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1 Department of Family & Community Medicine, University of California, San Francisco
2 Center for Dissemination and Implementation Research, Institute for Health Research, Kaiser Permanente of Colorado, Denver
3 Department of Social & Behavioral Sciences, School of Nursing, University of California, San Francisco
4 Department of Psychiatry, University of California, San Diego, La Jolla
CORRESPONDING AUTHOR: Lawrence Fisher, PhD, Department of Family & Community Medicine, Box 0900, University of California, San Francisco, San Francisco, CA 94143, fisherl{at}fcm.ucsf.edu
| ABSTRACT |
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METHODS We assessed 496 community-based patients with type 2 diabetes on the previously validated, 17-item Diabetes Distress Scale (DDS17) and 6 biobehavioral measures: glycated hemoglobin (HbA1c); non–high-density-lipoprotein (non-HDL) cholesterol; kilocalories, percentage of calories from fat, and number of fruit and vegetable servings consumed per day; and physical activity as measured by the International Physical Activity Questionnaire.
RESULTS An average item score of
3 (moderate distress) discriminated high- from low-distressed subgroups. The 4 DDS17 items with the highest correlations with the DDS17 total (r = .56–.61) were selected. Composites, comprised of 2, 3, and 4 of these items (DDS2, DDS3, DDS4), yielded higher correlations (r=.69–.71). The sensitivity and specificity of the composites were .95 and .85, .93 and .87, and .97 and .86, respectively. The DDS3 had a lower sensitivity and higher percentages of false-negative and false-positive results. All 3 composites significantly discriminated subgroups on HbA1c, non-HDL cholesterol, and kilocalories consumed per day; none discriminated subgroups on fruit and vegetable servings consumed per day; and only the DDS3 yielded significant results on the International Physical Activity Questionnaire. Because of its psychometric properties and brevity, the DDS2 was selected as a screening instrument.
CONCLUSIONS The DDS2 is a 2-item diabetes distress screening instrument asking respondents to rate on a 6-point scale the degree to which the following items caused distress: (1) feeling overwhelmed by the demands of living with diabetes, and (2) feeling that I am often failing with my diabetes regimen. The DDS17 can be administered to those who have positive findings on the DDS2 to define the content of distress and to direct intervention.
Key Words: Diabetes stress depression mass screening
| INTRODUCTION |
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In equations that included scores for major depressive disorder, depressive affect, and diabetes distress, we also found previously that diabetes distress was more strongly and independently related to behavioral and clinical measures of diabetes management than was depression. We argued that major depressive disorder was related to but distinct from diabetes distress, and that many patients with high levels of depressive affect were really experiencing diabetes distress, not depression. We raised concern that although major depressive disorder remains a prevalent condition among these patients, most patients with diabetes are not clinically depressed; they are, instead, distressed about their diabetes and its management.
Although many clinicians now regularly screen for depression among their patients with diabetes, there is as yet no time-efficient tool for use in the clinical setting that can be used to screen patients for disease-related distress and, if screening criteria are met, to identify stressful areas of diabetes management for intervention. Ideally, such a clinically useful instrument would be brief, easy to score, and lead directly to intervention. The DDS was developed to address these needs. The 17-item questionnaire was developed in previous studies with 4 separate samples totaling 683 patients with diabetes.9 The original scale statistics and factor analyses were replicated with another ethnically diverse sample of 498 patients with diabetes.10 With all samples, the scale yielded 4 reliable subscales that targeted different areas of potential diabetes-specific distress to help clinicians and patients identify areas where interventions might be helpful: emotional burden (feeling overwhelmed by diabetes), physician-related distress (worries about access, trust, and care), regimen-related distress (concerns about diet, physical activity, medications), and interpersonal distress (not receiving understanding and appropriate support from others). In this article we report the development of a diabetes distress screening instrument, derived from the previously reported 17-item scale, for use in clinical settings.
| METHODS |
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Measures
As described above, the DDS9 is a 17-item measure (DDS17) that uses a Likert scale with each item scored from 1 (no distress) to 6 (serious distress) concerning distress experienced over the last month (Appendix 1). Internal consistency was assessed by coefficient
(.93 for the total scale, and .88 to .90 for the 4 subscales). A mean item score of
3 (moderate distress) was used to distinguish high from low distress for each item, for the mean of the 17 items (DDS17), and for selected composites of potential screening items. The mean item score of each selected composite was compared to the mean item score of the DDS17, which was the primary criterion variable.
Selected composites and the 17-item scale were also compared with 6 biobehavioral measures. We reasoned that high levels of diabetes distress, measured by the composites and the DDS17, should operate similarly with respect to important diabetes variables, thus heightening our confidence in the use of the screener. The biological measures included HbA1c and non-HDL cholesterol. Three measures of dietary intake during the last year, derived from the Block 2000 Brief Food Frequency Questionnaire (Block Dietary Data Systems, Berkeley, California),11 also were used: average kilocalories, average calories of saturated fat as a percentage of total calories, and average number of fruit and vegetable servings consumed per day. The International Physical Activity Questionnaire12 was included to measure physical activity. It reflects the number of minutes of activity in the last week at each of 3 levels of activity, each weighted by a measure of energy expenditure with multiples of resting metabolic rate for a 60-kg person (light = 3.3, moderate = 4.0, vigorous = 8.0).
Analyses
Our data analysis strategy was to identify subsets of 2, 3, and 4 scale items from the DDS17 that most accurately distinguished high- from low-distress patients using the full DDS17 mean item score as the criterion, and that had a range of distressed responses of at least 25% (
3). Phi coefficients were used to correlate each scale item (
3 vs <3) with the total DDS17 score (mean item score
3 vs <3). The 4 items with the highest correlations with the DDS17 were combined into composites of 2, 3, and 4 items (DDS2, DDS3, DDS4), from highest to lowest. We decided on a maximum of 4 items so that the number of potential screening items did not exceed 25% of the number of items in the total scale. Cross-tabulations between each of the DDS2, DDS3, and DDS4 screening scales compared with the DDS17 indicated the number of patients correctly screened by each composite, the number of false-positive results, and the number of false-negative results. We then compared high vs low distress based on each DDS composite and the DDS17 with each of the 6 comparison measures to determine how similar the results from the analyses with the composites were in comparison with the results generated by the DDS17 (Students t tests).
| RESULTS |
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=1.4%). The DDS3 did not perform as well as the DDS2 or DDS4. The sensitivity/specificity of the DDS2, DDS3, and DDS4 was .95/.85, .93/.87, and .97/.86, respectively, indicating that all 4 composites were able to classify patients accurately, relative to the DDS17 (respective positive predictive value and negative predictive value: DDS2 = 58.4% and 99.2%, DDS3 = 74.3% and 98.3%, DDS4 = 60.8% and 99.2%).
Coefficients for the DDS2, DDS3 and DDS4 were .73, .83, and .86, respectively.
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| DISCUSSION |
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The raw (and item-corrected) correlations between each of the 4 items and the DDS17 ranged from .56 to .61, whereas the correlations between the scale composites and the DDS17 ranged from .69 to .71, indicating that a composite score of 2 to 4 items performed better than any single item. It is interesting to note that all 4 of the most highly correlated items came from the emotional burden and regimen distress subscales of the DDS17. Although not reported above, we ran additional analyses that included the highest correlated items from the interpersonal and physician distress subscales, but their inclusion did not substantively increase the correlation with the DDS17 criterion or improve the results of any subsequent analysis. Thus, items from the emotional burden and regimen distress subscales appear to capture most, but not necessarily all, of the distress assessed by the DDS17. Although the scale composites did not include item content from all 4 DDS17 subscales, the composites each have significant associations with the total DDS17 scale total, which was the primary objective of the study.
Measures of sensitivity and specificity were relatively similar for the DDS2, DDS3, and DDS4. Of the 3 composites, however, the cross-tabulations indicated that the DDS3 displayed the lowest percentage of accuracy and the highest percentage of false-negative results. The DDS2 and DDS4 displayed the highest level of accuracy (96.7%) and the same percentage of false-positive results (3.3%), but the DDS4 had a 1.4% lower rate of false-positive results than the DDS2. Similar results across composites were found in the comparisons with the biobehavioral measures for the DDS2 and DDS4.
When comparing the DDS4 with the DDS2 as a potential screening tool, the addition of 2 items to the DDS2 to achieve a relatively small improvement in the false-positive rate may not be worth the added time and complexity. We therefore suggest that the DDS2 (Appendix 2) be used as an initial screening instrument to assess diabetes-specific distress, to be followed by the administration of the complete 17-item scale for those patients whose average of the 2 screening items is
3, or whose sum is
6. The use of the full DDS17 after a positive screening test can then provide the clinician with indicators of the content of the patients distress across all 4 of the DDS17 factors, which can direct subsequent intervention. Furthermore, skimming through the patients responses to each of the 17 individual items scored
3 can be used to begin a conversation with the patient during the clinical encounter about specific sources or areas of distress. This process saves time and focuses the interaction on areas of major patient concern, thus allowing the clinician and patient to develop a focused plan that addresses specific needs. We provide both English and Spanish versions of the DDS17 and DDS2, along with instructions for use in the Supplemental Appendix, available online-only at http://www.annfammed.org/cgi/content/full/6/3/246/DC1.
We do not view the use of the DDS2 and DDS17 as a substitute for depression screening. The prevalence of both diabetes-specific distress and major depressive disorder is high among patients with diabetes, and both conditions warrant careful, regular assessment. To date, however, we know of no study that compares distress and depression screening in the same sample of patients with diabetes. Given previous findings,5,6 however, we suspect that 3 groups will emerge: a large group with diabetes distress alone, a relatively small group with major depressive disorder alone, and a much smaller group with both conditions. We urge careful assessment of these groups because there is good documentation that interventions that address one condition do not necessarily address the other, eg, interventions that effectively treat major depressive disorder do not also improve diabetes behavioral and biological outcomes,13,14 and interventions that treat diabetes management do not necessarily reduce major depressive disorder.15 Interventions are needed for each separately.
Diabetes-specific distress is a common condition that often includes high levels of negative affect. It is linked to poor biobehavioral disease management, and it can be easily confused with major depressive disorder or minor depression, which we suspect are distinct conditions. The DDS2 is an easily scored screening instrument to detect diabetes-specific distress. Future research should determine whether similar distress constructs apply to other chronic conditions.
| Appendix 1. Diabetes Distress Scale, English (DDS17) |
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Please note that we are asking you to indicate the degree to which each item may be bothering you in your life, NOT whether the item is merely true for you. If you feel that a particular item is not a bother or a problem for you, you would circle "1." If it is very bothersome to you, you might circle "6."
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| Appendix 2. The 2-Item Diabetes Distress Screening Scale (DDS2) |
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Please note that we are asking you to indicate the degree to which each item may be bothering you in your life, NOT whether the item is merely true for you. If you feel that a particular item is not a bother or a problem for you, you would circle "1." If it is very bothersome to you, you might circle "6."
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| ACKNOWLEDGMENTS |
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| FOOTNOTES |
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Funding support: Supported by grant DK062732 and grant DK061937 from the National Institute of Diabetes, Digestive and Kidney Diseases.
Received for publication August 2, 2007. Revision received November 16, 2007. Accepted for publication November 26, 2007.
| REFERENCES |
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This article has been cited by other articles:
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J. J. Frey III In This Issue: Doctor-Patient, Doctor-System, Doctor-Public Ann. Fam. Med, May 1, 2008; 6(3): 194 - 195. [Full Text] [PDF] |
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