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Keywords:

  • allergic rhinitis;
  • general practitioners;
  • prevalence

Allergic rhinitis (AR) is probably the most common IgE mediated disease. Its prevalence in the general population in industrialized countries is reported to range between 10% and 20% (1) with a certain variability that is attributable to the definitions used, to the methods of diagnosis and to the type of survey. It is hypothesized that the prevalence of AR remains underestimated, as a large proportion of patients do not seek for medical advice or specialist consultation. It is also conceivable that general practitioners (GPs) are, together with pharmacists, the first healthcare professionals to whom patients refer for their rhinitis symptoms (2). Although GPs with their databases have been sometime involved in epidemiological studies (3, 4), there is so far no evaluation of the prevalence of AR directly made by GPs. Thus, we searched a national GP database in order to get information on rhinitis prevalence in adults. A cross-search was also made for the prescriptions of antihistamines.

The data were obtained from the ‘Health Search/Thales Database’ (HSD), an Italian general practice research database set up in 1998 by the Italian College of General Practitioners (SIMG). Health Search/Thales Database includes, in electronic format, the complete medical data of all patients registered in the list of the physician (4, 5). Briefly, the HSD contains patient's demographic details, medical records (e.g. diagnoses, tests and tests results, hospitalization), drug history and prevention information. A unique identification number links all data for an individual patient anonymously, so that no direct identification is possible. All participating physicians had to use specially designed software allowing them to register all the disease episodes once and to link any medical intervention to the recorded disease. Data are subject to regular quality checks, mainly associated with the reliability, the completeness and the stability of the information recorded. General practitioners who fail to meet standard quality criteria are not involved in epidemiological studies (6).

The dynamic cohort searched, included all patients alive, aged >18 years, permanently registered in the lists of the participating physicians until December 2003, and with available information for at least 1-year prior to the study. By means of HSD, we identified those subjects with a diagnosis of AR (ICD-9: 477), and those with at least one prescription of antihistamines (ATC: R06A) in the year 2003.

Based on the quality standards, 320 GPs were included in this study. The population screened by these 320 GPs involved 441 376 patients aged >18 years (47% male). Of them, 19 789 had a diagnosis of AR, thus the overall prevalence was 4.5% with no significant difference among age deciles. Oral antihistamines had been prescribed to 18.6% of the general population. Thus, of the patients with a diagnosis of AR, around 73.7% received one or more prescriptions of oral antihistamines, whereas 82.3% of the general population received antihistamines without a diagnosis of AR. These data are summarized in Fig. 1.

image

Figure 1.  Distribution of the patients with a diagnosis of allergic rhinitis and those with antihistamines prescription in the general population (n = 479 217) screened by the Health Search/Thales Database.

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The main finding of this survey is that the prevalence of AR, as assessed by GPs in their database is, on average, lower than described in the large epidemiological studies. There are several possible explanations for this result. It is possible that AR is not spontaneously reported by some patients. Nevertheless, this cannot be the only determinant, as the electronic sheet of the computerized program has a specific entry for ‘allergies and allergic diseases’ that must be filled and updated at each visit. Another possible explanation is that the questionnaire-based surveys overestimate the prevalence of the disease because of the low specificity of the questions (4). On the other hand it is true that the majority of patients with a diagnosis of AR received systemic antihistamines that are considered a first-line therapy for the disease (7) and this confirms indirectly the appropriateness of the diagnosis itself. An accessory consideration is that the GPs’ clinical database may represent an useful tool for epidemiological investigations, providing a realistic cross-sectional picture of the population seeking for primary care.

References

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  2. References
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