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Journal of Clinical Psychology in Medical Settings

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Style file version Oct. 19, 2000

C 2002) Journal of Clinical Psychology in Medical Settings, Vol. 9, No. 2, June 2002 (°

The Beliefs About Medication Scale: Development, Reliability, and Validity Kristin A. Riekert1,3 and Dennis Drotar2

The purpose of the study was to develop and evaluate a psychometrically sound health belief measure, the Beliefs About Medication Scale (BAMS) that can be used with adolescent chronic illness populations whose prescribed treatment includes oral medication. One hundred and thirty-three adolescents (age 11–18 years) with asthma (n = 60), HIV (n = 31), or inflammatory bowel disease (n = 42) completed the BAMS and, along with their parent, a self-report medication interview. A confirmatory factor analysis supported the hypothesized subscales of Perceived Threat, Positive Outcome Expectancy, Negative Outcome Expectancy, and Intent to Adhere to treatment. The subscales evidenced good internal consistency and 3-week test-retest reliability. Univariate and multivariate analyses demonstrated that the health belief constructs accounted for 22% of the variance in medication adherence beyond demographic and illness characteristics. The study provides preliminary evidence of the reliability and validity of a theoretically based measure of health beliefs for adolescents. The BAMS may be a useful tool to evaluate the psychological barriers to adherence that place teenagers at risk for nonadherence. KEY WORDS: adherence; compliance; health beliefs; attitudes; social cognitive theory.

An estimated 31% of children in the United States are affected by chronic health conditions (Newacheck & Taylor, 1992). Data from the pediatric chronic health conditions literature suggest that rates for medication nonadherence vary from 21 to 52% (e.g., Ettenger et al., 1991; Meyers, Thompson, & Weiland, 1996; Schoni, Horak, & Nikolaizik, 1995). Most studies find, when examined by broad developmental stages (e.g., child, adolescent, adult), that nonadherence is more prevalent during adolescence (e.g., Ettenger et al., 1991; Kovacs, Goldston, Obrosky, & Iyengar, 1992). Nonadherence can lead to unnecessary hospitalizations, diagnostic tests, increased medical complications, and risk to patients’ lives (DiMatteo, 1994; Dunbar-Jacob, 1993; Fotheringham

& Sawyer, 1995). Moreover, in some instances, nonadherence may account for some of the unexplained relapses seen in children and adolescents with certain chronic health conditions (Davies & Lilleyman, 1995; Ettenger et al., 1991). Furthermore, during adolescence, children begin to assume more independent responsibility for their own treatment adherence. Consequently health professionals require the means to assess which adolescents and families will be at risk for nonadherence and evaluate their unique set of barriers to optimal adherence. An individual’s beliefs and attitudes about one’s illness and treatment have been found to be related to treatment adherence (Gochman, 1997; Janz & Becker, 1984; Norman & Conner, 1996). Health professionals, therefore, would benefit from tools to evaluate health beliefs that may place teenagers at risk for nonadherence with medication regimens. Unfortunately, the evaluation of health beliefs has been hampered by many methodological limitations. These problems include the use of unstandardized measures with unknown reliability and validity and a lack of theoretical consideration for the inclusion of items

1 Department

of Psychology, Case Western Reserve University, Cleveland, Ohio. 2 Division of Behavioral Pediatrics & Psychology, Rainbow Babies’ and Children’s Hospital, Cleveland, Ohio. 3 Correspondence should be addressed to Kristin A. Riekert, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, 5501 Hopkins Bayview Circle, Baltimore, Maryland 21224; e-mail: [email protected].

177 C 2002 Plenum Publishing Corporation 1068-9583/02/0600-0177/0 °

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178 (Boer & Seydel, 1996; Maddux & DuCharme 1997; Strecher, Champion, & Rosenstock, 1997). One reason for the lack of well-validated measures is that many scales focus on combinations of adherence behaviors for a specific chronic health condition rather than one adherence behavior common across many chronic conditions. This research strategy necessitates developing a different measure for every illness. Despite the potential utility of a cross-disease measure of health beliefs about a specific adherence behavior (e.g., taking medication, dietary restrictions, exercise), to our knowledge, no such measure has been developed and validated for children or adolescents with chronic health conditions. To address this need, the primary goal of this study was to assess the reliability and construct/ criterion validity of the Beliefs About Medication Scale (BAMS). The BAMS was designed to assess health beliefs concerning one domain of adherence behaviors (i.e., oral medication use) that involves similar adherence behaviors across many chronic health conditions. This focus on a specific behavioral domain has the advantage of detailed measurement of medication-specific health beliefs and adherence. Moreover, this approach allows direct comparisons of adherence behaviors among adolescents with diverse chronic health conditions. Adolescents with three chronic health conditions were included in the sample to enhance and evaluate the generalizability of results across illness groups. To develop the BAMS, major health belief theories were critically reviewed, including the health belief model, protection motivation theory, theory of planned behavior/theory of reasoned action, and selfefficacy theory (Bandura, 1997; Boer & Seydel, 1996; Janz & Becker, 1984; Maddux & DuCharme, 1997; Rogers & Prentice-Dunn, 1997). An integrated conceptual model of the relationship between health beliefs and adherence behaviors was synthesized from these theories. Based on previous research and theory, primary constructs in this hypothetical model included Perceived Threat, Positive Outcome Expectancy, Negative Outcome Expectancy, and Intent. Perceived Threat is composed of two related concepts: perceived severity and perceived susceptibility of the illness. Adolescents with higher Perceived Threat have been found to have poorer adherence to diabetes regimens (e.g., Bond, Aiken, & Somerville, 1992). Positive Outcome Expectancy is defined as one’s beliefs about the physical, emotional, and social benefits of taking the medicine. More perceived benefits (i.e., Positive Outcome Expectancy) are related


Riekert and Drotar to better adherence in teenagers with diabetes (e.g., Palardy, Greening, Ott, Holderby, & Atchison, 1998). Negative Outcome Expectancy includes beliefs about potential psychological barriers to performing the adherence behavior, and the consequences resulting from performing the adherence behavior. Higher perceived barriers (i.e. Negative Outcome Expectancies) to adherence are linked with poorer treatment adherence among adolescents with diabetes and cancer (e.g., Bond et al., 1992; Palardy et al., 1998; Tamaroff, Festa, Adesman, Walco, 1992). Although the relationship between adolescent’s adherence intentions and actual adherence behaviors has not been studied, adults’ intention to perform adherence behaviors predicts the performance of such behaviors (Flynn, Lyman, & Prentice-Dunn, 1995; Randall & Wolfe, 1994). We hypothesized that a confirmatory factor analysis (CFA) would support the assumption that the BAMS measures these four health belief constructs. At the univariate level, it was hypothesized that Positive Outcome Expectancy and Intent would be positively correlated with adherence to treatment, whereas Perceived Threat and Negative Outcome Expectancy would be negatively correlated with adherence to treatment. It was hypothesized that these relationships would hold true for all illness groups. At the multivariate level, it was hypothesized that health beliefs would account for a significant proportion of variance in adherence behaviors beyond that predicted by demographic and illness variables.

METHODS Participants Participants were 133 adolescents with one of the following chronic illness conditions: asthma (n = 60), human immunodeficiency virus (HIV; n = 31), and inflammatory bowel disease (IBD; n = 42). Participants were recruited from specialty clinics at Rainbow Babies and Children’s Hospital, Cleveland, OH, and the HIV/AIDS Malignancy Branch at the National Cancer Institute, Bethesda, MD. These three chronic health conditions were chosen because they all require daily oral medication use. To be eligible to participate in the study, adolescents had to be between the ages of 11 and 18 years and prescribed oral medication (e.g., pills, liquids, inhaler) to be taken on a daily basis. Adolescents were excluded from the study if they had a disease duration

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of less than 1 year or obvious developmental delays that would prevent them from completing the study requirements. One hundred and eighty-one adolescents were asked to participate in the study (82 with asthma, 32 with HIV, and 67 with IBD) and 75% agreed to participate in the study (73% with asthma, 97% with HIV, 66% with IBD). Reasons for refusal to participate in the study included no time (42%), teenager not interested (19%) and mother not interested (11%), and other (28%). Two adolescents with IBD were subsequently dropped from the study because they had been diagnosed less than 1 year. Fifty families were asked to participate in the test-retest portion of the study. Fifty families agreed, but only 27 mailed back the measures, representing 20% of the total sample. Sample demographic data are presented in Table I. The total sample included adolescents with a mean age of 14.2 years. The adolescents with asthma were significantly younger than the adolescents with IBD or HIV. The sample was almost evenly split between males and females. Overall, one fourth of the adolescents were members of ethnic minority groups, primarily African American. Adolescents with IBD were significantly more likely to be Caucasian than the teenagers with asthma or HIV, reflecting the epidemiology of the illness. The families in the total sample represented a wide range of socioeconomic status with annual household incomes ranging from less than $10,000 (8%) to over $100,000 (8.0%). The groups did not differ on physician rated illness severity, but did differ on duration of illness and number of medications prescribed, reflecting the epidemiology of the illnesses and the standard prescribed medication regimens.

Measures

Beliefs About Medication Scale The BAMS is a 59-item scale that asks adolescents to independently rate, on a 7-point Likert scale, how much they agree or disagree with statements about their illness and its treatment. The endpoint anchors of the scale were strongly disagree and strongly agree, except for four intent items, which had the anchors of definitely not likely and definitely likely. Previous health belief studies were utilized as the primary means of item generation. Therefore, many BAMS items are similar to those that have previously been found to be associated with adherence behaviors, except they have been rewritten to remove illness-specific references and to make them specific to medication use. Additional items were generated from the operational definitions of the health belief constructs and from informal consultation with health professionals involved in the treatment of adolescents with chronic health conditions (e.g., pediatric psychologists, social workers, and nurse practitioners) in an attempt to sufficiently represent the broad constructs. There were four hypothesized subscales: Perceived Threat (e.g., “I do not think my illness is a serious illness,” “I think I will become sicker than I am right now”), Positive Outcome Expectancies (e.g., “If I take my medicine the way the doctor says I should, it helps keep me feeling well,” “I want to take my medicine the way the doctor says I should because it matters to people I care about”), Negative Outcome Expectancies (e.g., “The side effects of my medicine are so bad that I do not want to take it,” “It is embarrassing for me to take my medicine in front of people I do not know”), and Intent (e.g., “I want to take every dose of

Table I. Demographic and Illness Characteristics Variable Age, M (SD) Gender (% male) Ethnicity (% Caucasian) Yearly household income (%) ≤$19,999 $20,000–59,999 ≥$60,000 Illness duration, M (SD) Physician rated severity (%) Mild Moderate Severe # Medications prescribed, M (SD)

Total (N = 133)

Asthma (n = 60)

HIV (n = 31)

IBD (n = 42)

14.2 (2.0) 54.9 75.2

13.5 (1.9) 58.3 63.3

15.0 (2.0) 61.3 77.4

14.7 (1.7) 45.2 90.5

18.4 44.8 36.8 8.1 (3.9)

20.3 45.7 33.9 10.0 (3.3)

29.6 44.4 25.9 10.0 (2.1)

7.7 43.6 48.7 4.4 (2.7)

34.1 45.0 20.9 3.8 (2.5)

35.0 50.0 15.0 2.8 (1.6)

33.3 40.0 26.7 6.0 (2.9)

33.3 41.0 25.6 4.0 (2.4)

F(2, 130) = 8.71, χ 2 (2) = 2.38, χ 2 (2) = 9.87, χ 2 (4) = 6.94,

p < .001 p = .304 p = .007 p = .139

F(2, 121) = 51.67, p < .001 χ 2 (4) = 2.56, p = .634

F(2, 130) = 20.93, p < .001

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180 my medicine the way the doctor says I should,” “What are the chances that you will miss at least one dose of your medicine?”).

Demographics Questionnaire The demographic questionnaire included questions such as the adolescent’s age, gender, ethnicity, and age at diagnosis. The parent was asked questions about the highest level of schooling completed by the mother and father, mother and father’s occupations, and mother’s marital status.

Physician Form The physician was asked, using a single item, to give a gross assessment (mild, moderate, or severe) of the adolescents’ illness severity relative to other adolescents with the same illness.


Riekert and Drotar ment. The first author or research assistant briefly explained this study to the family and assessed whether the adolescent met the eligibility criteria. If they agreed to participate in the study, the parent, typically the mother signed the consent form and the adolescent signed an assent form. The Medication Interview was completed with the parent and adolescent. The adolescent then completed the BAMS independently. After the medical appointment, the adolescent’s physician (or nurse practitioner for the adolescents with HIV) was given the Physician Form. Because adolescents who are nonadherent to their medical regimen often choose not to participate or fail to complete research requirements (Riekert & Drotar, 1999; Roberts & Wurtele, 1980), a raffle for $20 gift certificates to a national retail electronics store was held as an incentive to participate in the study. The Institutional Review Boards at both sites approved this protocol.

RESULTS

Medication Interview The semistructured interview took approximately 10–15 min and yielded a retrospective report of the adolescent’s medication adherence during the week prior to enrollment in the study. For each medication prescribed, the adolescent was asked about doses missed, doses taken early or late (defined as ±1 hr), and doses where more or less medication than prescribed was taken. The questions were directed toward the teenager, but occasionally the teen asked the parent to help with the interview or a parent corrected the adolescent. The interviewer then asked the adolescent if he/she agreed with their parent and did not proceed until consensus was reached. The primary outcome variable for this study was the percentage of the total number of doses prescribed taken exactly as prescribed (e.g., the percent of prescribed doses taken at the correct time and correct amount per dose). This variable served as the primary variable to assess the criterion validity of the BAMS. The questions on this interview were based on an existing adult medication adherence interview (Williams, Rodin, Ryan, Grolnick, & Deci, 1998). Procedures The first author or a research assistant approached the family when they arrived for the clinic appoint-

The results of the study are presented in three sections. First is a description of the adolescents’ adherence to their medication regimens. The second section provides a detailed description of the development of subscales for the BAMS. A CFA was used to evaluate the construct validity of competing hypothetical models of the factor structure of the BAMS. Based on the results of the CFA, subscales were developed. Descriptive and reliability data are provided for each subscale. The final section provides data on the criterion validity of the BAMS by using correlations and hierarchical multiple regression analyses to test a priori hypothesized univariate and multivariate relationships between the BAMS subscales and medication adherence

Description of Adolescents’ Medication Adherence The average adherence level based on the Medication Interview “total number of doses taken exactly right” was 73.25% (SD = 24.24, range 0–100%). Fifty percent of the sample reported taking less than 80% of their prescribed medication “exactly right” the week prior to their medical appointment. The three illness groups did not differ on adherence with 56, 37, and 50% of the adolescents with Asthma, HIV, and IBD respectively reporting