Study	Reason for exclusion
Avsar 2013	Intervention: comparing 4 different techniques of heparin injection
Babaie Asl 2008	Quasi‐experimental design
Balci Akpinar 2008	Quasi‐experimental design
Chan 2001	Quasi‐experimental design
Chenicek 2004	Participants used anticoagulant drugs during the study
Dadaeen 2015	Quasi‐randomised design
Dehghani 2012	Quasi‐randomised design
Deng 2009	Non‐random design
Fathi 2014	Intervention: comparing 10‐second heparin injection vs 30‐second heparin injection plus air lock
Gholam Nezhad 2004	Quasi‐experimental design
Jesús Gómez 2005	Intervention: comparing 4 administration techniques of heparin injection
McGowan 1990	Intervention: comparing 2 administration techniques of heparin injection
Nair 2008	Non‐random design
Pourghaznein 2014	Intervention: comparing 4 administration techniques of heparin injection with speeds of less than 20 seconds
Rahmani 1999	Participants used anticoagulant drugs during the study
Rahmani 2013	Intervention: comparing 10‐second injection and waiting for 10 seconds before withdrawal of the needle vs 10‐second injection
Sanagoo 2011	Quasi‐experimental design
Tehrani Neshat 2005	Quasi‐experimental design
Uzun 2016	Non‐random design
Vanbree 1984	Intervention: comparing 3 different techniques of heparin injection
Wooldridge 1988	Intervention: comparing 2 administration techniques of heparin injection