Objective: The aim of this substudy was to determine the agreement between 2 approaches for measuring health care resource utilization (eg, number of hospital visits, number of primary care physician visits) in trial participants with Parkinson's disease (PD).
Methods: A substudy of the 1-year multicenter futility trial of GPI-1,485 and coenzyme Q(10) (FS-TOO) was performed to assess health care resource utilization agreement by measuring participant utilization recall after 12 months versus measuring participant utilization recall at regular 3-month intervals. Trial participants were selected from patients in the National Institutes of Health-sponsored FS-TOO multicenter study. Persons aged >or=30 years with confirmed PD diagnosis within the previous 5 years were eligible for inclusion in the substudy. Participants were also required to have at least 2 of 3 cardinal manifestations of PD (tremor, rigidity, and bradykinesia). Participants were excluded from the study if they had presence of atypical Parkinson's syndromes due to drugs, metabolic identified neurogenetic disorders, encephalitis, or other degenerative diseases. Agreement was determined using Lin's concordance and Cohen's kappa statistics.
Results: Between March and July of 2004, a total of 424 potential subjects were identified and evaluated for trial eligibility. Of these, 213 subjects (139 men, 74 women; mean [SD] age, 61.5 [10.3] years) met entry criteria and were included in the study. Trial participants were randomized equally to 1 of 3 groups. The 3 groups had similar baseline characteristics in terms of demographic data (age, race, sex, employment status, and annual income), total Unified Parkinson Disease Rating Scale (UPDRS) score, and UPDRS subscores. In this substudy, 141 participants had a true baseline visit, indicating a clinical baseline date, and 182 participants completed the Baseline Resource Utilization Form within 3 months of the true baseline visit. The comparison of concordance between the summed information over 3-month recalls and the 12-month recall from baseline was derived from these 182 participants. The level of agreement between the 2 approaches was high, ranging from 64.4% to 95.1%. Where disagreement was identified, the more frequent measurement approach (every 3 months) led to higher estimates, ranging from 20.4% to 77.4%.
Conclusion: The results of this trial indicate internal consistency with the self-reported measures of health care resource utilization, suggesting that these simple measures might provide reliable information about units of health care resource utilization in the context of clinical trials for PD.