This is an open, prospective, longitudinal study designed to compare two cohorts of patients with advanced Parkinson's disease during 1 year, one undergoing bilateral subthalamic stimulation (STN-DBS) and the other receiving the best medical treatment (BMT), with respect to the clinical effects observed and the medical expenses produced. Assessments were done by using clinical measures and a generic health related quality of life scale. A questionnaire was used to collect direct healthcare resources. As a measure of cost-effectiveness, we calculated life years gained adjusted by health-related quality of life (QALY) and the incremental cost-effectiveness ratio (ICER). Clinical and demographic variables of both groups were comparable at baseline. Total UPDRS scores improved from 50.5 +/- 3.6 to 28.5 +/- 3.8 in STN-DBS patients and worsened from 44.3 +/- 3.3 to 54.2 +/- 4 in the control group. Pharmacological costs in the operated patients were 3,799 +/- 940 euro, while in the BMT group the costs were 13,208 +/- 4,966 euro. Other medical costs were 1,280 +/- 720 euro in the STN-DBS group and 4,017 +/- 2,962 euro in BMT patients. Nondirect medical costs were 4,079 +/- 1,289 in operated patients and 2,787 +/- 1,209 euro in the BMT group. Mean QALYs were 0.7611 +/- 0.03 in STN-DBS and 0.5401 +/- 0.06 in BMT patients. In STN-DBS patients, the ICER needed to obtain an improvement of one point in the total UPDRS score was of 239.8 euro and the ICER/QALY was of 34,389 euro. Cost-effectiveness parameters were mostly related to the degree of clinical improvement and the reduction of pharmacological costs after STN-DBS. An ICER of 34,389 euro/QALY is within appropriate limits to consider subthalamic stimulation as an efficient therapy.

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