Effect of L-dopa on course of Parkinson's disease.

A review of the progress of 176 patients with Parkinson's disease who were given maximum tolerated doses of L-dopa between November, 1969, and December, 1972, showed that the ratio of observed to expected deaths after 12 years' sustained therapy was 2.59 (2.14 for males and 3.64 for females). This contrasts with the overall 6-year follow-up figure for the same patients of 1.45 (1.29 for males and 1.85 for females). These findings indicate that although L-dopa may improve life expectancy during the first 6 years of therapy the protective effect subsequently declines.