title: Predictors of time to requiring dopaminergic treatment in 2 Parkinson's disease cohorts.
abstract: The rate of progression of Parkinson's disease (PD) is highly variable. Knowledge of factors associated with disease milestones and commonly used research outcome measures helps with patient counseling and guides the design and interpretation of clinical studies. The objective of the study was to identify prognostic factors for time to acquiring disability requiring dopaminergic therapy that are reproducible within 2 large prospectively followed cohorts. Potential prognostic factors were identified using data from the Deprenyl and Tocopherol Antioxidative Therapy of Parkinsonism (DATATOP) trial, and their reproducibility was examined using data from the Parkinson Research Examination of CEP-1347 trial (PRECEPT). In multivariable analyses of the DATATOP cohort, higher baseline Unified Parkinson's Disease Rating Scale (UPDRS) scores, full-time employment, a lesser smoking history, and onset on the left side were associated with a shorter time to disability requiring dopaminergic therapy. PRECEPT data confirmed the associations of higher baseline UPDRS scores and full-time employment with shorter time to requiring treatment. Any clinical trial using the end point of time to disability requiring dopaminergic therapy should ensure that groups are well balanced with respect to baseline UPDRS scores and the proportion of subjects employed full time and should consider including these variables as covariates in the statistical model for primary analysis of treatment effects. We suspect that individuals employed full time may have a lower threshold for requiring dopaminergic therapy because of occupational demands.
authors.affiliation: Morton and Gloria Shulman Movement Disorders Centre, Toronto Western Hospital, Toronto, Ontario, Canada. connie.marras@utoronto.ca
authors.forename: Connie
authors.initials: C
authors.lastname: Marras
authors.forename: Michael P
authors.initials: MP
authors.lastname: McDermott
authors.forename: Ken
authors.initials: K
authors.lastname: Marek
authors.forename: Paula
authors.initials: P
authors.lastname: Rochon
authors.forename: Gary
authors.initials: G
authors.lastname: Naglie
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Tanner
authors.forename: Alice
authors.initials: A
authors.lastname: Rudolph
authors.forename: Ira
authors.initials: I
authors.lastname: Shoulson
authors.forename: Anthony E
authors.initials: AE
authors.lastname: Lang
mesh_terms: D000368:Aged; D002986:Clinical Trials as Topic / Q000379:methods*; D015331:Cohort Studies; D004185:Disability Evaluation; D018450:Disease Progression; D015259:Dopamine Agents / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000188:drug therapy* / Q000503:physiopathology; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D013997:Time Factors
chemical_list: D015259:Dopamine Agents