App description
Basic characteristics of the 36 apps were summarized in Additional file
1: Table S1. Of these 36 unique apps, one was based in Germany, one in South Africa, one in New Zealand, two in Canada, two in Spain, two in Switzerland, three in Scotland, three in the UK, and the remaining 21 in the US.
Fourteen of the 36 apps were paid apps with prices ranging from $0.99 to $6.99. Table
1 shows the number of free and paid apps in each platform, and the price range of paid apps. The median, mean, and standard deviation of paid apps was 2.99, 3.76, and 2.17 for iOS apps. For Android apps, their price was 3.49, 3.38, and 1.44, respectively. There was no significant price difference between iOS apps and Android apps. However, we saw a clear difference between the two platforms in the percentage of free apps. While nearly 74% of Android apps were free, only 48% of iOS apps were free. Note in this table, the removed 5 free lite version apps were added to the 36 unique apps (41 apps in total). The 5 lite version apps and the 5 full version counterparts were counted separately for each platform and the count was shown after the “+” symbol in each table cell. The numbers in front of the “+” symbols are the counts of normal apps that did not have lite versions.
Table 1
Counts and price of free and paid apps in each platform
Free | 10 + 1 | 5 + 2 | 7 + 2 |
Paid | 0 + 1 | 6 + 2 | 3 + 2 |
Price | $3.99 | $0.99 - $4.99 | $0.99 - $6.99 |
Additional file
1: Table S2 summarizes the pain diary features of the 36 apps into nine categories, which include recordings of pain intensity, pain location, pain quality, pain’s impacts on daily life, other features of pain, other related symptoms, medication, patients’ habits and basic information, and other miscellaneous functions. Among these categories, pain intensity, pain quality, and pain location are essential information about pain. It is noted that 35 out of 36 apps record pain intensity. The only exception was a proprietary app (
Pain Toolkit) whose information about pain intensity was not available in the description. Twenty-three apps support pain location logging. Sixteen of them include a body map feature and the remaining 7 apps use a fixed list of body parts from which users can select. Only 12 apps support pain quality.
Regarding the pain diary feature, five of the 16 apps could not be evaluated on the test devices (one crashed; two could not register and log in; one was proprietary; one was not available in iOS 11). The remaining 11 functioning apps were used for analysis. Of these 11 apps, five allowed users to directly mark a pain area on the body map by drawing, and five only allowed users to select from predefined body parts. In the remaining app, the body map was only used to display users’ selections from a previous body part list and did not directly allow drawing or selection. These 11 apps used different ways to display pain intensity and pain quality.
The apps are summarized in Table
2, where X indicates an app includes the corresponding feature. As shown in Table
2, 10 apps allowed recording pain intensity on a body map. Only two apps could record pain intensity and pain quality on a body map at the same time. For the five apps that only support selection of body parts, users could not record more than one pain intensity level at the same time. Only one app could record multiple intensity levels and multiple pain qualities at the same time. Of the 11 apps supporting the body map feature, four apps used the pain scale of 0 to 10, four used 1 to 10, two used 1 to 5, and only one used 1 to 6.
Table 2
Body map features supported by 11 apps for pain management
Chronic Pain Tracker | X | | | | | |
My Pain Diary & Symptom Tracker: Gold Edition | X | | | X | | |
My Pain Diary: Chronic Pain & Symptom Tracker | X | | | X | | |
My Pain Tracker - Pain Diary | | X | | | | |
Pain Companion | | X | | | | |
Pain Diary & Forum CatchMyPain | | X | | | | |
Pain Tracker & Diary | | X | | | | X |
PainScale - Pain Diary and Coach | X | | | X | | |
Pain Assessment Tool for children | X | | X | | X | |
OurHurt - Chronic Pain | | | | | | |
Pain Tracker HD | X | | X | | | |
The impact of pain on daily life is also important information when assessing chronic pain. There were 17 applications supporting this feature. The apps measured the impact in activity level (6), affected activities (3), appetite level (1), bowel movement level (3), fatigue level (5), inability level (1), mood level (11), mobility aid (1), sleep quality (9), social interaction level (1), walking distance (1), and worry about finances (1). The numbers in parenthesis indicate the number of apps with the mentioned feature. Note these numbers are not mutually exclusive since some apps included more than one of these features.
Twenty-four apps collected more features about pain, including pain onset environment (2), factors not triggering pain (1), the change of pain (1), pain description (5), pain duration (6), pain frequency (4), pain can move or not (1), pain onset time (13), pain relieving factors (6), treatments of pain (8), pain triggers (13), and pain type (2).
There were fourteen apps supporting medication recording, including medication adherence (2), duration (1), side effects (2), dosage (9), drug name search (2), drug name browsing (1), drug name free text input (7), OTC drug (3), prescription drug (2), and pain killer usage frequency (2).
Six apps collected patients’ habits and basic health information, including alcohol consumption (1), coffee consumption (2), dairy consumption (1), water consumption (1), diet level (1), time since last meal (1), smoking frequency (1), exercise duration (1), exercise level (1), use of floss (1), sexual activity (1), blood pressure (3), and body weight (3).
Other features of 28 apps were grouped into the miscellaneous category, including audio note (1), note (17), physical therapy (1), find consultant (1), find similar patients (2), important events (2), meaningful activities (1), other comments (3), other factor (1), pain relieving tips (4), pain entry reminders (1), summary charts and plots (19), patient community (2), private messaging (1), and weather (7).
Nineteen apps summarized historical pain diary data by different types of visualizations. Sixteen apps supported line plots with time represented on the x-axis. Thirteen apps used a time interval of day and 3 used an hourly interval. Eight apps had bar charts and three provided pie charts. These counts are not mutually exclusive since some apps use more than one type of visualization.
Additional file
1: Table S3 shows the contents of y-axes in the line plots. It can be seen that pain intensity is supported by 15 apps, followed by mood level (4), pain location (4), other pain-related symptoms (4), medication taking (3), sleep quality (3), weather (3), affected body area (2), fatigue level (2), pain quality (2), activity level (1), body weight (1), events (1), exercise duration (1), pain interference (1), side effects (1).