the relationship between adherence and weight loss in a behavioral treatment program for overweight...

BEHAVIOR THERAPY 19, 25-33, 1988

The Relationship Between Adherence and Weight Loss in a Behavioral Treatment Program for Overweight Children

ALLEN C. ISRAEL, WENDY K. SILVERMAN, AND LAUREN C. SOLOTAR

State University o f New York at Albany

The adherence to programmatic assignments and its relationship to weight change were evaluated among families enrolled in a child weight-loss program. Overall adherence, as well as the contribution of subcategories (completing food intake and activity records, nutrition summaries, staying below calorie limits, meeting activity goals, and following cue control rules), were assessed. The results revealed that overall adherence as well as all subcategories of adherence were related to success during treatment. There was one exception to this finding-- meeting one's activity goals was not related to weight change during intensive treatment. Monitoring of food intake emerged as the best predictor of immediate success. These findings are discussed in the context of limita- tions on the degree of prediction achieved and in terms of a general construct of adherence. Relationships between some aspects of initial adherence and weight change during follow-up also emerged and within treatment weight loss did not add to the predictive value of these variables.

Despite appreciable progress in our knowledge, an important issue regarding the evaluation of the behavioral approach to the treatment of childhood obesity remains. This is the issue of adherence. Several aspects of this issue deserve attention. One concern is children's adherence to program behavioral assignments, e.g., modifying eating behavior and increasing activity level. Specifically, do participants actually perform the assignments prescribed by the program? A second aspect concerns the presumed relationship between behavior change assignments and improved weight loss. If program prescriptions are adhered to, are these behaviors actually related to weight loss? Furthermore, are certain aspects of behavioral programs more highly associated with improved weight loss than others? These aspects of the adherence issue are not only relevant to the relationship between program prescriptions and weight loss but they are also relevant to the more general issue of presumed mechanisms of behavior change as well (cf. Wilson & Brownell, 1980). The present study examined the problem of assignment adherence in a child weight-loss program.

This research was supported in part by grant number 1 RO 1 HD13460, awarded by the Na- tional Institute of Child Health and Human Development, Department of Health and Human Services. Requests for reprints should be sent to Allen C. Israel, Psychology Department, State University of New York at Albany, 1400 Washington Avenue, Albany, NY 12222.

25 0005-7894/88/0025-003351.00/0 Copyright 1988 by Association for Advancement of Behavior Therapy

All rights of reproduction in any form reserved.

26 ISRAEL, SILVERMAN, AND SOLOTAR

Client adherence to behavioral weight-loss assignments has been examined in only a few programs for adults (cf. Shelton & Levy, 1981). Although some investigators have reported a significant relationship between weight loss and prescribed behavioral activities (e.g., Katell, Callahan, Fremouw, & Zitter, 1979; Mahoney, 1974; Sandifer & Buchanan, 1983), others have reported a non- significant or a significant relationship with only one or two variables (Bel- lack, Rozensky, & Schwartz, 1974; Brownell, Heckerman, Westlake, Hayes, & Monti, 1978; Jeffery, Wing, & Stunkard, 1978; Stalonas, Johnson, & Christ, 1978). In addition to conflicting results, methodological problems exist in the ways in which adherence is typically assessed in these studies. Because of these problems of assessment, Stalonas and Kirschenbaum 0985) recently assessed clients' eating habits from three perspectives (self-report questionnaires, ther- apist ratings, and spouse ratings). The three assessment formats were all found to be equally strong and positively related to weight loss in addition to demon- strating considerable shared variance as predictors of weight loss. These results provide support for the importance of adherence to prescribed changes in eating habits and to improved methodology.

The need to examine adherence in the child area is even stronger since less is known. Coates and Thoreson's (1981) investigation of weight loss in two obese female adolescents suggests that adherence to treatment strategies is associated with weight loss, although different areas of adherence may be important for different participants. Epstein, Wing, Koeske, and Valoski (1984) reported that, of several behaviors they evaluated, only complete recording and limiting of the number of foods with high fat and high-sugar content were related to weight loss during initial treatment. None of the behaviors evaluated were related to long-term outcome.

The purpose of the present study was to further address the question of assignment adherence among families enrolled in a behavioral treatment program for childhood obesity. Of particular interest was the relationship between successful child weight loss and such adherence, and the relative contribution of different areas of adherence. Specifically, adherence to assignments was assessed during the intensive phase of treatment (weeks 1-8). The link between adherence and weight loss during this period and subsequent follow-up (26 weeks-1 year) was examined.

METHOD Subjects

Fifty-five children, ranging in age from 8 years, 4 months, to 13 years, 6 months (M = 10 yr, 4 mo), and at least one of their parents participated in treatment. The families were recruited through school nurses and other health professionals, word of mouth, and advertisements in local newspapers. All child participants (1) were at least 2007o above ideal weight for gender, age, and height, (2) received a release from a physician to participate, (3) had no concurrent involvement in other weight loss or psychological treatment(s), and (4) had at least one adult family member who agreed to attend all treatment sessions and participate in the program.

ADHERENCE AND WEIGHT LOSS 27

At the start of treatment, the children ranged from 21.73 to 86.99°70 overweight (M -- 47.79). Percentage overweight was calculated by assuming that "ideal" weight was the weight at the same percentile as the child's height. Per- centiles were based on comparisons with norms for the individual's gender and age.

Procedures Separate child and parent treatment groups comprised of four to six fami-

lies per group met for an orientation and eight weekly, 90-minute sessions during the intensive phase of treatment. Telephone calls were made between sessions to provide assistance with assignments and any problems that might arise. The treatment was a behavioral program based upon the "four prong" CAIR approach (cues/stimulus control, activity, intake, and reward) described in previous papers (cf. Israel, Stolmaker, Sharp, Silverman, & Simon, 1984; Israel, Stolmaker, & Andrian, 1985). In addition to information and discussion during each session, families were given homework assignments each week. These included monitoring eating and activity-related behavior, as well as en- gaging in and recording specific behavior change efforts. The specific content of assignments varied from week to week. Families were encouraged to in- volve the child in record-keeping as much as possible, although primary responsibility rested with the parent. Parents and children were instructed to complete certain assignments together, e.g., going over the day's food intake and calculating the number of calories consumed. Certain monitoring tasks ex- plicitly required the parent to include the child, e.g., foods consumed outside the home when the parent was not present. Due to this shared responsibility for assignment completion and record-keeping, adherence to the child's weight- loss program was conceptualized as family adherence rather than either child or parent adherence.

Following the intensive period of treatment, six sessions were scheduled at increasing intervals during an extended treatment phase (weeks 9-26). A follow- up was also conducted 1 year after week 26.

Assessment of Adherence Two types of adherence were measured. Adherence to monitoring tasks evalu-

ated the degree to which the family followed instructions to record certain aspects of their behavior. The second category of adherence addressed whether the family executed certain prescribed changes in their food- and activity-related behaviors. For example, recording the places in which one consumed food is an example of adherence to a monitoring task. However, following the recom- mendation to eat only in one place is an example of adherence to a prescribed change. This second category relied, as well, on the family's written report.

Degree of adherence was scored from the family's weekly homework sheets. The absence of a piece of information was considered as nonadherence to that aspect of the assignment in calculating adherence scores. Failure to complete an entire homework sheet, although rare, was considered as zero adher-


ence to that assignment. During the course of treatment, six different aspects of adherence were separately scored and evaluated. In addition, a measure of overall adherence was calculated. Completion of food intake records (IR) indicated the degree to which the family recorded all meals and snacks eaten. Each week families were also instructed to record other aspects of their intake such as amount, calories, or location where food was eaten. These additional categories varied from week to week. IR was a measure of monitoring and not an index of complying with other programmatic changes. Adherence to the task of completing food intake records was scored as a proportion of the information completed each week.'

Similar to IR, completion of activity records (AR) was a measure of the degree to which families completed activity monitoring. It was not an index of reaching activity goals. Similarly, nutritional summary (NS) was an index of monitoring. It refers to the families' recording of the nutritional category and food color group for all foods eaten. Food color group refers to a four- color system based on caloric density.

The remaining three adherence scores, in contrast to the above monitoring adherence scores, were indications of the degree to which particular categories of program recommendations were followed. It should be recognized, however, that they also are based on the families' report of actions taken rather than on some independent source of information. Thus, the use of this self- report measure of behavior change, without any independent or direct measure of such change, needs to be considered in any interpretation of findings. Calorie limit (CL) was an index of the degree to which assigned daily calorie limits were adhered. Activity goal (AG) indicated the average percentage of the prescribed minutes of exercise actually completed. Cue controls (CC) were a measure of the degreee to which families actually followed assigned cue control rules (e.g., eating in only one place).

Overall adherence (O) was indicated by a percentage score. Since actual assignments varied from week to week, adherence calculations vary weekly as well. This score, therefore, indicated the proportion of adherence for a particular week and allowed direct comparison and combination of weekly scores.

To evaluate the accuracy of adherence scoring, forty sets of a family's weekly records were randomly selected, so that one week's record was selected for each family and all treatment weeks were represented. These 40 records were scored by a second independent rater, and Pearson correlations were calculated for the two independent scorings. The obtained r's for overall adherence and each of the six subscores - IR, NS, CL, AR, AG, and C C - were .77, .98, .98, .99, .99, .99, respectively (all p's < .01).

RESULTS Adherence and Treatment Outcome

Table 1 presents the potential range and the means and standard deviations

~Further description of this and other scoring procedures for adherence can be obtained upon request from the authors.

ADHERENCE AND WEIGHT LOSS

TABLE 1 POTENTIAL RANGE AND MEANS OF ADHERENCE SCORES

29

Potential Mean Adherence category range (%) adherence

Overall (O) 0-100 74.34 (22.64)

Intake records (IR) 0-6 3.91 (1.14)

Activity records (AR) 0-16 10.76 (4.97)

Nutrition summary (NS) 0-4 2.98 (1.05)

Calorie limit (CL) 0-12 9.21 (2.98)

Activity goal (AG) 0-100 41.95 (37.45)

Cue controls (CC) 0-24 16.94 (6.56)

Note. Numbers in parentheses are standard deviations.

for obta ined adherence scores. Table 2 presents the correlat ions between the various adherence scores during intensive t reatment (weeks 1-8) and the change in the child's percent overweight dur ing this period.

The correlat ions among the various adherence scores are also presented in this table. The mean reduct ion in percent overweight for the children dur ing intensive t rea tment was 8.54°70 (SD = 5.38). Exa mi na t i on of Table 2 indicates that, overall, greater adherence was associated with greater reduct ions in per-

TABLE 2

CORRELATIONS AMONG ADHERENCE SCORES AND CHANGE IN

PERCENT OVERWEIGHT FOR AL~ FAMILIES

Change in % OW

Adherence scores

O IR NS CL AR AG CC

Overall (O) .39** Intake records (IR) .39** .83*** Nutrition summary (NS) .32* .75*** .58*** Calorie limits (CL) .28* .85*** .76*** .46*** Activity records (AR) .25* .76*** .52*** .62*** Activity goal (AG) .11 .46*** .24* .44*** Cue controls (CC) .35** .82*** .57*** .65***

.63***

.36** .48***

.65*** .61"** .41"**

* p < .05 ** p ~< .005 *** p ~< .001


cent overweight. This is also true for each of the separate adherence scores with one exception. The percentage of times that the activity goal was reached was unrelated to change in percent overweight. Furthermore, correlations among the adherence scores indicate that adherence to any one aspect of the program was associated with adherence in all other areas.

A step-wise multiple regression analysis was also conducted on the six separate adherence scores, using a 5°7o minimum increment/decrement in explained variance as a criterion for including or dropping additional predictors. Com- pletion of intake records (IR) was the only significant predictor. The squared multiple correlation was .20, and the standardized regression coefficient was .44.

Follow-Up The mean change in percent overweight from pretreatment to the follow-up

(approximately 18 months later) was a decrease of 4.56O7o (SD -- 14.80). The relationship between adherence during the intensive phase of treatment and change in weight status during the follow-up period (week 26-1 year later) was also examined. Data for 35 families was available for the follow-up period. Interestingly, monitoring adherence during the intensive phase and change in weight status during follow-up were inversely related. Intake record and activity record, both indices of monitoring during the intensive phase, produced negative correlations with change in the child's percent overweight during this follow-up period, r's (35) -- -0.31 and -0.33, both p's < .04. These were the only significant univariate correlations between adherence during treatment and change in percent overweight during follow-up.

A step-wise multiple regression analysis was performed with change in the child's percent overweight during the follow-up period (week 26-1 year) as the dependent variable. The six adherence subscores were used as predictors, and change in percentage overweight during the treatment period was also included as a predictor. A 5°7o minimum increment/decrement in explained variance was used as a criterion for including or dropping predictors. The results of the analysis indicate that completion of activity records (AR), staying below the calorie limit (CL), and completion of intake records emerged as significant predictors (squared multiple correlations were .10, .0025, and .10, respectively, and standardized regression coefficients were -.31, .41, and -.37, respectively).

DISCUSSION The present study examined adherence to assignments within a behavioral

weight control program for children and their relationship to weight loss. Levels of adherence were, in general, quite high. In addition, the various aspects of assignment adherence were, for the most part, positively and significantly related to weight loss during treatment, as indicated by the univariate correlations. The exception to this statement, meeting weekly activity goals, was characterized by lower levels and greater variability in assignment adherence. These findings, coupled with the relative lack of attention to the role of ac-


tivity modification in children's weight loss and previous findings (Epstein et al., 1984), suggest that this should be an important focus for future research.

Completion of intake records (IR) emerged from the multiple regression analysis as the best predictor of weight loss during the treatment period. The other measures of adherence did not add to the predictive ability offered by the IR measure. This finding might lead to the interpretation that completion of intake records represents the most important aspect of the treatment program. However, it may be the case that IR is simply the most sensitive index of a general construct of "adherence." The significant positive correlations obtained among the adherence measures would seem to provide support for the latter interpretation. The nature of the relative adherence tasks suggests one possible explanation as to why completion of intake records is the most sensitive measure of adherence. It is probably the case that IR is the most effortful of the recording tasks. In that sense, it may be most demanding on the families in terms of time and consistency. Completion of intake records also has multiple components. Given the view that each of the various aspects of programmatic recommendations is important to weight loss, it may be the case that IR is the most sensitive index of a general construct of adherence because it allows for more expression of variation in the families' initial com- mitment and consistency than do the other measures. It should be ac- knowledged that the degree of prediction suggested by the current regression analysis between assignment adherence and outcome is limited. Consistent with conceptualizations of compliance/adherence and outcome (e.g., Epstein & Cluss, 1982; Leventhal, Zimmerman, & Gutman, 1984; Sackett & Haynes, 1976), this may be attributable to current measurement strategies, questions of assignment adherence-behavior change relationships, issues of specific behavior change and changes in actual energy intake and output, and other related variables. These issues are further addressed below.

We also examined whether adherence during treatment was predictive of weight loss during the follow-up period. The child's weight loss during the treatment period was included as an additional potential predictor in this analysis. The factors, discussed above, related to limited predictability apply here as well. In addition, behavior during treatment would not necessarily be highly predictive of change during the later follow-up period. Behavior during this second period would more likely be closely related to outcome during this period. Although assessment of adherence during periods of follow-up presents a difficult challenge, the current results suggest that the patterns of adherence over time are an important area for future research. Three indices of adherence during treatment were, however, found to be predictive for later success- IR, CL, and AR. Interestingly, within-treatment weight change did not add to the predictive ability of these adherence variables. Staying below calorie limit during treatment was positively related to weight loss during the follow- up period. Completions of intake and activity records during the treatment period were both inversely related to weight loss during follow-up. It is possible that CL is a prescribed program behavior in which families tend to per- sist over time. Examination of individual family data suggests that the inverse


relationship found between IR and AR and weight loss is largely due to the fact that some of the families who fared rather poorly in their weight-loss efforts during intensive treatment were quite successful during the follow-up period. Thus, low initial adherence to these monitoring tasks occurred in some families who, during follow-up, did quite well in terms of weight loss. The present data cannot explain why this "sleeper" effect occurs.

Some of the measures focused on in this study assessed adherence to monitoring tasks, while others assessed adherence to prescribed change. How adherence is assessed is of both conceptual and methodological importance (cf. Epstein & Cluss, 1982; Gordis, 1976). Self-reports concerning adherence to monitoring assignments are essentially measures of the behavior of interest, i.e., monitoring/self-recording. In contrast, self-reports of adherence to prescribed behavior change may be viewed as more removed from the actual behaviors of interest and more subject to whatever distortions may be introduced by self-report. In the absence of evidence to indicate a significant relationship between this self-report data and other measures of the target behaviors, the present results could be viewed as limited. Indeed, we agree with this cautious approach. Two considerations do, however, support the utility of the present self-report measures of adherence to prescribed behavior change. All the measures of adherence were found to be intercorrelated and would thus seem to be tapping the same weight-loss-related dimension. This, of course, does not alone insure that this dimension is an accurate reflection of actual behavior. A second consideration is based upon recent findings that different assessment formats of Subjects' eating habits (self-report questionnaires, ther- apist readings, spouse ratings) demonstrate equally strong and positive associ- ations with weight loss as well as considerable overlap in the percent of variance in weight loss that each predict (Stalonas & Kirschenbaum, 1985). This suggests, therefore, that self-report is one method of describing the construct of target behavior change adherence. Nevertheless, further evaluations of criterion-related validity of the present method should, of course, be conducted.

Finally, two additional aspects of the current research and of the general compliance/adherence literature that address the issue of degree of prediction deserve mention. The current program, as do most others, makes use of group treatments. This requires participants to engage in a variety of assignments, only some of which may be germane to their problem. In addition, group data are relied upon. Thus variability among individuals regarding the existence of particular problems (e.g., rapid eating, more eating, low-activity level) may reduce obtained adherence-outcome relationships (Leventhal et al., 1984). Ad- herence to some tasks may be important for some individuals and not to others. The present study also sought to focus on the issue of adherence to program assignments and its relationship to outcome. This is indeed an important issue for behavior therapists in and of itself. However, links between assignment completion and actual behavior change, between particular behavior changes and changes in energy balance, and between energy balance and weight loss are parts of the complex task of addressing the problems of adherence and childhood obesity.


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RECEIVED: November 6, 1986 FINAL ACCEPTANCE: June 30, 1987

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