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Adult childhood cancer survivors are at higher risk for developing late medical effects related to their cancer treatments. Health promoting behaviors may reduce the risk of some late effects and the severity of others. This paper describes the design and recruitment of the Chicago Healthy Living Study (CHLS), an on-going study designed to examine the health behaviors and BMI of minority adult childhood cancer survivors as compared to non-minority survivors and non-cancer controls.
Survivors are identified by the hospital cancer registries at five treating institutions in the Chicago area, after which a multilevel recruitment plan is implemented with the goal of enrolling 450 adult survivors of childhood cancer (150 in each racial/ethnic group). Simultaneously, 300 African-American, Hispanic and Non-Hispanic White adult non-cancer controls (100 in each racial/ethnic group) living in the Chicago area are being recruited via listed, targeted digit dial. All participants complete a 2-hour interview of questionnaires related to diet, physical activity, smoking and associated mediators. Height and weight are also measured.
The Chicago Healthy Living Study will provide important information on the health behaviors of adult minority childhood cancer survivors that can be used to inform the development of interventions to improve modifiable risks.
In 2009, approximately 12,000 children will be diagnosed with cancer in the United States and 80% will likely survive disease-free for more than five years.1 Fortunately, advances in treatment have led to dramatic improvements in survival such that one in every 640 adults between the ages of 16 and 44 is estimated to be a survivor of childhood cancer.2, 3 Despite improved treatments, many pediatric cancer survivors develop adverse medical effects of treatment or “late effects” that include osteoporosis, cardiovascular disease (CVD) and secondary cancers.4–8 These late effects may be worsened by high-risk health behaviors.9 Adherence to health-promoting practices such as consuming a healthy diet, engaging in regular physical activity, maintaining a healthy weight and avoiding smoking may be particularly beneficial to adult survivors of childhood cancers.
To date, approximately 18 published studies have examined the weight status and health behaviors of adult childhood cancer survivors.4, 10–26 Overall, results suggest that, despite their childhood illness, this population has body habitus and health behavior profiles similar to the general population. Many consume diets that are high in fat, low in fruits and vegetables and do not include sufficient calcium. 4, 11, 13, 20, 22, 25 Many are also physically inactive, with a minority meeting the CDC recommendation for regular physical activity. 4, 11–14, 17, 18, 20, 22, 24, 25 These behaviors, along with the effects of some treatments, lead many survivors, particularly those who have survived ALL, to become overweight or obese.27–29 Smoking is one area that does not mirror the general population. Childhood cancer survivors appear to smoke either less or at similar rates compared to their siblings or age-matched peers.10, 15, 19, 21 However, any smoking is of concern given the higher risk for secondary cancers that many survivors have due to treatment exposures. Although the current literature provides a general understanding of the health behaviors of adult childhood cancer survivors, the methodological weaknesses of many studies limit their impact. Limitations include non-representative or single site convenience samples, lack of non-cancer comparison groups, lack of theoretical frameworks to guide methodology, and/or use of subjective and/or non-standardized measures. An additional and critical limitation is that studies to date include an over-representation of Non-Hispanic White survivors.
The limitations of current studies result in sparse knowledge about the health behaviors of minority childhood cancer survivors, interfere with the ability to recognize intervention needs, and prevent the development of appropriate interventions. There is only one published paper that focuses on the health behaviors of minority, although the study was not designed with this intent.12 Results showed that African-Americans and Hispanics were less likely to smoke than their Non-Hispanic White counterparts, but over 50% were physically inactive, a rate similar to Non-Hispanic Whites.12 A second study of physical activity among adult acute lymphoblastic leukemia (ALL) survivors considered race/ethnicity in its analyses and reported that being a racial/ethnic minority was associated with a higher likelihood of not meeting Centers for Disease Control’s (CDC) guidelines for physical activity.18 Neither study considered cognitive or cultural mediators, and only Florin et al.18 included a non-cancer comparison group. These methodological considerations are important because research shows that minorities in the general population are less likely to engage in health promoting activities.31–33 Some purport that this is due, in part, to cultural attitudes, health beliefs and limited knowledge about health promotion.34–36 Results from Florin et al.18 suggest that their sample of ALL survivors were more likely than participants in the 2003 Behavioral Risk Factor Survey Study to be inactive. Further data are needed to understand if and how the health behaviors of African-American and Hispanic survivors may differ from their non-cancer affected peers. This will allow for the development of appropriate interventions that may potentially enhance the health and quality of life in these underserved communities.
This paper describes the design and recruitment strategy of a study aimed at increasing our knowledge of health behaviors among African-American, Hispanic, and Non-Hispanic White childhood cancer survivors.
The Chicago Healthy Living Study (CHLS) is an observational, cross-sectional study with two primary objectives: 1) to describe and compare the influence of race/ethnicity (African-American, Hispanic, or Non-Hispanic White) and survivor status (cancer survivor or not) on individual health behaviors (diet, physical activity, smoking) and body mass index (BMI); and 2) to identify differences in the mediators of each health behavior and BMI between these groups. The study involves the collaboration of five Chicago-area healthcare institutions that treat childhood cancers. Recruitment is underway with the goal of enrolling 150 adult childhood cancer survivors within each of three ethnic/racial category (African American, Hispanic, Non-Hispanic White) equally mixed by gender. In addition, 100 non-cancer controls will be recruited within each racial/ethnic category. Eligibility for all participants require that they: 1) self-identify as African-American/Black, Hispanic/Latino, Non-Hispanic White/Caucasian, 2) are at least 18 years of age, 3) are not pregnant or less than 3 months post-partum, 4) have no significant cognitive delays or unmedicated mental illness, and 5) are agreeable to providing informed consent and completing the study interview. Survivors are also required to have been diagnosed with a childhood malignancy prior to the age of 21 and at least five years prior to study participation, be currently cancer free, and live/work within two hours driving distance from study site or be willing to come to the study site for the interview. Additional eligibility criteria for controls require that they have no prior diagnosis of any cancer with the exception of basal cell skin cancer, nor any diagnosis of any chronic illness that would have affected their diet and/or exercise patterns before the age of 18 (i.e., juvenile diabetes, arthritis, diabetes). They must also be willing to come to the study site or a community location for the interview. The study includes a one-time interview and was approved by the Institutional Review Board at the University of Illinois Chicago and all collaborating institutions.
The conceptual framework for the proposed study is based on an integration of Kornblith’s model for psychosocial adaptation to cancer,37, 38 the Health Belief Model (HBM)39–41 and Social Learning Theory(SLT).42 Tenets of cultural competency theory are also incorporated.43
Kornblith’s model of psychosocial adaptation to cancer holds that physical health and functioning are mediated by individual characteristics, social support, economic resources and other stressors to determine level of adaptation to cancer.37, 38 Health behaviors may be seen as an aspect of long term adaptation to cancer. As illustrated in Figure 1, the independent variables of cancer survivor status and ethnicity are mediated by health status, health care utilization, cognitive processes, social support, and sociocultural factors to determine the health behaviors and BMI of study participants.
Perceived vulnerability to illness and perceived importance of health promotion are mediators that come from the Health Belief Model (HBM). The HBM is one of several theories used to understand why people engage in particular behaviors when confronted with illness or health problems40 39, 41 According to the HBM, survivors of childhood cancers are more likely to practice a health promoting behavior if they believe they are vulnerable, for example, to secondary cancers, believe the risk is serious, and believe that there are benefits to taking action that outweigh the costs.
Rationale for including attitudes, knowledge and self-efficacy as mediators is based on Social Learning Theory (SLT).44 SLT proposes that behavior and behavior change occur as a result of the dynamic interaction between behavior, cognition (attitudes, knowledge, self-efficacy), and the environment (social support).
Finally, the potential mediating effects of ethnic identity, spirituality and cultural beliefs/practices are also being considered.43 Assessment of these variables will help to identify the inherent diversity that exists in the beliefs and practices of persons from different ethnic and racial backgrounds, and will be important to consider in intervention development.
Survivors are being recruited in a staggered process through five institutions that treat approximately 90% of the children diagnosed with cancer in the Chicago area. Recruitment goals for each race/ethnicity were calculated for each site, based on the approximate number of new cases diagnosed each year.
The multi-step recruitment process begins with the pediatric cancer registry at each institution generating a list of patients that meet the eligibility criteria. This list is checked for accuracy of inclusion criteria and then serves as the potential research pool for recruitment. Recruitment begins with the least intensive effort and proceeds through two increasingly intensive steps. Invitation letters are printed on letterhead and signed by the physicians and nursing staff at each treating institution. A self-addressed stamped response card (with an envelope to maintain confidentiality) is included. Survivors can decline to participate by returning the response card or calling study staff. In such cases the survivor is considered a refusal and no further contact is made. If survivors send back the response card or call study staff indicating they are interested, a CHLS interviewer contacts them to screen for eligibility and then, if eligible, to set up an interview appointment. Survivors who do not send back the response card or call within two weeks from its postage date, are called by CHLS study staff to gauge their level of interest in participating. In most cases, the contact information contained in the pediatric cancer registries is incorrect. If the initial recruitment letter comes back as undeliverable and/or the telephone contact is incorrect, recruitment efforts proceed to a third, more intensive level, “unable to locate” (UTL) searches (see Figure 2). Some cases begin at the UTL level; those for which there were no or incomplete address and telephone number from the hospital pediatric registry. If the initial UTL search fails to provide accurate contact information, a second search is conducted six to eight months later. When updated information is obtained, the recruitment cycle begins anew with the letter once an address is identified or with a telephone call if only a telephone number is identified. In cases where no information can be obtained after two UTL searches, the case is considered “Lost”. Recruitment goals are set at each site and once a racial/ethnic group goal is met, recruitment ceases for that group at that particular site.
Outside of the multi-step recruitment plan, recruitment may also occur in person at the treating institutions. A small number of adult childhood cancer survivors continue to see their oncology team for healthcare and are told about the study by their physician and/or nurse. Survivors may also self-refer having heard about the study from other survivors or from media publicity about the study.
Control participants are being recruited via listed, target digit dial by the Survey Research Lab (SRL) at UIC based on a stratified sampling design with the goal being to accumulate a specific number of controls stratified by age, gender, and race to ensure comparability with the survivor group. Recruitment is being done using listed telephone sample for which the age and gender of a household member is known. SRL purchased two categories of sample files from Marketing Systems Genesys, sample files based on Hispanic surnames and sample files to target African-American and Non-Hispanic Whites. To do this the files exclude Asian, Indian and Armenian surnames. This second sample file type is further controlled by the proportion of African-Americans within particular zip codes. Prior to screening, these two file types are combined so that any person who may not be eligible in one group (e.g. an African-American in the Hispanic surname file) can be used to fill one of the other target groups. Utilizing the sample in this manner is more efficient than screening each group separately from each sample file.
Once contact is made by SRL, staff informs the respondent about the study. If the respondent is interested the SRL caller conducts a brief interview to determine eligibility and to gather information about age, gender and ethnicity. This information is communicated to a CHLS interviewer who then contacts the potential participant to schedule the interview.
Participants complete a one-time interview that is preceded by the process of informed consent. Survivors are given several location choices for completing the interview including the study site, their treating institution (survivors only), their home or work (survivors only), or a community site (i.e., public library). Controls are first asked to come to the study site and then if they are unable or unwilling we offer a community location. The interview requires approximately two hours and consists of questionnaires related to demographics, health behaviors and mediating variables. Height and weight are also measured. Survivor participants are asked to sign a HIPAA waiver to access their medical record from their childhood cancer treating institution; however, this is not a requirement of participation. At the end of the interview, participants receive $50.00 for their time. Interviews are conducted by trained interviewers with extensive training and experience in collecting sensitive data. For quality control purposes 10% of all interviews are recorded and reviewed for consistency.
(See Table 1)
Data are collected on gender, date of birth, self-identified ethnic group, survivor status, marital status, reproductive history, education, occupational status, and annual income.
The Short Acculturation Scale (SAS) for Hispanics is a 5-item self-report measure of acculturation.45 Responses are provided on a 5-point scale. The SAS is available in English and an equivalent Spanish version. Concurrent validity of the SAS was supported with the Bidirectional Acculturation Scale.46 Only Hispanic participants complete this measure and data are used descriptively within the group.
Diagnosis and treatment history are abstracted from medical records following HIPAA authorization from the participant. Data are collected on a structured abstraction form that queries about disease, stage at diagnosis, and detailed treatment history. Medical data will be used for descriptive purposes.
The Multigroup Ethnic Identity Measure (MEIM)47 contains 15 items with two factors: 1) ethnic identity and affirmation and 2) belonging and commitment. This measure has been used in many studies and consistently shows good reliability (alphas above .80) across a wide range of ethnic groups and ages.
This questionnaire contains 29 items that query about traditional and nontraditional cultural beliefs and practices related to cancer. This measure is based on an extensive interview developed by Lannin and colleagues in a study of cultural factors in African-American and Non-Hispanic White breast cancer patients48 and further informed by studies of Hispanic cultural beliefs and practices.49–51
The Systems of Belief Inventory (SBI-15R)52 was developed for cancer patients/survivors and consists of 15 items and two subscales: religious/ spiritual beliefs and devotional practices and social support obtained from one’s religious peers and leaders.
Ten true/false items related to smoking were developed for this study based on information from the American Lung Association and the American College of Chest Surgeons.
This measure contains seven items that query about knowledge related to healthy eating. Questions were selected from those included in the Prototype Notebook for the Food Stamp Nutrition Education program that was developed by the USDA’s Economic Research Service in collaboration with Mathematica Policy Research, Inc.53
This questionnaire has eight items that ask about the recommended mode, frequency, duration, and intensity related to physical activity. Questions for this measure were drawn from Morrow et al. ’s54 interview on knowledge related to the Surgeon General’s report on physical activity.
This measure contains seven questions that assess the survivor’s knowledge of their cancer diagnosis, treatment, and potential late effects. These items come from the Childhood Cancer Survivors Study, a large multi-institutional study of a cohort of over 10,000 adult childhood cancer survivors.57 These data will be compared to the information obtained from the medical abstraction to evaluate the accuracy of survivors’ responses.
This measure contains two items and was based on a measure developed specifically for adult survivors of pediatric cancers by Eiser and colleagues.58 The first item asks respondents to rank on a scale of 1 to 5 (a lot less important to a lot more important), their perception of the importance of practicing certain health behaviors (i.e., eat a healthy diet), as compared to other individuals their age. Similarly, the second item queries about their perceived level of risk for developing a number of health conditions (i.e., cancer, lung problems) as compared to their peers.
Ten items from Sallis’s measure of self-efficacy for eating and exercise behavior were selected, after consultation with the author. This measure has strong psychometric properties.60 In our abbreviated version, seven items ask about healthy eating self-efficacy (eating low-fat foods and healthy portions despite high-fat temptations)., while three items assess exercise self-efficacy (i.e., beliefs about one’s ability to exercise five times a week in the face of barriers). In response to each item, participants rate how confident they are that they could really motivate themselves to do things like these consistently, for at least six months.” Ratings are made on a 5-point scale with responses ranging from “Sure I could not do it” to “Sure I could do it.”
This measure is an abbreviated version of Sallis’s social support for eating and exercise questionnaire. After consulting with the author, seven items were selected to assess social support for healthy eating and three items were selected to measure social support for exercise. Respondents rate on a five point scale (1 = none, 5 = very often) the frequency that friends and family have done or said certain things related to the respondents’ efforts to change dietary or exercise habits.
The SF- 36-item short-form health survey61 was constructed to survey health status in the Medical Outcomes Study. The SF-36 was designed for use in clinical practice and research, health policy evaluations, and general population surveys. The Sf-36 includes one multi-item scale that assesses eight health concepts: 1) limitation in physical activities because of health problems; 2) limitations in social activities because of physical or emotional problems; 3) limitations in usual role activities because of physical health problems; 4) bodily pain; 5) general mental health (psychological distress and well-being); 6) limitations in usual role activities because of emotional problems; 7) vitality (energy and fatigue); and 8) general health perceptions. This instrument has been widely used with diverse healthy and clinical populations and has good reliability and validity.62
The Modified Cumulative Illness Rating Scale63, 64 is administered to gain information on co-morbid conditions and late effects. This measure classifies comorbidities by 14 organ systems that may be affected and rates them according to severity from 0–4. This measure can generate four ratings including total score, number of categories endorsed, severity index (total score/number of categories endorsed), and number of categories at level 3.
Access to health care, health care utilization and health insurance status are being assessed by items drawn from the National Health Interview Survey, 2004.65
BMI is calculated as weight (kg)/height (m)2. Height is assessed using a portable stadiometer. Weight is assessed using a digital scale with shoes and outer clothing removed. To insure quality control, 10% of all subjects are weighed and measured a second time by a second research assistant.
The Brief Block 98 Food Frequency Questionnaire66 asks study participants to report on the frequencies and amounts of 60 different food items. The FFQ was developed from the NHANES III food intake data and includes a food list that was derived separately for African-Americans, Non-Hispanic Whites and Hispanics. Reliability and validity have been established for the measure in a wide range of age, gender, income, and ethnic groups.67, 68
The Modified Activity Questionnaire 69 assesses leisure and occupational activity, television viewing and inactivity due to disability. For leisure activity, respondents view a list of 29 popular activities (i.e. walking, jogging, gardening) and select those that they performed on at least 10 different occasions in the last year. Respondents then provide information on average frequency and duration for each activity. For occupational activity, respondents provide information on common activities performed at work and transportation to/from work. The MAQ has been used in a number of large studies with diverse samples, including cancer survivors70 and has well-established reliability and validity.69
Historical and current use of tobacco is being assessed by the “baseline luxury model” measure recommended by the Tobacco Working Group for use in the Behavior Change Consortium studies funded by the National Institutes of Health.71 This measure contains fourteen items that asks about current smoking, past smoking, quitting history, and other tobacco use.
Given the reliance on self-report measures that could invite socially desirable responses, the Marlowe-Crown Measure of Social Desirability72 is administered.
Estimating power for survey data which will be subsequently analyzed using complex regression models is a difficult task. For any given analysis, power will depend on not only the effect size of the variable(s) in question, but also on the number and effect size for the covariates in the model. For our purposes, a conservative approach is to think of the design as a simple two way factorial with race/ethnicity as one factor and cancer survivor status (yes/no) as the other, resulting in a 3 x 2 factorial. Although we are unlikely to achieve an exactly orthogonal result due to the departure from that should not be large. Equal allocation of cases to Non-Hispanic White, African-American and Hispanic assures maximal power for between group comparisons. For a continuous outcome, using Cohen’s (1988) (173) definitions of effect sizes, we find that the projected sample size of roughly 750 cases would allow us to detect effect sizes of approximately .2 or more for both main effects and the race/ethnic by survivor status interaction. The following table is based on calculations using PASS software. Results are shown in the table below.
|Fixed Effects ANOVA Power Analysis|
With the addition of covariates to the model, e.g. age, gender, SES, we would expect the error sum of squares to decrease and power to increase.
Most outcomes will be continuous but a few, e.g. marital status, will be categorical and require logistic regression. For dichotomous outcomes, power depends on the baseline probability, for example, it is easier to detect a between group difference of .4 versus .5 than a difference of .1 versus .2. For the latter comparison, which corresponds to an odds ratio of 2.2, we have 80 percent power for a dichotomous predictor, correlated with other IV’s at .2
The Chicago Healthy Living Study is designed to examine the health behaviors of adult African-American and Hispanic childhood cancer survivors and compare these to the health behaviors of their Non-Hispanic White and their non-cancer affected peers. The study seeks to recruit a sample that is majority Non-Hispanic White. Unlike CHLS, samples of previous childhood cancer survivor studies have been predominantly Non-Hispanic White.4, 10, 11, 13–17, 19–26, 57 For example, the Childhood Cancer Survivor Study (CCSS), perhaps the largest and most well-known study of adult survivors, has a sample that is 87% Non-Hispanic Whites, 2% African-Americans, and 5% Hispanics.57
Whereas CCSS includes non-cancer affected siblings as a comparison group, CHLS includes non-cancer affected peers. This is a major contribution to the literature as only one of the two published studies12, 18 that addresses health behaviors in African-American and Hispanic survivors included a non-cancer affected comparison group.18 Using a listed, targeted digit dial approach, CHLS will recruit 300 racially/ethnically matched non-cancer affected controls. Inclusion of the control sample will allow CHLS to provide important insight into the similarities and differences in health behaviors and their mediators between minority cancer survivors and their peers who have been unaffected by such an experience.
CHLS is further set apart from prior studies of health behaviors in adult childhood cancer survivors by its use of validated measures to assess diet, smoking and physical activity. Additionally, BMI is calculated based on a standardized measurement for height and weight, contrasted to much of the published work to date which relies upon self-report weight and non-standardized measures of health behaviors.11, 12, 14, 20, 22, 25, 27, 29
A final strength of CHLS is the underlying goal of collecting data that will inform future interventions. This goal guided much of the study methodology. Thus far, the majority of research on the diet, smoking and physical activity patterns of childhood cancer survivors has been descriptive.10–12, 14, 18, 19 Few studies have examined factors that potentially influence health behaviors and that require attention for interventions to be successful in promoting behavior change.16, 17, 22, 25 CHLS assesses a number of mediators whose selection was guided by the principals of well established health behavior theories. CHLS also includes socio-cultural mediators. Understanding the cultural beliefs and attitudes that are part of one’s “health culture” will be key in developing interventions that serve the needs of minority survivors.
In sum, studies of Non-Hispanic White survivors of childhood cancer report diet, physical activity and smoking behaviors similar to those in the general population. Few studies have considered the status of these behaviors in minority survivors of childhood cancers. Several lines of research support the rationale for the current study’s focus on minority survivors. First, health disparities are prevalent in minority populations, second up to 75% of adult survivors of childhood cancer experience adverse late effects of treatment. Third, obesity, CVD, and secondary cancers are late effects that may be amenable to preventive health behaviors. In the general population, minorities are more likely to exhibit high BMIs and fewer health promotion behaviors, have inadequate knowledge of preventive lifestyles and have less healthful attitudes than Non-Hispanic Whites. Thus, minority survivors of childhood cancer are potentially at higher risk than non-minorities for developing the late effects of obesity, CVD and secondary cancers. There is insufficient data to support or refute this hypothesis at this time. CHLS will provide critical data with which this hypothesis can be considered, and upon which appropriate interventions can be developed.
Grant sponsor: National Cancer Institute, Grant Number R01CA116750