Limitation
TG
The minimum version of the Android operating system was not considered as inclusion criteria and it caused some problems in sampling. Moreover, the performance of the app was different in a few smartphone brands, models, and versions of the operating system. Therefore, some features of the app, especially medication reminders, did not work properly all the time while videos were playing without any problem. Furthermore, in order to watch videos, connecting to the internet was essential to download them from the server. Some of the patients couldn’t connect to the internet and some of them refused to participate since they did not want to use their smartphone data for this reason. Besides, despite of willingness of some patients to take part in the study, their families or other patients, who did not accept to participate in the study themselves, were prevented to enroll. Furthermore, it was hard for some patients to use the app, despite having all inclusion criteria, because of being old, not having the ability to work with their phone properly, etc. Furthermore, in the Di Care app, it was impossible for the patients to ask questions and receive answers, which was one limitation facing this study. During the face-to-face training, however, the patients could be in direct contact with the trainer. Due to their easy access to the Internet, many patients were likely to compare this training and the information found in cyberspace, so the information retrieved from unreliable sources sometimes contraindicated the training provided and could largely confuse the patients. Very limited studies have beenconducted on the effects of training methods, particularly mobile apps, on the blood parameters of HD patients, using questionnaires to evaluate the impact of interventions on various aspects of treatment adherence. In addition, the highest focus in the literature has been on the serum K, P, urea (UR), creatinine (CR), and Kt/v levels, but the effect ​of training methods on other values, ​​such as the serum AL, FER, TC, and TG levels has not been examined, which can minimize the possibility of comparing the study results. Therefore, it was suggested to shed light on such issues in future studies. Moreover, owing to the limitation of budget and time, it was preferred to give up measuring other variables like hemoglobin, sodium, and so on. Finally, due to the regulation of the center and other conditions, it was impossible to control ultrafiltration volume and sodium concentration. Almost all dialysis machines were of the same brand and model. However, there were some different ones and it was not possible to use the same machine for all patients. Regarding dialyzers, there was approximately no choice even for the center to provide different types of filters, especially high-flux dialyzers, due to a shortage of material in Iran and difficulties to provide them because of sanctions. As a result, the majority of them were PS 16 LF and PS 180 HF.