Background: “Practice effects” (PE), or performance improvements due to prior exposure to testing, are known to confound cognitive test results, particularly when short intervals occur between two test sessions. Objective: We examined two subsamples with short or long re-test intervals from a recent clinical trial. Methods: Thirty-four non-depressed adults with mild Huntington Disease (HD) participated. Three cognitive tests were administered at screening and again at baseline, before active treatment randomization. Half the sample had a 24-hour retest interval while the other half was >6-days. Results: The two groups differed on demographic/clinical factors (age, Total Motor Score and Total Functional Capacity). After controlling for age and motor score, PE differences were found on three of the five UHDRS cognitive tests: the longer interval group showed larger PE on Symbol-Digit Modalities and Stroop color, while the rapid interval group had larger PE on Stroop interference. Controlling for screening cognitive performance yielded similar results. Conclusions: Length of interval between screening and baseline visits and level of disease severity may influence stability of UHDRS cognitive test results in clinical trials in HD.
National Randomized Controlled Trial of Virtual House Calls for People with Parkinson's Disease: Interest and Barriers
Background: Delivering specialty care remotely directly into people's homes can enhance access for and improve the healthcare of individuals with chronic conditions. However, evidence supporting this approach is limited. Materials and Methods: Connect.Parkinson is a randomized comparative effectiveness study that compares usual care of individuals with Parkinson's disease in the community with usual care augmented by virtual house calls with a Parkinson's disease specialist from 1 of 18 centers nationally. Individuals in the intervention arm receive four virtual visits from a Parkinson's disease specialist over 1 year via secure, Web-based videoconferencing directly into their homes. All study activities, including recruitment, enrollment, and assessments, are conducted remotely. Here we report on interest, feasibility, and barriers to enrollment in this ongoing study. Results: During recruitment, 11,734 individuals visited the study's Web site, and 927 unique individuals submitted electronic interest forms. Two hundred ten individuals from 18 states enrolled in the study from March 2014 to June 2015, and 195 were randomized. Most participants were white (96%) and college educated (73%). Of the randomized participants, 73% had seen a Parkinson's disease specialist within the previous year. Conclusions: Among individuals with Parkinson's disease, national interest in receiving remote specialty care directly into the home is high. Remote enrollment in this care model is feasible but is likely affected by differential access to the Internet.
Clinical-Genetic Associations in the Prospective Huntington at Risk Observational Study (PHAROS)
Abstract Background: In Huntington disease (HD), cognitive changes due to disease-progression or treatment are potentially confounded by “practice effects” (PE) — performance improvement from prior exposure to test materials. Objective: A practice run-in (“dual baseline”) was used in an HD cognitive trial to determine if PE could be minimized and evaluate performance trajectories over multiple visits. Methods: Non-depressed adults ( N = 36) with mild to moderate HD-related cognitive deficits participated in a clinical trial to examine the efficacy of citalopram to enhance cognition. Cognitive tests were administered at three visits (2 weeks separating each visit), before active treatment randomization. Some tests were also administered at screening. Therefore 3–4 pre-treatment repetitions were available. We examined test improvement using repeated-measures ANOVAs with planned pairwise comparisons. Results: Despite the practice run-in and use of alternate test forms, results indicated ongoing improvements over at least three test sessions on all three UHDRS cognitive tests. Trails A and B showed improvements between the third and fourth session, which suggests that one pre-baseline visit may not be effective in reducing practice on this important and commonly used test. Conclusions: Overall, 7 out of 13 variables showed some degree of short-term PE, even after multiple sessions and alternate forms. Tests assessing processing speed and memory may be particularly confounded by ongoing PE across at least 2–3 sessions. Practice run-in periods and alternate forms may help minimize the impact of such effects in HD clinical trials but awareness of which tests are most susceptible to PE is important in clinical trial design.
The past, present, and future of telemedicine for Parkinson's disease