# Toward a Comprehensive Understanding and Evaluation of the Sustainability of E-Health Solutions
## 1 Introduction  
Sustainability has been a challenge in many domains and development contexts. In e-health, in particular, it is challenging to define and apply sustainability to real projects due to several reasons [1]. Some of these reasons are the complex nature of healthcare, the increasing demand for resources [2], and the lack of a clear and consensus definition of sustainability in healthcare [3]. The importance of sustaining digital solutions in healthcare is laid upon the fact that healthcare is a critical sector involving many obstacles, in which implementing changes is difficult due to the strict regulations and complex, interrelated processes [4].  
Some studies proposed sustainability models; however, the models lack important aspects, such as economic and funding estimation, change impact on current employees, and patient and staff acceptance [3, 5]. Furthermore, several studies stated that the absence of a clear definition of sustainability in the literature results in the absence of rigorousevaluation methods of sustainability [3; 6; 7; 8; 9] and hinders the achievement of assessing e-health sustainability [10]. In addition, the absence of a comprehensive view of the sustainability of e-health solutions remains the main challenge in having sustainability frameworks and assessment methods [3].  
Hence, the main objective of this study is to provide a comprehensive sustainability model of e-health solutions and its assessment method. This is achieved by conducting a systematic literature review (SLR) that investigates and analyzes existing studies about the sustainability of e-health solutions. The SLR focuses on analyzing sustainability definitions, models, and assessment methods. Investigating existing definitions of the sustainability of e-health solutions will provide a general and wide overview of how sustainability is perceived in the context of e-health solutions and its main, high-level, dimensions. Additionally, the SLR results are used to propose a comprehensive sustainability model, dimensions, and aspects for e-health solutions that lay the foundations for sustainability analysis and assessment methods. Finally, the third part of the SLR focuses on analyzing existing sustainability assessment methods in the context of e-health solutions. That is, the SLR aims to learn the dimensions of sustainability that have been assessed and how they have been assessed in existing work to develop a comprehensive assessment method to the proposed sustainability model. The comprehensiveness and applicability of the proposed model was validated by three IT experts in the healthcare domain. The main contributions of this work are (1) providing an overview of sustainability definitions and proposing a comprehensive definition accordingly, (2) a thorough analysis of sustainability dimensions and aspects, (3) a comprehensive sustainability model for e-health solutions, and (4) an assessment method that is used to assess the sustainability of e-health solutions.  
The rest of the paper is organized as follows: Section 2 provides an overview of related work on sustainability models in healthcare. Section 3 illustrates the study protocol followed in conducting the SLR. Section 4 presents the results of the SLR. Section 5 presents our proposed sustainability model for e-health solutions, and Section 6 includes the assessment method. Section 7 presents the conducted case study. Section 8 discusses the results and important challenges in this area, while Section 9 states the limitations. Finally, Section 10 concludes and identifies future work items.