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Biomedical subjects

R J David

Publications and source records attributed to R J David.

31 records · Page 2Linked to original sources
PubMed1985

Pediatric health rationing. Recent trends and lessons from history.

Recent health care rationing proposals are related to shifting economic and political priorities. Pediatric implications of these proposals include restrictive policies toward premature and congenitally malformed newborns. Historical experience of similar developments suggests that early warning signals of such measures should be heeded to avoid major public health consequences. In the best interests of society-at-large, health care rationing should be rejected.

Abnormalities, Multiple↗
PubMed1985

An outcome-coded birth file from machine readable vital records.

We developed a computer program which generates an outcome-coded birth file from a standard birth file and a matched birth-infant death file. This program uses only anonymous computerized vital records of the kind available to researchers in most states. Despite a large population (Illinois 1977 births totaled 178,728) all death records were uniquely matched with birth records, allowing creation of the desired file. Such a file permits the researcher to use a variety of standard software packages without the problems of data re-entry or the use of multiple input files. Creating this outcome-coded file is relatively inexpensive, can be done without enlisting special assistance from state vital records personnel, does not require access to restricted files, and greatly streamlines use of perinatal vital records for research applications, especially multivariable modeling.

Birth Certificates↗
PubMed1985

Home pneumograms in normal infants.

To obtain age-specific normative data, we performed home cardiorespiratory recordings (pneumograms) in 56 normal infants at 1 month of age. A repeat pneumogram was performed at 3 months in 39 infants. Total sleep time was determined and all sleep intervals were summed and analyzed for five respiratory pattern variables: frequency of all apneic episodes greater than or equal to 6 seconds in duration (A6/D%), periodic breathing, longest apneic episode, and number of episodes greater than 11 and greater than 15 seconds. The normal infants at 1 and at 3 months were compared with 66 patients with apnea of infancy. Median A6/D% was 0.1 in the normal infants at 1 and 3 months, compared with 0.64 in those with apnea of infancy (P less than 0.001). Median periodic breathing was 0.4 and 0.2 episodes per 100 minutes in the normal infants at 1 and 3 months, respectively, compared with 1.25 in infants with apnea of infancy (P less than 0.001). Median longest apneic episode was 8.0 seconds in the normal infants at 1 and 3 months, compared with 11 seconds in those with apnea of infancy (P less than 0.001). No normal infant had an apneic episode greater than 15 seconds in duration, whereas the group with apnea of infancy had 0.4 +/- 1.0 episodes of apnea of greater than 15 seconds (P less than 0.01). Despite these significant group differences, use of these respiratory patterns either alone or in combination permitted only about 80% correct classification of normal infants and those with apnea of infancy.

Age Factors↗
PubMed1983

Population-based intrauterine growth curves from computerized birth certificates.

Screening of newborns with growth curves derived from populations dissimilar to their own can lead to sizable errors. I present a technique for constructing percentile curves for birth weight at different gestational ages, using North Carolina's computerized birth certificate file. This method eliminates from the analysis most erroneous data on gestational age. The resulting intrauterine growth curves show weights at term for North Carolina newborns. These curves differ from previously reported norms in that weights are higher than those reported for two low-income hospital subpopulations, and lower than birth weights in populations with better living standards and prenatal care. Plotting North Carolina births on the Colorado intrauterine growth curve resulted in considerable overdiagnosis of "large for gestational age," while most infants who were small for gestational age failed to be identified.

Birth Certificates↗
PubMed1983

Decline in neonatal mortality, 1968 to 1977: better babies or better care?

A state's declining neonatal mortality rate was studied over the decade 1968 to 1977 to determine how much of the decrease resulted from improved risk characteristics in the newborn population. A shift was found over time, mostly among white births, toward higher birth weights and longer gestations. Overall, there was a 19% reduction in the low-birth-weight rate. Considerable improvement in birth weight-specific mortality was also found, especially in babies weighing 1,000 to 2,500 g during the last 5 years of the study. A neonatal risk matrix model was applied to the changes over time to separate the improvement due to shifts in population risk characteristics from that due to better care of the newborn. Thirty-four percent of the decade's decrease in NMR was attributable to changes in the birth weight and gestational age makeup of the newborn population. This "better babies" component was more prominent early in the decade and among the white population.

Birth Weight↗
PubMed1981

Elevated IgA concentration in milk produced by mothers delivered of preterm infants.

Concentrations of immunoglobulins G, M, and A were measured by double-antibody radioimmunoassay in morning milk samples collected during the first month postpartum from 35 mothers delivered of preterm infants and 14 mothers delivered of term infants. Mean concentrations of IgG (1.8, to 2.8 mg/gm protein) and IgM (2.8 to 11.7 mg/gm protein) were similar in milk from both groups of mothers. In contrast, IgA was present in significantly higher concentrations throughout the first month postpartum in milk from mothers delivered of preterm infants than in milk from those giving birth at term (P less than 0.01). To determine the effect of milk flow on IgA concentration, IgA was also measured in complete 24-hour milk collections; milk from mothers with preterm deliveries again contained significantly higher concentrations of IgA than milk from mothers with term deliveries (P less than 0.01). This higher IgA concentration was not secondary to method of milk expression. The concentration of IgA was found, however, to vary inversely with milk volume (P less than 0.01). Although mean values of milk volumes for the groups were not statistically different, the overall lower volumes of milk produced by mothers giving birth preterm resulted in comparable total IgA production per 24 hours. There were no differences in serum IgA concentrations of preterm infants fed their own mother's milk and comparable infants fed a cow milk formula, suggesting that IgA in milk is not absorbed from the intestine in significant amounts.

Animals↗
PubMed1981

Prevention of umbilical artery catheter clots with heparinized infusates.

49 neonates requiring umbilical artery catheters (UACs) were randomly assigned to receive standard or heparin-containing infusates. 3 of 23 (13%) of the patients receiving heparin had catheters removed because they became functionally occluded compared to 15 of 26 (58%) in the control group (p less than 0.005). 4 of 13 (31%) single injection aortograms obtained in control infants demonstrated thrombi, compared to none of 7 in the heparin group. 1 patient in the heparin group had an aortic clot demonstrated at post-mortum examination. There were neither clinical coagulopathies nor abnormalities of partial thromboplastin time attributable to the administration of heparinized fluids. Heparinization of UAC infusates appears to be a safe method of reducing the risk of catheter occlusion. Heparin effect on large vessel clot risk remains unproven.

Blood Coagulation Disorders↗
PubMed1980

Nutritional composition of milk produced by mothers delivering preterm.

The nutritional composition of milk obtained during the first month postpartum from 33 mothers delivering preterm and 18 mothers delivering at term was determined. Milk produced by mothers delivering preterm contained significantly higher concentrations of protein, sodium, and chloride, and significantly lower concentrations of lactose than milk produced by mothers delivering at term. The caloric concentration of milk produced by the two groups of mothers was similar, as were the concentrations of potassium, calcium, phosphorus, and magnesium. PT milk appears to approximate more closely the nutritional needs of the preterm infant than does other breast milk.

Calcium↗
PubMed1980

The quality and completeness of birthweight and gestational age data in computerized birth files.

Computerized birth files compiled by the State of North Carolina for the years 1975-1977 were analyzed for omissions and inaccuracies. A wide range in the per cent missing values was found for different data items, from essentially none missing (birthweight, sex, race) to about 20 per cent missing (gestational age, paternal social data). Recorded birthweight showed the expected skewing from a normal distribution. The only demonstrable inaccuracy was in the form of digit preference, probably causing errors of +/- 1 oz (28.3 g). Reported gestational ages were more suspect, falling outside the range of biologically plausible gestation length in 2.8 per cent of cases. An additional 1.5 per cent of gestational ages were found to be misdated by four to 20 weeks based on the observed bimodal weight distributions among births of the same reported gestational age. Hospitals of various sizes and administrative affiliations submitted records with missing or inaccurate gestational age data with roughly equal frequency. These records were found to come from a socio-demographically high-risk subpopulation. The implications of elimination of incomplete or erroneous birth record data in perinatal epidemiologic research are discussed.

Adult↗
PubMedDate not supplied

Comparative accuracy of clinical estimate versus menstrual gestational age in computerized birth certificates.

OBJECTIVE: This study compares gestational age data obtained by clinical estimate with data calculated from the date of the last menstrual period (LMP) as recorded on birth certificates. METHODS: The authors analyzed 476,034 computerized birth records from three overlap years, that is, those that contained both menstrual and clinical estimates of gestational age, concentrating on cases within the biologically plausible range of 20-44 weeks. RESULTS: The overall exact concordance between the two measurements was 46%. For +1 week it was 78%, and for +2 weeks it was 87%. Incidence of prematurity was 16% with menstrual gestational age, while it was 12% with clinical estimate. About 47% of the LMP-based preterm births were classified as term by clinical estimate. Eighty-three percent of clinical estimate-based preterms were also preterms by LMP-based gestation. Birthweight frequency distribution curves for LMP-based gestational age are bimodal, indicating probable miscoding of term births. An apparent over-representation of births coded as exactly 40 weeks by clinical estimate suggests rounding off near term for this method. CONCLUSION: Agreement between menstrual and clinical estimates of gestational age occurs most often close to term, with significant disagreement in preterm and postterm births. Use of different methods of determining gestation in different years or geographic populations will result in artifactual differences in important indicators such as prematurity rate.

Bias↗