Bollettino epidemiologico nazionale

Diabetes Prevalence and the Epidemiology of Diabetes Admissions in the Emilia-Romagna Region

Anna Vittoria Ciardullo,¹ Menna A,¹ Brunetti M, ¹ Daghio MM, ¹ Magrini N, ¹ Paganelli A,² Lazzarato M²

¹Center for the Evaluation of Efficacy of Health services (CeVEAS) – Local Health Agency, Modena

²Health Directorate, Emilia-Romagna Region

The prevalence of diabetes in the general population of Italy is estimated at 3-4% and increases with age. Ninety percent of diabetes patients have Type 2 diabetes, which usually has its onset in adulthood. Diabetes is increasing in Italy and elsewhere in Europe, and the World Health Organization estimates that there will be a doubling of cases in the region by 2025, largely as a result of lack of physical activity and poor dietary habits, both of which are risk factors for the disease (1).

Diabetes causes a variety of serious complications that involve primarily the eyes, the kidneys, the peripheral nervous system, and the cardiovascular system. Given the importance of diabetes, in 1989, the Declaration of St. Vincent to reduce the burden of morbidity and mortality caused by diabetes was endorsed by patients, physicians and European governments.

The purpose of this study is to evaluate the prevalence of diabetes in the Emilia-Romagna (ER) region of northern Italy and to examine recent trends, comparing regional data on exemption of payment data for 1999 and 2000 (Editor’s note: in some regions of Italy, a small co-payment is required for medications and/or laboratory tests, although exemption can be obtained for certain diagnoses if appropriate documentation is provided. In the case of diabetes, the patient must present a certificate issued by a diabetologist or other recognized documentation [Ministerial Decree n. 296/2001]). In addition, the study was conducted to compare admissions for acute complications such as coma for Type 1 and Type 2 diabetes and also for chronic conditions such as micro- and macrovascular complications.

The prevalence of diabetes was estimated as the total number of exemptions granted by the local health authorities of the region divided by the number of residents of the region; age specific data were not available. Criteria used for granting exemptions are based on pre-2001 cutoffs that define diabetes on the basis of an oral glucose tolerance test (OGTT) in which the fasting blood glucose >140 ml/dL and/or a blood glucose at 2 hours is  >200 mg/dL; (the 2001 criteria consist of a blood glucose >126 mg/dL and a 2 hour blood glucose of 200 mg/dL. ).

The hospitalization rates for those with diabetes exemptions were estimated from the computerized hospital discharge records maintained by the health directorate of the region, selecting those records in which the primary ICD-9-CM diagnosis was coded as 250.1, 250.2, 785.4, 443.8, 250.4, 250.5, 250.6, 250.7, 428, 410.-, 434.-, 435.-). Results were examined separately for type 1 and type 2 diabetes, which were distinguished on the basis of the fifth digit of the ICD9-CM code. The ratio between the admission rates and 95% confidence intervals were calculated for type 2 versus type 1.

In the E-R region, which has a population of more than 4 million residents, the prevalence of diabetes at the end of 1999 was estimated on the basis of exemption records to be 2.2%, ranging from 1.5% in Rimini to 3.3% in Ferrara. By the end of 2000, the mean prevalence was 2.4%, ranging from 2.0% in Bologna South to 4.0% in Ferrara; this represents an annual mean regional increase of 10.6%.

The total number of admissions in 2000 among residents with exemptions for diabetes was 20,462, which corresponds to a rate of about 1 admission for every 5 patients with an exemption (rate 212.5/1000 exempt patients). Most (85.1%) were for complications of Type 2 diabetes. Diabetic coma and micro and macrovascular complications together accounted for 42.1% of all admissions (8,618/20,462).

The distributions of discharge diagnoses for patients with type 1 and 2 disease were significantly different (Table 1). In patients with type 1, hospitalizations for circulatory disturbances were 33% more common than for type 2 diabetes; similarly, ketoacidotic coma was 75% higher, as were renal problems (49% higher), gangrene (68% higher), and peripheral vascular complications (54% higher). By contrast, heart failure was more common (19% higher than for type 1 diabetes), as were infarct (27% higher) and transient ischemic attacks (41% higher). No significant differences were seen between the two types of diabetes with respect to ocular manifestations, neurologic problems, and hyperosmolar coma.

It is clear that estimates based on exemptions are subject to error by virtue of policies of the individual local health authorities (as is the case in Ferrara, which has actively sought out diabetes cases), because residents may seek care in health authorities other than the one in their area, when patients do not seek exemptions, or when patients do not require drugs to manage their diabetes. It is likely that exemption data results in an underestimate of the true prevalence of the disease. Nonetheless, if the increase we observed over the two-year period is real, it is likely that the region will experience the doubling of prevalence predicted by WHO for 2025 (1) will occur many years earlier.

It is also clear that using the fifth digit of the ICD9-CM code to distinguish between type 1 and type 2 diabetes lacks both sensitivity and specificity; for example, clinicians may classify as type 1 those patients who are on insulin but who, from a clinical point of view, have type 2. Despite this problem, however, the findings for the two groups are coherent with the findings on the types of complications for the two; patients with type 1 are more likely to have acute decompensation (ketoacidotic coma) and to develop nephropathy and peripheral vascular disease, while those with type 2 are more likely to develop cardiovascular or cerebrovascular disease (heart failure, infarct, and transient ischemic episodes).

Nota Editoriale

Giuseppina Imperatore, MD PhD

Division of Diabetes Translation

Centers for Disease Control and Prevention, Atlanta, GA, USA

Diabetes mellitus is a major health problem associated with excess morbidity and mortality. The prevalence of this disorder worldwide will double over the next 25 years (2), resulting in a substantial increase in health care costs. It is, therefore, crucial to prevent or delay the onset of diabetes and its complications.

In Italy, the prevalence of diabetes has been estimated by various different methods. In a study of 1,821 subjects aged 40 to 89 years conducted in Cremona in 1990-91, researchers estimated that the prevalence of diabetes, defined as a fasting glucose level >126 mg/dl or ³ 200mg/dl 2 hours after oral glucose tolerance test or treatment for diabetes, was 12% among men and 11% among women (3). In a screening conducted from 1998 through 2000 in a representative sample of the Italian population (8,030 individuals, 4,032 men and 3,998 women, aged 35-74 years) researchers found the prevalence of diabetes, defined as a fasting glucose level >126 mg/dl or treatment for diabetes, to be 9.2% among men and 6.6% among women; 35% of those who met these criteria did not know they had diabetes. (4).

In the study reported in this issue of the BEN Ciardullo et. al. used data on conditions for which exemption from patient co-payment can be obtained (i.e. chronic diseases such as diabetes, hypertension, and cancer) to estimate that the diabetes prevalence in the Emilia-Romagna region was 2.4%. One reason that this estimate is much lower than those previously cited is that Ciardullo et al. used a different methodology and diagnostic criteria. However, the results of Ciardullo et al. are comparable with those of studies that have used similar case ascertainment methodology. For example, in 1986 the prevalence of diagnosed diabetes in Naples, as ascertained by drug prescription records was 2.01% (5). Similarly, in a recent study conducted in England and Wales with data from the general practitioner database, researchers estimated that the prevalence of diagnosed diabetes was 2.2% among men and 1.6% among women (6). These data also indicate that more than a third of subjects with diabetes are unaware that they have it and therefore do not receive appropriate and timely treatment.

Data from the Emilia-Romagna region also showed that among those with known diabetes the annual rate of hospitalizations for diabetes-related complications is approximately 20%. Randomized clinical trials have demonstrated that by controlling blood glucose, blood pressure, and lipid levels, individuals with diabetes can delay or prevent the onset of diabetes complications such as blindness, renal failure, and cardiovascular diseases (7-9). Unfortunately, the data presented by Ciardullo et al. indicate that these measures of secondary prevention may be underutilized. Type 2 diabetes, the most prevalent form of the disease (90-95%) can be present for many years before diagnosis (10). Because a substantial proportion of subjects with type 2 diabetes already have microvascular complications when their disease is diagnosed, health officials need to implement strategies aimed at more timely diagnosis. Engelgau et al. (11) recently proposed that opportunistic screening may be the most cost-effective strategy for doing so. This will certainly enhance case detection among symptomatic individuals. Health officials also should design and implement educational programs for both patients and health care providers about the importance of secondary prevention measures.

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