Introduction
Obstructive sleep apnea (OSA) is characterized by repetitive episodes of upper airway obstruction occurring during sleep. Snoring, daytime sleepiness, insomnia, and poor sleep quality are common among people who suffer from OSA [
1]. According to an epidemiological survey in Guangxi, China, the prevalence of OSA was 4.1% [
2]. OSA may lead to hypertension, an increased risk of coronary heart disease, and certain psychosomatic diseases [
3,
4].
The standard diagnosis of OSA requires the presence of typical clinical symptoms, such as snoring and daytime sleepiness, and polysomnography (PSG) results [
5]. However, polysomnography needs to be performed in a hospital by specially trained doctors and nurses and is not available at many hospitals. Besides, the cost of polysomnography is quite high. Recently, telemedicine using mobile health applications (apps) has become broadly accepted and has helped with the distribution of limited medical resources.
Mobile phones have become an essential necessity, and smart phone applications (apps) have greatly facilitated tasks in our daily lives. In 2016, there were approximately 660 million people surfing the Internet with mobile phones. There are more than 2.2 million apps available for the iOS system in China and more than 1.6 million apps available for the Android system. Globally, the number of mobile health app downloads in 2017 was approximately 3.7 billion [
6]. Apps are poised to become a major source of health guidance, and sleep apps are one of the most popular among all of the mobile health apps [
7].
The purpose of this study was to evaluate the quality of sleep apps that can be acquired in China and to assess the capacity of Chinese sleep apps to primarily screen for the diagnosis of OSA. Using the results of the study, our goal was to determine how to develop a science-based and practical app to conveniently screen for OSA.
Discussion
People in China have become more concerned about their health, and not only consult doctors but also surf the Internet to get information [
18]. Mobile health apps play important roles in disease self-management and disease screening. Based on a Chinese survey in 2018, compared with nonusers, patients who used mobile health apps tended to have better short-term outcomes and better medical experiences [
19]. Sleep apps are one of the most popular mobile health apps. In this study, we found high levels of interest and utilization of sleep apps in China, with the most popular app receiving more than 8000 comments.
Our content quality assessment showed that the total scores of most apps were low, especially in the Scientific domain. The maximum total score of our evaluation scale was 53, but the average score for all apps was only 14.23. Furthermore, the average score of scientific basis was less than one-fifth of the total score of the Scientific domain, indicating that the adherence of the content of these apps to the diagnostic criteria for OSA was low. Most apps only measured movement during sleep, which is not sufficient to diagnose OSA. In addition, movement recorded by the accelerometer in a mobile phone is questionable because of the low specificity. The
Sleep Time app was one of the apps with total score of more than 20. However, a recent study showed that the
Sleep Time app performed poorly when compared to PSG [
20]. Thus, sleep parameters or sleep staging provided by mobile apps might be unreliable.
Some apps could connect to accessory devices, such as bracelets, bands and a micromovement-sensitive mattress with a sleep monitoring system. These apps provided more information.
In this study, some apps provided heart rate (62.20%) and oxygen saturation (8.66%) data by connecting to an oximeter. Other apps provided electrocardiogram and electroencephalogram data. No apps performed electrooculography or electromyography or measured nasal-oral airflow.
We analyzed the differences between apps that needed to be connected to other devices and the apps that could work independently. The results showed that when connected to other devices, the apps would be more scientific and reasonable. People can use these apps with accessory devices to monitor their sleep conveniently. In fact, the performance of accessory devices fluctuated greatly, especially in the measurements of sleep duration and sleep stage [
21]. The correlation between accessory devices, such as an oximeter, and PSG is not high [
22].
To improve sleep monitoring apps, researchers are working on optimizing algorithms, improving device design, and combining multiple devices to improve diagnostic efficiency. Portable monitoring (PM) has been suggested to shorten the time to diagnosis and to monitor the effects of OSA treatment [
23‐
25]. In our study, some apps with a high Scientific score, such as the
Taiir SleepCare app and the
Huadaifu app, could be connected to portable monitoring devices.
We found that app popularity was significantly related to Functionality and Usability. People preferred multifunctional apps that could provide information about sleep, could play sleep-inducing music and could be used as a smart alarm clock to help people wake up at the best time. Some apps also provided the capacity to consult with a doctor. According to an online survey, this is the most popular function of mobile health apps [
26]. However, Functionality and Usability was not correlated with the Scientific domain in our study. This suggests that apps with multiple functions were not necessarily better than other apps. Besides, there is no family doctor system in China, and doctors may not have time to provide prompt feedback online [
27].
For web-based information, consumers and professionals usually use the Silberg score to judge the accountability of the information [
15]. The mean Silberg score of our apps was 5.80 out of 9. This was lower than the Silberg score of depression-related websites, which was reported to be 6.47 out of 9 [
28]. Most of the apps provided complete authorship information. Only 4 apps disclosed their sponsorship. The disclosure rate was much lower than the rate of 29.81% for obesity-management apps in Korea [
16]. For attribution, only 22.83% of the apps provided information sources, and only 3.14% provided references, suggesting that the companies that designed these apps did not collaborate with reliable institutions. This might explain the low Scientific score of the sleep apps. For apps with higher Accountability scores, the Functionality and Usability score was generally higher. The Accountability score might reflect the quality of the designers. Professional designers would provide convenience for consumers, so the score of Functionality and Accountability would increase.
The adherence of app content to OSA screening recommendations was low. Considering the large number of app users in China, this should be recognized as a missed opportunity for OSA screening and the promotion of sleep quality. According to our study, apps should connect to reliable devices to collect sleep information, such as oral-nasal air flow, movement, and real sleep duration. Apps should also provide information about sleep, wake people up at the best time, and help them connect to doctors to obtain professional advice. An ideal app that can monitor sleep and screen for OSA should be designed by a collaboration between app designers and doctors. Studies have indicated increasing acceptance for remote sleep monitoring and screening for OSA [
16,
29]. Some of the apps in our study could connect to portable monitoring devices, but we could not find user ratings for these apps. These apps may all be recommended by doctors, and consumers just regarded them as remote treatments rather than smart phone applications. People prefer multiple functional apps; thus, designers should optimize these apps to improve customers’ satisfaction.
At this time, most sleep apps are consumer apps, meaning that the main purpose of these apps is to earn money rather than to provide medical help. However, more and more people are downloading these apps to monitor their sleep. It is important to make sure that these apps can play a role in clinical surveillance or OSA screening. With the help of these sleep apps, sleep specialists could help more people who may suffer from OSA and could also monitor patients after diagnosis. Our results showed that great progress should be made to improve the quality of these apps to achieve these goals.
In our study, the ICC of the evaluation scale was quite high, meaning that the inter reliability of our evaluation scale was good. However, only two assessors conducted the evaluation procedure in our study, and the second assessor was not blind to the primary results; thus, more assessors should be recruited in the future to test the consistency of the evaluation scale.
Limitations
While 127 apps were evaluated in this study, it is possible that some apps that met the inclusion criteria were missed. There is no published, validated, content analysis tool to evaluate sleep apps. Therefore, the evaluation scale for apps might not be comprehensive. In our study, the evaluation procedure was conducted by one assessor the first time, after which the results were verified by a second assessor. If there were differences between the two assessors, the results would be discussed by two assessors to obtain the final evaluation score. Therefore, the second assessor was not blind to the initial evaluation, which may have affected the accuracy of the results and the inter reliability. We did not recruit volunteers to test the consistency of Chinese sleep apps with PSG; this might be performed in the future.
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