Non-Hodgkin lymphoma (NHL) accounts for approximately 41% of the entire hematological cancer population. Improving symptom self-management of patients in NHL treatment and care is among the important goals. Symptom self-management in NHL patients is considered an important factor in the early detection and control of symptoms. Although treatment and care have an important role in the concept of symptom self-management in NHL patients, it is reported that the symptom self-management levels of the patients are generally low. Since NHL patients often experience disease and treatment-related side effects after discharge from the hospital, it seems necessary to develop web-based decision support systems that can support symptom management at home. Decision support system applications developed for symptom self-management; help patients manage their symptoms, coordinate treatment plans, receive comprehensive care, update their knowledge and encourage continuous learning. The study aims to evaluate the effect of the decision support system developed for symptom self-management in NHL patients on symptom management, quality of life, and unplanned hospital admissions.

In the study, a web-based decision support system for symptom self-management in NHL patients will be developed. The website content and decision support system will be prepared in line with current literature, national and international websites, and guidelines, evaluated with expert opinions and readability index, and will be finalized by testing with preliminary application. The study was designed as a randomized study with a single-blind and active control group. This study will be carried out with an NHL patient who is followed up and treated in the Hematology Outpatient Clinic and Daytime Chemotherapy Unit and meets the inclusion criteria of the sample. It will be prepared in line with the Consolidated Standard of Reporting Trials - CONSORT 2018 guidelines.

In the study, the sample size was calculated based on 80% power and 5% confidence interval on the G\*POWER software package. The study will be conducted with cancer patients (n=52), 26 in the intervention group and 26 in the control group. Patients with NHL diagnosis (Diffuse Large B-Cell Lymphoma and Follicular Lymphoma), over 18 years of age, who received at least two cycles of chemotherapy, had an ECOG performance score of 0-1-2, were treated with chemotherapy for the first time due to NHL diagnosis and had no verbal communication disorder. Literate patients, have internet access, and use the internet will be included.

As a randomization method, the "block randomization method" will be chosen so that the participants in the intervention and control groups have similar characteristics. An independent researcher who was not involved in the research will be assigned to the intervention and control groups with the mobile application program. Randomization will be done in a computer environment using the http://www.r-bloggers.com/example-2014-2-block-/randomization/ website and put in opaque envelopes. After obtaining informed consent from patients who meet the inclusion criteria, pre-tests will be performed by the researcher. After the pre-tests are applied, the participants will be assigned to the groups with opaque envelopes prepared by an independent researcher. Thus, assignment bias will be prevented in the randomization process. As the participants do not know the hypothesis of the research and in which group they are, it will be ensured that the participants are blinded. For the patients in the control group not to understand the application to the intervention group, the link of the website prepared for the intervention group, which contains only information on the evaluation of symptom frequency and severity, will be opened to the patients in the control group with a password. Algorithms in the decision support system intervention protocol developed for symptom self-management to be tested in the intervention group will not be included in the website shared with the control group. Blinding the patients will be ensured by having a website that will be applied to both the intervention and control groups. Since the attempt is made by the researcher, the researcher cannot be blinded.

The decision support system designed for symptom self-management will be evaluated by experts, researchers by calculating the readability formula, and patients with NHL who will be included in the preliminary application. Pre-application will be made with NHL patients who meet the inclusion criteria and consent to participate in the study. It is aimed to make a preliminary application to 10% (n=5) of the sample. Patients who were taken into pre-application will not be included in the study.

A website for symptom self-management strategies of NHL patients will be developed. On the website, patients will be asked to evaluate the frequency and severity of symptoms with a visual analog scale. The severity of symptoms was categorized as mild, moderate, or severe in line with evidence-based guidelines; In line with the algorithms created according to the severity of the symptoms, the patients in the intervention group will be provided to use the decision support systems developed for symptom self-management. It is planned that the patients in the intervention group will use the decision support system for the evaluation of symptom frequency and severity and symptom self-management on the 3rd, 7th, and 10th days of the 3rd, 4th, and 5th chemotherapy courses. In addition, a short SMS message will be sent to the patients on the 3rd, 7th, and 10th days of the 3rd, 4th, and 5th chemotherapy cycles to remind the user of the decision support system developed for self-management. Three repeated SMS will be sent to patients who do not use the decision support system, and if the system is still not used, patients will be contacted by phone. Patients in the control group will benefit from routine hospital services for three months, and only the link of the website developed for symptom self-management strategies of NHL patients to evaluate symptom frequency and severity with a visual analog scale will be shared with patients. On the 3rd, 7th, and 10th days of the chemotherapy course, they will be asked to evaluate their symptom experience and severity. To remind the patients in the control group to evaluate the frequency and severity of symptoms, a short SMS message will be sent to the patients on the 3rd, 7th, and 10th days of the 3rd, 4th, and 5th chemotherapy cycles. In addition, the link to the "Lymphoma Patient Guide" on the Turkish Society of Hematology page for the symptom management system will be sent to the control group via SMS.