Original Article
Patients with type 2 diabetes had higher rates of hospitalization than the general population

https://doi.org/10.1016/j.jclinepi.2004.02.015Get rights and content

Abstract

Objective

We describe the rate, causes, and predictors of hospitalization for all patients with type 2 diabetes in a diabetes clinic in Turin, Italy and compare their hospitalization rates with those of the general population.

Study design and setting

All patients were recruited and followed up for hospital admissions from January 1996 to June 2000. The role of risk factors was analyzed with a conditional proportional hazard model for repeated events.

Results

More than 50% of the patients had been admitted to hospital at least once for any cause, and 30% had had multiple admissions, accounting for nearly 90% of all days in hospital. For these patients, older age, high glycated hemoglobin level, obesity, insulin treatment, presence of nephropathy, coronary and peripheral artery disease and comorbidity were statistically independent predictors of hospital admission. The standardized hospital admission ratios were 158.8 for men <65 years of age and 113.3 for men ≥65 years and 245.2 for women <65 years of age and 135.3 for women ≥65 years of age. The highest ratios were for diabetes, vascular (cardiac and cerebral) diseases, and eye diseases in younger women.

Conclusion

Patients with type 2 diabetes, and particularly younger women, had higher rates of hospitalization than the general population, with an excess risk of about 30%.

Introduction

The rates of hospitalization of patients with diabetes mellitus have been reported to be higher than those of the general population [1], [2], [3], [4], and the resources used for their inpatient care are estimated to be considerable [5], [6], [7]. The identification of risk factors for hospitalization of people with diabetes and the selection of subgroups of subjects who could be managed as outpatients might reduce health care costs [4]. The principal risk factors include age, chronic complications [8], duration of diabetes, number of drugs used for other conditions [9], dysphoria in older patients [2], high glycated hemoglobin (HbA1c) levels [4], older age, fasting glycemia, and chronic complications [10]. No study has assessed the role of comorbidity, with, for instance, cancer or cirrhosis, which can strongly affect the probability of hospitalization, and none has appropriately analyzed multiple admissions as repeated events because the risk for further admissions is conditioned by previous hospitalization.

The aims of the present study were (1) to evaluate the clinical and biochemical features, including pre-existing comorbidity and chronic complications of diabetes, that predict hospitalization in a cohort of patients with type 2 diabetes and (2) to compare the rates and causes of hospitalization in the cohort with expected figures for the general population. This is the first large study of risk factors for hospitalization that takes account of pre-existing comorbid conditions and addresses multiple admissions as repeated events.

Section snippets

Patients

All 3,892 patients ≥35 years of age with type 2 diabetes residing in Piedmont (northwest Italy) and attending the Diabetes Clinic of the San Giovanni Battista Hospital in Turin during 1995 and who were alive on 1 January 1996 were identified. Approximately 70% (n = 2,678) lived in Turin, the largest city in the Piedmont Region. They represented approximately 12% of all patients with type 2 diabetes in the city: 22,997 out of a population aged ≥35 years of 569,638, giving a prevalence of 4.0%.

The

Results

A total of 2,122 patients (54.5%) accounted for 5,465 admissions in Piedmont and elsewhere in Italy. Re-admissions accounted for 83.7% of the total, and 31.6% of the patients had more than one re-admission. The patients who had had one or more hospital admissions were older; more frequently received insulin; had had diabetes for longer; and had higher HbA1c levels and higher prevalences of hypertension, retinopathy, nephropathy, coronary and peripheral artery disease, and comorbidity (Table 1).

Discussion

More than 50% of our cohort had had at least one hospital admission for any cause during the 4.5-year follow-up; furthermore, our data confirm that patients with type 2 diabetes are hospitalized more frequently than the general population, with an excess risk of about 30%; this is more evident for patients under 65 years of age and for women. The small excess in older patients probably reflects a progressive selection in the cohort with aging, favoring healthier patients with better prognostic

Conclusions

Our data confirm the higher rates of hospitalization for patients with type 2 diabetes patients than for the general population, above all among patients <65 years of age and women; in particular, older patients with chronic complications and comorbidity had a high risk for hospitalization. Multiple admissions accounted for a considerable portion of the total days of hospital stay. Our results confirm that diabetes-related diseases, such as circulatory diseases, are the main reasons for

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