Impacts of Tobacco Smoke Exposure and Outlier Body Mass Indices on Pediatric Asthma Outcomes

There are seven million children in the United States impacted by asthma [1]. When assessing the severity of a child's asthma, it is important to take into account risk factors known to affect child hood asthma. Two such risk factors that are modifiable include parental tobacco smoke exposure (TSE) and body mass indices (BMI). The main objective of this study was to determine how patients with both TSE and outlier BMIs (>90% or <10%) compared to the whole study population. In particular, three main outcomes were examined: cost of hospitalization, length of stay, and severity of illness. It was determined that TSE and outlier BMI correlated with increased hospitalization length (p=0.05). However, severity of illness (p=0.09) and cost of hospitalization (p=0.1) were not significant. Further studies need to be conducted in order to determine if other pediatric asthma outcomes could change for TSE and outlier BMI patients.

IMPACTS OF TOBACCO SMOKE EXPOSURE AND OUTLIER BODY MASS INDICES ON PEDIATRIC ASTHMA OUTCOMES by Madison Taylor Black A Senior Honors Thesis Submitted to the Faculty of The University of Utah In Partial Fulfillment of the Requirements for the Honors Degree in Bachelor of Science In Bioengineering Approved: ______________________________ Dr. Kevin Nelson Thesis Faculty Supervisor _____________________________ Dr. Patrick Tresco Chair, Department of Bioengineering _______________________________ Dr. Kelly Broadhead Honors Faculty Advisor _____________________________ Sylvia D. Torti, PhD Dean, Honors College May 2015 ABSTRACT There are seven million children in the United States impacted by asthma [1]. When assessing the severity of a child’s asthma, it is important to take into account risk factors known to affect childhood asthma. Two such risk factors that are modifiable include parental tobacco smoke exposure (TSE) and body mass indices (BMI). The main objective of this study was to determine how patients with both TSE and outlier BMIs (>90% or <10%) compared to the whole study population. In particular, three main outcomes were examined: cost of hospitalization, length of stay, and severity of illness. It was determined that TSE and outlier BMI correlated with increased hospitalization length (p=0.05). However, severity of illness (p=0.09) and cost of hospitalization (p=0.1) were not significant. Further studies need to be conducted in order to determine if other pediatric asthma outcomes could change for TSE and outlier BMI patients. ii TABLE OF CONTENTS ABSTRACT ii INTRODUCTION 1 METHODS 5 RESULTS 7 DISCUSSION 12 REFERENCES 16 iii INTRODUCTION Asthma is one of the most common chronic childhood illnesses in the United States [1]. As a disease that affects the respiratory airways, it has three major components [2]. These include airway muscle tightening, airway tissue inflammation, and increased mucus production [2]. A visual depiction of asthma’s effects on the airways is shown in Figure 1. Figure 1: Depiction of the respiratory system demonstrating the effects of asthma on the airways, as compared to non-asthmatic (normal) airways [2]. A chronic narrowing in a child’s airways leads to wheezing and breathing difficulties that can occur rapidly. This, in turn, can also lead to long-term health problems [3]. If the severity of these symptoms increases, emergency room visits or even hospitalizations can be necessary. [3]. In fact, asthma is a common cause of childhood hospitalizations [4]. When caring for children who are hospitalized with asthma, it is important to evaluate for modifiable triggers that may increase the severity of the asthma symptoms and a child’s hospital course [4]. Identifying “trigger” factors that worsen asthma symptoms and lead to exacerbations requiring hospitalization should be identified [5]. Some possible triggers include environmental allergens, such as pollen, dust mites, pet dander, or mold; exercise; irritants such as tobacco smoke or industrial pollutants; food allergies; viral infections; and pharmacological agents, including aspirin or beta-blockers [5]. By identifying triggers, clinicians are able to provide better asthma management options for patients [5]. Modification of triggers such as avoidance of TSE or achieving a healthier weight may lead to improved asthma symptoms in the future and prevent the need for hospitalizations. Triggers for pediatric asthma exacerbation require the physician to not only educate the patient but also the parent. This can pose some challenges, since the habit of the parent can be what is triggering the patient’s asthma symptoms. In this case, that habit is smoking. According to the American Academy of Pediatrics, tobacco smoke exposure questions and possible preventions should be incorporated into a child’s health care plan. Since tobacco dependence is a treatable chronic illness, clinicians must take time to make the proper recommendations to provide possible medicinal treatments and smoking cessation counseling for parents. Whether or not a child is exposed to tobacco in the home when assessing asthma severity is critical knowledge to have, since there is a strong correlation between parental smoking (TSE) and hospitalizations of children with asthma [2]. 2 It is also important to consider the effect a child’s BMI may have on his or her asthma symptoms. BMI is an index that utilizes the ratio of the child’s weight in kilograms divided by the child’s height squared in meters [6] that indicates whether a child is overweight or underweight [6]. An outlier body mass index is defined as underweight when a child has a BMI less than the 10th percentile or overweight when greater than the 90th percentile. BMI is a significant indicator of a child’s overall health. In fact, higher BMIs have been known to increase a child’s risk of heart disease, respiratory illnesses, Type 2 Diabetes, and asthma [7]. Overweight children, meaning children with higher BMIs, who were admitted with asthma were more likely to have subsequent emergency department visits [8]. Current literature, for the most part, involves examining TSE and BMIs as separate entities that impact asthma; more work needs to be done to examine the impact of TSE and outlier BMI together [7]. The prevalence of both childhood asthma and obesity are incredibly high currently, indicating clinicians and researchers must act [8]. When a child is hospitalized for a respiratory related event, the hospital collects data for the patient that allow for a better understanding of his or her pediatric asthma; these indicators, often referred to as the asthma outcomes, can be useful in improving childhood asthma. Some include the severity of illness, cost of hospitalization, and length of hospital stay. Specifically, I examined how outlier BMI and parental smoke exposure contributes to these specific pediatric asthma outcomes. My hypothesis was children with outlier BMIs and TSE would have a longer length of stay, higher severity of illness, and greater cost of hospitalization than the whole population. By attempting to gain a 3 better understanding of the effects of TSE and outlier BMI on hospital outcomes, it may help lead to strategies that improve overall child asthma control. 4 METHODS Data Source The data for this study was provided by Primary Children’s Hospital, an Intermountain Health Care facility. Data Collection The data was retroactively collected between the years 2008 and 2010, for children ages two to seventeen that were previously diagnosed with asthma and hospitalized for a respiratory-related event. Each patient had a specific number known as an “EMPI” that was assigned as a unique identifier. This number correlates with all of the data for that patient, which included their length of stay, severity of illness, cost, and other demographic and socioeconomic factors. Intermountain Healthcare analysts used a query of the Intermountain Enterprise Data Warehouse to provide me with the demographic and hospital outcome data. I collected the TSE and BMI data through 1426 charts via manual chart review. TSE and BMI data was not initially provided because whether the parent or guardian smoked in the home, the height in meters, and the weight in kilograms needed to be gathered and verified manually. This was found in the patient’s health history or the admission notes in the electronic medical record. Studies like this have been difficult accomplished and been limited in the past because the data must be collected manually. By collecting this information manually, my data augmented what was already available from Intermountain Healthcare’s electronic archived electronic health data. 5 Population The population for this study was children with asthma between the ages two and seventeen that were admitted to the hospital between 2008 and 2010 for a respiratoryrelated event and a previous diagnosis of asthma. This particular sample involved 1426 patients. However, the data provided included children younger than two, reducing the study population to 1173. Defined Variables There were five variables being examined for each patient. These variables included parent/guardian tobacco smoke exposure, severity of illness, length of hospitalization and cost of stay. Parental/guardian tobacco smoke exposure referred to whether the child was exposed to tobacco smoke by their parent or guardian. If a parent or guardian smokes, even if it is not around the child, it is considered tobacco smoke exposure. Examining the patient health history or admission note for each patient determined this variable. Thus, we relied on the veracity of the responses from the parents. Severity of illness refers to “the extent of physiological decompensation or organ system loss of function” [8]. A scale determined by the National Association of Children’s Hospitals, it is based on a system between 1-4, with 1 being minor and 4 being extreme [8]. Table 1 is an example of the scale for respiratory events. 6 Table 1: Severity of Illness Levels and Examples Severity of Illness Example 1-Minor Bronchitis 2-Moderate Asthma wit Status Asthmaticus 3-Major Viral Pneumonia 4-Extreme Respiratory Failure Cost of stay refers to the total cost associated with a patient’s stay during the hospital. This can include the initial ER visit, inpatient stay, tests performed, and medications or other treatments. Since this study was conducted for two years, the cost was adjusted for inflation in 2013 dollars. Body Mass Index (BMI) is an index that utilizes the ratio of the child’s weight in kilograms divided by the child’s height squared in meters [6]. After calculating the BMI for each child, it was determined whether the child was considered to be overweight (>90%), underweight (<10%), or neither. Demographic data that was provided by Intermountain Healthcare is also included to help provide context for the results. Statistical Analysis Frequencies and means were reported for demographic and outcome variables. The patients were separated into groups for analysis. First, the outlier BMI patients were assessed; from this group, patients who had TSE were used to create a group is referred to as outlier BMI and TSE. The “TSE and outlier BMI” group was compared to the rest of the population as a whole. The variables for these two groups that were compared included severity of illness, cost of hospitalization, and length of stay. T-tests were conducted for each, and their respective P-values were determined. P-values were 7 measured using chi-square or Fisher’s exact test for categorical values. T-tests were calculated using publicly available statistical software on openepi.com. 8 RESULTS The overall study population examined 1173 children with asthma. Children with both TSE and outlier BMI totaled 28. We identified demographic characteristics for the overall population and the “TSE and outlier BMI” population. Gender was different between the overall study population and “TSE and outlier BMI” population. The overall population was 60% male and 40% female while “TSE and outlier BMI” was 32% male and 68% female (p=0.003).” Children in the overall population had 63% private insurance, 30% government insurance, and 6% self-insurance. In the “TSE and outlier BMI” population, there were 43% private insurance, 57% government insurance, and 0% self-insurance (p=0.01). The overall population was 79% white and 21% other, compared with 89% white and 11% other for the TSE and outlier BMI group (p=0.01). 9 Table 2: Characteristics of Children with Asthma, TSE, & Outlier BMI in the Study Population Overall Population TSE + Outlier BMI (n=1173) (n=28) Characteristics Amount Percentage Amount Sex Male 702 60% 9 Female 471 40% 19 Race White 927 79% 25 Other 21% 246 3 Insurance Private 743 63% Insurance 12 Gov. Insurance 356 30% 16 Self-Insured 74 6% 0 Age 5.6 (3.4)* 7.6 (3.9)* *Mean age with standard deviation is reported in the table. Percentage Statistical Significance 32% 68% p=0.003 89% 11% p=0.19 43% 57% 0% p=0.01 p=0.01 We examined the length of stay, severity of illness and total cost of hospitalization (Table 3). Length of stay was 60.1hours (standard deviation 46.6) compared with 85.4 hours (standard deviation 63.4) in the “TSE and outlier BMI” population (p=0.045). Severity of illness was 1.4 (standard deviation 0.7) for the overall population and 1.7 (standard deviation 0.9) for the “TSE and outlier BMI” group (p=0.09). For the overall population, the cost of hospitalization was $5,350 (standard deviation $5,713) compared to $7,446 (standard deviation $6,741) for “TSE and outlier BMI” (p=0.1). While the length of stay was statistically significant (p=0.045), the severity of illness (p=0.09) and cost of hospitalization (p=0.1) were not. 10 Table 3. Asthma Outcomes for the Overall Population vs. the TSE+Outlier BMI Population Overall Population TSE + Outlier BMI Statistical (n=1173) (n=28) Significance Length of Stay* 60.1 (46.6) 85.4 (63.4) p=0.045 (hours) Severity of Illness* 1.4 (0.7) 1.7 (0.9) p=0.09 Cost of Hospitalization* $5,350 ($5,713) $7,446 ($6,741) p=0.1 (2013 dollars) *Results reported as mean and standard deviation. 11 DISCUSSION My study examined differences in hospital outcomes among children with asthma and children with asthma who had tobacco smoke exposure and outlier body mass indices. Length of stay was 25.3 hours longer among the TSE and outlier BMI population, compared with the overall population (p=0.045). This result suggests that children who have TSE and outlier BMIs may have more severe asthma symptoms and not well-controlled asthma which requires them to remain in the hospital for a longer period of time. The results also showed a higher severity of illness and total cost of hospitalization for children with TSE and outlier BMIs; however, these results were not statistically significant. Although the severity of illness and total costs were higher, they were not different enough to demonstrate a disparity between the two. This may indicate that there are other factors that need to be considered when evaluating asthma severity for children. The study also considered demographic differences between the overall population and the “TSE and outlier BMI” population. Gender, insurance type, and age were all found to be statistically significant with p-values of 0.003, 0.1, and 0.1, respectively. Therefore, these factors could have an impact on the results of this study. Future studies should also include a regression model analysis to control for the effects of demographic factors on hospital outcomes. This type of analysis was beyond the scope of the present study but lays the groundwork for future studies. 12 It is possible that children with outlier body mass indices and tobacco smoke exposure have different outcomes than the overall population of children. Since their hospital stays are significantly longer than the overall populations, clinicians should be aware of this disparity as they make treatment plans for their stay during the hospital. In addition to awareness during hospitalizations, the primary care physicians of patients in this outlier group need to be informed and provide educational resources and consultations to parents and patients about healthy diet, exercise, and smoking cessation. Although this study has a significant population of children to provide statistical support for the findings, this population is only considering children between the ages of two and eighteen who have been hospitalized at Primary Children’s Hospital. Since the average age of hospitalized children was 5.64 and the median age was 5, it is apparent that the majority of the patients for this study were concentrated around the age of 5. An increased prevalence of asthma diagnosis in younger children is often observed; this is a period of time where a child may first be experiencing asthma medications and treatments, demonstrating that their asthma is not well controlled. Overall, this could be related to the possibility of being hospitalized for an asthma-related event [10]. Future studies could also stratify by age to further examine this possibility. With regards to age, the “TSE and outlier BMI” group had an average age of 7.6, which is statistically significant compared to the whole population. The age difference could be an indication that the outlier group does not have asthma that is well controlled by an earlier age. Some reasons for this could be lack of resources to gain access to primary care physicians who have the ability to provide treatment plans. It could also 13 indicate that being overweight, underweight, or being exposed to tobacco smoke make it increasingly difficult to control asthma symptoms. One of the most significant limitations may be the fact that smoking is highly underreported. In the inpatient setting, 35% of caregivers and parents reported smoking while the biochemical marker cotinine indicated that 80% of the pediatric population was exposed to tobacco smoke [11]. Since our data is based upon the reports of the parent or caregiver, the data could be limited, and there could potentially be more subjects in the study who may be tobacco smoke exposed. If this study included the cotinine values rather than the parental smoking report, I think there would be a greater number of tobacco smoke exposure observed in the study population. Children with TSE and outlier BMIs need to be closely evaluated when they are hospitalized for an asthma-related event, since it likely that they will have a longer length of stay. To improve the outcomes for these patients, it would be wise to consider providing the parents and caregivers smoking cessation education and materials. While doing so, it is important to ensure a good working relationship with the clinician and the parent to provide the best opportunity for smoking cessation success [12]. Another recommendation would be to provide nutritional counseling for the caregivers and children in order to improve their BMIs, which could, in turn, assist in better regulation of asthma [7]. Currently, childhood asthma and obesity are historically high [8]. Thus, it is crucial to better understand and explore the intermingling between childhood asthma, tobacco smoke exposure, and outlier body mass indices. The combination of these factors can lead to an increased number of emergency department visits and longer 14 hospitalizations [8]. This, in turn, can increase health care costs and cause stress for both parents and children [12]. By learning more about the impacts and outcomes of tobacco smoke on asthmatic children with outlier BMIs, clinicians can provide better care to their patients, helping to place the child first and always. 15 REFERENCES [1] Centers for Disease Control and Prevention: National Center for Health Statistics, National Health Interview Survey Raw Data, 2011. Analysis by the American Lung Association Research and Health Education Division using SPSS and SUDAAN software. [2] J. M. Torpy, “Chronic Diseases of Children,” Jama, vol. 303, no. 7, p. 682, 2010. [3] Cook, D., & Strachan, D. (1999). Health effects of passive smoking 10: Summary of effects of parental smoking on the respiratory health of children and implications for research. Thorax, 54, 357-366. 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