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Biomedical subjects

C A Field

Publications and source records attributed to C A Field.

At least 19 recordsLinked to original sources
PubMed2002

Marginally specified generalized linear mixed models: a robust approach.

Longitudinal data modeling is complicated by the necessity to deal appropriately with the correlation between observations made on the same individual. Building on an earlier nonrobust version proposed by Heagerty (1999, Biometrics 55, 688-698), our robust marginally specified generalized linear mixed model (ROBMS-GLMM) provides an effective method for dealing with such data. This model is one of the first to allow both population-averaged and individual-specific inference. As well, it adopts the flexibility and interpretability of generalized linear mixed models for introducing dependence but builds a regression structure for the marginal mean, allowing valid application with time-dependent (exogenous) and time-independent covariates. These new estimators are obtained as solutions of a robustified likelihood equation involving Huber's least favorable distribution and a collection of weights. Huber's least favorable distribution produces estimates that are resistant to certain deviations from the random effects distributional assumptions. Innovative weighting strategies enable the ROBMS-GLMM to perform well when faced with outlying observations both in the response and covariates. We illustrate the methodology with an analysis of a prospective longitudinal study of laryngoscopic endotracheal intubation, a skill that numerous health-care professionals are expected to acquire. The principal goal of our research is to achieve robust inference in longitudinal analyses.

Biometry↗
PubMed2001

Association of alcohol use and other high-risk behaviors among trauma patients.

BACKGROUND: Risk behaviors and psychological problems may limit recovery after trauma, may be related to injury recidivism, and may limit the effectiveness of alcohol interventions in trauma patients. The aim of the current study was to evaluate the prevalence of behaviors associated with injury and their relationship with alcohol use in adult trauma patients. METHODS: A prospective cohort of 301 adult patients admitted to a single Level I trauma center were interviewed regarding risk behaviors and alcohol use. RESULTS: There was evidence of acute and/or chronic alcohol use in 48.2% of cases. Over three fourths of patients (77%) engaged in one or more high-risk driving practices, 40% engaged in one or more violence-related behaviors, and 19% reported suicidal ideation in the last year. These risk behaviors were more common in patients who evidenced acute and/or chronic alcohol use. CONCLUSION: Behaviors that place an individual at greater risk for traumatic injury are common among seriously injured adult patients admitted to an urban Level I trauma center and frequently coexist with alcohol use. Their importance to injury, injury recidivism, and recovery after trauma requires further investigation.

Adult↗
PubMed1984

Relationship between neurological and urological status in patients with multiple sclerosis.

The relationship between neurological urinary symptoms and urodynamic findings in patients with multiple sclerosis was examined. The duration of multiple sclerosis was significantly longer in patients with urinary symptoms. The presence of urinary symptoms correlated with the severity of the pyramidal or sensory lesions and the total disability score. Cystometrograms revealed detrusor hyperreflexia in 67 per cent of the patients, areflexia in 21 per cent and a normal detrusor in 12 per cent. Somatic dyssynergia was found in 20 of the 39 patients whose examination revealed clear-cut results. Positive correlation was found between urge incontinence and detrusor hyperreflexia, and between hesitancy and detrusor areflexia but no relationship was found between urological symptoms and sphincter function. Analysis of the neurological lesions in relation to the cystometric findings revealed a positive correlation among pyramidal lesions, detrusor hyperreflexia and detrusor areflexia, and between cerebellar lesions and detrusor areflexia. The correlation between detrusor dysfunction and high total disability score disappeared when patients with high pyramidal scores were excluded. No correlation could be detected between somatic dyssynergia and the various neurological lesions.

Adolescent↗
PubMed1981

Biliary lipid, bile acid composition, and dietary correlations in Micmac Indian women. A population study.

The precursor state for cholesterol gallstone formation is cholesterol-saturated bile. We studied a high-risk group for cholesterol gallstones to determine whether dietary variables affect bile cholesterol. Bile samples were analyzed from 46 Micmac Indian women without gallstones and 13 with gallstones for molar percentage cholesterol (MPC) and bile acid composition. The data were analyzed by multiple regression analysis with MPC as the dependent variable and the dietary variables, obtained from four consecutive-day food records, and biliary bile acid composition as the independent variables. In the 46 women without gallstones, obesity, calorie range/calorie intake, and iron and calcium intake were, in their order of importance, significant factors. In normal weight subjects (ponderal index > 12.5) relative obesity was still a significant correlate. Obesity and iron intake were positive correlates while calorie range/calorie intake and calcium intake varied inversely. When the effect of obesity was controlled, these factors were still significant in this group, as they were in the gallstone group. In addition, the duration of overnight fast obtained by history, together with the proportions of deoxycholic and chenodeoxycholic acids in bile were correlates of the biliary molar percentage cholesterol.

Adolescent↗