Comparison of infant mortality rates across counties in Florida

American Journal of Health Studies, Summer-Fall, 2005 by Graham Watts, Sr., Fern Jureidini Webb, Dawn Goodridge Carney

Abstract: This secondary data analysis study examined infant mortality rates (IMR) of counties in Florida to explore whether rates significantly differ by location and racial group. A sample of 18 counties that had at least 20 infant deaths during the year 2000 was selected. Analyses examined bivariate relationships between sociodemographic variables and county IMR, with and without stratification by race. Findings show residents of northern counties have significantly poorer outcomes compared with residents in the central and southern counties of Florida. Health education professionals can play a role in designing and conducting community assessments that identify underlying causes of disparities in IMR.

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The health of succeeding generations depends on the well being of mothers, infants, and children (U.S. Department of Health and Human Services, 2002). The importance of maternal, infant, and child health became salient as early as the late 19th century when political and military leaders in France observed that French soldiers born to women of poor health status had substandard performance compared to German military forces (Brosco, 1999). Awareness of the relationship between maternal and child health and the health of nations preceded identification of maternal health and family planning as priority health issues in the United States.

The United States has made significant progress in reducing infant mortality since creation of "... the American Association for [the] Study and Prevention of Infant Mortality" in 1909 (Brosco, 1999). During the last two decades of the 20th century, the U.S. overall infant mortality rate (IMR) declined from 12.6 to 6.9 deaths per 1,000 live births (Centers for Disease Control and Prevention, 2002). Consequently, the national 2010 target (Healthy People 2010) for public health policies and programs has been set to 4.5 infant deaths per 1,000 live births (U.S. Department of Health and Human Services, 2002).

While national family planning programs and reproductive health services have had an impact, reducing infant mortality remains one of the major health challenges in America today. Andrulis, Puchon and Reid (2002) documented that infant mortality rates vary by place of residence in the United States. Andrulis et al. grouped data for 100 of the largest American cities into four regions to compare infant mortality rates with Healthy People 2000 and 2010 standards. During 1999, only the West region of the U.S. had cities that achieved infant mortality rates lower than the Healthy People 2000 goal of 7 per 1,000 live births. When suburban areas were examined, the highest infant mortality rates were observed in the South (Andrulis et al., 2002). These data suggest that location is a critical factor for infant mortality and requires increased public health attention.

Given the trend toward higher infant mortality rates in the Southern region of the United States, this secondary data analysis compared infant mortality rates of counties in Florida by examining whether

rates significantly differed by location and racial groups. Specific aims of this analysis were to 1) determine whether county IMR significantly differ from the overall IMR in Florida, and 2) determine whether race influences the county-state IMR relation.

METHOD

A purposive sample of counties was drawn from a sampling frame of 67 counties that provided data during the year 2000. All counties that had aggregated data on individual-level infant deaths that included 20 or more cases were included in the sample. This sampling method was patterned after a study by Franzini, Ribble and Spears (2001) that selected counties with 20 or more cases to provide more statistically reliable rates.

This ecological investigation used counties as the units of analysis. The Florida Department of Health, Office of Planning, Evaluation, and Data Analysis, and the Public Health Indicator Data Systems website were used to gather infant mortality data (Office of Planning, Evaluation and Data Analysis, 2000). Similarly, the U.S. Census Bureau (2000) website was used for sociodemographic data.

For the purposes of this study, infant mortality was the dependent variable. Age, county, marital status, and race were examined as either independent or grouping variables. Infant mortality was defined as the number of deaths that occurred on or before the first year of life (numerator) divided by the total number of live births (denominator), during a defined period of time. County is defined as the 67 divisions of Florida. Marital status was defined as either being a married-couple, family, or other. The category, other, included single, separated, divorced, or partnered individuals. Finally, race was defined as either white or Non-white, including individuals classified as black or African-American, and individuals of Hispanic origin.

Data were analyzed using Microsoft Excel. Analyses proceeded in multiple steps. First, IMR was tabulated for each county by obtaining total infant deaths for each county. The total number of deaths were then divided by the corresponding number of live births for each county, and converted to rates per 1,000. Next, a difference statistic and a critical value were calculated for each county. The difference statistic shows the disparity between each county's infant mortality rate and the overall infant mortality rate for the state. The critical value is a product of the z-score at the critical alpha level (.05) and the standard error of the difference statistic. Statistical significance at the .05 alpha level was observed when the difference statistic was greater than the critical value at .05 alpha.