Biomedical subjects

Allen A Mitchell

Publications and source records attributed to Allen A Mitchell.

41 records · Page 3Linked to original sources

PubMed2002

Causal knowledge as a prerequisite for confounding evaluation: an application to birth defects epidemiology.

Common strategies to decide whether a variable is a confounder that should be adjusted for in the analysis rely mostly on statistical criteria. The authors present findings from the Slone Epidemiology Unit Birth Defects Study, 1992-1997, a case-control study on folic acid supplementation and risk of neural tube defects. When statistical strategies for confounding evaluation are used, the adjusted odds ratio is 0.80 (95% confidence interval: 0.62, 1.21). However, the consideration of a priori causal knowledge suggests that the crude odds ratio of 0.65 (95% confidence interval: 0.46, 0.94) should be used because the adjusted odds ratio is invalid. Causal diagrams are used to encode qualitative a priori subject matter knowledge.

Bias↗

PubMed2002

Maternal medication use and risks of gastroschisis and small intestinal atresia.

Gastroschisis and small intestinal atresia (SIA) are birth defects that are thought to arise from vascular disruption of fetal mesenteric vessels. Previous studies of gastroschisis have suggested that risk is increased for maternal use of vasoactive over-the-counter medications, including specific analgesics and decongestants. This retrospective study evaluated the relation between maternal use of cough/cold/analgesic medications and risks of gastroschisis and SIA. From 1995 to 1999, the mothers of 206 gastroschisis cases, 126 SIA cases, and 798 controls in the United States and Canada were interviewed about medication use and illnesses. Risks of gastroschisis were elevated for use of aspirin (odds ratio = 2.7, 95% confidence interval: 1.2, 5.9), pseudoephedrine (odds ratio = 1.8, 95% confidence interval: 1.0, 3.2), acetaminophen (odds ratio = 1.5, 95% confidence interval: 1.1, 2.2), and pseudoephedrine combined with acetaminophen (odds ratio = 4.2, 95% confidence interval: 1.9, 9.2). Risks of SIA were increased for any use of pseudoephedrine (odds ratio = 2.0, 95% confidence interval: 1.0, 4.0) and for use of pseudoephedrine in combination with acetaminophen (odds ratio = 3.0, 95% confidence interval: 1.1, 8.0). Reported fever, upper respiratory infection, and allergy were not associated with risks of either defect. These findings add more evidence that aspirin use in early pregnancy increases risk of gastroschisis. Although pseudoephedrine has previously been shown to increase gastroschisis risk, findings of this study raise questions about interactions between medications and possible confounding by underlying illness.

Acetaminophen↗

PubMed2002

Erythromycin use during pregnancy in relation to pyloric stenosis.

OBJECTIVE: Newborn infants treated with erythromycin may be at risk for developing pyloric stenosis. Because erythromycin is known to cross the placenta and is a recommended treatment for chlamydia and other infections in pregnancy, we explored whether erythromycin taken during pregnancy might similarly lead to an increase in risk of pyloric stenosis. STUDY DESIGN: We used data collected between 1976 and 1998 as part of an ongoing case-control surveillance program. Cases were 1044 infants with a diagnosis of pyloric stenosis. Two control groups were used: 1704 nonmalformed infants and 15,356 infants with a wide range of other malformations. Odds ratios and 95% CIs were calculated by using data from each control group. RESULTS: All odds ratio estimates are close to 1.0, all CIs include 1, and all upper 95% confidence bounds are less than 2.0. CONCLUSION: We found no evidence of an increased risk of pyloric stenosis among infants born to mothers exposed to erythromycin during pregnancy.

Adult↗

PubMed2002

Asthma morbidity after the short-term use of ibuprofen in children.

OBJECTIVE: To test the hypothesis that short-term use of ibuprofen increases asthma morbidity in children. METHODS: A randomized, double-blind, acetaminophen-controlled clinical trial was conducted. Children who had asthma and a febrile illness were randomly assigned to receive either acetaminophen suspension or ibuprofen suspension for fever control. Rates of hospitalization and outpatient visits for asthma during follow-up were compared by randomization group. RESULTS: A total of 1879 children receiving asthma medications were studied. Rates of hospitalization for asthma did not vary significantly by antipyretic assignment; compared with children who were randomized to acetaminophen, the relative risk for children who were assigned to ibuprofen was 0.63 (95% confidence interval: 0.25-1.6). However, the risk of an outpatient visit for asthma was significantly lower in the ibuprofen group; compared with children who were randomized to acetaminophen, the relative risk for children who were assigned to ibuprofen was 0.56 (95% confidence interval: 0.34-0.95). CONCLUSIONS: Rather than supporting the hypothesis that ibuprofen increases asthma morbidity among children who are not known to be sensitive to aspirin or other nonsteroidal antiinflammatory drugs, these data suggest that compared with acetaminophen, ibuprofen may reduce such risks. Whether the observed difference in morbidity according to treatment group is attributable to increased risk after acetaminophen use or a decrease after ibuprofen cannot be determined. These data provide evidence of the relative safety of ibuprofen use in children with asthma.

Acetaminophen↗

PubMedDate not supplied

Use of herbal/natural supplements according to racial/ethnic group.

OBJECTIVES: The aim of this paper was to determine similarities and differences in the use of herbal/natural supplements among various racial/ethnic groups. DESIGN: A random-digit dial (RDD) telephone survey of medication use during the week before the interview was used. SETTINGS/LOCATION: Households in the 48 contiguous United States comprised our study. SUBJECTS: One (1) subject was selected by a random procedure from each contacted household, including interviews conducted from 1998 through September 2004. There were 13,436 subjects at least 18 years of age, including 10,372 non-Hispanic whites, 1174 African Americans, 1109 Hispanics, 335 Asian/Pacific Islanders, and 446 others. OUTCOME MEASURES: Use of any herbal/natural product during the prior week served as outcome measures. Prevalence of use was weighted according to household size; for comparisons among the three largest groups, estimates were also adjusted for age, gender, and education. RESULTS: The overall prevalence was lowest in African Americans (9.5%; 95% confidence interval [CI], 7.8%-11%), intermediate in Hispanics (12%; 10%-14%), and highest in non-Hispanic whites (19%; 18%-20%). Use was higher among women and generally higher for subjects 45-64 years of age, regardless of race/ethnicity; use increased with increasing years of education. The most commonly taken individual herbal/natural substances were similar among the groups. Hispanics used the largest number of products. Distribution of product type differed somewhat, with Hispanics taking more monopreparations and herbal mixtures than the other groups, and herbal mixture use particularly uncommon among African Americans. Use between 1998 and 2004 increased slightly for non-Hispanic whites, increased then declined for African Americans, and did not change for Hispanics. CONCLUSIONS: Based on nationally representative U.S. data, these results provide a comparative picture of contemporary use of herbal/natural supplements in the largest racial/ethnic groups in the United States. The prevalence of use was lowest among African Americans, with a possible decline in recent years, whereas Hispanics take the greatest number of products.

Adult↗