Efficient Use Of Resources Research Articles

Case cancellations and associated factors on the day of surgery in hospitals of Wolaita Zone, South Ethiopia

BackgroundCancellations of elective surgery cases are frequent and have significant negative consequences. It causes wasting of valuable resources, patient unhappiness, and psychological stress of patients. Despite this, little is known about the case cancellation and associated factors on the day of surgery in Ethiopia, particularly in the study area.ObjectiveThis study aimed to assess the magnitude of case cancellation and associated factors on the day of surgery in hospitals in Wolaita zone, South Ethiopia, from May 17 to June 17, 2023.MethodsA hospital-based cross-sectional study involving 322 patients was conducted at Wolaita Sodo Zone, South Ethiopia. All elective surgical cases scheduled during the study period were included. The entire number of participants was selected using a systematic random sampling process. Epidata V.3 was used to enter data, and SPSS V.25 was used to analyze it. Binary logistic regression was used to check for a possible association. P-values < 0.05 and 95% CI were used on multi-variable analysis as the threshold for the significant statistical association.ResultA total of 313 study participants were scheduled for elective surgical procedures during the study period and gave a response rate of 97.2%. The mean (± SD) age of the study participants was 39.18 (± 10.64) years. The two-third of patients, 53(64%) were rural residents, and more than half (178, or 55.3%) of the participants were female. This finding showed that the case cancellation was 22.4% (95% CI: 19.3 -25.9%). Among the total canceled cases, 49(58.3%) were males. Variables like rural residence (AOR = 3.48 95% CI: 1.22–9.95), Lack of lab result (AOR = 2.33, 95%CI:1.20–4.51), ophthalmology dept. (AOR = 2.53 95% CI:1.52–4.49), HTN (AOR = 2.53, 95% CI:1.52–4.49), patient refusal (AOR = 3.01 95% CI:1.22–5.05), and age b/n 31 and 43 (AOR = 1.50, 95% CI:1.02–2.01) were significantly associated factors with cancellation of elective surgical cases.ConclusionIn this study schedule of case cancellation was high. The contributing factors of case cancellation were rural residence, Lack of lab results, ophthalmology dept, HTN, patient refusal, and age. To decrease unnecessary cancellations and increase cost efficiency, hospital administration and medical staff must plan ahead carefully, communicate effectively, and make efficient use of hospital resources.

Quantification of Regression Test Suite Execution Time in Parallel Execution Setup with Weighted Test Suite Split Algorithm

Regression test suite execution time study focus is essentially on two aspects. They are execution time reduction and making effective use of available hardware resources and manpower. This paper investigates how the regression test suite can be split into subsets to make use of parallel execution across several machines with identical execution speeds and asymmetrical execution speeds. In the symmetrical execution speed setup, long test execution time test cases are evenly distributed across all the hardware machines. However, in asymmetrical execution speed machines, more test cases are distributed to speed machines to make efficient use of hardware resources. In all the situations where there is automation tool to execute the individual test cases of test suite this approach can be employed to make effective use of hardware resources and to keep the execution time within bounds. The Algorithms can also be used in situations where there are queues involved and serial, fixed time service takes place for each of the entity being served.

Quantification of Regression Test Suite Execution Time in Parallel Execution Setup with Weighted Test Suite Split Algorithm

Regression test suite execution time study focus is essentially on two aspects. They are execution time reduction and making effective use of available hardware resources and manpower. This paper investigates how the regression test suite can be split into subsets to make use of parallel execution across several machines with identical execution speeds and asymmetrical execution speeds. In the symmetrical execution speed setup, long test execution time test cases are evenly distributed across all the hardware machines. However, in asymmetrical execution speed machines, more test cases are distributed to speed machines to make efficient use of hardware resources. In all the situations where there is automation tool to execute the individual test cases of test suite this approach can be employed to make effective use of hardware resources and to keep the execution time within bounds. The Algorithms can also be used in situations where there are queues involved and serial, fixed time service takes place for each of the entity being served.

Morphological diversity, correlation studies, and multiple-traits selection for yield and yield components of local cowpea varieties

Abstract The evaluation of the diversity in the cowpea local varieties (CLVs) allows the efficient use of genetic resources for cultivar development. This study aimed to evaluate the diversity of CLVs based on observation of morphological characteristics and to identify the relationship among morphological traits and potential varieties as donor genes to improve yield potential. The CLVs were collected from five provinces in Indonesia during 2017–2018. The evaluation of the performance of CLVs’ morphological characteristics was carried out in the Indonesian Legumes and Tuber Crops Research from March to July 2019. The observed data were 43 agronomic characters which consist of qualitative and quantitative characters. There is a high variation in stem pigmentation and seed color in 214 CLVs. There were nine qualitative characters with no variation. Most quantitative characters showed significant variation among CLVs. The clustering of 214 CLVs results in five clusters in which some CLVs maintain valuable characteristics that could be used in the breeding program. The number of pods per plant, number of racemes per plant, and 100 seed weight were useful for indirect selection in the yield improvement. Based on the genotype by trait biplot, the CLV 112, 191, and 111 could be used as donor parents for seed size improvement and the CLV 169 could be used as a donor parent for the yield potential improvement in the cowpea breeding program. Four cowpea genotypes can be recommended for commercial release or used as potential breeding material in cowpea cultivar development programs. The new findings of this study could provide a basis for the genetic improvement of cowpea.

Modelling the system dynamics of household food, water, and energy nexus effects

The food-energy-water nexus (F-E-W) serves as a crucial resource for the sustainability of households, while the efficiency of resource use largely depends on our understanding and management of the nexus including all three factors. Limited research has been conducted on this topic thus far because of the increasing complexity of home technologies and data availability. This study develops an evidence-based system dynamics model for assessing the synergy and trade-offs of the household F-E-W. By applying the system dynamics (SD) methodology, the FEW consumption and generation originating from home appliances were modelled and simulated. The model was applied to an eco-house in Tokyo, and its efficacy was validated with one-year hour-based observations of a home energy management system (HEMS). The findings revealed that water-related and food-related energy use accounted for approximately 55% of the total energy use. In addition, water-related energy use showed high uncertainty, suggesting a management potential of approximately 24% for reduction, and was significantly correlated with household carbon emissions. Moreover, this result verified that the effective management of household energy consumption requires the adept manipulation of the diverse array of energy sources employed for air and water heating, while HEMSs could play a key role in implementation.

Using high-throughput phenotype platform MVS-Pheno to reconstruct the 3D morphological structure of wheat.

It is of great significance to study the plant morphological structure for improving crop yield and achieving efficient use of resources. Three dimensional (3D) information can more accurately describe the morphological and structural characteristics of crop plants. Automatic acquisition of 3D information is one of the key steps in plant morphological structure research. Taking wheat as the research object, we propose a point cloud data-driven 3D reconstruction method that achieves 3D structure reconstruction and plant morphology parameterization at the phytomer scale. Specifically, we use the MVS-Pheno platform to reconstruct the point cloud of wheat plants and segment organs through the deep learning algorithm. On this basis, we automatically reconstructed the 3D structure of leaves and tillers and extracted the morphological parameters of wheat. The results show that the semantic segmentation accuracy of organs is 95.2%, and the instance segmentation accuracy AP50 is 0.665. The R2 values for extracted leaf length, leaf width, leaf attachment height, stem leaf angle, tiller length, and spike length were 0.97, 0.80, 1.00, 0.95, 0.99, and 0.95, respectively. This method can significantly improve the accuracy and efficiency of 3D morphological analysis of wheat plants, providing strong technical support for research in fields such as agricultural production optimization and genetic breeding.

Abstract TP107: Quantifying Hospital Opportunities to Increase Thrombolysis

Introduction: Emergency-department-based implementation strategies to increase thrombolysis are promising. We sought to quantify the number of hospitals with opportunities to increase thrombolysis under various tPA treatment thresholds. Methods: We used data from the 2018 State Inpatient Databases (SID) from 17 states. The study population was limited to ischemic stroke patients admitted to the hospital. The primary outcome was the sum of patients receiving stroke thrombolysis (tPA) at each facility (DRG 61-63, ICD-10 procedure code 3E03317, ICD-10 diagnosis code Z92.82). The primary exposure was hospital stroke volume categorized into quartiles (1 st Quartile [Low]: 1-7, 2 nd Quartile: 8-53, 3 rd Quartile: 54-178, 4 th Quartile [High]: 179-1431). To estimate the number of additional patients treated if hospitals improve their thrombolysis rates across various thresholds, we calculated the expected number of thrombolysis treatments (tPA thresholds multiplied by hospital stroke volume and subtracted by the number of patients receiving tPA at each facility). Results: We identified 203,843 hospital admissions with a primary ischemic stroke diagnosis from 1608 hospitals. On average, 13.3% of patients received tPA. The proportion of stroke patients receiving tPA was higher in higher stroke volume hospitals (Table 1). Black people were more likely to receive care at high-stroke volume hospitals. Among 1608 hospitals, 1131 (70%) had tPA rates below 10%. If these 1131 hospitals improve their tPA rates to 10%, 2655 (2.3 patients/hospital/year) additional stroke patients would be treated with tPA. Conclusions: Low stroke volume hospitals have the lowest thrombolytic treatment rates, but interventions at these hospitals will have limited population benefits and may not be an efficient use of hospital resources. Intervening at high-volume, low-performing hospitals offers the largest opportunity to increase thrombolysis and will promote stroke racial equity.

A Cost-Utility Analysis Comparing Traditional Clinical, Manikin-Based Simulation, and Screen-Based Virtual Simulation Activities.

Simulation activities are used increasingly in nursing education to augment or replace traditional clinical experiences. Educators and regulators are called on to make evidence-based decisions about the use of limited clinical and simulation resources. This cost-utility analysis addresses the final aim of a study comparing cognitive learning, patient care performance, and self-perceptions of how well learning needs were met among students who were exposed to 4 hours of traditional clinical experience, 2 hours of manikin-based simulation, or 2 hours of screen-based virtual simulation. The costs of each activity were calculated and divided by a composite measure of the utility of each activity. The cost-utilities for 4 hours of traditional clinical experience, 2 hours of manikin-based simulation, and 2 hours of screen-based virtual simulation were $0.15, $0.62, and $0.38, respectively, in U.S. dollars per unit of utility. The data provide evidence for educators and administrators to make effective and efficient use of limited resources to prepare nurses for practice. [J Nurs Educ. 2024;63(2):79-85.].

ІНТЕГРАЦІЯ ПРИНЦИПІВ SMART-CITY ТА ЗАПРОВАДЖЕННЯ ЕНЕРГЕТИЧНИХ ІННОВАЦІЙ У ПРОЦЕС ПІСЛЯВОЄННОЇ ВІДБУДОВИ БЛАГОУСТРОЮ АДМІНІСТРАТИВНО-ТЕРИТОРІАЛЬНИХ ОДИНИЦЬ

The article explores the possibilities and challenges of integrating Smart City principles and energy innovations into the post-war reconstruction process of administrative-territorial units. In today's world, where environmental pollution and efficient use of energy resources are becoming increasingly critical, implementing energy-efficient projects in urban development has become necessary for community development. One of the essential aspects of successfully implementing energy-efficient projects is their integration into the city's strategic planning. To address challenges such as financial constraints and technical difficulties, implementing energy-efficient projects will bring numerous benefits, including emission reduction, energy consumption reduction, and improvement of urban environment quality. Since many urban amenities in Ukraine having suffered damage during the war, there is an increased opportunity for the restoration of progressive and modern spaces using advanced technologies. This new stage of reconstruction includes adopting innovative approaches, such as using alternative energy sources, implementing energy-saving systems, introducing Smart City principles, greening territories, and more. This opens up opportunities for creating modern, environmentally friendly, and energy-efficient spaces that improve the quality of life and restore administrative-territorial units' infrastructure. The article explores key concepts such as smart technologies, energy efficiency, and sustainable development while presenting the fundamental principles and mechanisms for implementing these principles in the post-war reconstruction of Ukraine. Utilizing the case-study method, the article highlights the best practices for implementing Smart City principles worldwide. Additionally, the authors examine the advantages and obstacles associated with adopting these principles.

Enhancing service availability and resource deployment in IoT using a shared service replication method

In many real-world contexts, the Internet of Things (IoT) is valued for its capacity to facilitate the smooth operation of interoperable applications and services. It is critical to ensure the accessibility and replication of IoT resources to improve the agility of these applications. As a solution, the Network Function Virtualization (NFV) paradigm is embedded into the IoT design to leverage information from various endpoint applications better and maximize resource utilization. In this study, the Shared Replication Augmenting Method (SRAM) is proposed to increase resource usage in underutilized NFVs and maintain service availability simultaneously. The regressive decision-making learning used by SRAM enables the detection of NFV needs for data and application portability across various real-time use cases. This regression method can uncover data needs and their causes, allowing for prompt answers and more efficient use of available resources. The suggested SRAM technique dynamically modifies the procedure while considering computation-less function allocations, making it suitable for various interoperable applications. It distributes root-to-service virtualization and availability based on historical use and data replication. Therefore, SRAM improves resource usage by 7.09 % with no increase in latency or delays. It also increases service availability by 10.4 %, reduces latency by 11.89 %, eliminates backlogs by 11.1 %, and reduces data repetition by 8.97 %. This study enhances resource consumption and productivity in IoT settings by offering SRAM as a viable solution. The study's results prove its potential to reduce the occurrence of replication, delay, and queues while raising the availability of services.

Investigating the Influence of Patient Eligibility Characteristics on the Number of Deferrable Rheumatologist Visits: Planning for a Patient-Initiated Follow-Up Strategy.

Patient-initiated follow-up (PIFU) for rheumatoid arthritis (RA) is a model of care delivery wherein patients contact the clinic when needed instead of having regularly scheduled follow-up. Our objective was to investigate the influence of different patient eligibility characteristics on the number of potentially deferred visits to inform future implementation of a PIFU strategy. We conducted a retrospective chart review of 7 rheumatologists' practices at 2 university-based clinics between March 1, 2021, and February 28, 2022. Data extracted included the type and frequency of visits, disease management, comorbidities, and care complexities. Stable disease was defined as remission or low disease activity with no medication changes at all visits. The influence of patient characteristics on the number of deferrable visits in patients with stable disease was explored in 4 criteria sets that were based on early disease duration, medication prescribed, presence of care complexity elements, and comorbidity burden. Records from 770 visits were reviewed from 365 patients with RA (71.5% female, 70% seropositive). Among all criteria sets, the proportion of visits that could be redirected varied between 2.5% and 20.9%. The highest proportion of deferrable visits was achieved when eligibility criteria included only stable disease activity and patients with RA on conventional synthetic disease-modifying antirheumatic drugs or no medications (n = 161, 20.9%). PIFU may result in a more efficient use of specialist healthcare resources. However, the applicability of such models of care and the number of deferred visits is highly dependent on patient characteristics used to establish eligibility criteria for that model. These findings should be considered when planning implementation trials.

Large-Scale Bio-Inspired FPGA Models for Path Planning.

The hippocampus provides significant inspiration for spatial navigation and memory in both humans and animals. Constructing large-scale spiking neural network (SNN) models based on the biological neural systems is an important approach to comprehend the computational principles and cognitive function of the hippocampus. Such models are usually implemented on neuromorphic computing platforms, which often have limited computing resources that constrain the achievable scale of the network. This work introduces a series of digital design methods to realize a Field-Programmable Gate Array (FPGA) friendly SNN model. The methods include FPGA-friendly nonlinear calculation modules and a fixed-point design algorithm. A brain-inspired large-scale SNN of ∼21 k place cells for path planning is mapped on FPGA. The results show that the path planning tasks in different environments are finished in real-time and the firing activities of place cells are successfully reproduced. With these methods, the achievable network size on one FPGA chip is increased by 1595 times with higher resource usage efficiency and faster computation speed compared to the state-of-the-art.

Toolkit for increasing the efficiency of land resource use in the territorial communities' management

The article examines the main tools for achieving more efficient and sustainable use of land resources in managing territorial communities. The place of use of land resources in the management of territorial communities is analyzed. In this context, land resources are objects of the management of territorial communities, which include the territory, the air space above it, soils, vegetation, and natural resources that have material form and monetary value and can also potentially participate in the production of agricultural or industrial products, performing works, providing services, and bringing income to their owners in the form of land rent. It was emphasized that Ukraine is currently facing numerous problems caused by the war, particularly insufficient funding at the disposal of territorial communities, and therefore, the main goal is the most efficient use of all available resources, in particular land resources, to ensure development and increase their independence. Primarily financial, maximizing the potential of individual territories. The main tools for increasing the efficiency of the use of land resources in the management of territorial communities are identified the implementation of geo-information systems, economic mechanisms, land development, and zoning planning, the establishment of environmental standards, public involvement in the process of land resource management, and raising the level of awareness and education in the field of effective land use. Having analyzed the management of land resources in Ukraine, especially in the context of new territorial communities, it was noted the presence of several significant problems, in particular, such as: insufficiently defined boundaries of the territory of the community, restrictions on the use of land outside settlements, insufficient income to the local budget from land payments, limited possibility of making strategic plans due to lack of information about land resources, problems of land pollution, refusal to grant land to citizens, difficulties in attracting investors and business development in the territory of the community, underestimation and incorrect reservation of promising territories for development, low quality of maintenance of reclamation systems and problems with illegal use of forest resources. Keywords: land resources, management of land resources, territorial communities, efficiency of use of land resources, decentralization.

Innovative financial tools in the enterprise development system

This article explores using innovative financial instruments to support business growth. Starting with analyzing traditional financial instruments to support enterprises, the article considers innovative approaches. In particular, the advantages of using innovative financial instruments over traditional methods are investigated. In addition, the article analyzes the risks and challenges associated with the implementation of such innovative tools. The study reflects current trends and opportunities for businesses to use the latest financial tools to support their growth. The article discusses innovative financial instruments such as cryptocurrencies, crowdfunding and crowdlending, smart contracts, financial derivatives, distributed financial technologies (DeFi), and robotic investing (Robo-advisors). It also looks at how these new approaches can help raise capital for startups and small businesses with limited access to traditional funding sources. This article points out the prospects for the development of innovative financial instruments. The most important directions for possible further research in this area are also outlined. The advantages of embracing innovative financial instruments are not just apparent, they are transformative. These tools can expedite access to capital, slash administrative costs, and foster a more efficient use of resources. Take crowdfunding, for instance. It opens the doors to a vast pool of investors through online platforms, revolutionizing the financing process for small and medium-sized enterprises. This is just one example of how innovative financial instruments can pave the way for a brighter, more prosperous future. However, it's crucial to acknowledge the risks and challenges that come with the territory of innovative financial instruments. Market volatility, regulatory constraints, and the potential for financial pitfalls can pose significant hurdles to the successful utilization of these instruments. The absence of a legislative framework limited public awareness, high technological demands, and a dearth of historical data are all factors that need to be considered. Therefore, the research and analysis of innovative financial instruments is not just a task, but a responsibility for enterprises. It's a path that can lead to sustainable growth and enhanced competitiveness in the market, but one that must be trodden upon with caution and thorough understanding. Keywords: Financial instruments, blockchain, innovation, investment, financing, capital, credit, enterprises.

Industry 4.0 Innovation: A Systematic Literature Review on the Role of Blockchain Technology in Creating Smart and Sustainable Manufacturing Facilities

Industry 4.0 has revolutionized manufacturing processes and facilities through the creation of smart and sustainable production facilities. Blockchain technology (BCT) has emerged as an invaluable asset within Industrial Revolution 4.0 (IR4.0), offering increased transparency, security, and traceability across supply chains. This systematic literature review explores the role of BCT in creating smart and sustainable manufacturing facilities, while exploring its implications for supply chain management (SCM). Through a detailed examination of 82 research articles, this review highlights three areas where BCT can have a dramatic effect on smart and sustainable manufacturing: firstly, BCT can promote green production methods by supporting efficient resource use, waste reduction strategies and eco-friendly production methods; and secondly, it allows companies to implement smart and eco-friendly manufacturing practices through BCT solutions. BCT promotes intelligent manufacturing systems by facilitating real-time data sharing, predictive maintenance, and automated decision-making. Furthermore, BCT strengthens SCM by increasing visibility, traceability, and collaboration between partners of SC operations. The review also highlights the potential limitations of BCT, such as scalability challenges and the need for standardized protocols. Future research should focus on addressing these limitations and further exploring the potential of BCT in IR4.0.

CONTROL OF THE EFFECTIVENESS OF MANAGEMENT OF ASSETS OF HIGHER EDUCATION INSTITUTIONS

A key part of the discussion is the analysis of Tashkent State University of Economics. This case study exemplifies the impact of methodical financial results management on the universitys asset status. It illustrates that the strategic organization of financial outcomes can significantly alter the property holdings and financial standing of an institution.Furthermore, the article underscores the necessity of effective financial resource management and utilization. It posits that adept handling of these resources is instrumental in enhancing the performance of various activities within the institution. The correlation between judicious financial resource management and the overall operational success of higher education institutions is a central theme.This shift towards financial autonomy in higher education is not without its challenges. The paper explores these challenges, offering insights into how institutions can navigate this new financial landscape. It proposes that adopting innovative management strategies can lead to more efficient and effective use of financial resources, thereby improving institutional outcomes.

Symbiotic Relationship between Capital Budgeting and Financing Decision-Making

This study aims to explore the symbiotic relationship between capital budgeting and financing decision-making in corporate financial management. The research design and methodology involve a comprehensive literature analysis, incorporating seminal theories and recent empirical studies to elucidate the interconnectedness of investment choices and funding strategies. Findings indicate that effective coordination between capital budgeting and financing decisions is essential for firms to optimize resource allocation, manage financial risks, and enhance shareholder value. Strategic capital allocation enables firms to prioritize investments that offer the highest potential for value creation while aligning investment decisions with financing considerations, which ensures efficient use of financial resources. The implications of this research suggest that integrating capital budgeting and financing decision-making enables firms to navigate dynamic market conditions, adapt to regulatory changes, and capitalize on emerging opportunities. By addressing these research gaps, scholars can better understand the factors driving firms' strategic planning and value-creation initiatives.

Analysis on Modern Application and Development Demand of Electronic Information Engineering

In recent years, there has not been a large-scale promotion of high-precision technology, resulting in the core technology can not be effectively applied in enterprises and related industries still need to further develop electronic information engineering. In this regard, combined with the market economic development situation, intelligence and digitalization has become the main direction of the development of electronic information engineering, through the construction of a perfect information management platform, can make efficient use of resources, a wide range of popularization of science and technology. In the context of the Internet era, people's daily life has changed dramatically, especially the information transmission will become more rapid, efficient and convenient. In the expanding scope of application of computer network technology, can realize the efficient transmission and sharing of information, in the field of electronic information engineering, through the application of computer network technology can effectively ensure the quality of information, and lay a good foundation for the smooth progress of information engineering reform work. In the process of promoting the efficient integration of the two, can make the electronic information engineering needs to be met, which should also increase the integration of resources, computer network technology research and development and application work, so that people's daily lives to enjoy more convenient conditions. The application of digital information processing technology can break through the traditional mode of communication in the application of the process of various shortcomings, prompting the development of digital information engineering more and more rapid. The application of this technology can make all walks of life for information activities to fully meet the needs of all sectors of society, to ensure the smooth and stable information construction activities, so we need to combine the actual situation to further optimize the digital signal construction system, so that it plays a greater role in electronic information engineering. Based on the above situation, this paper focuses on the innovation and development of modern electronic information engineering.

Mechanical Behaviour Slenderness Ratio of 13 Solid Wall Panels Under Uniformly Distributed Load

Recently, there has been a lot of research in the concrete industry on a sustainable approach using concrete waste as a substitute for natural aggregates. The reason for this is that the quantities of construction and demolition waste generated today pose a significant threat to the environment but can be used as a useful concrete material in the construction industry. The aim of this study is therefore to investigate the mechanical behaviour of solid concrete wall panels containing recycled concrete aggregates as a partial substitute for natural fine aggregates. Mortar cubes and wall panels with dimensions of 50 mm x 50 mm x 50 mm and 1000 mm x 300 mm x 75 mm, respectively, were produced. The wall panels were made from a 1:4 concrete mix consisting of 50% recycled concrete and 5% perlite (to reduce the weight of the concrete, and improve its workability), and 1% superplastizer, while the control wall was made with 100% natural fines. The wall panels were subjected to a compression test under uniformly distributed load. The cube samples were tested at 28 days of age. Mortar cubes with RCA achieved the highest compressive strength of 16.27 MPa compared to the control sample. The control wall panel has a higher ultimate load of 147.51 kN compared to the sample that contains RCA and perlite, which has an ultimate load of 128.68 kN. By 2030, our country needs to achieve sustainable management and efficient use of natural resources. By recycling this solid waste through separating, cleaning and crushing the concrete waste into small particles so that it can be used as a building material to replace sand. This shows that recycled concrete aggregate can be a potential material for making wall panels.

Two-phase designs with failure time processes subject to nonsusceptibility.

Epidemiological studies based on 2-phase designs help ensure efficient use of limited resources in situations where certain covariates are prohibitively expensive to measure for a full cohort. Typically, these designs involve 2 steps: In phase I, data on an outcome and inexpensive covariates are acquired, and in phase II, a subsample is chosen in which the costly variable of interest is measured. For right-censored data, 2-phase designs have been primarily based on the Cox model. We develop efficient 2-phase design strategies for settings involving a fraction of long-term survivors due to nonsusceptibility. Using mixture models accommodating a nonsusceptible fraction, we consider 3 regression frameworks, including (a) a logistic "cure" model, (b) a proportional hazards model for those who are susceptible, and (c) regression models for susceptibility and failure time in those susceptible. Importantly, we introduce a novel class of bivariate residual-dependent designs to address the unique challenges presented in scenario (c), which involves 2 parameters of interest. Extensive simulation studies demonstrate the superiority of our approach over various phase II subsampling schemes. We illustrate the method through applications to the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial.