A list of applications was collected on June 24, 2009, using the Power Search function of iTunes version 8.1, available for download at www.apple.com/itunes
. The search was restricted to apps compatible with the iPhone. The phrases “quit smoking”, “stop smoking”, and “smoking cessation” were used as search queries.10
The search initially identified 62 unique apps. Apps that included a basic and deluxe version were counted as separate apps in the event that they might differ in their smoking cessation attributes. Of the 62 apps, 10 were excluded because their description in the iTunes store indicated that were irrelevant for reducing or quitting smoking (e.g., an app about preparing barbequed foods which was retrieved with “quit smoking”); Four were eventually removed from the sample because they were no longer in the iTunes store at the time of downloading; One app was removed because the basic and deluxe versions proved to be identical. The final sample consisted of 47 apps, which were downloaded to an iPhone and analyzed.
Each app was coded for its primary approach to smoking cessation, based on categories identified by the National Tobacco Cessation Collaborative.9
Apps were categorized into: (1) “calculators” that generally tracked dollars saved and health benefits accrued over time since quitting, (2) “calendars” that generally tracked days until and after the quit date, (3) “hypnosis” that used hypnosis techniques for smoking cessation, (4) “rationing” that limited the numbers of cigarettes and/or the time in which cigarettes could be smoked, or (5) “other” for apps that did not primarily fit into one of these categories or used multiple categories. Each app was independently categorized by two coders with no disagreement between coders.
Apps were also coded for their level of adherence to the U.S. Public Health Service’s 2008 Clinical Practice Guideline for Treating Tobacco Use and Dependence.11
To measure adherence to the Clinical Practice Guidelines, an index of 20 items was developed, which were adapted from an index created by Bock et al.12
While guidelines developed for a clinical setting may not be appropriate for a mobile-phone app, the Clinical Practice Guidelines were used because they are a leading set of guidelines, have been successfully applied in past to computer-mediated smoking cessation programs12
, and given the newness of apps on mobile phones, no other mobile-specific set of guidelines exist.
The items included in the adherence index are shown on the left side of . Each app was independently coded by two reviewers on each of the 20 guidelines using a scale which ranged from 0 to 3. A 3 indicated that the feature was fully present, and a 0 indicated that it was not present at all. For example, for the guideline to “recommend the use of approved medications”, apps that did not mention any approved medications received a score of 0, while apps that made a weak recommendation for approved medications received a score of 1, a clear recommendation received a score of 2, and a clear and strong recommendation received a score of 3. The two coders were found to be in agreement 86.6% of the time. Where coding scores differed by 1 point (9.9 %), the two scores were averaged. Where coding scores differed by 2 or more points (3.5 %), a third reviewer (LA) was used to resolve differences. The maximum possible score on the index was 60 for each app.
Percentage of Apps (and Numbers of Apps) Exhibiting Strong Adherence to Guidelines, Rank Ordered by Guideline
Popularity was measured by looking on July 23, 2009 at the frequency of downloads of each app. Information about downloads was obtained from the iTunes store using the iTunes basic search function. For a given search term, this search function lists apps by name and provides information about each app, including “Popularity”, a measure of downloads since the app was released, which is depicted with vertical bars. Because of the design of this search function, searches can be obtained for only one search term at a time (e.g., quit smoking) and information is provided on only the relative downloads of apps within a given search term, that is, on how much a given app is downloaded relative to the other apps retrieved by the same search term. (Information on the actual number of downloads for apps is not available). Levels of downloads are updated daily with information from the previous day’s downloads (iTunes Store Customer Support, Apple, personal communication to Dr. Abroms, 3/3/2010).
A search was conducted for the term, “quit smoking”, which had originally retrieved the highest number of apps. This search identified 52 total apps, of which 30 were part of the original sample. A count was made of the vertical bars under the “Popularity” header associated with each of the apps in the sample. These values, which ranged from 1 to 36, served as the measure of download frequency for the apps in the current sample.