This disease is characterized by ischemic necrosis of the lining of the intestines. Premature babies are at particular risk of developing NEC, and the focus is on reducing exposure to risk factors and implementing interventions that will prevent the disorder such as human milk feeding and the avoidance of hypertonic formulas (2008). Epidemiology is the main science of public health and is portrayed as an assemblage of specialties with a common goal: optimal health for the whole community (Stanhope & Lancaster, 2008). Epidemiologists strive to find the root of diseases and why they affect certain populations. These causes allow public health representatives to assess and evaluate disorders, identify vulnerable populations, plan for changes in treatment, implement evidence-based practice, and evaluate outcomes for better health of vulnerable populations. There are many steps and methods involved in epidemiology such as surveillance, randomized surveys, observational studies, and cohort studies (Stanhope & Lancaster, 2008). Epidemiologists rely on scientific methods, experience, expert judgment, and exceptional knowledge of specific populations or communities in order to follow disease paths.
Common steps in the epidemiologic approach include performing an initial observation to confirm outbreaks, disease definition, disease description by time, place, person, the creation of a hypothesis, the conduction of analytical studies, the summarization of findings, and recommendations (2008). In terms of methods related to epidemiology, one of the first issues to address in any epidemiologic study is how to obtain the data. There are three major categories of data sources including routinely collected data such as census data and vital records, data collected for other purposes such as medical and insurance, and original data collected for specific studies (Stanhope & Lancaster, 2012). One method that is used quite frequently by epidemiologists is the morbidity survey which collects data on the health status of a population group. Purposes of morbidity surveys are to determine the frequency of chronic and acute diseases and disability, collect measurements of bodily characteristics, conduct physical examinations and lab tests, and probe other health related characteristics of specific concern to those who sponsor the survey (Friss & Sellers, 2009). The CDC reports 342 deaths per year of necrotizing enterocolitis the newborn (CDC, 2013).
Epidemiologists studying the incidence of NEC might use a population-based survey to identify cases of NEC such as the one done in upstate New York in 2002. A survey was done in a well-defined, six county perinatal area. The purpose of the study was to describe the birthweight, gender, and race specific incidence as well as any demographic and clinical correlates in a population of infants born during an eight-year period (Llanos, et al., 2002). The investigators received their data by reviewing all the medical records for infants discharged with a diagnosis of NEC, the number of lives births, gestational age of the newborns, birth weight, age at diagnosis of NEC, sex of newborn, and maternal race/ethnicity (2002). By collecting this medical data, the epidemiologists were able to create their hypothesis, summarize their finding, and make their recommendations based on findings. In the case of the Llanos, et al., 2002 study, the investigators were able to determine the highest incidence of NEC was among infants born less than 2500 grams and there is a direct association of the development of NEC and the start of enteral feedings.
Gestational age at the time of feeds played a factor as well as the kind of milk the infants are being fed, with breast milk lowering the incidence of NEC (Llanos, et al., 2002). The three elements of the epidemiology triangle are the agent, host and the environment. A persons risk for disease can be increased or decreased by changing one of the elements on this triangle (Stanhope & Lancaster, 2012). The agent is the element that causes the disease. While the pathophysiology of NEC remains unclear, evidence points to prematurity and genetic predisposition as causative agents (Maheshwari, et al, 2011). Prematurity and immaturity of the gastrointestinal tract are the most important predictors for developing NEC. The host is the premature baby and the environment is the immature gastrointestinal tract. The job of the epidemiologist is to try to break one of the sides of the epidemiology triangle which disrupts the connection between the environment, the host, and the agent; thus stopping the perpetuation of the disease. In the case of NEC, the focus is more on prevention through interventions such as introducing artificial milk through enteral feedings to the immature gastrointestinal tract (2011).
Although NEC can occur in infants who have never been fed, 95% of cases occur in infants with a history of enteral feedings (2011). Infants fed artificial formulas as opposed to receiving human milk are at a higher risk of developing NEC due to the lack of substances such as immunoprotective factors and anti-microbials (2011). Premature babies are very vulnerable to contracting necrotizing enterocolitis with low birth weight being the most important risk factor (Fitzgibbons, et al., 2009). Because of advancement in the care of premature neonates, more low-birth weight premature babies are surviving under the care of a Neonatal Intensive Care Unit. Compared with term infants, premature neonates have increased gut mucosal permeability which increases their vulnerability to developing NEC (Maheshwari, et al., 2011). Preterm infants commonly have a patent ductus arteriosus (PDA) with its characteristic left-to-right shunt, diminishing blood flow to the bowel mucosa (2011). In addition, mothers who choose not to breastfeed are putting their pre-term infant at increased risk of developing NEC. Human milk contains components that help mature the gut of newborns.
The gastrointestinal system plays a major role in serving as a barrier to pathogens and allergens and as an instrument for nutrient absorption (Walker, 2011). Artificially fed infants do not receive human milk elements that foster the closure of the tight junctions between cells, increasing the newborns risk of developing NEC. Necrotizing enterocolitis infant mortality rates are highest among black women (Holman, et al., 1997). Black women are more likely to give birth to premature babies, and they have the lowest rates of exclusive breastfeeding (1997). Healthcare providers are aware of the importance of feeding all infants but particularly premature infants human milk. All mothers are educated about optimal feeding practices, but the final decision is up to the mother. At the very least, if a mother chooses not to breastfeed or pump her milk for her baby, she should be offered donor milk. Many healthcare providers are torn between honoring the choices of the mother and providing optimal care to the infant. If all infants were given donor human milk, the death rate from NEC could be significantly decreased.
Healthcare providers must weigh the ethical risks of dishonoring the mothers wishes over the overall well-being of their vulnerable patient. When counseling the new mother about optimal feeding practices for the premature baby, evidence-based practice must be considered and taught to the mother. Clinical studies show a protective effect of human milk feeds against NEC when compared to infant formula (Maheswari, 2011). These protective effects have been proven to be retained in donor milk as well (2011). For this reason, the use of human milk or donor human milk should be strongly encouraged in all premature infants. The three levels of prevention, primary, secondary, and tertiary provide a framework used in public health nursing (Stanhope & Lancaster, 2012).
The goal of primary prevention is to provide interventions that help to prevent the occurrence of disease. In the case of necrotizing enterocolitis, prevention should start during pregnancy by providing access to early prenatal care, delaying preterm labor when possible, and the avoidance of artificial infant formulas in the preterm newborn. Secondary preventions incorporates interventions designed to increase the probability that a person with a disease will have that condition diagnosed at a stage when treatment is likely to result in a cure (Stanhope & Lancaster, 2008). Health screenings are the mainstay of secondary prevention (2008).
An example of secondary prevention in relation to NEC would be slow feeds, monitoring for feeding intolerance, and the use of prophylactic antibiotics (Gibbons, et al., 2008). Tertiary prevention is aimed at limiting disability from disease and usually occur in the hospital setting. Premature newborns are already hospitalized so if they do get to the primary level of prevention, the most likely need a higher level of care such as intubation, surgery, volume replacement, antibiotics, TPN, and pain control (Gibbons, et al., 2008).
Epidemiology is the core of public health and has reformed disease prevention and health promotion significantly over the years, continuing to find new disease trends and preventive measures. NEC is a devastating disease that has a high mortality rate among premature newborns. By trying to break one of the arms in the epidemiology triangle and focusing on the three levels of prevention, public health workers and neonatologists can assure positive outcomes for premature babies.
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