BACKGROUND: The study was a follow-up of an inception cohort of 373 patients with Crohn's disease.

METHODS: Annual assessments, life table analyses, and Markov chain analyses, estimating the probability for remission and relapse with time, and working capacity were carried out.

RESULTS: The clinical course of Crohn's disease differs markedly over time, from ever-relapsing cases to a quiescent course with remission for several years, interrupted by years with relapse. No predictive factors have been found for the subsequent course with regard to age, sex, extent of disease at diagnosis, and treatment in the year of diagnosis. The relapse rate within the year of diagnosis and the following 2 years, however, does correlate positively (p = 0.00001) with the relapse rate in the following 5 years. Furthermore, the relapse rate for 1 year during the disease course influences the relapse rate the following year, indicating a disease pattern over time with waves of at least 2 years' duration. A slight tendency towards burning out was found. The disease course reflected in working capacity for the patients showed that a minor part--up to 15% after 15 years--will become incapable and obtain disablement pension, while 75% of the patients each year are fully capable of work. Within 10 years 50% of the patients will not have experienced any year with impaired capacity for work.