The International Patient Decision Aid Standards (IPDAS) Collaboration, which initiated official activities in 2003 [18,19], defines PtDA as “tools designed to help people participate in decision making about health care options.” In other words, PtDA presents various options to patients in certain conditions to make well-informed final decisions from among possible options by weighing them according to their own personal value. From this active participation aspect, PtDAs are differentiated from educational materials to help patients better understand specific diseases or passive informed consent materials designed to obtain informed consent forms [17,20].

The contents of the PtDA developed by the American Society of Clinical Oncology [21,22] as tools for making decisions about the PSA test designed for the early detection of prostate cancer are divided in the following seven item clusters: (1) general introduction to the PSA test, (2) interpretation of the PSA test results, (3) possible options in the case of high PSA levels, (4) benefits and risks of the PSA testing, (5) personalized items for identifying individual values as decisional needs, (6) overall and final decision, and (7) reference materials. This exemplifies that a good PtDA presents a benefit-risk balance by providing disease information and allows systematic checking of the related elements that are likely to influence the final decision, concretizes individual value assessment levels, and gives examples of other cases with coaching throughout the stages of the decision-making process [13,16,17,20].

All PtDAs developed worldwide to date are presented by countries in the clearinghouse system [14,20]. PtDAs on a variety of diseases have been developed in many different forms [14,23], and the current trendsetters are audiovisual materials and web-based programs for self-administrated tools that are designed to save time and medical personnel costs [13,20].

Table 1 outlines the purpose- and application-related usability of PtDAs extracted from the literature [13,17,19,20]. The main objectives of PDA development are to induce patients’ active participation in the decision-making process, enhance the understanding of the disease in question, reduce the stress related to decision making by facilitating consistent decision-making according to individual value assessments, and improve quality of decision-making process. On the other hand, they should also prevent patients from choosing multiple options and should not replace medical counseling or tools intended to enhance treatment compliance.

To accomplish these objectives, PtDAs should be developed in compliance with international standards [14,24,25] using meticulous planning and implementation processes. The IPDAS Collaboration presented a PtDA development process consisting of the following five steps (Table 2) [24]. (1) Clarification of the necessity for development: after clarifying the need to develop a PtDA, development objectives are set and information materials about clinical decisional options and their results necessary for decision-making are reviewed. (2) Constitution of the development committee (expert panel): the development committee is divided into focus groups participating in the actual development and steering group managing conflicts of interest. (3) Compilation: the PtDA is drafted after determining the presentation frames such as audiovisual materials or computational systems [26]. (4) Alpha testing and feedback process: the draft PtDA is applied to patients and their reactions are converged and reflected upon draft review. (5) Beta testing: opinions of external experts and patients are reflected in the final review. The developed PtDA is implemented [13] and updated to reflect newly acquired insights or decisional factors [14]. Due to this highly complicated and time-consuming process [14], PtDA development is implemented under ongoing international cooperation under the flag of the IPDAS Collaboration [27].

A qualitative evaluation is essential for the efficient applications of existing PtDAs [14], so the IPDAS Collaboration presented a quality checklist [27], while the Canadian Ottawa Hospital Research Institute presented its own 19-item checklist [28]. On the other hand, there is a research need for investigation of the actual effects of the PtDAs whose validity has been established. According to the systematic review conducted by Stacey et al. [17], the impacts of the three papers reporting on the statistically significant effects of PtDA as a decision-making tool for PSA testing as prostate cancer screening were 9% to 42% (Table 3) [29-31]. This wide gap is indicative of the fact that the effects of PtDAs vary considerably due to differences in the health insurance systems among countries, efforts of health care personnel to introduce PtDAs, and acceptance among patients and caregivers.