# Anomaly Detection in Elderly Health Monitoring via IoT for Timely Interventions
## 1 Introduction
### Health Monitoring Using Sensor-Based Wearable Devices  
The paper by [PERSON] et al. [3] analyzes smart health monitoring devices. In the studies analyzed in this research, 4433 patients were evaluated, and some of the findings outline a series of benefits of the devices, including reduced mortality. However, the study analyzes a few samples, making it impossible to draw a definitive conclusion. There is a variety of devices that promise to monitor users' health status. For example, [PERSON] et al. [4]propose a device that measures blood pressure and heart rate but is not precise enough to measure respiration, temperature, and blood oxygen levels. The study by [PERSON] et al. [5] uses a sample of 21 patients monitored over 5 days in their homes after being discharged from the hospital. According to the results, 92% of the patients reported comfort in using the device. The data was collected to identify possible post-operative complications in real time but remotely (with the patient at home). An unstable internet connection resulted in temporary data loss in 5% of cases. The study notes that remote monitoring reduces unexpected hospital visits by approximately 15%, provided that well-established protocols are used. Similarly to this study, the research by [PERSON] et al. [6] includes 20 patients with a 7-day post-operative monitoring period. The paper combines patient monitoring with telephone consultations, and the results indicated a data loss rate of 25%. This value is high for a patient who has undergone surgery.  
In recovery, 5153 patients were monitored using 31 wearable devices. The monitoring duration ranged between 15 h and 3 months. The studies mainly focused on measuring physical activity (71.8%). The research highlighted the early detection of postoperative complications compared to standard care [7]. In the study conducted by [PERSON] et al. [8], 39 patients were monitored for a total of 3999 h, averaging 103 h per patient. The system proposed in this paper generated approximately 0.49 daily alarms per patient. Of these, only 42% were true positive alarms, making the number of false alarms an indicator of the need for algorithm improvement. [PERSON] et al. [9] synthesize 35 studies from the specialized literature, summarizing results related to wearable devices. These studies used retrospective data on vital signs collected with the help of these devices and demonstrated their importance in the evolutionary analysis of diagnoses. Multiple studies have analyzed the improvements brought about by wireless wearable devices. However, [PERSON] et al. [10] note the low quality of the materials. The paper concludes that wireless wearable devices for continuous monitoring are still in the clinical validation phase.  
A special category of wearable devices is fitness. The study by [PERSON] et al. [11] integrates a flexible photo-detector (PD) into bracelets. The proposed device's operating principle employs a Light-Emitting Diode (LED) that illuminates the skin, and a photodetector measures light variations caused by blood vessels. In transmission mode, ambient light passes through the tissue and is detected by the PD. Another area of applicability includes safe driving [12], identifying SARS-CoV-2 infection [13], monitoring vital signs in children [14; 15], or in low-resource contexts such as those in Burkina Faso and Kenya [16].