Background/aims: Compared with alcoholic pancreatitis, little is known about the natural history of idiopathic pancreatitis. Two hundred forty-nine patients with alcoholic pancreatitis and 66 patients with idiopathic chronic pancreatitis seen at our institution between 1976 and 1982 were investigated.
Methods: Records were analyzed retrospectively from the onset of symptomatic disease, and patients were followed up prospectively until 1985. Patients with early-onset (n = 25) and late-onset (n = 41) idiopathic chronic pancreatitis had a median age at onset of symptoms of 19 and 56 years, respectively.
Results: The gender distribution was nearly equal in idiopathic chronic pancreatitis, but 72% of patients with alcoholic pancreatitis were men (P = 0.001 vs. idiopathic). In early-onset idiopathic pancreatitis, calcification and exocrine and endocrine insufficiency developed more slowly than in late-onset idiopathic and alcoholic pancreatitis (P = 0.03). However, in early idiopathic chronic pancreatitis, pain frequently occurred initially (P = 0.003 vs. late and alcoholic) and was more severe (P = 0.04 vs. late and alcoholic). In late-onset idiopathic pancreatitis, pain was absent in nearly 50% of patients.
Conclusions: There are two distinct forms of idiopathic chronic pancreatitis. Patients with early-onset pancreatitis have initially and thereafter a long course of severe pain but slowly develop morphological and functional pancreatic damage, whereas patients with late-onset pancreatitis have a mild and often a painless course. Both forms differ from alcoholic pancreatitis in their equal gender distribution and a much slower rate of calcification.