TABLE 1.

Summary of ADR identification strategies used in the rule

Number	Search strategies		Included trigger words e
S1	Keywords implying an ADR	Conjugations of	Drug‐induced
			Allergy
			Side‐effect
			Intolerance
			Toxicity
			Reaction
S2a	Prepositions followed closely b by a drug group c , a generic drug name, a drug brand, trade name or abbreviation a drug c or drug therapy d	Conjugations of	By
			With
			After
			Of
			On
			Since
S2b	Abbreviations using the included prepositions	Conjugations of	a.r. (as a result)
			b.o. (based on)
			a.c.o. (as a consequence of)
S3	Content of forms labelled a	Conjugations of	Allergies:
			Anaphylaxis:
S4	Content of complication registration containing key field drug‐induced	…	…
S5	Content of ADR module	…	…

Notes: The maximum number of characters (ie, proximity between a preposition and a drug name) was set at 16.

Abbreviations: ADR, adverse drug reaction.

^a Forms labelled allergy and anaphylaxis using free‐text entries were employed prior to the introduction of the ADR module in 2015.

^b The maximal number of characters between the preposition and the drug name was 16.

^c The drug group names were based on the Anatomical Therapeutic Chemical (ATC) therapeutic subgroup, pharmacological subgroup, chemical subgroup or chemical substance (ie, second to fifth levels of ATC main groups classified by WHO).

^d Examples are PPI (proton‐pump inhibitor), HCTZ (hydrochlorothiazide), FOLFOX (combination therapy of fluorouracil and oxaliplatin). A full list of abbreviations is provided in Table S2.

^e English translations of the trigger words are presented here; Dutch trigger words are presented in Table S1.