walking. RESULTS: Four men and seven women completed the study pain scores, measured by McGill Pain Questionnaire part 2, significantly improved when the patient used TENS-R vs. conventional TENS (P = 0.006, analysis of variance). Placement of TENS electrodes on the back significantly decreased pain compared with lead placement on the legs for McGill Pain Questionnaire part 1 (P = 0.007), McGill Pain Questionnaire part 2 (P = 0.042), and the Visual Analog Scale (P = 0.026) measures. CONCLUSIONS: Qualitative pain scores significantly improved when the patient used TENS-R vs. conventional TENS. Lead placement of any TENS modality over the back vs. over the leg improved all pain scores.

Adult↗