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Biomedical subjects

G G Rhoads

Publications and source records attributed to G G Rhoads.

At least 37 records · Page 2Linked to original sources
PubMed1998

Accuracy and reproducibility of blood lead testing in commercial laboratories.

OBJECTIVE: To assess the proficiency of commercial laboratories in analyzing lead in clinical blood samples from subjects without overt lead exposure. DESIGN: We submitted masked duplicate blood lead specimens to 8 masked laboratories. Each laboratory received blood aliquots immediately following drawing (time 1) and 2 weeks later (time 2) from 7 human subjects and 3 bovine blood samples with known lead levels of 0.26, 0.57, and 0.79 micromol/L (5.4, 11.8, and 16.4 microg/dL). Of the 8 laboratories, 5 were commercial laboratories, 1 was a state laboratory, 1 was a research laboratory, and 1 was the Centers for Disease Control and Prevention reference laboratory. OUTCOME MEASURES: Correlation coefficients were calculated, and differences within and between laboratories were assessed by analysis of variance. RESULTS: Results were obtained for all specimens, with all the human subjects' overall mean lead levels being less than 0.48 micromol/L (<10 microg/dL). Each laboratory reported all human blood specimens appropriately, as having lead levels less than 0.48 micromol/L (<10 microg/dL) and within 0.14 micromol/L (3 microg/dL) of the overall mean for that subject. All internal reproducibilities were very high (range, 0.92-1.00) except for one (0.60), possibly lower because of 1 pair of specimens. Mean differences between blood samples analyzed at time 1 and time 2 ranged from -1.4 to 1.2, with only 2 laboratories having significant differences (P<.01). CONCLUSIONS: Overall, there was strong reproducibility within and among laboratories, with no overall time trend or interlaboratory or intralaboratory variance. The storage conditions did not seem to affect the aggregate results. The data suggest that through implementation of the Centers for Disease Control and Prevention/Wisconsin Blood Lead Proficiency Testing Program, the Centers for Disease Control and Prevention's Blood Lead Laboratory Reference System, and mandated federal and state proficiency programs, laboratories in this geographic region have improved their performance as compared with previous published studies and an unpublished study.

Humans↗
PubMed1998

Childhood lead screening knowledge and practice. Results of a New Jersey physician survey.

CONTEXT: As the nation moves toward targeted childhood lead screening, CDC continues to recommend universal screening in states with no childhood lead poisoning prevalence data. OBJECTIVE: The study was conducted, prior to the new universal screening state law, to determine physician screening practices and their consistency with key CDC recommendations as a basis for future education activities. DESIGN/SETTING/PARTICIPANTS: A statewide cross-sectional self-administered multiple choice survey of 541 randomly selected New Jersey pediatricians and family practitioners. OUTCOME MEASURES: Risk assessment, screening and case management practices and their consistency with CDC recommendations. RESULTS: We obtained 333 usable responses (69.4%). Most respondents reported confirming blood lead level, initiating case management, and identifying medical emergencies at blood lead levels lower than recommended by CDC. More than half reported not assessing the risk of the majority of their patients. At least one third were not screening infants, children between 1 and 2 years, or children between 2 and 6 years of age. Physicians who assessed risk tended to screen high-risk children in all age groups. Only 42% of pediatricians and 24% of family practitioners said they screened the majority of the children in their practice by age 2 years. About 60% of all respondents reported not providing lead exposure education to half their patients. CONCLUSIONS: Passing a universal screening law, as New Jersey has done, is one way to obtain baseline childhood lead poisoning prevalence data. Private practice-targeted physician education led by preventive medicine specialists may also be helpful.

Child↗
PubMed1998

Empirical comparison of the results of randomized controlled trials and case-control studies in evaluating the effectiveness of screening mammography.

The gold standard for evaluating screening programs is the randomized controlled trial (RCT). Case-control studies are easier to perform but their role in this area is controversial. The purpose of this article is to compare empirically the results of RCTs and case-control studies conducted to evaluate the efficacy and effectiveness of screening mammography and examine possible explanations for differences in their results. We located eight RCTs and five case-control studies of screening mammography. For women aged 40-74 years at screening, comparison of the summary risk estimates of the RCTs (0.76, 95% CI: 0.69-0.83) with that of the case-control studies (0.44, 95%, CI: 0.38-0.50) showed RCTs to have a significantly higher summary risk estimate than case-control studies (ratio = 1.74, 95% CI: 1.48-2.04). It is notable that the RCTs were compromised in most instances by low compliance rates (50-80%) in the treatment groups and by significant use of screening in the control groups (20-30%). Adjustment of the RCT results for these cross-overs yields results that are in reasonable agreement with the summary estimate for the case-control studies. These findings support the use of case-control studies to estimate the efficacy of mammographic screening where RCTs are not feasible. They suggest that the efficacy of mammography in women aged 50 years and above is somewhat greater than the effectiveness measured by the intent-to-treat analysis of RCTs.

Adult↗
PubMed1998

Capsular polysaccharide types of group B streptococcal isolates from neonates with early-onset systemic infection.

The distribution of serotypes of group B streptococci (GBS) isolated from 67 infants with early-onset sepsis are described. Case-infants were assembled from 13 hospitals across the United States from 15 July 1995 to 5 February 1997 through prospective active surveillance. The distribution of GBS serotypes was Ia, 40%; Ib, 9%; II, 6%; III, 27%; V, 15%; and nontypeable, 3%. Type V occurred more frequently in the northeast region (New York and New Jersey) than in other regions (29% vs. 9%, P = .06). Conversely, type III occurred significantly less frequently in the northeast region than other regions (10% vs. 35%, P = .04). GBS types Ia, III, and V accounted for 82% of the isolates. This report supports previous observations about the emergence of GBS type V, but our data caution that conclusions about serotype distributions based on one geographic location or on a small number of patients may not be generally applicable. Continued monitoring seems necessary for the design of a GBS vaccine.

Bacterial Capsules↗
PubMed1998

Infant and maternal outcomes in the pregnancies of asthmatic women.

We examined the relationship between infant and maternal outcomes and asthma complicating pregnancy, using historical cohort analysis of singleton live deliveries in New Jersey hospitals between 1989 and 1992 (n = 447,963). Subject mother-infant dyads were identified from linked birth certificate and maternal and newborn hospital claims data. Women with an International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis code (493) for asthma (n = 2,289) were compared with a fourfold larger randomly selected control sample (n = 9,156) from the remaining pool of women. After controlling for the effects of important confounding variables, maternal asthma was associated with the following adverse infant outcomes: preterm infant (odds ratio [OR] = 1.36; 95% confidence interval [CI], 1.18 to 1.55), low birth weight (OR = 1. 32; 95% CI, 1.10 to 1.58), small-for-gestational age (OR = 1.26; 95% CI, 1.10 to 1.45), congenital anomalies (OR = 1.37; 95% CI, 1.12 to 1.68), and increased infant hospital length of stay (OR = 1.44; 95% CI, 1.25 to 1.65). The adverse maternal outcomes associated with maternal asthma were: pre-eclampsia (OR = 2.18; 95% CI, 1.68 to 2. 83), placenta previa (OR = 1.71; 95% CI, 1.05 to 2.79), cesarean delivery (OR = 1.62; 95% CI, 1.46 to 1.80), and increased maternal hospital length of stay (OR = 1.86; 95% CI, 1.60 to 2.15). The results emphasize the need for maternal asthma to be added to the list of conditions that increase the risk of adverse pregnancy outcomes.

Asthma↗
PubMed1998

Maternal asthma and transient tachypnea of the newborn.

OBJECTIVE: To examine the relationship between transient tachypnea of the newborn and asthma complicating pregnancy. DESIGN: Historical cohort analysis. Setting. Singleton live deliveries in New Jersey hospitals during 1989 to 1992 (n = 447 963). PATIENTS: Mother-infant dyads were identified from linked birth certificate and maternal and infant hospital claims data. Women with an International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis code (493) for asthma (n = 2289) were compared with a four-fold larger randomly selected control sample (n = 9156) from the remaining pool of women. MAIN OUTCOME MEASURE: Transient tachypnea of the newborn. RESULTS: In the overall sample, after controlling for the confounding effects of important variables, infants of asthmatic mothers were more likely [odds ratio (OR), 1. 79; 95% confidence interval (CI), 1.35-2.37] than infants of control mothers to exhibit transient tachypnea of the newborn. A stratified analysis by gestational age and sex revealed larger and statistically significant associations in term infants (OR, 2.02; 95% CI, 1.42-2.87) as opposed to preterm infants (OR, 1.51; 95% CI, 0.94-2.43) and in male infants (OR, 1.91; 95% CI, 1.35-2.71) as opposed to female infants (OR, 1.51; 95% CI, 0.92-2.47). On the other hand, after adjusting for important confounding variables, respiratory distress syndrome and maternal asthma were not found to be associated (OR, 1.14; 95% CI, 0.79-1.64). CONCLUSION: The results of this study provide evidence that maternal asthma is a risk factor for transient tachypnea of the newborn and differences in gestational age and sex were apparent in this association. The mechanism for this association remains to be determined.

Adolescent↗
PubMed1997

Vitamin A and birth defects.

OBJECTIVE: Our objective was to determine whether moderate doses of vitamin A are teratogenic. STUDY DESIGN: This was a geographically based case-control study. Women whose pregnancies produced offspring with neural tube defects (n = 548) or major malformations other than neural tube defects (n = 387) and normal control subjects (n = 573) were interviewed to determine periconceptional vitamin A supplement exposure levels. RESULTS: The proportion of women consuming doses of vitamin A between 8000 and 25,000 IU was no greater in the major malformations group or the group with neural tube defects than in the normal control group. For exposure from supplements and fortified cereals combined, women consuming >8000 and >10,000 IU daily had odds ratios for major malformations of 0.79 (95% confidence interval 0.40 to 1.53) and 0.73 (95% confidence interval 0.27 to 1.96), respectively, compared with women consuming <5000 IU. The results for neural tube defects were similar. For cranial neural crest defects the odds ratios were 0.76 (0.22 to 2.56) and 1.09 (0.24 to 4.98) for exposure to >8000 and >10,000 IU, respectively, versus exposure to <5000 IU. CONCLUSIONS: This study found no association between periconceptional vitamin A exposure at doses >8000 IU or >10,000 IU per day and malformations in general, cranial neural crest defects, or neural tube defects. If vitamin A is a teratogen, the minimum teratogenic dose appears to be well above the level consumed by most women during organogenesis.

Adult↗
PubMed1997

The importance of histologic type on breast cancer survival.

Breast cancer is a morphologically and genetically heterogeneous disease. The Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute provides the large number of cases necessary to study individual histologic types of female invasive breast cancer that for practical reasons are otherwise unattainable. Attention was specifically focused on 4082 cases of mucinous adenocarcinoma and 139,154 cases of infiltrating duct carcinoma identified for the years 1973-1990. Life table analyses were conducted to compare survival by histologic type using death due to breast cancer as the outcome; Cox proportional hazards analysis was used to adjust for important covariates. Findings were that women diagnosed with mucinous adenocarcinoma have a rate of mortality due to breast cancer that is 0.38 that of the rate of women diagnosed with infiltrating duct carcinoma (95% confidence interval 0.34-0.42). We conclude that histologic type is important to consider in the prognosis and treatment of women diagnosed with breast cancer.

Adenofibroma↗
PubMed1997

Trichomonas vaginalis associated with low birth weight and preterm delivery. The Vaginal Infections and Prematurity Study Group.

BACKGROUND: Several studies have suggested that pregnant women infected with Trichomonas vaginalis may be at increased risk of an adverse outcome. GOAL: To evaluate prospectively the association between T. vaginalis and risk of adverse pregnancy outcome in a large cohort of ethnically diverse women. STUDY DESIGN: At University-affiliated hospitals and antepartum clinics in five United States cities, 13,816 women (5,241 black, 4,226 Hispanic, and 4,349 white women) were enrolled at mid-gestation, tested for T. vaginalis by culture, and followed up until delivery. RESULTS: The prevalence of T. vaginalis infection at enrollment was 12.6%. Race-specific prevalence rates were 22.8% for black, 6.6% for Hispanic, and 6.1% for white women. After multivariate analysis, vaginal infection with T. vaginalis at mid-gestation was significantly associated with low birth weight (odds ratio 1.3; 95% confidence interval 1.1 to 1.5), preterm delivery (odds ratio 1.3; 95% confidence interval 1.1 to 1.4), and preterm delivery of a low birth weight infant (odds ratio 1.4; 95% confidence interval 1.1 to 1.6). The attributable risk of T. vaginalis infection associated with low birth weight weight in blacks was 11% compared with 1.6% in Hispanics and 1.5% in whites. CONCLUSIONS: After considering other recognized risk factors including co-infections, pregnant women infected with T. vaginalis at mid-gestation were statistically significantly more likely to have a low birth weight infant, to deliver preterm, and to have a preterm low birth weight infant. Compared with whites and Hispanics, T. vaginalis infection accounts for a disproportionately larger share of the low birth weight rate in blacks.

Adult↗
PubMed1996

The contribution of the case-control approach to vaccine evaluation: Pneumococcal and Haemophilus influenzae type B PRP vaccines.

Case-control studies have had an increasing role in the postlicensure evaluation of vaccine efficacy. We review the contribution of case-control studies to the evaluation of vaccines for Streptococcus pneumoniae (pneumococcus) and Haemophilus influenzae type b (Hib) and compare these studies with clinical trials of these vaccines. We located one clinical trial and eight case-control studies of Hib PRP vaccine efficacy and three clinical trials and four case-control studies of pneumococcal vaccine efficacy. The pooled estimate of Hib PRP vaccine efficacy based on the case-control studies (0.38, 95% CL = 0.15-0.55) was lower than the efficacy of the clinical trial conducted in Finland (0.8, 95% CL = 0.57-0.98). The pooled estimate of pneumococcal vaccine efficacy based on the case-control studies (0.56, 95% CL = 0.44-0.66) was also lower than the pooled efficacy of the South African clinical trials (0.79, 95% CL = 0.69-0.86). Although the clinical trials provided crucial evidence that these vaccines worked in selected international settings, the direct evidence of efficacy in the United States rests largely on the case-control results. The utility of the case-control approach is supported.

Adolescent↗
PubMed1996

Sonographic assessment of endometrial pattern and thickness in patients treated with human menopausal gonadotropins.

OBJECTIVE: To analyze sonographically the endometrium in patients undergoing controlled ovarian stimulation with menotropins in order to determine the significance of endometrial pattern and thickness on pregnancy rate. DESIGN: This is a prospective, nonrandomized study comparing pregnancy rates in patients with hyperechoic homogeneous patterns with those in patients with isoechoic or hypoechoic trilaminar patterns. SETTING: Tertiary infertility center. PATIENTS: All patients receiving menotropin therapy at a tertiary infertility center. INTERVENTIONS: All patients received individualized dosing of hMG starting on cycle day 3. Transvaginal sonography was performed 15 hours before hCG administration and the endometrium was assessed. MAIN OUTCOME MEASURE: Occurrence of pregnancy as determined by serially rising beta-hCG titers and sonographic confirmation. RESULTS: During the study period, 175 patients were evaluated. Thirty-four (19%) patients had a homogeneous endometrium, whereas 141 (81%) patients had a trilaminar pattern. There was 1 pregnancy (2.9%) among women with a homogeneous endometrial pattern and 33 pregnancies (23%) among those with a trilaminar pattern. No significant differences were found in mean E2 level, follicle numbers, parity, and diagnosis between the two groups. CONCLUSION: In patients receiving menotropins, a homogeneous pattern is a bad prognostic sign, regardless of endometrial thickness.

Adult↗