P530 Is microscopic colitis a rare disease in Southern Europe? A prevalence population-based study in Terrassa (Spain)
F. Fernández-Bañares*1, A. Salas2, Y. Zabana1, M. Aceituno1, M. Esteve1
1Hospital Universitari Mutua Terrassa, Gastroenterology, Terrassa, Spain, 2Hospital Universitari Mutua Terrassa, Pathology, Terrassa, Spain
Few studies have assessed the prevalence of microscopic colitis (MC). Two studies conducted in the USA and Sweden have reported prevalence rates of 219 and 123x105 inhabitants, respectively. In Spain there is only one study showing a prevalence of 48x105 inhabitants. In Europe a rare disease is that affecting less than 1 in 2000 people, so the figures described in Spain fall into this definition. The natural history and the need for long-term maintenance treatment in MC are not well known.Objective: 1. To evaluate the prevalence of MC in the catchment area of Terrassa (Barcelona, Spain); 2. To assess the need for long-term maintenance specific treatment.
Methods: Cases were obtained from the pathology department registry of the HUMT. The belonging to the catchment area, the current residence in the area and to be alive at 31-August-2014 were confirmed for each case. The prevalence rate by age and sex using as a reference the general population in the catchment area was calculated. Current active drugs for MC in every patient (excluding those diagnosed in the last year) were also recorded.
Between January 1993 and August 2014, 410 MC patients were diagnosed. Of these, 201 patients (96 CC and LC 105) were alive and living in the area (75% women; 68 ± 1 years). The prevalence of MC was 94.3x105 inhabitants (95% CI, 80.3-110), being 45.6 and 48.6 for CC and LC. In the group aged 15-44 years, there were 8 MC, with a prevalence of 11x105 (women, 19.9; men, 2.7; p<0.05). In the group aged 45-64 years there were 56 MC, with a prevalence of 130.7x105 (women, 186.5; men, 74.8; p=0.001). In the group aged 65 years or older there were 96 MC, with a prevalence of 372.6x105 (women, 487; men, 223.5; p<0.001). 24% of the patients were receiving maintenance treatment for MC: 13.2% budesonide, 6.6% mesalazine, 1% cholestyramine, 0.5% methotrexate, 1.6% anti-TNF, and 1% other drugs after a mean follow-up of 7.8 ± 0.38 years from diagnosis.
Conclusions: The prevalence rate of MC in our geographical area is greater than 50x105 inhabitants, not fulfilling the definition of rare disease. However, both CC and LC separately accomplish this criterion. There is a clear increase in prevalence rate according to older age and female gender. Only one quarter of patients require long-term maintenance treatment and only a minority of them require biological drugs / immunosuppressants for severe diarrhoea unresponsive to budesonide.