Methods are needed to help decrease interdialytic weight gains in hemodialysis patients. One potential method for accomplishing this goal is to develop an app for smartphones that allow patients to track their fluid intake throughout the course of the day. NCT 03759847 was designed to test the safety and efficacy of this app. In this protocol, part of the same IRB number, patients with large interdialytic fluid gains (3.5% or greater) will use the app to to determine the association between the interdialytic weight gain and the fluid consumed as recorded by use of the app for each interdialytic period.

In this full scale study, the app will be used to try and influence fluid intake behavior in those patients who are identified to have large fluid weight gains, as defined by a greater than 4% increase in interdialytic weight.

There will be two parts to the full scale trial. In the first part of the full scale study, denoted as the active phase, which will last for two months, study participants will be encouraged to use the app on a daily basis and will meet with the study coordinator on weeks 1, 2, 4, 6, and 8 to further assist the participant in decreasing fluid intake between dialysis sessions. In the second portion of the study, denoted as the passive phase, which will last for six months, the patient will use the app and meet with the study coordinator only when requested by the patient. The number of these sessions will be recorded. At the end of the six month passive phase, the participant will meet for the last time with the study coordinator. During each study visit, subjects will be asked to transfer the data from the App to the study coordinator via the data export function of the app.

Inclusion Criteria:

• Subject, upon briefing of the content of the present study, fully understanding and agreeing to its objective and having given written (dated and signed) informed consent form to take part in the study.
• Adult chronic hemodialysis patient who is at least 18 years of age
• Average interdialytic fluid gains of 3.5% or greater of body weight for both weekdays and weekends for a 30 day period
• Availability of interdialytic weight gains for the 2 month period prior to enrollment into the study
• Access to a smartphone for use of the app and comfort with using apps on a regular basis
• Access to a smartphone running under either iOS or Android operating systems
• Sufficient knowledge and understanding of the English language to use the application available only in English (US) language
• Mental capacity to use and understand the fluid management app
• Willingness to share intake data collected with the research team

Exclusion Criteria:

• Scheduled for a living related renal transplant in the next seven months
• Hospitalization within 30 days of entry into the study
• Current participation in a randomized clinical trial or in the exclusion period of another clinical trial
• Vulnerable subjects defined as individuals whose willingness to volunteer in the clinical trial may be unduly influenced by the expectation, whether justified or not, of benefits associated with participation, or of a retaliatory response from senior members of a hierarchy in case of refusal to participate.