The impact of treatment non-compliance on mortality in people with type 1 diabetes,☆☆

https://doi.org/10.1016/j.jdiacomp.2012.10.006Get rights and content

Abstract

Aims

To determine if a diagnostic record of poor treatment compliance (medication non-compliance and/or non-attendance at medical appointments) was associated with all-cause mortality in people with type 1 diabetes.

Methods

This is an observational cohort study of data extracted from The Health Improvement Network (THIN) database, comprising data on patients served by over 350 primary care practices in the UK. Participants were included in the study if they had diagnostic codes indicative of type 1 diabetes. Treatment non-compliance was defined as missing one or more scheduled appointment, or one or more codes indicating medication non-compliance.

Results

Of 2946 patients with type 1 diabetes, 867 (29.4%) had a record of either appointment non-attendance or medication non-compliance in the 30 month compliance assessment period. The crude, unadjusted mortality rate for those patients who were treatment non-compliant was 1.462 (95% CI 0.954–2.205). Following adjustment for confounding factors, treatment non-compliance was associated with increased all-cause mortality (HR = 1.642; 95% CI 1.055–2.554).

Conclusions

Treatment non-compliance was associated with increased all-cause mortality in patients with type 1 diabetes. Understanding and addressing factors that contribute to patient treatment non-compliance will be important in improving the life expectancy of patients with type 1 diabetes.

Introduction

Type 1 diabetes is responsible for approximately 10% of all cases of diabetes mellitus and usually occurs in those under 40 years of age. Exogenous insulin administration is an essential, life-sustaining treatment in these patients. Insulin therapy can prevent the development of acute complications such as ketoacidosis and diabetic coma, and good glycaemic control is necessary to reduce the risk of developing longer term chronic vascular complications (Borch-Johnsen, 1999).

The life expectancy of patients with type 1 diabetes continues to improve (Borch-Johnsen, 1999, Secrest et al., 2010); however, the average life expectancy remains reduced by approximately 20 years relative to the general population (Diabetes UK, 2010, Morgan et al., 2000). On average, patients with type 1 diabetes are approximately 2–3 times more likely to die relative to a standard population (Brown et al., 2001, Soedamah-Muthu et al., 2006), with relative mortality being highest in patients aged 30–39 years (standardised mortality ratio of 9) (Wysocki, Hough, Ward, & Green, 1992). The principal causes of death for patients with type 1 diabetes are coronary heart disease (33%) and stroke (18%) (Ioacara et al., 2009, Soedamah-Muthu et al., 2006).

In a previous study investigating patients with insulin-treated type 2 diabetes, we reported that clinic non-attendance and/or medication non-compliance were each independently associated with increased all-cause mortality (Currie et al., 2012). We concluded that treatment compliance was therefore important in order to maximise patient outcomes and minimise the risk of premature death. In type 1 diabetes, certain groups of patients, such as adolescents and young adults, may be less compliant with medication for reasons such as fear of hypoglycaemia (Di Battista, Hart, Greco, & Gloizer, 2009) or weight gain from insulin use (Bryden et al., 1999), lack of understanding of long-term complications (Dovey-Pearce, Hurrell, May, Walker, & Doherty, 2005), the impact of self-management upon lifestyle (Lancaster et al., 2010) and issues surrounding the change from paediatric to adult care services (Wysocki et al., 1992). However, the effect of treatment compliance on mortality in type 1 diabetes has not been previously described.

The aim of this study was to determine if poor treatment compliance was associated with increased all-cause mortality in patients with type 1 diabetes.

Section snippets

Subjects

Patients with a diagnosis of type 1 diabetes were included in the study.

Data source

THIN (The Health Improvement Network) database (The Health Improvement Network Cegedim Strategic Data/EPIC, 2010), is a longitudinal, anonymised research database holding in excess of 8 million patient records. Approximately half of these records belong to patients who are currently registered with the participating practices. The database also maintains records for patients who have left a participating practice due to

Results

A total of 2946 insulin-using patients with type 1 diabetes were identified for inclusion into the study with a mean of 4.5 ± 2.7 years follow up. A total of 867 (29.4%) patients were classified as treatment non-compliant. Of these patients, the number receiving a specific diagnosis of medication non-compliance or missing at least one scheduled clinic appointment during the assessment period was 62 (2.1 %) and 837 (28.4%), respectively. The number of Read codes documenting medication

Discussion

This study has found that a record of treatment non-compliance is associated with increased all-cause mortality in patients with type 1 diabetes after adjustment for demographic variables and other risk factors. Moreover, patients with a history of treatment non-compliance were more likely to have both increased BMI and HbA1c at baseline, to have smoked and to have had an increased number of primary care appointments in the 12 months prior to the index date of this study. Thus, this routinely

Conclusion

Within the current UK health care system, treatment non-compliance was associated with increased all-cause mortality in patients with type 1 diabetes. Further research will be required to substantiate these findings; to ascertain which, if any, specific aspects of treatment non-compliance carry the highest risk of mortality; and the extent to which addressing these factors can improve life expectancy in this group of patients.

Acknowledgments

This study was funded by an unconditional research grant from Novo Nordisk.

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    The study hypothesis was developed prior to inspection of the data. Ethics approval was granted from the EPIC Database Research Company-reference number SRC_10-034.

    ☆☆

    C.J.C. has received consulting fees and/or research grants from Amylin, Aryx, Astellas, Boeringher Ingelheim, Bristol-Myers Squibb, Eisel, Ferring, GSK, Ipsen, Eli-Lilly, Medtronic, Merck, Pfizer, Sanofi-Aventis, Takeda, and Wyeth. M.E. has received consulting fees from Abbott, Allergan, BMS, GSK, Lilly, Novartis, Novo Nordisk, MSD, Roche, Sanofi-Aventis, and Takeda. M.P. has received consulting fees and/or research grants from Amylin, Animas, CPEX, Eli Lilly, Genentech, Healthy Interactions, Mannkind, Medtronic, Novo Nordisk, Patton Medical Devices. C.M.B. and R.R.R. have received consulting fees from Novo Nordisk. C.L.M., C.D.P. and S.J.J. are employees of Pharmatelligence.

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