Mortality of patients with type 2 diabetes in Taiwan: A 10-year nationwide follow-up study

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Abstract

Aims

This study aims to investigate the distribution of underlying-causes-of-death (UCOD) among deceased patients with type 2 diabetes mellitus (DM) in Taiwan and assess the influence of socio-demographic characteristics on mortality in type 2 DM patients.

Methods

A cohort study on patients who sought medical care for type 2 DM from 2000 to 2008 was conducted on 65,599 type 2 DM patients retrieved from the 1-million beneficiaries randomly selected from Taiwan's National Health Insurance Database. The study cohort was then linked to Taiwan's Mortality Registry to ascertain the patients who died between 2000 and 2009. We examined the distribution of UCOD in the deceased subjects. The hazard ratios of mortality in relation to socio-demographic characteristics were estimated from Cox proportional hazard model.

Results

The leading causes of death in type 2 DM included neoplasm (22.68%), cardiovascular diseases (21.46%), and endocrine diseases (20.78%). Male gender and older ages were associated with significantly increased risk of mortality. In addition, lower urbanization and greater co-morbidity score were also significantly associated with an increased risk of mortality with a dose-gradient pattern.

Conclusions

Neoplasm accounts for the largest portion (22.68%) of deaths in type 2 DM patients closely followed by with cardiovascular diseases (21.46%). An increased risk of mortality in type 2 DM patients in lower urbanized areas may reflect poor diabetes care in these areas.

Introduction

Diabetes mellitus (DM) is an epidemic disease in the world. Marked changes in human health behaviors and lifestyle have resulted in higher incidence and prevalence of DM [1]. It has been recently estimated that the global prevalence of diabetes is 8.3% [2]. The number of people with diabetes is also rising because of population growth, aging, urbanization, and increasing prevalence of obesity and physical inactivity. The potential for increase in patients with diabetes is greatest in Asia [3].

Type 2 DM has become an important public health threat for the ethnic Chinese population living in mainland China, Hong Kong, Taiwan, and Singapore, with a prevalence of one-fifth of the adult population [4]. Given the genetic susceptibility and rapid westernization of food and lifestyle, a striking increase in incidence and prevalence of type 2 DM is anticipated [5]. The rapid increase in incidence and prevalence of type 2 DM is a health or medical issue and an economic and social problem for most governments. In developed countries, the largest increase in the number of type 2 DM is recorded in the elderly population aged more than 65 years, but the larger part of new onset type 2 DM occurred in the 45–64 year old population,2 who are vulnerable to premature death from various complications related to DM.

Increased public awareness on the adverse health consequences of type 2 DM has resulted in intensive monitoring and aggressive clinical management of DM worldwide. However, type 2 DM still accounts for a considerable number of deaths from discrete complications each year globally. Hence, cause-specific mortality statistics based on the underlying-cause-of-death (UCOD) recorded on the death certificate are important to compare the cause-of-death statistics between countries and across time. Most countries follow the guidelines determined by the World Health Organization (WHO) and would register mortality data according to the UCOD [6]. The UCOD is characterized as the disease or injury that triggers the sequence of morbid events leading directly to death. Information on the UCOD of diabetic patients may help estimate the disease burden of DM.

Although several previous studies have suggested an association between urbanization and higher type 2 DM incidence [7], [8], only few studies have examined the association of urbanization with mortality in DM. Taiwan introduced a universal health insurance to cover all citizens in 1995. The national health insurance (NHI) program was intended to assure the accessibility of health care at acceptable cost [9] and eliminate the financial barrier that prevents the poor from receiving health care services. Recognizing the association between urbanization and mortality in patients with type 2 DM under the above medical care system is important. This study aimed to investigate the distribution of UCOD in a nationally representative sample of type 2 DM patients. In addition, this study also sought to assess the influence of urbanization on the risk of mortality in patients with type 2 DM.

Section snippets

Source of data

Data investigated in this study were retrospectively retrieved from the medical claims of the National Health Insurance Research Database (NHIRD) provided by the Bureau of National Health Insurance (BNHI). NHIRD provides all inpatient and ambulatory medical claims for about 99% of Taiwanese [10]. To confirm the accuracy of claim files, the BNHI performs periodical expert reviews on a random sample for every 50–100 ambulatory and inpatient claims [9]. Therefore, information attained from NHIRD

Results

Approximately 52.1% of the patients in our study cohort were males and patients aged 50–69 years accounted for more than half of the patients. Approximately 30.6% of the patients first appeared in the medical claims for type 2 DM in 2000, whereas 7–10% were first seen in the subsequent years between 2001 and 2008. Most of the patients lived in areas with higher urbanization. With respect to the co-morbidity noted three years prior to date of recruitment, the most prevalent co-morbidity was

Discussion

We conducted a 10-year population-based follow-up study and found that the leading causes of death in Taiwanese patients with type 2 DM included neoplasms and cardiovascular diseases (CVD). In addition, compared with female type 2 DM patients, male patients had a higher risk of mortality within 10 years. The risk of mortality was also significantly associated with older ages, lesser urbanization, and higher co-morbidity scores.

One US study reported that CVD are involved in the preponderance of

Conclusion

We found that neoplasm accounts for the largest proportion of deaths in Taiwanese patients with type 2 DM, implying that cancer screening programs is important in patients with type 2 DM. Patients with type 2 DM should be carefully assessed for liver and biliary, lung, and colorectal neoplasms. Our study also indicated an increased risk of mortality in type 2 DM patients residing in areas with lesser urbanization, which may suggest inadequacy of health care and cancer screening for type 2 DM

Conflict of interest

The authors declare that they have no conflict of interest.

Acknowledgments

This study was partially supported by a grant with National Scientific Council (NSC101-2314-B-006-076-MY3), who however has no role in this study. The interpretation and conclusions contained herein do not represent those of BNHI, Department of Health or NHRI.

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