The different courses of early- and late-onset idiopathic and alcoholic chronic pancreatitis.

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. 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. 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. 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.