Biomedical subjects

Benjamin French

Publications and source records attributed to Benjamin French.

3 recordsLinked to original sources

PubMed2006

Risk of new-onset atrial fibrillation in relation to body mass index.

BACKGROUND: Obesity is associated with increased risk of atrial fibrillation (AF), but it is unknown whether the association differs by duration or persistence of AF. It is also unknown to what extent cardiovascular risk factors may mediate this association. METHODS: This population-based case-control study included 425 subjects with new-onset AF and 707 controls. The AF cases were identified through International Classification of Diseases, Ninth Revision codes for inpatient and outpatient visits and verified by medical record review. Medical records provided data on height, weight, and cardiovascular risk factors. RESULTS: On average, AF risk was 3% higher (95% confidence interval [CI], 1%-5%) per unit increment in body mass index (BMI) (calculated as weight in kilograms divided by height in meters squared). For sustained AF (duration > or =6 months), risk was higher by 7% (95% CI, 3%-11%) per unit BMI increment; for intermittent AF (duration > or =8 days or recurrent), 4% (95% CI, 1%-6%); and for transitory AF (duration <8 days), 1% (95% CI, -1% to +4%). Compared with those with normal BMI, the odds ratios for overweight and obese subjects were as follows: overweight, 0.97 (95% CI, 0.68-1.38); obese class 1, 1.18 (95% CI, 0.80-1.73); obese class 2, 1.34 (95% CI, 0.82-2.18); and obese class 3, 2.31 (95% CI, 1.36-3.91) (P = .002 for trend). When diabetes mellitus, a possible mediator, was added to the model, the odds ratio per unit increment of BMI decreased from 1.034 to 1.028. Adjustment for other cardiovascular risk factors including hyperlipidemia and blood pressure did not attenuate the BMI-AF association. CONCLUSIONS: The association with BMI was stronger for sustained AF than for transitory or intermittent AF. The obesity-AF association appears to be partially mediated by diabetes mellitus but minimally through other cardiovascular risk factors.

Adult↗

PubMed2006

Effect of switching medically vulnerable patients with uncontrolled diabetes from isophane insulin human to insulin glargine.

PURPOSE: The purpose of this observational study was to determine if switching from isophane insulin human (NPH) to insulin glargine would improve glycemic control in a medically vulnerable population with uncontrolled diabetes. METHODS: A retrospective cohort review of patients' medical records was performed that recorded events occurring between January 1, 2001, and December 31, 2003. The cohort consisted of patients with diabetes in an adult medicine clinic at a county hospital. Patients were included if they were receiving NPH insulin for a minimum of six months and subsequently switched to insulin glargine for a minimum of six months. RESULTS: The study included 43 patients. There was no significant difference in mean glycosylated hemoglobin (HbA(1c)) between NPH insulin (9.6%) and insulin glargine (9.7%) regimens (p = 0.78, 95% confidence interval, -0.62%, 0.82%). Neither was there a significant difference in the frequency or severity of hypoglycemic episodes between the two treatments. Patients experienced significantly fewer diabetes-associated visits over six months while on insulin glargine. Refill frequency did not differ significantly when patients were receiving NPH insulin versus insulin glargine. When analyzing patient characteristics, those of Hispanic ethnicity experienced HbA(1c) values significantly higher than white patients. Several characteristics were associated with refill frequency. CONCLUSION: The results of our study indicate that both NPH- and glargine-based basal insulin regimens result in similar levels of glycemic control in a medically vulnerable population with diabetes, without significant differences in the number or severity of hypoglycemic episodes or in refill frequency.

Adult↗

PubMed2006

Simple estimates of haplotype relative risks in case-control data.

Methods of varying complexity have been proposed to efficiently estimate haplotype relative risks in case-control data. Our goal was to compare methods that estimate associations between disease conditions and common haplotypes in large case-control studies such that haplotype imputation is done once as a simple data-processing step. We performed a simulation study based on haplotype frequencies for two renin-angiotensin system genes. The iterative and noniterative methods we compared involved fitting a weighted logistic regression, but differed in how the probability weights were specified. We also quantified the amount of ambiguity in the simulated genes. For one gene, there was essentially no uncertainty in the imputed diplotypes and every method performed well. For the other, approximately 60% of individuals had an unambiguous diplotype, and approximately 90% had a highest posterior probability greater than 0.75. For this gene, all methods performed well under no genetic effects, moderate effects, and strong effects tagged by a single nucleotide polymorphism (SNP). Noniterative methods produced biased estimates under strong effects not tagged by an SNP. For the most likely diplotype, median bias of the log-relative risks ranged between -0.49 and 0.22 over all haplotypes. For all possible diplotypes, median bias ranged between -0.73 and 0.08. Results were similar under interaction with a binary covariate. Noniterative weighted logistic regression provides valid tests for genetic associations and reliable estimates of modest effects of common haplotypes, and can be implemented in standard software. The potential for phase ambiguity does not necessarily imply uncertainty in imputed diplotypes, especially in large studies of common haplotypes.

Algorithms↗