Table 1.

Search terms in the literature review

	MEDLINE	EMBASE	CINAHL
Thesaurus terms for ‘headache’	Headache disorders/ Headache disorders primary/ Migraine disorders/ Migraine with aura/ Migraine without aura/ Tension type headache/	Headache/ Primary headache/ Migraine/ Tension headache/ Chronic daily headache/	Headache/ Migraine/ Tension headache/
Text words for ‘headache’  (Title & Abstract)	Chronic daily headache*.tw. Migraine*.tw. Tension headache*.tw. Tension type headache*.tw. TTH*.tw. CDH*.tw.	Chronic daily headache*.tw. Migraine*.tw. Tension headache*.tw. Tension type headache*.tw. TTH*.tw. CDH*.tw.	Chronic daily headache* Migraine* Tension headache* Tension type headache* TTH* CDH*
Thesaurus terms for ‘health care quality’	Quality of health care/ Quality assurance health care/ Total quality management/ Outcome and process assessment (health care)/ Quality indicators, health care/ Peer review, health care/ Programme evaluation/ Bench marking/ Clinical audit/ Medical audit/ Nursing audit/	Health care quality/ Quality indicators, health care/ Peer review, health care/ Medical audit/	Quality assessment/ Clinical Indicators/ Nursing audit/ Outcome assessment/ Outcome assessment information set/ Peer review/ Process assessment (health care)/ Program evaluation/ Quality of health Care/ Quality of nursing care/ Quality assurance/ Quality improvement/ Evaluation and quality improvement program/ Benchmarking/ Quality management organizational/
Text words for ‘healthcare quality’   (Title & Abstract)	Health service* research*.tw. Health service* evaluation*.tw.	Continuous quality improvement*.tw. Health service* research*.tw. Health service* evaluation*.tw. Nursing audit*.tw.	Continuous quality improvement* Health service* research* Health service* evaluation*