Fig. 1. Articles grouped by study characteristics.

The number of articles belonging to each category are shown as n = . Number of ED visits were considered equivalent to number of participants. Articles deemed to have control groups were those with comparator groups (e.g. nurse-led triage). The positive and negative classification included articles where there was a mix of both outcomes (with the more predominant outcome favoured). Categories for recency of publication were divided into 2-year groups (excluding the last category since the search was completed in early 2022).