BEN - Notiziario ISS - Vol.16 - n.1
A Simple Method for Monitoring Endemic Goiter
Enrico de Campora1, Sergio Lodato, and Renato Pizzuti2
1Regional Health Agency of Campania, Naples
2Epidemiologic Observatory for the Campania Region, Naples
Goiter represents the most frequent clinical manifestations of iodine deficiency (ID). Iodine is an essential element for human grown and development. Endemic goiter represents a disease of adaptation that occurs as a consequence of chronic stimulation of the thyroid gland by thyrotropin. In populations exposed to iodine deficiency, increased rates of abortion, stillbirth, transient neonatal hypothyroidism, neuropsychiatric and minor cognitive deficits, and cretinism are observed (1). Goiter is more commonly seen in hilly or mountainous areas where levels of iodine in the soil are lower.
The clinical manifestations of goiter are usually unremarkable and in the initial stages, consist of a simple increase in the volume of the thyroid. In goiters of long duration, the most common complication is nodular goiter with resulting thyroid hyperfunction (2).
Iodine-deficiency goiter may be prevented by iodine prophylaxis. Despite the availability of a ready means of prevention, use of iodised salt in Italy is low, accounting for less than 3% of table salt sales (3).
To monitor the prevalence and distribution of ID, periodic screenings of school-age children are commonly used. The methods used to identify ID include palpation of the thyroid, ecography, and determination of urine iodine.
Goiter is defined as endemic when more than 5% of the total population or more than10% of the school age population are affected (1). In a recent review of epidemiologic studies conducted in Italy over the past 20 years according to WHO guidelines, the prevalence of goiter in the young population was more than 20% and was invesrsely correlated with urinary iodine excretion (UIE). In some areas of Campania, the prevalence was as high as 73% of the young persons examined (4)
In a study conducted in Campania, Italy between 1993-1996 among 3480 children in adults in both urban and rural areas in which UIE was measured, the mean EIU was significantly lower among residents of the provinces of Benevento, Avellino, and Caserta compared with Naples. The authors concluded that in many areas of the Campania region, there is a mild-moderate iodine deficiency and that a program of iodine prophylaxis is warranted (5).
The methods currently used for screening require a high level of standardization of technique to guarantee precision, accuracy of the test, and the reproducibility of the results. Furthermore, costs of such campaigns and the difficulties of organizing such surveys are important obstacles to the repetition of periodic surveys by local health authorities.
To evaluate whether the frequency of hospitalisation for non-toxic thyroid goiter could provide an indication of endemic areas, we analyzed the hospital discharge records for residents of Campania for 2000, regardless of where they had been hospitalised.
Since 1995 in Italy, it has been required that a form known as the SDO (scheda di dimissione ospedaliera) be filled out for each hospital admission in the country. The SDO summarizes the contents of the clinical chart and includes, among other variables, the clinical diagnoses made during the hospital stay, the hospital, and the residence of the patients. Clinical diagnoses are coded using the International Classification of Diseases (ICD9 CM) scheme. This classification system, although not entirely precise from the epidemiologic point of view because of lack of standard case definitions, nonetheless can provide a picture of the frequency of hospitalisation and geographic distribution as well as the health-care expenditures related to specific diagnoses.
With this in mind, we analyzed SDO data for residents of Campania (5.8 million population) regardless of site of hospitalisation; in 2000, there were 1, 191,000 admissions within the region and 93,000 in other regions. Analysis was limited to those records which had as the principal diagnosis the ICD-9 CM codes related to “Simple or non-specific goiter’ (240.0-241.9). For comparison purposes, we examined national data for the same diagnostic categories using the national SDO database maintained by the Ministry of health. For both populations, we examined inpatient admissions by age and sex. Denominators were obtain from population estimates from ISTAT for 2000.
In 2000, 28,577 hospitalizations occurred in Italy among persons whose principal diagnosis was simple or non-specific goiter, resulting in a rate of 49.5 hospitalizations per 100,000 residents. The corresponding rate for Campania residents, standardized for age, was 79.7, 1.6 times that of the country as a whole. Among those diagnosesd with simple or non-specific goiter in Italy, 59% had a principal diagnosis of non-toxic multinodular goiter ( ICD-9 421.1); in Campania, the corresponding figure was 57%.
In Campania, a total of 8,588 had the principal diagnosis of simple or non-specific goiter (0.7% of all hopsitalizations among Campania residents). The costs relative to these hospitalisations for the year 2000 was 10.5 million Euro. A total of 48% of the admissions were inpatient admissions (3,883 persons, each with 1.1 hospitalizations), and 47% of the inpatients underwent surgical interventions.
A total of 80% of those admitted at least once were female, and the mean age was 47.9 years. 3.2% were < 25 years, and 23 of the total were < 15 years.
In Campania, the geographic distribution of the hospitalisations varied greatly among areas, with higher concentrations observed in those areas known to have a low iodine content in the soil and a high incidence of endemic goiter. In particular, the province of Benevento, had a rate of hospitalisation for goiter of 217 cases/100,000 residents, 1.5 times the regional mean). In the province of Salerno, major differences were seen between Local Health Authorities, with the rate in Salerno 3, which includes several mountainous districts to the south of the city of Salerno, and that of the coastal city of Salerno and its surrounding areas (189.3 cases per 100,000 versus 84/100,000; Table). The relative risk (RR calculated using the lowest of the rates as the referent population (Salerno 1), showed that 7 of the 13 Local Health Authorities of the Campania region had RR values >1.5, while only 2 of the 13 exceeded the 90th percentile when the rates were compared.
The usefulness of the SDO to evaluate the frequency of certain diseases is becoming commonplace, and linkage with the SDO archives, where they exist, has been used for many disease registries, despite the limitations identified by some authors. Obviously, hospitalisation, especially inpatient hospitalisation, represents only a single event during the course of the illness, which in the case of goiter, seems to be related to the appearance of complications (nodular goiter) that requires a surgical intervention.
To be able to use the SDO as a direct estimator of the level of endemicity of goiter in an area, it would nonetheless be necessary to know the proportion of cases hospitalized among all cases of simple goiter diagnosed according to WHO criteria in the same area. At any rate, if it can be assumed that there is a consistent relationship between ambulatory and inpatient cases, Campania would seem to be an area with high goiter incidence, given the 1.6-fold higher standardized rate for the Campania population compared with the rest of Italy.
The rates of admission for goiter in Campania show that there is a high level of heterogeneity across the region. In addition, data on expenditures suggest that this problem remains relevant in spite of health education efforts on the part of some of the Local Health Authorities to increase the consumption of iodised salt.
The system proposed of using the SDO could contribute to the identification of areas at major risk of goiter such that public health interventions can be better targeted in order to eliminate the disease. In addition, such analyses can serve to monitor, especially among the younger cases, the success of the information campaigns in a manner that is more rapid and economic that the periodic mass school-based.screening programs
1. Pinchera A, Rago T e Vitti P, Fisiopatologia della carenza iodica. Ann. Ist. Super. Sanità, 1998; vol. 34, n. 3: 301-305;
2. Macchia PE e Fenzi G, Gozzo endemico: quadro clinico ed evoluzione. Ann. Ist. Super. Sanità, 1998; vol. 34, n. 3: 307-310;
3. Aghini-Lombardi F, e Antonangeli L, Legislazione sulla iodoprofilassi in Italia. Ann. Ist. Super. Sanità, 1998; vol. 34, n. 3: pp. 363-366.
4. Nasti A et al., Escrezione urinaria di iodio nella regione Campania. Ann. Ist. Super. Sanità, 1998; vol. 34, n. 3: 413-416.
5. Aghini-Lombardi F, Antonangeli L e Vitti P, Epidemiologia del gozzo endemico in Italia. Ann. Ist. Super. Sanità, 1998; vol. 34, n. 3: pp. 311-314.