Available measures of diabetes treatment adherence (1–5) are typically based on measuring deviation from a prescribed regimen and cannot readily capture problem solving and self-regulation that typify modern regimens. Measurement of diabetes self-management must accommodate these advances in therapy.
The Diabetes Self-Management Profile (DSMP), a previously validated structured interview assessment of adherence in type 1 diabetes (6–8) was modified by the DirecNet research group and the authors of the DSMP to construct the DSMP for Flexible regimens (DSMP-F). This paper evaluates the psychometric properties of the DSMP-F both cross-sectionally and longitudinally. Data were obtained from youths with type 1 diabetes and their parents during a DirecNet trial of the GlucoWatch G2® Biographer (GW2B; Cygnus, Inc., Redwood City, CA) (9).
Research Design and Methods
The randomized trial included 200 youth with type 1 diabetes who were enrolled at five centers; the methodological details have been published previously (9). Each child was randomized to GW2B use or Usual Care (UC). Diabetes management in both groups was similar, except for use of the GW2B. Within the sample, 161 youths were treated using flexible insulin regimens (93 on insulin pumps and 68 on “basal-bolus” regimens). HbA1c was measured at baseline and after 3 and 6 months at the DirecNet central laboratory.
The DSMP-F interview quantifies adherence to the prescribed regimen and self-management behaviors such as remediation or prevention of unwanted glucose excursions through adjustment of insulin, diet or exercise. Four DSMP diet items were re-worded to be more consistent with dietary management using carbohydrate counting and insulin adjustment based on carbohydrate to insulin ratios. Two trained interviewers completed the 15–20 minute DSMP-F interview by telephone separately with parents and children ≥11 years of age and jointly with parents and children <11 years of age at baseline and after 6-months. Higher scores reflect more meticulous self-management. Analyses for this report were limited to DSMP total scores.
Results
Table 1 presents descriptive statistical analyses of the DSMP-F (n = 161 parents and 117 adolescents). Total scores (Mean ± SD) were virtually identical for parents (62.7 ± 8.7) and adolescents (62.7 ± 7.0). There were no significant between-group differences in baseline DSMP-F total scores for parents (62.0 ± 8.6 and 63.5 ± 8.8 for GW2B and UC, respectively) or adolescents (63.5 ± 6.4 and 61.8 ± 7.4 for GW2B and UC, respectively). These scores indicate mean adherence scores of 73% of the maximum DSMP total score (86), suggesting that over-reporting of adherence was unlikely.
Table 1.
Mean ± 1 standard deviation of raw scores for each DSMP-F subscale and total obtained from 161 parents and 117 youths ≥11 years of age.
| Parents | Youths | Maximum Score | |
|---|---|---|---|
| Exercise | 9.0 ± 2.6 | 8.0 ± 2.9 | 12 |
| Eating | 11.5 ± 3.2 | 12.4 ± 2.9 | 17 |
| Hypoglycemia | 8.9 ± 1.6 | 8.8 ± 1.6 | 11 |
| BG Testing | 22.1 ± 4.0 | 21.9 ± 3.6 | 30 |
| Insulin | 11.2 ± 3.2 | 11.6 ± 2.7 | 16 |
| Total | 62.7 ± 8.7 | 62.7 ± 7.0 | 86 |
Internal consistency (Cronbach’s alpha coefficient) for the DSMP-F total score, with the GW2B and UC groups combined, was .69 for parents and .47 for adolescents at baseline, and .70 for parents and .65 for adolescents at 6 months. The alpha coefficient obtained in the earlier DSMP study (6) was .76 for parents and for youths. Among the 117 parent-adolescent pairs who were both interviewed with the DSMP-F, parent and adolescent DSMP total scores correlated .59 (p < .001). Test-retest reliability of the DSMP-F (Pearson correlations between baseline and 6-month scores) were similar in the UC (parents r = .73, p < 0.001; adolescents r = .42, p = 0.002) and GW2B (parents r = .71; adolescents r = .51; both p < 0.001) groups.
Compared with the prior study (6), associations of the total score with HbA1C were similar in this study (r = −.20 versus r = −.28). The present study enrolled a more selected sample of patients that were in better glycemic control and were well-motivated to improve their diabetes self-management. These characteristics might decrease variability in DSMP-F scores and HbA1c, reducing the magnitude of statistical associations. Changes in DSMP-F Total scores from parents or adolescents were not correlated significantly with change in HbA1C over the 6-month study (p = .79 and 1.00, respectively).
Conclusions
The present study yielded substantial psychometric data on the DSMP-F, including descriptive data obtained from a multi-center sample that can be used for comparison with DSMP-F scores obtained in future studies. The modest internal consistency estimates may indicate that the DSMP-F measures several independent dimensions of diabetes self-management behavior, as has been shown by others (10,11) and so a high alpha coefficient would not be expected.
This work extends the previous validation of the DSMP-F by evaluating an adapted interview protocol appropriate for patients treated with flexible insulin regimens. Further research could compare the interview procedure with varied modes of data collection such as questionnaire, hand-held computer, or automated interactive telephone interview methods. Examination of the psychometric properties of the DSMP when administered to adult patients would be another valuable contribution.
Acknowledgments
This research has been supported by the following NIH/NICHD Grants: HD041919-01; HD041915-01; HD041890; HD041918-01; HD041908-01; HD041906-01 and by Nemours Research Programs.
The GlucoWatch G2® Biographers were purchased from Cygnus, Inc. at a discounted price.
Alexandra Taylor, M.A.C.P. and Amy Milkes, M.A. of Nemours Children’s Clinic completed all interviews of participants in this study.
Portions of these data were previously published as an abstract in Diabetes 53 (Suppl. 2), A436 and presented at the Scientific Sessions of the American Diabetes Association in Orlando, Florida, June, 2004.
Footnotes
• A list of the entire DirecNet Study Group appears in the Appendix to: Diabetes Research in Children Network (DirecNet) Study Group: A randomized multicenter trial comparing the GlucoWatch Biographer with standard glucose monitoring in children with type 1 diabetes. Diabetes Care 28:1101-1106, 2005
• The writing committee for this paper consisted of: Tim Wysocki, PhD, ABPP; Dongyuan Xing, MPH; Rosanna Fiallo-Scharer, MD; Elizabeth A. Doyle, MSN; Jennifer M. Block, RN, CDE; Eva Tsalikian, MD; Roy W. Beck, MD, PhD; Katrina J. Ruedy, MSPH; Craig Kollman, PhD; Michael Harris, PhD; William V. Tamborlane, MD.
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