3. Secondary outcomes: scales used.

Outcomes	Number of studies	Studies and instruments
Social support (perceived)	3	Cheung 2014: Multidimensional Scale of Perceived Social Support (Zhang 2002; Zimet 1988) Clemow 2018: social support subscales tangible, belonging, appraisal of Interpersonal Support Evaluation List (ISEL) (Cohen 1983a) Varker 2012: ISEL‐12 (Cohen 1985)
Optimism	3	Gelkopf 2008: single item modified from Children’s Future Orientation Scale (Bleich 2003; Saigh 1997) Mache 2015a: optimism subscale of Self‐Efficacy, Optimism, and Pessimism (SWOP‐K9) (Scholler 1999) Mache 2015b: optimism subscale of SWOP‐K9 (Scholler 1999)
Self‐efficacy	11	Berger 2011: Disaster‐Helper Self‐Efficacy Scale (DHSE) (Gelkopf 2008) Bernburg 2019: self‐efficacy subscale of SWOP‐K9 (Scholler 1999) Cheung 2014: 13‐item self‐efficacy scale (self‐developed based on literature; Bandura 1997; Allen 2010) Cieslak 2016: trauma self‐efficacy ‐ Secondary Trauma Self‐Efficacy Scale (Cieslak 2013); work stress and burnout management self‐efficacy ‐ Work Stress and Burnout Management Self‐efficacy Scale (Lua 2008) Gelkopf 2008: personal sense of self‐efficacy ‐ single item (Bleich 2003); professional self‐efficacy ‐ DHSE (Gelkopf unpublished manuscript) Mache 2015a: self‐efficacy subscale of SWOP‐K9 (Scholler 1999) Mache 2015b: self‐efficacy subscale of SWOP‐K9 (Scholler 1999) Mache 2016: self‐efficacy subscale of SWOP‐K9 (Scholler 1999) Smith 2019: Occupational Coping Self‐Efficacy Questionnaire for Nurses (Pisanti 2008) Wild 2016: General Self‐Efficacy Scale (Schwarzer 1995) NCT03645798: General Self‐Efficacy scale (no citation specified in trial registration)
Active coping	5	Cheung 2014: adaptive coping subscale (items from 8 adaptive coping responses) from Brief Coping Orientations to Problems Experience scale (Brief COPE) (Carver 1997) Gelkopf 2008: subscale refocusing on planning of Cognitive Emotion Regulation Questionnaire (Garnefski 2002) Medisauskaite 2019: active coping ‐ Coping Mechanisms Scale (see trial registration); Brief COPE according to publication (Carver 1989) Villani 2013: 2 items for active coping of Brief COPE (Carver 1997) Wild 2016: ability to problem‐solve and achieve goals ‐ unpublished questionnaire; active coping ‐ subscale of Brief COPE (Carver 1989)
Self‐esteem	1	Berger 2011: Rosenberg self‐esteem scale (Rosenberg 1965)
Hardiness	1	Tierney 1997: Third Generation Personal Views questionnaire (Personal Views Survey) (Dane unpublished manuscript)
Positive emotions	3	Fei 2019: positive affect ‐ positive affect subscale from positive affect subscale from Positive and Negative Affect Schedule (PANAS) (Huang 2003; Watson 2005) Lin 2019: positive affect ‐ positive affect subscale from positive affect subscale from PANAS (Huang 2003; Watson 1988) Stetz 2007: positive affect ‐ positive affect subscale MAACL‐R (Zuckerman 1965)