Figure 1. Estimated probability of one or more additional biliary drainage interventions after a biliary bypass operation in 1,919 Medicare beneficiaries 65 years of age or older newly diagnosed with pancreatic cancer between 1991 and 1996, according to the type of initial biliary bypass procedure performed. Solid line, gallbladder bypass as initial procedure; broken line, bile duct bypass as initial procedure. Numbers in parentheses indicate the cumulative number of subjects who had an additional procedure. The curves were truncated at 5 years. P value for the comparison of the curves was <.001 by the log-rank test.