Table 1.

Eligibility criteria for the identification of studies reporting HK prevalence or incidence

Category	Inclusion criteria	Exclusion criteria
Population	• Patients with HK	Animal/in vitro studies
Study type	• Non-interventional studies, e.g. observational studies and population surveys
	• Meta-analyses of relevant study designs	Other study types, e.g. randomized controlled trials, case series or reports
Publication type	• Original research studies
	• Conference abstracts
	• SLRs of relevant primary publications (these will be considered relevant at the title/abstract review stage and hand-searched for relevant primary studies, but will be excluded during the full-text review stage)	N/A
Outcomes	• Incidence or prevalence or rate or occurrence or frequency of patients with HK	No reporting of relevant epidemiological outcomes
Date limits	• Conference abstracts will be limited to those published in the last 3 years (i.e. in 2018 or later)	N/A
Language	• Any	N/A
Geographic region	• Any	N/A