ADHERENCE TO INSULIN IN SINGAPOREAN PEDIATRIC TYPE 1 DIABETES PATIENTS AND ITS IMPACT ON GLYCEMIC CONTROL AND HEALTH-CARE UTILIZATION
Objective: Optimizing glycemic control is challenging with insulin non-adherence. This study aimed to characterize the prevalence of non-adherence among Singaporean pediatric patients with type 1 diabetes mellitus (T1DM) and investigate its associated outcomes.
Methods: Singaporean patients with T1DM aged ≤18 years old with ≥1 year of insulin prescription between 2012 and 2016 were included in this retrospective, single-center longitudinal study. Patients on insulin pumps were excluded from the study. Non-adherence was defined as medication possession ratio (MPR) <100%. Glycemic control was defined using mean hemoglobin A1c (HbA1c) within the study period. Health-care utilization was defined as the number of outpatients, inpatient, and emergency visits. The t-test, Chi-square test, logistic regression, and Poisson regression were used to analyze means, proportions, factors associated with non-adherence, and association of non-adherence and health-care utilization, respectively. Sensitivity analyses were performed for MPR thresholds of 80% and 95%.
Results: A total of 206 patients were included in this study. Non-adherent patients were older, had a longer duration of diabetes since diagnosis and shorter duration of follow-up. Gender, race, financial class, and number of concurrent medications were comparable between groups. The prevalence of non-adherence was 34.0% (95% confidence interval [CI]: 27.9–40.7%). Non-adherent patients had a higher average HbA1c (non-adherent: 9.6% [2.1] vs. adherent: 8.6% [1.3], p<0.001). Non-adherence was not associated with health-care utilization. Patients with >5 years of diabetes were more likely to be non-adherent.
Conclusion: Non-adherence defined as MPR <100% is associated with poorer glycemic control. Further interventions may focus on patients with >5 years of diabetes to improve their adherence to insulin therapy.
2. Maahs DM, West NA, Lawrence JM, Mayer-Davis EJ. Epidemiology of Type 1 diabetes. Endocrinol Metab Clin North Am 2010;39:481-97.
3. Schwartz DD, Cline VD, Hansen JA, Axelrad ME, Anderson BJ. Early risk factors for nonadherence in pediatric Type 1 diabetes: A review of the recent literature. Curr Diabetes Rev 2010;6:167-83.
4. Nathan DM, DCCT/EDIC Research Group. The diabetes control and complications trial/epidemiology of diabetes interventions and complications study at 30 years: Overview. Diabetes Care 2014;37:9-16.
5. McEwan P, Bennett H, Bolin K, Evans M, Bergenheim K. Assessing the economic value of maintained improvements in type 1 diabetes management, in terms of hbA1c, weight and hypoglycaemic event incidence. Diabet Med 2018;35:557-66.
6. Clifford S, Perez-Nieves M, Skalicky AM, Reaney M, Coyne KS. A systematic literature review of methodologies used to assess medication adherence in patients with diabetes. Curr Med Res Opin 2014;30:1071-85.
7. Stolpe S, Kroes MA, Webb N, Wisniewski T. A systematic review of insulin adherence measures in patients with diabetes. J Manag Care Spec Pharm 2016;22:1224-46.
8. Cheen HH, Lim SH, Huang MC, Bee YM, Wee HL. Adherence to premixed insulin in a prefilled pen compared with a vial/syringe in people with diabetes in singapore. Clin Ther 2014;36:1043-53.
9. Osterberg L, Blaschke T. Adherence to medication. N Engl J Med 2005;353:487-97.
10. Peterson AM, Nau DP, Cramer JA, Benner J, Gwadry-Sridhar F, Nichol M, et al. A checklist for medication compliance and persistence studies using retrospective databases. Value Health 2007;10:3-12.
11. Morris AD, Boyle DI, McMahon AD, Greene SA, MacDonald TM, Newton RW, et al. Adherence to insulin treatment, glycaemic control, and ketoacidosis in insulin-dependent diabetes mellitus. The DARTS/ MEMO collaboration. Diabetes audit and research in tayside scotland. Medicines monitoring unit. Lancet 1997;350:1505-10.
12. Ying CL, Shah NM. Adherence to insulin treatment in children with Type I diabetes mellitus at a hospital in Malaysia. Asian J Pharm Clin Res 2017;10:356-61.
13. Naing L, Winn T, Rusli B. Practical issues in calculating the sample size for prevalence studies. Arch Orofac Sci 2006;1:9-14.
14. Gandhi K, Vu BK, Eshtehardi SS, Wasserman RM, Hilliard ME. Adherence in adolescents with Type 1 diabetes: Strategies and considerations for assessment in research and practice. Diabetes Manag (Lond) 2015;5:485-98.
15. Hood KK, Peterson CM, Rohan JM, Drotar D. Association between adherence and glycemic control in pediatric Type 1 diabetes: A meta-analysis. Pediatrics 2009;124:e1171-9.
16. Borus JS, Laffel L. Adherence challenges in the management of Type 1 diabetes in adolescents: Prevention and intervention. Curr Opin Pediatr 2010;22:405-11.
17. Lam WY, Fresco P. Medication adherence measures: An overview. Biomed Res Int 2015;2015:217047.
18. Gellad WF, Thorpe CT, Steiner JF, Voils CI. The myths of medication adherence. Pharmacoepidemiol Drug Saf 2017;26:1437-41.
19. Clifford S, Coyne KS. What is the value of medication adherence? J Manag Care Pharm 2014;20:650-1.
20. Sutton SS, Hardin JW, Bramley TJ, D’Souza AO, Bennett CL. Single versus multiple-tablet HIV regimens: Adherence and hospitalization risks. Am J Manag Care 2016;22:242-8.
This work is licensed under a Creative Commons Attribution 4.0 International License.
The publication is licensed under CC By and is open access. Copyright is with author and allowed to retain publishing rights without restrictions.