Editorial

 

Inflammatory bowel disease in Spain: problems grow

 

In medical research a variety of fields diversely contribute to the understanding and eventually to the solution of problems. The relevant role played by epidemiology in this setting is clear for all of us. Specifically, its contribution in the field of inflammatory bowel disease (IBD) is of particular interest. Why is this so?

In the first place we are facing diseases whose causes have not yet been established. Albeit different authors are increasingly unveiling the pathogenesis and pathophysiology of Crohn's disease and ulcerative colitis in an elegant way, we still ignore which factor triggers the cascade of events that in both cases leads the patient to suffer from these conditions in full. A controversy on the nature of such factor divided researchers, and it still does, into geneticists and environmentalists, the latter further splitting up into those who believe that factors determining the development of the disease are purely immunologic, and those who rather claim a dietary, environmental or even microbial origin. While not detracting from the important role played by genetics, we should not lose sight that the changing, generally increasing incidence of these conditions clearly suggests that an environmental factor may collaborate with genetic predisposition in their development. In fact, this is the primary contribution of epidemiology.

Secondly, the magnitude of costs associated with inflammatory bowel disease is just beginning to be understood (1). Fortunately, drugs used in the caring of individuals diagnosed with this disease are becoming increasingly sophisticated, but their cost is also rising. From an era of unexpensive chemical therapies, their clearest representatives being glucocorticoids and azathioprine, we are entering a time of biological therapy. Its cost is presumably high, even though savings from other aspects (hospital stay, work incapacity, decreased quality of life) may likely make up for it.

Finally, let us recall that these conditions affect an increasing number of individuals who, in addition, are going through a particularly susceptible time in their lives (1,2). Approximately elapsing from adolescence to first maturity, this is a time when human beings grow both personally and socially, complete their education, become integrated in groups, develop affectively, pair-bond, maybe reproduce, and end up in the complex world of labour relations; in summary, from a safe viewpoint, they are growing-up persons with an already significant capability to generate wealth. Ignorance of the number of subjects affected by these conditions will preclude our taking a first step towards quantifying the grand total of indirect expense brought forward by this ailment (1). A need for correct quantitative data should also be included in this section, which will allow us to assess the influence of inflammatory bowel disease in the quality of life of involved subjects.

In this issue of Revista Española de Enfermedades Digestivas, Rodrigo et al. (3) competently and clearly discuss the incidence of inflammatory bowel disease in a population area that may be deemed paradigmatic for our days: a predominantly urban, town-centered zone. Their careful study demonstrates that in that area, for two consecutive years, the adjusted incidence rate per 10⁵ inhabitants between 15 and 64 years of age was 9.1 for ulcerative colitis (95% confidence interval, 5-13.1) and 7.5 for Crohn's disease (95% confidence interval, 3.8-11.2). These rates are higher than those early reported by Cristina Saro and the co-authors of Estudio Asturiano -performed a few years before in a nearby geographic area (4)- and by many other Spanish groups, as revealed by a recent, comprehensive systematic review (5). According to the latter, in Spain, we should expect rates nearing 2 cases per year per 10⁵ inhabitants for Crohn's disease, and 4 cases per year per 10⁵ inhabitants for ulcerative colitis; even though the authors themselves emphasize that retrospective data must be cautiously interpreted in this and other contexts. In fact, Spanish estimations in the European corporate prospective study from the 1990s are somewhat higher (6). The likely present reality becomes clear as later reports by the Asturian group (7,8) show higher incidences and, regarding prospective data (7), incidence rates that are virtually identical to those found by Rodrigo et al. (9.52 per 10⁵ inhabitants for ulcerative colitis and 5.95 per 10⁵ inhabitants for Crohn's disease).

To sum it up, the incidence of Crohn's disease and ulcerative colitis in other Asturian areas -as was already known (7,8)- and in Oviedo's area -as we know it now (3)- approaches that of Northern European countries. In the face of such disquieting European convergence, the same old question of whether increased rates result from better prospection (a better access of the population to diagnostic means, greater concern for health, etc.) or from the aforementioned alleged environmental factor acting on an increasingly higher number of compatriots arises. In this respect two points should be clarified. First, let us consider that the frequency of inflammatory bowel disease, as with all diseases, increases with the thoroughness of its search. Not long ago, in an almost detective prospective study including a door-to-door survey throughout the territory of their healthcare area, some authors from India, a country with a minor incidence of inflammatory bowel disease, surprised us all with prevalence data that were much greater than those previously reported (9). Secondly, however, we should also state that Spain is no longer in the socioeconomic transition stage that characterized previous studies, and that being cared for by a physician capable of diagnosing inflammatory bowel disease has been relatively easy for a long time now (10). We are inclined to think that an actual increase in inflammatory bowel disease rates has occurred in Spain.

Other similarly interesting data were found in this study. Such is the case with the relative proportion of Crohn's disease and ulcerative colitis cases, the latter's anatomical distribution (which greatly conditions treatment), and the forms of Crohn's disease that were found according to the Vienna classification, which is becoming increasingly widespread in descriptive studies.

Finally, as the authors point out, this study is original in that it examines the incidence of inflammatory bowel disease among children. In children below 15 years of age they find an incidence of 5.7 per 10⁵ for Crohn's disease and of 1.4 per 10⁵ for ulcerative colitis, always near puberty. Unfortunately, Crohn's disease and ulcerative colitis are increasingly common in pediatric departments. No doubt, this sets a trend towards paying particular attention to this age group within epidemiologic studies on inflammatory bowel disease, which other researchers must necessarily follow into the future.

A. López San Román and F. Bermejo¹

Intestinal Bowel Disease. Service or Gastroenterology.
Hospital Ramón y Cajal. Madrid
¹Service of Digestive Diseases. Hospital de Fuenlabrada. Fuenlabrada, Madrid

 

REFERENCES

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