In 2019, researchers at the Department of Pain Surgery at Hospital Virgen de las Nieves in Granada, Spain, initiated approaches to improve the remote monitoring of patients implanted with epidural spinal cord stimulators for chronic pain management. The aim was to reduce the number of face-to-face consultations or hospital visits while providing additional support to these patients. Therefore, we decided to develop an app complemented by a support center to improve patient monitoring as much as possible. After reviewing the relevant literature, we adapted the tool kit published by Marvel et al [10] to suit our needs, following the four key steps outlined in Table 1. As we already had a multidisciplinary group, we sought the agreement of existing team members and assembled a group of experts. Instead of accelerating the project, we adapted our current workflows and protocols to the new working framework. We also developed the follow-up system after adapting the protocols already in place and enrolled patients only after the system was finalized.

The concept of a remote follow-up system was presented to a multidisciplinary committee composed of anesthesiologists, neurologists, neurosurgeons, neurophysiologists, and rehabilitation specialists. This committee meets monthly to assess patients with chronic pain who may benefit from interventional therapies such as spinal cord stimulation when conservative treatments have failed. The target population was identified as patients who could benefit from spinal cord stimulation and had not yet started the trial phase, to enable data collection before and after implantation.

The inclusion criteria for patients eligible for spinal cord stimulation system implantation at our center are shown in Textbox 1.

Once the committee had approved the implantation of a spinal cord stimulator, the procedure was performed in 2 phases, as shown in Figure 1. In the trial phase, one or more electrodes were implanted in the epidural space and connected to an external stimulator. The efficacy of the system was then assessed over a 4-week period using the verbal numerical rating score (VNRS). The intervention was considered effective if the patient’s reported subjective perception of pain relief was at least 50%. If the trial phase was successful, it was followed by the implantation phase, in which a permanent stimulator was implanted in the adipose tissue of the abdomen or lower back. If the 50% threshold was not reached, the system was removed completely.

Ethics approval was obtained from the Comité de Investigación Provincial de Granada (study: NC-D-01; ethics committee reference: SICEIA-2020‐000438), and informed consent for the procedure and follow-up system was obtained from all included patients. To maintain privacy, each patient was assigned a code with a number so that only health care professionals could access the personal data. The platform meets all the standards of Regulation (EU) 2016/679 of the European Parliament and of the Council of April 27, 2016, and has been approved by local and state authorities. This ensures that only health care professionals can access all the data collected and that data security is contractually guaranteed. The study participants have not been compensated in any way.

The remote follow-up system consists of 3 main components: a mobile app for patients, a website for health care professionals, and a remote follow-up center. The mobile app was designed to ensure close monitoring during all phases of treatment, using feedback from all health care professionals involved. The app was developed in collaboration with Clinical Care Connect (Persei) and customized by our team to meet our specific needs. It offers various features including educational content such as brochures and videos, questionnaires with validated scales, pop-up notifications, and a form to contact the remote support center. The validated scales used include Doleur Neuropathique 4 (DN4) to assess neuropathic pain, Oswestry Disability Index/Neck Disability Index (ODI/NDI) to assess back pain, VNRS to assess pain, and 36-item Short Form Survey (SF-36) to assess quality of life. In addition, patient-reported experience measures were used to assess experience and satisfaction with the app. Since pain is a subjective perception, the use of validated scales can help to measure it and compare it between patients.

The website designed by Persei (Vivarium S.L., Spain) can be accessed from anywhere with the necessary authorizations. It also provides alerts using different colors depending on the urgency of the detected problem: red for infection, yellow for insufficient pain relief, and blue for low battery. These alerts are monitored by the remote support center, which contacts the specialist by making a telephone call if necessary, such as, in the event of an infection. For nonemergency issues, such as insufficient pain relief, the support center contacts the patient to analyze the cause, and a priority appointment for treatment is scheduled. This remote support center was set up to increase the efficiency of treatment and improve pain management. The aim was to maximize treatment adherence and ensure the sustainability of the remote follow-up system. Previously, follow-up was carried out 1 month after implantation, 1 year after implantation, and subsequently, as required.

We collected data from all patients who were approved for spinal cord stimulation between January 2020 and August 2023 and enrolled in the remote monitoring program. If the committee approved the patient for spinal cord stimulation, informed consent for the remote follow-up system was obtained in addition to consent for implantation. Data were collected automatically and prospectively through surveys completed via the app. The questionnaires were distributed according to the protocol shown in Textbox 2.

The support center sends a notification each time a survey needs to be completed, for a maximum of 3 times. If the questionnaires were not completed, a notification was sent to the hospital so that a specialized caregiver can contact the patient. One of the biggest challenges was ensuring privacy. To achieve this, each patient was coded with a number so that only health care professionals had access to the personal data and that data security was contractually guaranteed.

The data were collected automatically when a survey was answered via the app and stored in a private cloud. This allowed us to minimize potential errors. In addition, the support center guaranteed that the data collected via the app belonged to our hospital’s patients and was only accessed and analyzed when a specialist at our center requested it. Demographic information was collected for data analysis. Adherence was measured by calculating the percentage of completed surveys relative to the total number of surveys sent. We analyzed adherence rate during each treatment phase and for the overall study, and compared adherence by demographic variables using ANOVA, adjusting for gender, age, diagnosis, and phase. Age was categorized into 2 groups, with 40 years as the cutoff point, since previous studies have found significant differences in prevalence rates for chronic pain and quality of life [11]. Regarding completeness, we only considered a survey as answered if it was completed. If data were missing, a notification was sent to the patient to complete the survey.

In recent years, there has been increasing interest in the use of pain control apps for various purposes, such as postsurgical follow-up, pain self-management, and chronic pain management [6-10,12-14]. However, many of these tools have not been as effective as expected, often due to inadequate planning and a lack of preliminary studies to anticipate necessary roles [15]. However, some studies have demonstrated that these apps can outperform traditional follow-up methods [6,14]. Our study introduces a remote support center, a feature that we believe is not yet widely adopted internationally. The aim of this study is to determine whether the inclusion of a support center improves adherence compared to other systems.

An analysis of the medical apps across various app stores shows that approximately 86% of these apps were developed without the involvement of medical professionals [16]. Lalloo et al [17] examined 1019 apps developed for postoperative pain management or education and found that only 10 apps met the established criteria. When evaluating apps developed with the involvement of health care professionals, only 5 (0.49%) of them were deemed suitable. Similarly, Bhattarai et al [16] examined 373 apps focused on arthritis pain self-management with only 4 apps meeting the Stanford criteria for pain self-management. Portelli and Eldred [18] evaluated 195 apps for pain management against the guidelines for cognitive behavioral therapy. Of these, only 6 (3%) of these apps met the standards, leading to the conclusion that neither health care professionals nor patients were involved in their development. Despite these limitations, a recent meta-analysis of 4767 patients in 22 randomized trials found that these apps offer a small but significant improvement in long-term pain management [19].

For patients undergoing spinal cord stimulation, close follow-up is required to adjust the type and parameters of stimulation, which usually necessitates face-to-face visits. This increases the time and cost burdens for patients and caregivers, especially for those who live far from specialized centers [20]. Our remote follow-up system was developed to overcome these challenges and ensure optimal patient monitoring. The mobile app in combination with the remote support center reduces the need for in-person examinations while ensuring a high standard of care. The app’s alert system helps to detect problems at an early stage, such as infections or low battery levels so that immediate action can be taken.

In addition, the use of validated scales during an in-person consultation is challenging due to the limited time available. Consequently, this system has allowed a better understanding of the patient’s condition. Furthermore, some patients have found that expressing themselves via the app helps them [20] in experiencing privacy and without any time pressure.

Adherence to medical app use is crucial as studies show that 75% of users stop using an app within 48 hours of downloading, and 15% delete it after initial use [21]. A review by Wikström et al [9] found that none of the studies focused on improving adherence or motivating users to continue using medical apps. The easiest way to increase motivation is through notifications, which is why our study focused on the role of the remote support center. We consider this as a key factor in the success of our study. However, numerous motivational elements in medical apps have been analyzed in previous studies, as summarized in Table 5.

Our remote follow-up system was developed based on relevant literature to maximize adherence and achieved an overall mean adherence rate of 87.37% (SD 15.37%). Comparison of this rate with previous studies is difficult, as most of these focused on adherence to a treatment or intervention rather than the use of an app. For example, Gomis-Pastor et al [34] showed that the use of an app significantly improved adherence to treatment and medication regimen, which led to significantly better symptom control, as found in a 2022 review [35]. However, Wikström et al [9] have shown that adherence to app use decreases over time, potentially due to improvement in health status or loss of interest [29], among other factors [26,29,32]. Our study aligns with these findings and shows a decrease in adherence from 94.53% in the pretreatment phase to 77.36% in the testing phase and 65.58% in the implantation phase [36-38].

The main limitation of our study is the specificity of the target population, as spinal cord stimulation is a specialized treatment for patients experiencing chronic pain. These patients often display a significant emotional component that can influence the outcomes of the interventions, posing challenges during designing this study and its remote follow-up system. In addition, these systems rely on new technologies that can be challenging for older patients, potentially limiting their ability to fully benefit from them. By using self-reported data, we also acknowledged that omissions or misunderstandings in the surveys may be introduced, which we attempted to minimize using validated scales. Finally, setting up a system similar to this study requires a significant financial investment.

Digital systems are a part of medical care, and it is important that health care professionals are involved in the development of tools to ensure the achievement of desired standards. We have developed a remote monitoring system for patients undergoing spinal cord stimulation, based on scientific evidence and supported by a remote support center that improves treatment adherence. This system also provides us with detailed information about each patient. However, there is a tendency for patients to abandon the app usage over time, which could be related to long-term pain control. Further studies are needed to investigate the relationship between adherence and pain control.