3 research outputs found
Park Aid Systems: Factors That Affect Consumer Purchase Decisions
No full textBackover crashes in the United States result in at least 300 fatalities and 17,000 injuries every year. Backover crashes occur when a non-occupant of a vehicle is struck by a vehicle moving in reverse. Children are particularly vulnerable. Of the 300 fatalities, at least 100 deaths are children under the age of five. Limited visibility is one factor behind these deaths. The deaths are especially tragic, since the availability of a simple park aid device can expand a driver’s field of vision during a reversal maneuver. Park aid devices include a rearview camera or a sensory system.
This project is undertaken to determine the factors which influence a consumer’s willingness to pay for a vehicle with an already installed park aid system. We determine that these factors include consumer demographics (income and age), vehicle attributes (including drive type, width, height, mileage, make), vehicle operating costs (annual expenditure on fuel, gas price), and locational variables (an urban/rural setting, town population). We set up a binary iii choice model to capture the impact of these variables. For the analysis, we rely on several datasets to build two regression models. The first model combines vehicle registration data from the Maine Bureau of Motor Vehicles with data from the 2010 US Census. The second regression model uses survey results from the 2009 National Household Travel Survey. The results show that older, more affluent consumers are more likely to purchase these vehicles. Additionally, park aid devices are usually found in luxury vehicle models or vehicles with a higher retail price. Furthermore, these devices are more likely to be included in family vehicles such as minivans, or larger vehicles such as vans and SUVs. Finally, a simple forecast shows that the number of vehicles with a park aid system will continue to grow. A Bass model and a Gompertz model are used for forecasting purposes.
The data used for this study has several limitations. We could only include vehicles with a pre-installed park aid device. We could not measure customers who chose an optional vehicle package solely based on the reason that they wanted the technology. Furthermore, we cannot include customers who chose to install an aftermarket park aid option. We believe that these factors will have a significant impact on our results. Once consumers who chose the optional package or the aftermarket installation are taken into account, it can greatly increase the stock of vehicles with a park aid device. An aftermarket device costs less than $100 and is more affordable
Group sequential design for time-to-event outcome with non-proportional hazards using the concept of relative time utilizing two different Weibull distributions
No full textA group sequential design allows investigators to sequentially monitor efficacy and safety as part of interim testing in phase III trials. Literature is well developed in the case of continuous and binary outcomes, however, in case of trials with a time-to-event outcome, popular methods of sample size calculation often assume proportional hazards. In situations where the proportional hazards assumption is inappropriate as indicated by historical data, these popular methods are very restrictive. In this paper, a novel simulation-based group sequential design is proposed for a two-arm randomized phase III clinical trial with a survival endpoint for the non-proportional hazards scenario. By assuming that the survival times for each treatment arm follow two different Weibull distributions, the proposed method utilizes the concept of Relative Time to calculate the efficacy and safety boundaries at selected interim testing points. The test statistic used to generate these boundaries is asymptotically normal, allowing p-value calculation at each boundary. Many design features specific to time-to-event data can be incorporated with ease. Additionally, the proposed method allows the flexibility of having the accelerated failure time model and the proportional hazards model as constrained special cases. Real life applications are discussed demonstrating the practicality of the proposed method
Pain and Health-Related Quality of Life in Autosomal Dominant Polycystic Kidney Disease: Results from a National Patient-Powered Registry
No full textRationale & Objective: Autosomal dominant polycystic kidney disease (ADPKD) affects health-related quality of life (HRQoL) including pain, discomfort, fatigue, emotional distress, and impaired mobility. Stakeholders prioritized kidney cyst-related pain as an important core outcome domain in clinical trials, leading to the development of disease-specific assessment tools. Study Design: The ADPKD Registry is hosted online with multiple disease-specific patient-reported outcomes modules to characterize the patient experience in the United States. Setting & Participants: The ADPKD Registry allows consented participants access to a Core Questionnaire that includes demographics, comorbid conditions, current symptoms, and kidney function. Participants complete subsequent modules on a 3-month schedule, including 2 validated HRQoL tools, the ADPKD-Pain and Discomfort Scale (ADPKD-PDS), the ADPKD Impact Scale (ADPKD-IS) and a Healthcare Access and Utilization module. Exposures: Patient-reported latest estimated glomerular filtration rate or creatinine used to calculate stage of chronic kidney disease. Outcomes: Health-related quality of life, measured using validated ADPKD-specific tools; access to polycystic kidney disease-specific health care. Analytical Approach: For the 2 HRQoL tools, scores were calculated for physical, emotional, and fatigue domains; pain severity; and pain interference (based on the licensed user manuals). Associations to health care access were also assessed. Results: By July 2022, 1,086 individuals with ADPKD completed at least 1 of the HRQoL modules, and 319 completed 4 over a year. Participants were an average age of 53. In total, 71% were women, and 91% were White, with all chronic kidney disease (CKD) stages represented. In total, 2.5% reported being treated with dialysis, and 23% had a kidney transplant. CKD stage 4/5 participants reported the most dull kidney pain, whereas sharp kidney pain was evenly distributed across early CKD stages. Dull kidney pain had an impact on sleep regardless of CKD stage. There was a strong positive correlation between the ADPKD-PDS and ADPKD-IS. Patients with a neutral or positive HRQoL were less likely to have been denied access to imaging or other care. Limitations: Currently, all the information collected is patient reported without health record validation of clinical variables. Conclusions: Use of the HRQoL tools in the ADPKD Registry provided a broad cross-sectional assessment in the United States and provided granular information on the burden of pain across the CKD spectrum in ADPKD. The ADPKD Registry allowed assessment of ADPKD impact in a community that experiences decline in health and kidney function over decades. Plain-Language Summary: The Autosomal Dominant Polycystic Kidney Disease Registry is a longitudinal, patient-powered research tool created with the goal to better understand the impacts of ADPKD on affected individuals in the United States. Here, we analyze pain and other health-related quality of life outcomes in 1,086 individuals using validated tools and comment on the utility of these tools for future use in clinical trials and observational studies. We found that sharp pain, dull pain, fullness discomfort, and other related impacts affected individuals across the disease spectrum, although some participants reported more dull pain in later stages (CKD stages 4 and 5). Future analysis of these trends over time will be valuable in understanding how to assess and address the burden of pain in autosomal dominant polycystic kidney disease
