Comparison of infant mortality rates across counties in Florida.

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.

The effective sample consisted of 18 Florida counties since these counties had at least 20 infant deaths during the year 2000. Counties were grouped into their main geographic region, such as Central, North, or South. The first analysis examined all socio-demographic variables by each county's IMR statistics. A second analysis repeated the first analysis and stratified data by race.

RESULTS

Table 1 presents sociodemographic data. North and South Florida had four counties each while Central Florida had 10 counties. The median age ranged from 29 to 51 years. All Central counties, except Orange County (median age 33.3), had a median age above 35. Except for Dade County, all Southern counties had a median age above 35 years. (Dade County did not report data.) In the North counties, 3 of 4 counties had a median age of less than 35 years. Regarding race, the proportion of Whites ranged from approximately 66 to 94% of the total population. In the North, slightly less than 75% of the population was white. In contrast, at least 75% of the population in the Central and Southern counties were white, with the exception of Orange (68.6%) and Broward (70.6%) counties. The proportion of married couple families throughout the 17 counties ranged from 39-56%, with 46% being the average. Almost all (90%) Central counties had at minimum the average number of married couple families. Pinellas County was the one exception; less than half (44.8%) of the population was married. The percent married reported in Southern counties was lower than those reported for Central Florida, each ranging from 4656%. By comparison, 50% of counties in the North had fewer than the average number of married couple families, and no percent married higher than 48%.

Table 2 shows IMR for all races compared with the IMR for whites. All county rates, except Polk County, significantly differ from the State rate. Two trends evident in these data. The first trend shows that the county IMR (except Polk) for all races varied significantly from the state's IMR, ranging between 0.01 and 5.25. Intuitively, some counties have IMR that are less than or greater than Florida's overall infant mortality rate (6.97/1,000 live births). Specifically, half of the counties (Seminole, Brevard, Pinellas, Orange, and Pasco) in Central Florida experienced the lowest infant mortality rates, ranging from 4.80 to 6.65 per 1,000 live births. This trend is similar to South Florida counties. For example, Broward (IMR = 5.84) and Dade (IMR = 5.76) Counties had lower IMR when compared with the state IMR. In contrast, all of the North Florida counties (Duval, Leon, Alachua, and Escambia) experienced the highest infant mortality rates, 7.91 to 12.22 per 1,000 live births.

The second trend was that whites experienced lower infant mortality when compared with Non-whites (see Table 2). Among the white population, all county rates, except those for Lee County, significantly differed from the state rate of 5.40 per 1,000 live births. Consistent with trends observed for overall county rates, the white population living in Central Florida counties experienced the lowest infant mortality rates compared to the overall rate for all whites in Florida. Specifically, white residents of Seminole, Brevard, Pinellas, and Orange Counties had IMR ranging from 3.97-5.16 for every 1,000 live births, respectively. Also evident, the Southern counties of Broward (4.08), Dade (4.41) and Palm Beach (4.66) had lower IMR among whites. Seventy-five percent of all Southern counties had rates lower than the overall state rate. In addition, the IMR for Lee County in the Southern region was marginally higher (5.45) compared with the overall state rate (5.40). In contrast, 75% of all counties located in North Florida (Duval, Escambia, and Alachua) had the highest infant mortality rates, 6.19 to 8.89 per 1,000. The remaining Northern county, Leon, had an IMR of 4.56.

Table 3 shows IMR for Non-whites. Among the Non-white population, all county rates, except Pinellas, significantly differed from the state rate. Findings revealed that location influences infant mortality rates. Comparisons by location revealed that six counties (Pasco, Seminole, Polk, Orange, Pinellas, and Volusia) in Central Florida had significantly lower infant mortality rates, ranging from 4.57 to 10.51 for every 1,000 live births. Non-whites in Southern counties also experienced significantly lower IMR compared to their counterparts throughout the state. Specifically, the IMR for Dade and Broward Counties were 8.65 and 8.73 per 1,000 live births, respectively. In contrast, 100% of the counties located in North Florida had the highest infant mortality rates. Specifically, Alachua Duval, Leon, and Escambia counties infant mortality rates ranged from 15.21 to 19.08 for every 1, 000 live births, respectively. Each county had significantly higher IMR than the overall state rate of 11.39 for Non-white Floridians. Comparisons by race also revealed that differences exist. The IMR for Non-whites in the state was 11.39 compared to 5.40 for whites, and 6.97 for all groups combined.

DISCUSSION

Previous analysis of data for the 100 largest cities in the U.S. indicated that location is a factor of infant mortality (Andrulis et al., 2002). This study examined whether intra-state IMR differences parallel regional differences by comparing county IMR for differences by location and racial groups. Florida had an overall infant mortality rate of 6.97 per 1,000 live births during 2000. The Healthy People 2000 infant mortality target was 7 per 1,000. The proximity of these two rates may imply progress with regard to infant mortality in Florida. However, a closer examination of infant mortality across counties, stratifying by race, revealed trends that significantly differ by county. Clearly, residents of Northern counties have significantly poorer infant mortality outcomes compared with residents in the Central and Southern counties of Florida.

Data for these counties revealed three trends. North Florida residents 1) include younger women of reproductive age, 2) have more births occurring in a non-marital status, and 3) have more Non-whites in their population. Results from this analysis also revealed that Non-white resident newborns throughout Florida experienced significantly more infant mortality compared to their white counterparts.

The social context that provides the background for the infant mortality trends was not explored in this study. However, prior research has identified some social factors that are antecedents of infant mortality. For example, social factors in the context of sociodemographic characteristics have been reported by Rich-Edwards and colleagues (2001) showing that babies born to college-educated African American women have poorer birth outcomes compared to black women who immigrate to the U.S. This information suggests that factors other than socioeconomic may influence pregnancy outcomes in Non-white populations.

The findings of this study should be interpreted with caution for two reasons. First, only 18 of 67 counties qualified for the analyses. Second, these data represent a cross-section of population-based statistics. However, the decision to use only 18 counties was based on a requirement to calculate statistically reliable rates. Because this study used cross-sectional data, the ability to explain differences between counties and racial groups is also limited. Future research should examine what factors contribute to disparities in local infant mortality rates.

Public health practice should make greater use of the assessment function of public health. Engaging in more community-wide needs assessments is important for two reasons. First, assessments en gage the training and skills of health education professional who work in public health, and inform the design and implementation of comprehensive community assessments that can provide insights into the underlying causes of disparities in infant mortality rates. Second, local public health policy makers are better equipped to make decisions for allocating resources to insure that conditions conducive to rearing healthy newborns. Adopting an evidence-based approach to public health holds the greatest promise to empower maternal and child health practitioners in local Healthy Start programs to acquire a better understanding of why some newborns are at higher risk of mortality than others and to develop tailored interventions to address needs identified in diverse geographic and ethnic groups.

REFERENCES

Brosco, P. J. (1999). The early history of the infant mortality rate in America: "A reflection upon the past and a prophecy of the future. Pediatrics, 103, 478-485.

Centers for Disease Control and Prevention. (2002). Infant mortality and low birth weight among Black and White infants--United States, 1980-2000. Morbidity and Mortality Weekly Report, 51 (27), 589592.

Andrulis, P. D., Duchon, M. L., & Reid, M. H. (2002). Healthy cities, health suburbs: Progress in meeting Healthy People goals for the nation's 100 largest cities & their suburbs. Retrieved December 9, 2002, from http://www.downstate.edu/urbansoc_healthdata/.

Franzini, L., Ribble, J., & Spears, W. (2001). The effects of income inequality and income level on mortality vary by population size in Texas. Journal of Health and Social Behavior, 42, 373-387.

Office of Planning, Evaluation and Data Analysis (2000). Florida annual statistical reports. Retrieved December 9, 2002, from http://dohiws.doh.state.fl.us/Divisions/Planning_Evaluation/INDEX.html.

Rich-Edwards, J., Krieger, N., Majzoub, J., Zierler, S., Liberman, E.,& Gillman, M. (2001). Maternal experiences of racism and violence as predictors of preterm birth: Rationale and study design. Paediatric and Perinatal Epidemiology, 15, 124-135.

U.S. Census Bureau (2000). State and county quickfacts. Retrieved December 9, 2002, from http:// quickfacts.census.gov/qfd/states/120001k.html.

U.S. Department of Health and Human Services (2002). Healthy People 2010 (Stock Number 017001-001-00-550-9). Washington, DC: Government Printing Office.

CHES AREAS

Responsibility I--Assessing Individual and Community Needs for Health Education Competency A--Obtain health-related data

Competency B--Distinquish between behaviors that foster and those that hinder well-being

Graham Watts, Sr., PhD is affiliated with The Shegra Consulting Group in Mesa, Arizona. Fern Jureidini Webb, PhD is affiliated with the University of Florida Department of Community Health and Family Medicine. Dawn Goodridge Carney, RN, MSPH is affiliated with Shands Jacksonville Medical Center. Address all correspondence to Dawn Goodridge Carney, RN, MSPH, Shands Jacksonville Medical Center, 655 West 8th Street, Jacksonville, FL 32209; PHONE: [phone]; FAX: [phone]; E-MAIL: [e-mail].

Table 1. Socio-Demographics of Selected Florida Counties

                                     Year 2000

                                                       Married
               Geographic        Median                 Couple
County         Location           Age     White (%)   Family (%)

Central
Orange         Central            33.3      68.6         47.0
Polk           Central            38.6      79.6         54.4
Seminole       Central            36.2      82.4         54.3
Brevard        Central East       38.7      78.0         50.4
Volusia        Central East       42.4      86.1         50.4
Hillsborough   Central West       35.1      75.2         47.7
Manatee        Central West       43.6      86.4         52.7
Pasco          Central West       44.9      93.7         54.6
Pinellas       Central West       43.0      85.9         44.8
Sarasota       Central West       50.5      92.6         52.7

North
Alachua        North Central      29.0      73.5         38.8
Leon           North Central      29.5      66.4         39.8
Duval          Northeast          34.1      65.8         46.5
Escambia       Northwest          35.4      72.4         47.8

South
Broward        Southeast          37.8      70.6         46.1
Dade           Southeast           --        --           --
Palm           Beach Southeast    41.8      79.1         50.8
Lee            Southwest          45.2      87.7         55.5

Data Source -- US Census Bureau

Dash (--) Unable to access census website for specific county

% is expressed as a function of the total in the state as a whole

Table 2. Comparison of Infant Morality Rates for All Races and Whites
by Counties

                           Year 2000 Infant Deaths

                                 All Races

                                                 State-
               Rate per     Critical             County
County         1000 Live     Value                Rate
                Births     ([dagger])          Difference

Florida           6.97         --        --

Central
Seminole          4.80        0.14      -2.17
Brevard           5.19        0.15      -1.78
Orange            6.61        0.11      -0-36
Pinellas          6.36        0.13      -0.61
Pasco             6.65        0.21      -0.32
Polk              6.98        0.17       0.01 ([double dagger])
Hillsborough      7.91        0.13       0.94
Manatee           7.42        0.26       0.45
Sarasota          8.09        0.31       1.12
Volusia           8.75        0.26       1.78

North
Duval             9.70        0.17       2.73
Leon              9.70        0.35       2.73
Alachua          10.77        0.42       3.80
Escambia         12.22        0.39       5.25

South
Broward           5.84        0.08      -1.13
Dale              5.76        0.07      -1.21
Lee               6.74        0.19      -0.23
Palm Beach        7.13        0.12       0.16

                          Year 2000 Infant Deaths

                                  Whites

                                                 State-
               Rate per     Critical             County
County         1000 Live     Value                Rate
                Births     ([dagger])          Difference

Florida          5.40          --        --

Central
Seminole         3.97         0.13      -1.43
Brevard          3.38         0.11      -2.02
Orange           5.16         0.11      -0.24
Pinellas         5.06         0.12      -0.34
Pasco            6.79         0.23       1.39
Polk             6.43         0.17       1.03
Hillsborough     5.56         0.11       0.16
Manatee          6.39         0.24       0.99
Sarasota         6.35         0.26       0.95
Volusia          8.39         0.27       2.99

North
Duval            6.19         0.14       0.79
Leon             4.56         0.22       0.84
Alachua          8.89         0.43       3.49
Escambia         8.46         0.33       3.06

South
Broward          4.08         0.07      -1.32
Dale             4.41         0.06      -0.99
Lee              5.45         0.16       0.05 ([double dagger])
Palm Beach       4.66         0.10      -0.74

Data Source -- Florida Department of Health, Office of Planning,
Evaluation and Data Analysis, Public Health Indicator Data Systems

([dagger]) = The state and county rate difference is significant at
the 95% confidence interval when it is greater than the  the critical
value

([double dagger]) = Not statistically significant at the 95%
confidence interval

Table 3. Comparison of Infant Morality Rates for All Races and
Non-Whites by Counties

                         Year 2000 Infant Deaths

                                All Races

                                                 State-
               Rate per     Critical             County
               1000 Live     Value                Rate
                Births     ([dagger])          Difference

Florida           6.97         --        --

Central
Seminole          4.80        0.14      -2.17
Brevard           5.19        0.15      -1.78
Orange            6.61        0.11      -0.36
Pinellas          6.36        0.13      -0.61
Pasco             6.65        0.21      -0.32
Polk              6.98        0.17       0.01 ([double dagger])
Hillsborough      7.91        0.13       0.94
Manatee           7.42        0.26       0.45
Sarasota          8.09        0.31       1.12
Volusia           8.75        0.26       1.78

North
Duval             9.70        0.17       2.73
Leon              9.70        0.35       2.73
Alachua          10.77        0.42       3.80
Escambia         12.22        0.39       5.25

South
Broward           5.84        0.08      -1.13
Dale              5.76        0.07      -1.21
Lee               6.74        0.19      -0.23
Palm Beach        7.13        0.12       0.16

                         Year 2000 Infant Deaths

                               Non-Whites

                                                 State-
               Rate per     Critical             County
               1000 Live     Value                Rate
                Births     ([dagger])          Difference

Florida         11.39          --        --

Central
Seminole         8.68         0.61      -2.71
Brevard         13.95         0.93       2.56
Orange           9.61         0.30       1.78
Pinellas        11.08         0.49       0.31 ([double dagger])
Pasco            4.57         0.61      -6.82
Polk             9.08         0.48       2.31
Hillsborough    15.54         0.52       4.15
Manatee         12.20         1.00       0.81
Sarasota        19.77         2.06       8.38
Volusia         10.51         0.75       0.88

North
Duval           15.21         0.45       3.82
Leon            17.09         0.96       5.70
Alachua         14.24         0.93       2.85
Escambia        19.08         1.02       7.69

South
Broward          8.73         0.21      -2.66
Dale             8.65         0.20      -2.74
Lee             13.94         0.98       2.55
Palm Beach      12.79         0.41       1.40

Data Source -- Florida Department of Health, Office of Planning,
Evaluation and Data Analysis, Public Health Indicator Data Systems

([dagger]) = The state and county rate difference is significant at
the 95% confidence interval when it is greater than the  the critical
value

([double dagger]) = Not statistically significant at the 95%
confidence interval