Table 2.

Screening criteria used to remove papers.

Criterion number	Screening criteria	Justification	Removed in pre-peer-review search	Removed in post-peer-review search
1	Papers not containing abstracts	The papers cannot be analyzed at the abstract-screening stage and were therefore excluded.	75	0
2	Papers from 2013-2016	As an emerging technology, ideas about blockchain’s possibilities and limitations are often changing. Older papers were not included, as they may contain information that does not reflect the current state of blockchain technologies. Papers before 2017 were chosen to be excluded, as 2017 was a year characterized by a significant change in blockchain valuation and regulation [26].	328	52
3	Full conference proceedings	The relevant full papers in the conference proceedings should have been identified as individual papers in database searches and included in the 1808 papers.	63	0
4	Duplicate titles	These articles contain repeated information.	125	2
5	Does not contain “block” in abstract	Articles that do not mention “block” in their abstract were deemed unlikely to be focused discussions of blockchain technologies and were therefore not included.	419	89
6	Does not contain “design” in abstract	As a PICOa term, a focus on blockchain design was essential to the papers. No alternative MeSHb terms for “design” were identified, so an absence of “design” in abstracts was used to filter out papers.	590	486
7	Title contains “Bitcoin” and not “block”	Papers that mentioned “Bitcoin” in their title and not “blockchain” were deemed to be too focused on the cryptocurrency to provide useful information concerning principles relevant to blockchain design.	12	6
8	Title contains “IoT” or “Internet of things”	Many papers contained a reference to IoTc devices. The abstracts of these papers contained little-to-no relevant information about blockchains. This exclusion criterion was thus used to remove papers.	15	24
9	Title contains “finance”	It was a concern that papers relating to financial elements of blockchains would be too focused on the economic aspects of cryptocurrency. As the intent of this research is to examine the technical, not economical, aspects of blockchains, these papers were removed.	15	2

^aPICO: Population, Intervention, Comparison, and Outcome.

^bMeSH: Medical Subject Headings.

^cIoT: internet of things.