Term	Definition
Terms related to harms
Harms	“Harms” is a general umbrella term to cover the concept of risk that may be associated with an intervention. “Harms” is used to refer to all related ideas, such as adverse events, side effects, tolerability, or safety.
Systematically collected harms	According to The Final Rule, ‘‘‘systematic assessment’ involves the use of a specific method of ascertaining the presence of an adverse event (e.g., the use of checklists, questionnaires, specific laboratory tests at regular intervals)’’. Like a potential benefit of treatment, a systematic AE can be defined using five elements: (1) domain, (2) specific measurement, (3) specific metric, (4) method of aggregation, and (5) time-point [13]. For example, ‘‘proportion of participants with 50% change from baseline to 8 weeks on the Young Mania Rating Scale total score.’’
Non-systematically collected harms	According to The Final Rule, ‘‘‘non-systematic assessment’ relies on the spontaneous reporting of adverse events, such as unprompted self-reporting by participants.’’ Non-systematic adverse events may be collected by asking questions like ‘‘Have you noticed any symptoms since your last examination?’’
Unique harms	A specific harm such as would be reported by someone receiving an intervention, such as “dizziness”, “edema”, or “somnolence”.
General assessment of harm	A non-specific method of assessing harms that aims to summarize multiple aspects of risk into a single measure, such as “occurrence of any harm”, “occurrence of serious adverse events”, or a composite of several unique harms.
Proxy for harm	A surrogate method of assessing harm that is not a direct representation of harm from an intervention, such as “loss-to-follow-up or drop-out due to harms”.
Terms related to review methods
Pre-specification of harms	An approach to assessing harms in systematic reviews whereby reviewers have one or more harms in mind that they consider important and pre-specify as outcomes of interest for their review. These pre-specified harms are the only harms that are assessed in the review.
No pre-specification of harms (“exploratory”)	An approach to assessing harms in systematic reviews whereby reviewers do not pre-specify any harms of interest as outcomes for their review. Reviewers assess only harms identified in the review process. A review can specify that they will broadly assess harms as an outcome and still be exploratory if they do not note any specific harms of interest.
Hybrid	An approach to assessing harms in systematic reviews whereby reviewers pre-specify at least one harm to assess in the review and also assess harms identified during the review process.
Primary search for evidence	The principal sources of evidence for a search that are recommended as standard for all systematic reviews, including: bibliographic databases, grey literature, study registries, content experts, and reference lists of included studies.
Supplemental search for evidence	The additional sources of evidence for a search that are not standard for systematic reviews and are uncommonly performed, including: searching unpublished data, adverse event reporting systems, and hospital and other databases.
Descriptive assessment of harm	A narrative description of the harm(s) reported in studies included in the review that does not involve meta-analysis of estimates across studies.
Quantitative assessment of harm	The statistical combination of estimates for harm(s) across two or more studies included in the review. (i.e., meta-analysis for a harm).
Selection criteria	The specific rules that are used to define a subset of harms that will be reported among all of the harms collected. Selection criteria are often based on numerical threshold and participant group (e.g., ≥ 5% of participants in the intervention group).