Search PubMed⌕ Search

Biomedical subjects

R Neutra

Publications and source records attributed to R Neutra.

32 records · Page 2Linked to original sources
PubMed1977

A pitfall in sampling medical visits.

Samples of outpatient visits often must be used to identify users of a health facility with a given chronic condition. Such samples can lead to biases, however, because patients with more frequent visits are overrepresented. These biases can be avoided by a weighting procedure in which each sampled visit is weighted inversely to the number of clinic visits made by that patient during the sample period. This procedure proved critical in estimating the number and characteristics of hypertensive patients seen in the medical clinic of a teaching hospital. The unweighted estimate of the number of hypertensives was 7,373 patients, more than three times the weighted estimate of 2,250. Similarly,, the number of visits per year by these patients would be overestimated by almost 50 per cent without weighting. The estimated proportion of hypertensives still under treatment after 18 months was 68 per cent without weighting, compared to 51 per cent with weighting. Thus biases from failure to weight may be substantial. Analogous biases and solutions apply to other sampling problems in health services research.

Humans↗
PubMed1975

Fetal death in eclampsia: I. Its relation to low gestational age, retarded fetal growth and low birthweight.

Of 173 eclamptics admitted to the only public maternity hospital in Cali, Colombia 44 had stillbirths making a rate of 25-4 per cent. Fetuses delivered before 32 weeks had nearly four times the stillbirth rate of those delivered at term. Those weighing less than 1600 g. had stillbirth rates about six times higher than those weighing above 2500 g. An attempt was made to divide the risk conveyed by low birthweight into two components; that which was due to low gestational age, and that which was due to an abnormally low rate of growth during the gestational time available. Deviation of birthweight below that expected for age (retarded fetal growth, RFG) was used as a measure of the latter component. RFG became more common as gestation progressed and was associated with fetal death only in the latter part of gestation and with marginal statistical significance. After 35 weeks, fetuses at or below two standard deviations from Gruenwald's mean weight for gestational age (Gruenwald, 1966) had a fetal death rate five times higher than those at the mean. The risk of fetal (intrauterine) death conveyed by low gestational age has not been definitively explained. Alternative pathophysiological mechanisms are discussed.

Birth Weight↗
PubMed1975

Fetal death in eclampsia: II. The effect of non-therapeutic factors.

The ability of 15 variables to predict fetal death is examined among 173 eclamptic women admitted to the only public maternity hospital in Cali, Colombia, between 1st Janurary 1964 and 31st December 1970. In addition to low gestational age and retarded fetal growth, high systolic pressure and the unmarried status carried excess risk. Primiparae appeared to be of lower risk because their eclampsia tended to occur late in gestation and was characterized by less retarded fetal growth. Older women and women with a history of abortion appeared to be of higher risk because they tended to have higher systolic pressures. A discriminant function risk formula is presented which generated groups with a nine-fold difference in fetal death rates. This formula could be used to standardize for relevant non-therapeutic factors which meant vary between patient groups who had received different therapeutic regimens.

Abortion, Spontaneous↗
PubMedDate not supplied

Hydrogeologic assessment of exposure to solvent-contaminated drinking water: pregnancy outcomes in relation to exposure.

We recently concluded that exposure to solvent-contaminated drinking water was an unlikely explanation for observed excesses of adverse pregnancy outcomes during 1980-1981 in the Los Paseos neighborhood of Santa Clara County, California, because these excesses were not observed in an adjacent exposed area. The validity of this conclusion depends on the assumption that the two areas had comparable exposure. Using quantitative methods to model movement of the solvent leak plume and water flow within the distribution system, we estimated that women with adverse outcomes were no more likely to have received contaminated water than women with normal live births. These results strengthen the conclusion that exposures to water from the contaminated well were not responsible for the excess of adverse outcomes observed in the Los Paseos area.

Abnormalities, Drug-Induced↗
PubMedDate not supplied

Pesticide exposures to children from California's Central Valley: results of a pilot study.

In response to concerns about pesticide use and evidence that contaminants may accumulate in house dust, the California Department of Health Services (DHS) conducted a pilot study of pesticide contamination in rural children's home environments. House dust samples for pesticide analysis were collected from eleven homes, five of which had at least one farmworker (FW) resident. Handwipe samples were collected from one child at each residence (ages 1-3 years). Ten of 33 pesticides tested in house dust were detected. Excluding non-detects, concentrations for diazinon ranged from 0.7-169 ppm in four FW homes and 0.2-2.5 ppm in three non-farmworker (NFW) homes (overall median = 1 ppm), suggesting a difference between FW and NFW homes. Chlorpyrifos ranged from 0.2-33 ppm in three FW homes and < 1 ppm in two NFW homes (overall median < 0.5 ppm). All other pesticides were detected at < 2 ppm at four or fewer homes. The sources of these compounds could not be determined. Co-located samples were considerably different in concentration and loading, indicating intra-household variation. Of nine compounds tested, diazinon and chlorpyrifos were found on the hands of two or three FW children (20-220 ng/hand). Dust ingestion scenarios show child exposures could exceed the United States Environmental Protection Agency Office of Pesticide Program diazinon chronic reference dose (9 x 10(5) mg/kg/day). The results suggested that pesticide residues are present in the home environment of some California children and are likely to contribute to exposures. Additional research is feasible and needed to assess the magnitude and distribution of these risks.

Administration, Oral↗