Table 1.

National Library of Medicine guidelines for information quality and our operational definitions.

NLM guideline	Operational definitions
Providing information on who is in charge of the app	Provides information that could help users understand who is in charge of the app (eg, information about the app provider’s name). Such information is typically found via the About Us button in the app and/or on the app’s iTunes page.
Providing information about why the app is being provided	Provides information that could help users understand the app’s purpose, intended users, and functionalities. Such information is typically found on the app’s iTunes page and/or via the About Us button in the app (eg, indicating that the app is developed for CVDa patients, or to provide CVD-related information, or to provide one-on-one consultation with a CVD physician).
Providing the app provider’s physical address	Provides information about the physical address of app developer or administrator.
Providing information on the source of the app’s information	Provides information that could help users understand where the information used by the app came from (eg, an article or book with author names, or, for Web-based information, the website from which the information was retrieved).
Providing information on how the app’s content was selected	Provides a logical explanation for how the app’s information was selected (eg, information selected from peer-reviewed journals).
Having expert review of the information	Provides information to make clear that information presented in the app has been reviewed by qualified health care professionals.
Financial disclosure	Provides information on where the money to support an app comes from (eg, government agencies, nonprofit organizations, drug companies). This information could help users understand whether the app’s providers have financial motives that users should be aware of (eg, the sale of CVD drugs).
Content is up-to-date	The original NLMb guidelines did not specify what timeframe would be considered up-to-date; in our study, we operationalized this indicator as app content updated in the past 3 months.
Does not have advertisements	Whether or not an app contains advertisements. Note: if a drug or treatment option mentioned in an app was a part of scientific results (eg, if reported in a research article) then it was not considered an advertisement.
Does not use unbelievable or emotional claims	Whether or not an app makes claims that are too good to be true, or are based on emotions instead of scientific facts (eg, “Lose 30 pounds in 2 weeks!”).
Does not ask for personal information	Whether or not users must submit personal information (eg, name, phone number, email address) in order to use certain app functions.

^aCVD: cardiovascular disease.

^bNLM: National Library of Medicine.