Effectiveness of neonatal transport in New York City in neonates less than 2500 grams--a population study.

In the past two decades, there has been a gradual trend to regionalization of perinatal care, categorization of hospitals and transport services for neonatal health care. The literature alludes to both beneficial and deleterious effects of neonatal transport (T) but no controls such as a matched nontransport (NT) population have been utilized to date. The major goal of this study was to evaluate the effect of neonatal transport from Level I and II high risk less than or equal to 2500 gm. neonates (born in NYC in one calendar year, 1979) compared to a cohort nontransported population matched for hospital of birth, weight, race, sex and risk. All transported less than or equal to 2500 gm. from Level I and II (n = 328) were studied and a stratified random sample of the nontransported (NT) infants less than or equal to 2500 gm. from these same hospitals (n = 2042) was used for comparison. The principle outcome variable was survival. The major conclusion of this study is that in Level I and II hospitals the transport group had a significantly increased survival in infants who were sick (Apgar less than 6) compared to cohorted nontransported controls. Interhospital differences in survival were noted among Level I and II but not seen in the subdivisions of (A) and (B) hospitals.

Analysis of air pollution patterns in New York City distribution of air pollutants over the city.

Distribution of daily levels of sulfur dioxide and smokeshade over the five boroughs of New York City are described in terms of a coordinate grid covering the area of the City and heights above ground level and above sea level. Implications for the design of epidemiologic studies of the health effects of air pollution are discussed.

Distribution of seasonal mean levels of air pollutants over New York City.

Distributions of seasonal average levels of sulfur dioxide and smoke-shade over the five boroughs of New York City are described in terms of the distance between stations and the heights of the stations above ground level and sea level. An assessment of the suitability of the data for epidemiologic studies of acute and chronic health effects of air pollution is made.

Methodological problems arising from the choice of an independent variable in linear regression, with application to an air pollution epidemiological study.

In epidemiological studies using linear regression, it is often necessary for reasons of economy or unavailability of data to use as the independent variable not the variable ideally demanded by the hypothesis under study but some convenient practical approximation to it. We show that if the correlation coefficient between the "practical" and "ideal" variables can be obtained, then a range of uncertainty can be obtained within which the desired regression coefficient of dependent on "ideal" variable may lie. This range can be quite wide, even if the practical and ideal variables are fairly well correlated. These points are illustrated with data on observed regression coefficients from an air pollution epidemiological study, in which pollution measured at one station in a large metropolitan area (containing 40 aerometric stations) was used as the practical approximation to the city-wide average pollution. The uncertainties in the regression coefficients were found to exceed the regression coefficients themselves by large factors. The problem is one that may afflict application of linear regression in general, and suggests caution when selecting independent variables for regression analysis on the basis of convenience, rather than relevance to the hypotheses tested.