Development and testing of a text messaging (SMS) monitoring software application for acute decompensated heart failure patients*

Objective: to develop and test an SMS monitoring software application for patients with acute decompensated heart failure. Method: the waterfall model was used for software development. All expected functionalities were defined, program modules were codified and tests were done so as to ensure good performance by the software application. Ten patients participated in the prototype test. Results: the system sends two types of messages: questions that should be answered by patients and unilateral educational reinforcements. In addition, the system generates alarms in case of no response or according to a flow chart to detect congestion in the patient previously created by the team. Of the 264 SMS texts sent, 247 were answered. The alarm was triggered seven times: three patients woke up with shortness of breath for two consecutive nights, and four patients felt more fatigued for two consecutive days. All patients took the prescribed medications during follow-up. The study nurse guided the patients who generated alarms in the system. Conclusion: the SMS software application was successfully developed and a high response rate and preliminary evidence of improvements in self-management of HF were observed. With this regard, telehealth is a promising alternative in the treatment of chronic diseases


Introduction
Hospitalizations for heart failure (HF) in Brazilian public hospitals represent approximately 28% of all hospitalizations due to cardiovascular diseases and 2% of those for all other diseases (1) . In the elderly adult population, HF is already the main cause of hospitalization in the country. Another alarming rate is related to high mortality: it is estimated that from 2 to 17% of the patients admitted for HF will die while in hospital. However, for those treated in the outpatient setting, survival is greater because of stability (2) .
In this case, HF incidence was higher than that of other cardiovascular diseases (3)(4) , resulting in high costs (5) . These costs are the sum of several components, including acute decompensation management, clinical consultations, medications, home care and the increasing cost of implantable devices (6)(7)(8) . Despite all the advances in the care for patients with HF, results after hospitalization are still fewer than expected (9) . Strategies and new approaches are necessary in the current worldwide panorama of HF epidemiology, in relation to both hospital readmissions and the morbidities caused by this clinical syndrome (10)(11) .
It is in this scenario that we can use the beneficial results of recent studies showing that telehealth can be a promising alternative in the management of chronic diseases (12)(13)(14) . In Brazil, monitoring and education programs involving complex methodologies and technologies could have limited practical applicability, taking into account the social, economic and cultural peculiarities of the country.
Mobile technology, in particular the Short Message Service (SMS), is emerging as a promising platform for chronic disease management in low-income populations (15)(16)(17) because it has high rates of utilization across socioeconomic groups (18)(19)(20) . Public health researchers have sought to capitalize on this potentially game-changing communication modality by developing and testing SMS interventions designed to provide information that results in improved health outcomes and/or changed health behaviors. In slightly more than a decade of innovative research, dozens of studies and more than 20 systematic reviews and meta-analyses have been conducted to explore the potential of SMS for public health (21) .
Given this scenario, SMS seems to be a promising possibility because it is a simple and low-cost technology that facilitates real-time and individualized monitoring of patients. Telemonitoring HF patients will prevent or reduce congestive symptoms, as well as help the early identification of clinical deterioration signs through a rigorous system of monitoring such signs and symptoms (22)(23) . Thus, this technology will enable the early detection of HF decompensation through real-time intervention, achieving better results and reducing costs in the health system (24) .
It is not known that an SMS prototype has been developed as a monitoring strategy for patients with HF and recent hospitalizations in a public university hospital. Aiming to fill this gap, the present study was conducted in order to test a monitoring prototype for patients with HF through SMS.

Method
This is a study on the development of a remote monitoring software application for patients with acutely decompensated HF.   In order to be able to use the system simultaneously in different places, it runs on a server, and access to it is obtained via the web. Thus, it allows the gain of scale in its use without the need for specific software tools to the work machines located in hospitals. At the same time, the system limits access to patients in a specific hospital in order to ensure privacy of information. The infrastructure of the proposed system is shown in Figure 2.
The main components of the system architecture are: -Machines: Conventional computers with Internet and/or intranet connection. They do not require specific tools for use. The software application and logistics test proposed by this development study were planned. Ten patients were invited to participate in the test. After acceptance by the patient during his/her hospitalization, all guidelines were provided, and doubts were addressed in subsequent visits. At this stage, the patient received a care manual with the most important information concerning the prototype. According to the literature, patients' hospital readmissions are more frequent during the first few weeks after discharge (25) . For this reason, the patients received the message during the first week after discharge.

Results
The approximate time for the software application days. All patients took the prescribed medications during the follow-up. The study nurse guided the patients who generated alarms in the system (Figures 3 and 4).
The patients' mean age was 67±13 years. They were predominantly males and lived with relatives. Their mean ejection fraction was 35±7%. Table 1

Conclusion
In conclusion, a software application was developed successfully, and it is working properly.
After testing, some changes, such as redefining the graphic interface, database and system engineering specifications, have been made to improve its operation. From the positive results in this study, it is considered that sending SMS messages can be a useful tool to improve self-management of HF by patients after hospital discharge. Although the software application works properly, further studies are needed to achieve significant results in clinical outcomes, such as morbidity and mortality.