Journal of Pediatric Psychology,
Vol. 15, No. 5, 1990, pp. 633-641
Lisa B. Green, Tim Wysocki,2 and Barbara M. Reineck Ohio State University Received July 6, 1989; accepted October 27, 1989
Extended a study of diabetic adults which showed that fear of hypoglycemia is common and may affect diabetic control. That study evaluated the psychometric properties of the Hypoglycemic Fear Survey (HFS), an instrument designed to measure fear of hypoglycemia. The present study evaluated the psychometric properties of the HFS with diabetic youth. The HFS was completed by 128 Ss on arrival at a diabetes summer camp, by 127 Ss at the end of the 7-day camp, and by 74 Ss 12 weeks after camp. The results support the internal consistency and test-retest reliability of the HFS with this age group. Factor analytic and multiple regression techniques support the construct validity of the scale. HFS scores enhanced prediction of diabetic control. The HFS appears to be useful as a research tool with children and adolescents, although cross-validation is needed before clinical use can be justified. KEY WORDS: hypoglycemia; fear; diabetes; children; adolescents.
'This work could not have been completed without the cooperation of Timothy F. Reymann, Executive Director and Patricia Price, Youth Director, of the Central Ohio Diabetes Association. Ms. Reineck was supported in part by the Central Ohio Diabetes Association. This paper was presented at meetings of the Florida Conference on Child Health Psychology, Gainesville, April 1989, and the American Diabetes Association, Detroit, June 1989. An abstract reporting a portion of these data was previously published in Diabetes, 1989,38, Suppl. H2,109A. John R. Hayes provided statistical consultation. 2 All correspondence should be sent to Tim Wysocki, Children's Hospital F-241, 700 Children's Drive, Columbus, Ohio 43205. 633 OI46-8693/90/IO0O-O633J06.00/O © 1990 Plenum Publishing Corporation
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Fear of Hypoglycemia in Children and Adolescents with Diabetes1
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METHOD Participants The participants were recruited from among the 163 children who were at least 9 years old and were attending a 7-day diabetes summer camp. The
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Insulin-dependent diabetes mellitus (IDDM) is a common endocrine disorder characterized by defective glucose metabolism due to insulin deficiency (Travis, Brouhard, & Schreiner, 1987). Management of IDDM is directed at the maintenance of normal blood glucose concentrations through insulin injections, a prescribed diet, and exercise. Individuals with IDDM often suffer episodes of hypoglycemia (abnormally low blood glucose concentration) which may be manifested in such symptoms as nausea, dizziness, faintness, trembling disorientation, and irritability. If not interrupted by the ingestion of a high-carbohydrate food or drink, these episodes may culminate in hypoglycemic seizures. In a study of 158 adults with IDDM, Cox, Irvine, Gonder-Frederick, Nowacek, and Butterfield (1987) concluded that fear of hypoglycemia was prevalent and a significant determinant of glycemic control in these patients. They found that many of these patients acknowledged significant anxiety about the occurrence of hypoglycemic episodes manifested in such symptoms as the maintenance of marginally elevated blood glucose concentrations and premature treatment of apparent hypoglycemia. Their study included a report of the construction and validation of the Hypoglycemic Fear Survey (HFS), a 27-item scale for measuring this construct. The authors reported data confirming the internal consistency, construct validity, and test-retest reliability of the HFS, as well as providing a factor analysis of the scale responses. Irvine and Saunders (1989) reported a replication of these findings with a revised 23-item form of the HFS. Based on these studies, the HFS appears to be a reliable, valid, and convenient measure of fear of hypoglycemia among adults. Children and adolescents with IDDM quickly learn that hypoglycemic episodes are physically aversive, potentially dangerous, and a source of possible social embarrassment (Brouhard, 1987). Lacking the cognitive and emotional maturity which adults may enlist in coping with these threatening events, younger patients may be at an even greater risk for developing fear of hypoglycemia. The present study was undertaken in order to extend the work of Cox et al. (1987) to the pediatric age group. The primary purposes of the study were to evaluate the psychometric properties of the HFS with the pediatric age group, to analyze the factor structure of the scale, and to provide preliminary normative data for this age group.
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Procedure A revised form of the HFS (Irvine & Saunders, 1989) was obtained from the authors. The HFS is divided into two scales, Behavior (10 items) and Worry (13 items), which focus on the patient's actions and emotions about hypoglycemia, respectively. Each item requires the patients to respond on a 5-point Likert scale regarding the extent to which a given statement characterizes their actions and emotions surrounding hypoglycemia, ranging from (1) never, (2) rarely, (3) sometimes, (4) often, to (5) always. Cox et al. (1987) reported that the reading difficulty of the HFS is at the 4th- to 5th grade level. Administration time was approximately 10 min. Each participant completed the HFS upon arrival for registration for the camp. Sample items for the HFS are shown in Table I. During camp attendance, blood glucose concentrations were determined at least four times daily for each child, under the supervision of a nurse. These test results, as well as documentation of episodes of hypoglycemia, were recorded routinely for each patient by camp counselors or nursing staff on individual medical charts. A medical history form completed by the patients during the camp registration included information on the child's previous frequency of hypoglycemia and the presence or absence of hypoglycemic seizures. These various sources of information provided the following measures: mean blood glucose concentration (mg/dl) during the camp, number of episodes of hypoglycemia during the camp which were documented by
Table I. Sample Items From the Hypoglycemic Fear Survey Behavior scale 1. I eat large snacks at bedtime. 4. I keep my sugar high when I will be alone for awhile. 9. I avoid exercising when I think my sugar is low. Worry scale 12. I worry about not having food, fruit, or juice with me. 14. I worry about passing out in public. 18. I worry about no one being around to help me during a low blood sugar reaction.
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parents of each eligible child who had registered to attend the camp were contacted by mail with information about the study. An informed consent form was signed by both the parent and child and returned to the investigators on the first day of the camp. Of the 163 potential participants, consent to enroll in the study was obtained from 128 children and adolescents and their parents. Characteristics of the study participants were age, 12.5 ± 2.25 years; and duration of IDDM, 4.8 ± 3.24 years; 60 male and 68 female.
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RESULTS There was no significant loss of participants between the first (n = 128) and second (n = 127) HFS administrations. Student's t tests indicated that the 74 respondents to the third HFS administration did not differ from nonrespondents in terms of age, duration of diabetes, or scores on the first HFS administration. Chi-square tests revealed no differences in gender distribution between these groups. Table II presents the means and standard deviations for the Total, Behavior, and Worry scores obtained from each of the three administrations of the HFS. These scores were comparable with those found by Irvine and Saunders (1989) with diabetic adults. The scale scores were sufficiently variable to permit adequate sensitivity of the HFS and to justify further data
Table 11. Scores for Each of the Three HFS Administrations
Precamp HFS
Total Behavior scale Worry scale
Postcamp
12-week follow-up
M
SD
M
SD
M
SD
59.5 27.8 31.7
14.2 5.8 10.6
58.2 27.0 31.2
14.0 6.4 10.6
58.2 27.6 30.5
15.2 6.0 11.9
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a blood glucose concentration below 60 gm/dl and treated by a camp counselor or nurse, previous frequency of hypoglycemia (episodes/year), and previous history of hypoglycemic seizures. One child left the camp within 3 days due to illness and did not participate further in the study. The remaining 127 participants completed the HFS for a second time on the final day of camp attendance. Approximately 12 weeks after the conclusion of the camp, each participant was mailed another copy of the HFS along with a stamped envelope addressed to the investigators. Parents were asked to insist upon independent completion of the survey by their children. These mailed follow-up surveys were returned by 74 participants. Finally, 44 of the participants had received at least some previous medical care for IDDM at the Children's Hospital, Columbus, OH. Results of routinely obtained glycosylated hemoglobin (GHb) assays were retrieved from their medical records if the samples had been drawn within 90 days of the first day of the summer camp. This criterion was met for 39 of these participants.
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analysis. These analyses included assessments of the reliability, factor structure, and construct validity of the instrument. Reliability
Validity The results of the first HFS administration were submitted to confirmatory factor analysis using the Bentler EQS Structural equation model (Bentier, 1985). The generalized least squares solution was used to test the hypothesis that the HFS measures two independent factors that loaded on items from the Behavior scale and Worry scale. This model was not rejected, with x2(229) = 262.4, p < .06. Further, the obtained Bentler-Bonnett normed-fit index of .959 indicated an excellent fit of the hypothesized model to the data. The Behavior factor loaded significantly on 6 Behavior scale items, while the Worry factor loaded significantly on all 13 of the Worry scale items. In an effort to further evaluate the construct validity of the HFS, a stepwise multiple regression analysis was performed (SAS Institute, Inc., 1985). This analysis evaluated prediction of glycosylated hemoglobin values for the 39 participants for whom these data were available. These 39 participants differed from the remainder of the sample only in that their par-
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Internal consistency was calculated using Cronbach's (1951) alpha coefficient based on the scores from the first administration of the HFS. The obtained alpha coefficients for the Total, Behavior, and Worry scales were .85, .64, and .88, respectively. All 23 items were positively correlated with the Total scale. In order to determine if internal consistency of the HFS varied according to the child's age, the participants were divided into two groups based on a median split for age (at 152.5 months). Internal consistency of the HFS Total for the younger children (.86) was comparable to that of the older children (.84). Test-retest reliability was assessed by calculating Pearson correlation coefficients for the HFS Total, Behavior, and Worry scores at 1-week and 3-month intervals. One-week test-retest reliabilities were .85, .76, and .87 for the Total, Behavior, and Worry scales, respectively. Correlations between the postcamp and 12-week follow-up administrations were .62, .67, and .53, respectively. Finally, correlations between the first administration of the HFS and the 12-week follow-up administration were .44, .58, and .44 for the three scales. All correlations were significant at p < .0001.
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DISCUSSION
This study reported scores for the HFS for a large prediatric sample and evaluated certain psychometric properties of this instrument. Scores obtained on the HFS Behavior scale with our sample are virtually identical to Table III. Results of the Multiple Regression Analysis for the Prediction of Glycosylated Hemoglobin Values Variable
Beta weight
P
Age History of hypoglycemic seizures HFS worry scale (first administration) Mean blood glucose at camp Sex HFS behavior scale (first administration)
.57
.0002
-.36
.017
-.33
.021
.30 -.29
.023 .037
.26
.071
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ents reported a higher previous frequency of hypoglycemia, f(43) = —2.20, p < .034 (degrees of freedom were reduced to compensate for unequal variance between groups), perhaps reflecting the fact that these patients all received care for their diabetes at a tertiary care pediatric medical center. No other differences in measured demographic characteristics were found. Predictor variables included scores for the HFS Behavior and Worry scales for the first administration, as well as the participants' age, sex, duration of diabetes, presence of hypoglycemic seizures, previous frequency of hypoglycemia, mean blood glucose concentration during the camp, and the frequency of hypoglycemia at camp. The method used was forward stepwise regression with both F-to-enter and F-to-remove set at 1.0. Table III summarizes the results of this analysis, which yielded a multiple R of .74, accounting for 54.8% of the variance in GHb values. Scores for the first administration of the HFS Worry scale accounted for a significant proportion of the variance (p < .021), whereas scores from the first administration of the HFS Behavior scale approached significance (p < .071). Other variables that entered the model included age, mean blood glucose at camp, sex, and previous history of hypoglycemic seizures. Consequently, better diabetic control was associated with younger age, a history of hypoglycemic seizures, higher scores on the HFS Worry scale, lower mean blood glucose during camp, being female, and, very weakly, lower scores on the HFS Behavior scale.
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those reported by White, Johnson, Wolf, and Anderson (1989) with adolescents. Several lines of evidence suppor the reliability of the instrument. Measures of internal consistency suggest that it is a highly reliable instrument for use with adolescents and children as young as 9 years of age. The estimates of internal consistency obtained in this study are comparable to those reported by Cox et al. (1987) with an adult population. The stability of the instrument over time was demonstrated by its high test-retest reliability at a 1-week interval. The decline in the correlation coefficient over a 12-week interval, although still statistically significant, suggests that fear of hypoglycemia may be more labile over a longer time. Among the factors that could yield greater variability in hypoglycemic fear, perhaps the most important is parental anxiety and behavior surrounding hypoglycemic episodes. Several authors have reported that parental anxiety and behavior may influence children's responses to a variety of medical stressors (e.g., Jay, Ozolins, Elliott, & Caldwell, 1983; Melamed & Siegel, 1980; Siegel, 1988). Other evidence collected in this study supports the validity of the HFS. Confirmatory factor analysis showed that the obtained factor structure closely approximates the hypothesized structure. Also, the emergent factors are comparable to those reported by Cox et al. (1987) with adults, who noted that a single factor loading heavily on Worry items (eigenvalue = 7.4) accounted for 44% of the response variance. Although a rather small sample of subjects was available, the multiple regression analysis suggests that HFS scores enhance prediction of diabetic control, as assessed by glycosylated hemoglobin levels. Differing from the conclusions of Cox et al. (1987), higher scores on the Worry scale were predictive of lower GHb values among children and adolescents. This may indicate that, in the pediatric age group, the HFS Worry scale measures a more general anxiety about diabetic control which may mediate avoidance of both hypoglycemia and hyperglycemia. Although the multiple regression analysis confirms that HFS scores enhance prediction of diabetic control, the findings also suggest that the construct measured by this instrument may function differently in the pediatric age group compared with adults. Further, the results suggest that anxiety related to hypoglycemia may serve a therapeutic function in the pediatric age group. Additional study of the construct validity of the HFS in the pediatric age group is needed. Consistent with the results of White et al. (1989), scores on the HFS Behavior scale contributed little to the prediction of GHb values. This may be a function of the high intercorrelation between scores on the Worry and Behavior scales (r = .42; p < .01). Otherwise, the influence of multicollinearity appeared to be minimal since the only other significant intercorrelation was between sex and history of hypoglycemic seizures (r = - .43; p < .01), indicating that females reported more seizures.
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REFERENCES Bentler, P. M. (1985). Theory and implementation o/EQS: A structural equations program. Los Angeles: BMDP Statistical Software. Brouhard, B. H. (1987). Hypoglycemia. In L. B. Travis, B. H. Brouhard, & B. J. Schreiner (Eds.), Diabetes mellitus in children and adolescents {pp. 169-178). Philadelphia: W. B. Saunders. Cox, D. J., Irvine, A., Gonder-Frederick, L. A., Nowacek, G., & Butterfield, J. (1987). Fear of hypoglycemia: Quantification, validation and utilization. Diabetes Care, 10, 617-621. Cronbach, L. (1951). Coefficient alpha and the internal structure of tests. Psychometrika, 16, 297-334. Irvine, A., & Saunders, T. (1989). Fear of hypoglycemia: Replication and validation. Diabetes, 38 (Suppl. 2). 109A.
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Some limitations of this study merit discussion. First, although 127 of the original 128 participants completed both the first and second administrations of the HFS, the response rate declined to 74 participants at the 12-week follow-up. There appeared to be no systematic loss of participants, in that these 74 participants were representative of the study sample along all of the pertinent dimensions that assessed. Second, the multiple regression analysis included the data from only a small subset (n = 39) of the original sample of participants. Not only was this a small sample relative to the number of variables entered into the multiple regression analysis, but also these children may not have been representative since they all received care for IDDM at a large tertiary care pediatric hospital. However, the participants included in this analysis did not differ significantly from the other participants in terms of HFS scores, age, sex, duration of diabetes, or diabetic control during the camp. Cross-validation of the HFS is needed to clarify these issues. A third limitation of this study is that all participants were children who chose to attend a diabetes summer camp. These children and adolescents may differ in important ways from others with IDDM, including family support, knowledge of diabetes, and other factors. However, the participants represented a broad range of demographic and disease-related characteristics and their HFS scores varied over an equally broad range. As noted earlier, White et al. (1989) reported virtually identical scores on the HFS Behavior scale with their sample of 81 adolescents. Replication of the present study with a nonselected sample of children and adolescents with IDDM could clarify this concern. The results of this study indicate strong support for the reliability of the HFS and some support for its validity. As a result, the HFS appears to be an acceptable research tool for use with children and adolescents with IDDM. The clinical application of the HFS should await further verification of its validity.
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Jay, S. M., Ozolins, M., Elliott, C. H., & Caldwell, S. (1983). Assessment of children's distress during painful medical procedures. Health Psychology, 2, 133-147. Melamed, B. G. & Siegel, L. J. (1980). Behavioral medicine (pp. 307-355). New York: Springer. SAS Institute, Inc. (1985). SAS User's Guide: Statistics, Version 5 Edition. Cary, NC: Author. Siegel, L. J. (1988). Dental treatment. In D. K. Routh (Ed.), Handbook of pediatricpsychology (pp. 448-459). New York: Guilford. Travis, L. B., Brouhard, B. H., & Schreiner, B. J. (1987). Diabetes mellitus in children and adolescents. Philadelphia: W. B. Saunders. White, N. H., Johnson, P. D., Wolf, F. M., & Anderson, B. J. (1989). Behaviors aimed at avoiding hypoglycemia in adolescents with IDDM. Diabetes, 58(Suppl. 2), 8A.