a Research and Evaluation, Kaiser Permanente Southern California, Pasadena, California
b Children's Hospital Medical Center, Cincinnati, Ohio
c Children's Hospital and Regional Medical Center, Seattle, Washington
d Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center, Denver, Colorado
e Division of Diabetes Translation, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia
f Department of Public Health Sciences, Wake Forest University Health Sciences, Winston-Salem, North Carolina
g Arnold School of Public Health, University of South Carolina, Columbia, South Carolina
h Pacific Health Research Institute, Honolulu, Hawaii
| ABSTRACT |
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METHODS.A total of 2672 youth (aged 1021 years) who had diabetes for a mean duration of 5 years completed a SEARCH study visit, in which their HbA1c was measured and information about their demographic characteristics, diabetes type and duration, and episodes of DKA, hypoglycemia, hospitalizations, and ED visits over the previous 6 months was collected. Their level of depressed mood was measured using the Center for Epidemiologic Studies Depression Scale (CES-D).
RESULTS.Among these youth, 14% had mildly (CES-D 1623) and 8.6% had moderately or severely (CES-D
24) depressed mood. Females had a higher mean CES-D score than males. After adjusting for demographic factors, and duration of diabetes, we found the prevalence of depressed mood to be higher among males with type 2 diabetes than those with type 1 diabetes and to be higher among females with comorbidities than those without comorbidities. Higher mean HbA1c and frequency of ED visits were associated with depressed mood. The prevalence of depressed mood among youth with diabetes was similar to that of published estimates of depressed mood among youth without diabetes.
CONCLUSIONS.Physicians and other health care professionals should consider screening youth with diabetes for depressed mood in clinical settings, particularly youth with poor glycemic control, those with a history of frequent ED visits, males with type 2 diabetes, and females with comorbidities.
Key Words: adolescent depression diabetes type 1 diabetes type 2 health service utilization
Abbreviations: HbA1cmean glycosylated hemoglobin DKAdiabetic ketoacidosis EDemergency department CES-DCenter for Epidemiologic Studies Depression MODYmaturity-onset diabetes of youth CDCCenters for Disease Control and Prevention ORsodds ratios CIsconfidence intervals
Diabetes mellitus is 1 of the 3 most prevalent chronic diseases among youth, with the majority of affected youth having type 1 diabetes.1 Although numerous studies have shown an association between diabetes and depression among adults,26 only a few studies of depression have been conducted among youth with diabetes. Most have been small cross-sectional studies and have included only youth with type 1 diabetes. In a longitudinal study, Kovacs et al7 estimated that rates of psychiatric disorders were up to 3 times higher among youth with diabetes than among unaffected youth, with major depression accounting for the largest proportion of these disorders. Norris and Klingensmith8 found that, like among adults, adolescents with diabetes have more depression than those without diabetes and that rates of depression are higher among females than among males. The extent of the association between metabolic control and depression among adolescents remains unclear. In a review article on this topic, Dantzer et al9 reported that only 210, 11 of 8 studies found an association between depression and poor metabolic control. La Greca et al12 reported that gender-related differences in metabolic control during adolescence were associated with differences in the frequency of depressive symptoms, with female adolescents experiencing more depressive symptoms and poorer metabolic control than males.
Estimates of the prevalence of depressed mood among youth vary by study design, the screening or diagnostic tool used, the diagnostic criteria used, and the training of the interviewers.13 Estimates of the point prevalence of depressive disorders among adolescents range from 2% to 10%,14, 15 whereas the cumulative prevalence of depression during the adolescent period has been reported to be as high as 20%.16 Depression during adolescence has been associated with a variety of factors, including female gender, race or ethnicity other than non-Hispanic white, not living with both parents, lower parental education level, and lower socioeconomic status.14, 1721
In this study, we examined the prevalence of depressed mood among youth with diabetes and explored the associations between depressed mood among youth with diabetes and the duration and type of diabetes, mean glycosylated hemoglobin (HbA1c) level, comorbidities, use of psychiatric medications, and frequency of diabetic ketoacidosis (DKA) hypoglycemia, emergency department (ED) visits and hospitalizations in the previous 6 months after adjusting for sociodemographic variables that have been associated with depressed mood in published studies.
| METHODS |
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Of the 8784 youth newly diagnosed with diabetes through December 31, 2003, that were identified by SEARCH whose diabetes was not secondary to other conditions, 3866 (44%) participated in a SEARCH study visit. Reasons for nonparticipation included a decision by youth or their parents/guardians not to participate, the nonresponse of potential participants after repeated attempts to contact them by telephone or mail, and lack of contact information on potential participants because of privacy rules of the Health Insurance Portability and Accountability Act (HIPAA).
Before the study was implemented, Institutional Review Board(s) for each site approved the study protocol. At the time of the study visit, informed consent was obtained from participants aged 18 or older and from the parent/guardian of participants aged 17 or younger, and physical measurements and fasting blood samples were taken. Interviewers elicited information about participants' demographic characteristics, comorbidities and complications, current treatment and medications, and use of health care services. Participants who were at least 10 years of age completed the Center for Epidemiologic Studies Depression (CES-D) scale. CES-D scores were not determined for youth from 1 of the 4 Native American sites because an abbreviated study protocol that did not include the CES-D was implemented in that location. Those participants who scored high on the CES-D were referred to mental health services in accordance with site-specific guidelines, and their parents/guardians were notified if they were minors. All study questionnaires were administered in the preferred language of the participant, which was English or Spanish in most cases
CES-D
The CES-D is a 20-item scale originally developed to measure depressive symptomatology in adult populations,23 and it has subsequently been used in studies of youth as young as 12 years of age.17, 20, 24, 25 Respondents are asked how often they experienced 16 symptoms of depression and 4 symptoms of mental well-being during the previous week using a 4-point Likert scale (0, 1, 2, and 3). Their responses to each item are then added to create a single composite score, ranging from 0 to 60. In adult populations, a score of 16 or higher has been used to identify persons with depressive symptoms.23 When this cut point has been used for studies of adolescents, it has yielded rates of depressed mood that have approached 50%, and reports on its sensitivity and specificity have been mixed.2629 A cut point of 24 for adolescents was suggested to improve the correlation of "depressed mood" as determined by the CES-D with "depression" as defined by the Diagnostic and Statistical Manual of Mental Disorders.30 Rushton et al19 adopted this cut point to stratify depression severity as minimally (015), mildly (1623), and moderately/severely (2460). We used their 3-category stratification for the present study.
Participants' type of diabetes was based on the clinical diagnosis made by their physician or other health care provider and was collected from these providers, abstracted from medical charts, or reported by the participant. Youth with a clinical diagnosis of type 1a, type 1b, or type 1 diabetes were considered to have "type 1," whereas those with a diagnosis of type 2 or maturity-onset diabetes of youth (MODY) were considered to have "type 2." Youth with a clinical diagnosis of other or unknown types of diabetes and those whose type was missing were considered to have diabetes of "other/unknown/missing type."
We considered participants to have comorbidities (kidney disease, celiac disease, hypertension, asthma, or polycystic ovarian syndrome) if they reported having been diagnosed with
1 of these conditions. Participants or their parents/guardians reported the number of hospitalizations and ED visits and episodes of DKA and severe hypoglycemia that participants experienced in the previous 6 months. Hospitalizations and ED visits were not restricted to those for diabetes. Participants were also asked to report all prescribed medications that they were currently taking. Medications that fit into the antidepressant, antianxiety, or antipsychotic/antimanic drug classes were considered to be psychiatric medications.
Glycemic Control
Blood samples were processed locally and shipped on ice to a central laboratory (Northwest Lipid Laboratory, University of Washington, Seattle, WA) for analysis. A dedicated ion exchange unit, Variant II (Bio-Rad; Diagnostics, Hercules, CA), quantified the HbA1c. The reference range for normal HbA1c values is 3.9% to 6.1%. Optimal goals for HbA1c in youth are <8.0% for 10- to 12-year-olds, <7.5% for 13- to 18-year-olds, and <7.0% for >18-year-old.31
We calculated participants' body mass index (BMI) by dividing their measured weight in kilograms by their measured height in meters squared. We defined overweight as a BMI at or above the 95th percentile for one's gender and age based on algorithms prepared by the US Centers for Disease Control and Prevention (CDC) from 2000 CDC growth chart data.32, 33
Participants' race and ethnicity, ascertained from the standard census questions,34 parental education, household income, family composition, and insurance status were ascertained from participants' self-reports. Participants were categorized as living in a 2-parent household, a 1-parent household, or other living situation. Their insurance status was classified as private insurance (provided by an employer or purchased by the participant or their family), state-funded (a category that included Medicaid, Medicare, and other state funded sources), other forms (including Indian Health Service, student health clinics, military, or other/unknown sources), and no insurance.
Statistical Analysis
We used SAS 8.02 (SAS Institute, Cary, NC) for all statistical analyses. Analysis of variance and t tests were used to test for significant differences in continuous variables and
2 analyses for differences in categorical variables. Polychotomous logistic-regression analyses were used to adjust for potential confounders when examining the associations between diabetes-related factors (diabetes type and duration) and the 3 levels of depressed mood. In these models, participants with minimally depressed mood (defined as a CES-D score of <16) served as the reference group for those in the 2 higher categories of depressed mood. Odds ratios (ORs) and 95% confidence intervals (CIs) are shown for these models. Level of depressed mood is the dependent variable for these analyses.
We used Poisson regression to estimate the risk ratios for episodes of DKA, hypoglycemia, hospitalizations, and ED visits and the general linear model procedure to calculate the least square means HbA1c among participants with mildly and moderately/severely depressed mood compared with participants with minimally depressed mood. Level of depressed mood is an independent variable in these models. Analyses were limited to youth with diabetes for at least 1 year because we wanted to exclude events associated with diagnosis and the acute phase of the preliminary illness. In addition to demographic and diabetes-related variables, these models were adjusted for participants' use of psychiatric medication because of a suggestion by Musselman et al35 that glucose regulation may be affected by depression.
For all of the models described here, participants for whom we had incomplete information on the covariates of interest were excluded from the models.
Because the CES-D was administered to youth as young as 10 years of age, we compared the internal consistency of the scale for youth aged 10 to 11 years of age with that for youth in the other age strata using Cronbach's
.36 Because females are known to have higher rates of depression, we stratified all analyses by gender. Results that apply to only 1 gender have that gender indicated in parentheses. Of the 2813 youth aged 10 years or older who completed the study visit in the sites where the CES-D was administered, 2672 (95%) had a valid score on the CES-D.
| RESULTS |
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Participants' mean score on the CES-D was 10.7 ± 8.6 (range: 050; median: 8.5) (Table 2); 77.4% reported no or few depressed symptoms ("minimal depressed mood"), 14.0% were mildly depressed, and 8.6% were moderately/severely depressed The mean score was higher for females than males (P < .001). The Cronbach's
values by age group were: 10 to 11 years, .85; 12 to 15 years, .79; 16 to 18 years, .74; and
19 years, .79. The Cronbach's
for all age groups exceeded Nunnally's37 suggested threshold value of .70.
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The associations between level of depressed mood and mean HbA1c, number of episodes of DKA and hypoglycemia, number of hospitalizations, and number of ED visits in the previous 6 months among the 2281 youth who had had diabetes at least 1 year (mean age: 15.6 ± 3.2 years) are shown in Table 5. In the unadjusted models, participants' mean HbA1c, number of ED visits, and number of hospitalizations (females only) differed significantly by their level of depressed mood. After adjusting for demographic covariates as well as type of diabetes, its duration, and use of psychiatric medications, we found that participants' level of depressed mood was associated only with their HbA1c and number of ED visits.
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| DISCUSSION |
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Even after adjusting for participants' age, which is associated with duration of diabetes, as well as for their gender and type of diabetes, we found no association between duration of diabetes and the level of depressed mood. Results from previous studies of the possible association between depression and diabetes duration among youth have been mixed. Kovacs et al40 found that depression was not uncommon among non-Hispanic white youth soon after they were diagnosed with diabetes but that the depression tended to resolve within 6 months, and that their mood then remained relatively stable over a 6-year period.41 In contrast, Grey et al42 found that the rate of depression measured in a cohort of non-Hispanic white, black, and Hispanic youth with diabetes around the time of diagnosis and again 2 years later was higher than that among peers without diabetes. Both of these studies were limited to youth with type 1 and used repeated measures among the same group of youth, whereas our study reports measures of depressed mood at only 1 point in time in cohort of youth with type 1, type 2, and other types of diabetes.
After adjusting for potential confounders, we found that mildly depressed mood in both genders and moderately/severely depressed mood among females were associated with higher HbA1c, although the absolute difference in HbA1c was relatively small. La Greca et al12 found that gender and depressive symptoms were associated with poor glycemic control among 42 non-Hispanic white, black, and Hispanic teens with type 1 diabetes, whereas Dantzer et al9 found an association between depression and glycemic control in only 2 of the 8 pediatric studies that they reviewed. Results of a meta-analysis of depression and glycemic control in adults showed that depression was associated with poor glycemic control among adults with type 1 and type 2 diabetes.43
We found no association between the prevalence of depressed mood and the number of DKA and hypoglycemic episodes that participants reported. We found that depressed mood was associated with the number of ED visits reported by both genders. Depressed mood was also associated with a higher number of hospitalizations among females, but this association was no longer significant after we adjusted for demographic factors and for diabetes type and duration. Because we did not ascertain whether the ED visits and hospitalizations were the result of diabetes, comorbidities, or other health problems for youth in the cohort, and because other studies of depression among youth with diabetes did not look at acute health care service utilization as an outcome, these results cannot be compared directly with those from other studies. In a recent study using data from the Pediatric Health Information System, Garrison et al44 found no association between internalizing disorders (which included depressive disorders) and repeat hospitalizations among children and adolescents with diabetes.
Among females, we found that having a comorbid condition was associated with an increased risk for both mildly and moderately/severely depressed mood. The most prevalent comorbid condition among youth in this study was asthma.
We found that 15.6% of the males and 26.9% of the females who had moderately/severely depressed mood reported being on psychiatric medication. Because we did not measure the duration of medication use, we could draw no conclusions about the effectiveness of these medications. However, our findings may suggest that some youth with diabetes are being screened and treated for depressed mood as part of their diabetes-related or general health care.
We found the prevalence of mild or moderate/severely depressed mood among youth with diabetes to be similar to published estimates of depression prevalence among youth without diabetes produced with the same screening tool. For example, in the AddHealth study of over 13000 youth whose mean age and racial/ethnic composition were similar to those of our study participants, 9.2% of all youth, 12.6% of females, and 5.9% of males had a CES-D score
2419 (vs 8.6%, 10.9%, and 6.1%, respectively in the SEARCH study). The mean CES-D score reported by AddHealth (12.2) was lower than scores from previously published studies17, 28, 30, 45 but still higher than the mean score from the SEARCH study (10.7)
Our study included youth as young as 10 years of age. In assessing the performance of the CES-D scale using the Cronbach's
test statistic,36 we found good internal consistency across all age groups. When we removed the 10- and 11-year-old youth from our analyses, the associations between depressed mood and the demographic and diabetes-related factors under study were quite similar.
Limitations
This study has several limitations. First, because it was a cross-sectional study, we were unable to establish a temporal relationship between the onset of depressed mood and other variables of interest. Second, the results of this study are based on participants' scores on the CES-D, a screening tool used to identify persons who have experienced symptoms of depression during the previous week and who thus may be at risk for depression; it is not a diagnostic test for clinical depression. Although results of studies to evaluate the effectiveness of the CES-D to screen for depressed mood in multiethnic cohorts of adults and adolescents have been mixed,4648 it has been used to screen for depressed mood in multiethnic cohorts of youth, including participants in the National Longitudinal Study of Adolescent Health.19
Another limitation of the SEARCH study is the participation rate. The likelihood that youth with diabetes registered for the SEARCH study would participate in the SEARCH study visit decreased with age in a linear manner; 18- to 19-year-olds were 4 times less likely to participate than were children <8 years of age. In addition, females were slightly more likely to participate than were males, and youth with type 1 diabetes were more likely to participate than were those with type 2. Our overall estimates of the prevalence of depressed mood among youth should be interpreted cautiously in view of the differential response rates by age and gender. Although it is unlikely that the small difference in participation rates by gender resulted in a substantial bias, the lower rate of participation by youth with type 2 diabetes, which was likely associated with the substantial age-related differences in participation rates, may have affected our findings.
| CONCLUSIONS AND CLINICAL IMPLICATIONS |
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Because some episodes of depression may be mild and short-lived, whereas others may be significant and last a long time, health care providers should develop management strategies that include following these youth over time and providing them with counseling to address issues related to depression. Because youth with type 2 diabetes are usually older at diagnosis than youth with type 1 diabetes, health care providers should also assess the history of depression among youth diagnosed with type 2 diabetes, because they may have had depression that predated their diagnosis of diabetes. Youth with a history of depression may benefit from more intensive psychosocial interventions at the time of their diagnosis with diabetes because their depression may place them at increased risk for poor glycemic control and resultant health problems.
The prevalence of depressed mood that we found among youth with diabetes was similar to that in unaffected populations, suggesting that the majority of youth with diabetes do remarkably well in coping with diabetes while also undergoing the often stressful psychosocial and physiological changes that occur during adolescence. Prospective studies are needed to screen youth with all types of diabetes for depressed mood at the time of their diagnosis. These studies should focus both on their history of depression and their current symptoms, and attempt to determine if interventions to reduce depressive symptoms among youth identified as depressed will also improve their glycemic control and reduce their emergency department visits.
| ACKNOWLEDGMENTS |
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We acknowledge the contributions of the SEARCH Study Group, the study participants, their families, and their health care providers.
| FOOTNOTES |
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Address correspondence to Jean M. Lawrence, ScD, MPH, MSSA, Research and Evaluation, Kaiser Permanente Southern California, 100 S Los Robles, 2nd Floor, Pasadena, CA 91101. E-mail: jean.m.lawrence{at}kp.org
The authors have indicated they have no financial relationships relevant to this article to disclose.
Preliminary results from this analysis were presented at the American Diabetes Association annual meeting; June 1014, 2005; San Diego, CA.
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