Bromocriptine lessens the incidence of mortality in L-Dopa-treated parkinsonian patients: Prado-study discontinued

Summary

L-Dopa supplemented by a peripheral decarboxylase inhibitor is considered the most potent therapeutic regimen prolonging active life in Parkinsonian patients. The long-term benefit of therapy is limited by adverse effects, such as dyskinesia and on-off phenomena, which can be mitigated by the concomitant administration of dopamine agonists, such as bromocriptine. In order to quantify the beneficial impact of early combination therapy, a controlled clinical trial (PRADO:PRA vi-del¹ +DOpa) in patients with early Parkinson's disease was carried out, whereby L-Dopa monotherapy (in a fixed combination with benserazide (DoBe) was being compared with the same combination plus bromocriptine (DoBeBro). Patients were recruited and treated by 101 practising neurologists in the Federal Republic of Germany and in Hungary. 'Twenty seven clinical university centers cross-checked the patients at regular intervals. The trial started with 3 months of DoBe monotherapy (median dose of 375 mg L-Dopa for both randomized groups) followed by gradual substitution of DoBe by bromocriptine over 3 months in one of the groups (250 mg L-Dopa/10 mg bromocriptine). The target medication was maintained from study months 6 to 54.

Parkinsonian symptoms were classified according to the Webster rating scale, the Hoehn and Yahr scale and the Zung Self-Rating Depression Scale. Adverse events and life status were checked at regular intervals. Special emphasis was given to motor performance tests. 587 patients (302 in the DoBe group and 285 in the DoBeBro group) were available for intention-to-treat analysis. Both groups were homogeneous at baseline in all observed parameters. DoBe and DoBeBro proved equi-effective in terms of antiparkinsonian activity after the substitution phase (P II) had been completed. In September 1991, after a median observation period on target medication of 38.4 months in the DoBe group and 40.1 months in the DoBeBro group, 18 versus 8 deaths had been registered. The Logrank test as well as analysis using the Cox model, both adjusted for age and sex, showedP-values of 0.018 and 0.021, respectively. The mortality risk associated with L-Dopa therapy was reduced by more than 50 % by its combination with bromocriptine. The study was terminated due to this difference in mortality. The causes of death were classified by the treating physicians and consultants. At the time of study termination 152 patients in the DoBe group and 121 in the DoBeBro group had already discontinued study medication. Of those further 26 patients had died by the date of the final evaluation, 15 on DoBe and 11 on DoBeBro.

The results imply that combination therapy with bromocriptine should be preferred over L-Dopa monotherapy from the very beginning.