Characteristics of studies included in the meta-analysis (n=12)
| Study | Country | Training description | Sessions (total training hours) | Methods | Sample size (before attrition) | Follow-up period (months) | Quality summary | Scales of outcomes of interest |
| Arnetz et al (2009)18 | Sweden | Psychoeducation including relaxation training, use of guided imagery to facilitate imaginal stressful incidents and mental practices | 10 (20) | Simple randomised experiment | 18 TG=9 CG=9 | 12 | Fair | VAS |
| Brouzos et al (2022)8 | Greece | Positive psychology and CBT approach including management of negative thoughts and relaxation techniques, coping strategies and mindfulness-based problem solving, role of meaning, positive mindset and strengths and empathy | 6 (6) | Quasi-experimental design | 94 TG=49 CG=45 | 1st: 1 2nd: 1.5 | Fair | CD-RISC-10, DASS-21, GAD-7, PHQ-9 |
| Chitra and Karunanidhi (2021)9 | India | CBT approach, mindfulness and relaxation techniques | 20 (30) | Simple randomised experiment | 63 TG=33 CG=30 | 2 | Good | OSI, CD-RISC-25, PGWBI |
| Christopher et al (2018)28 | USA | Mindfulness-based resilience training | 8 (20) | Block randomised experiment* | 61 TG=31 CG=30 | 3 | Fair | CD-RISC-25, PROMIS, PSQ |
| Fitzhugh et al (2019)40 | UK | Two online interventions: Headspace (a commercially available mindfulness application) and Mindfit Cop (a bespoke online 8-week mindfulness course for policing) | Online intervention | Simple randomised experiment* | 1337 Headspace=446 Mindfit Cop=445 CG=446 | 6 | Fair | BRS |
| Grupe et al (2021)10 | USA | Mindfulness-based training | 8 (18) | Block randomised experiment* | 114 TG=57 CG=57 | 3 | Fair | BRS, PSQ, PSS, PROMIS, PTSD Checklist for DSM-5 |
| Horan (2017)25 | Australia | ACT-based resilience training including coping skills, recognising and appraising stressors, goal significance and activating coping strategies | 3 (5.5) | Cluster randomised experiment* | 240 TG=120 CG=120 | Post-training only | Fair | ERS, DASS-21, PTSD checklist |
| McCrafty et al (1999), McCrafty and Atkinson (2012)23 39 | USA | HeartMath Coherence Advantage Training | 3 (12) | Simple randomised experiment* | 65 TG=29 CG=36 | 4 | Fair | POQA |
| Navarrete et al (2022)27 | Spain | Mindfulness-based training | 8 (16) | Quasi-experimental design* | 62 TG=21 CG=41 | Post-training only | Fair | DASS-21 |
| Romosiou et al (2019)22 | Greece | CBT approach and positive psychology to address emotional intelligence, empathy and resilience | 4 (16) | Quasi-experimental design | 50 TG=23 CG=27 | 3 | Fair | CD-RISC-25, PSS |
| Rosmith (2013)24 | USA | Stress inoculation training including breathing exercises, relaxation techniques, cognitive restructuring and relapse prevention | 4 (6), booster: 1 (.5) | Simple randomised experiment* | 24 TG=8 TG with booster=8 CG=8 | 1.25 | Fair | POMS-SF, PSS, PSQ |
| Trombka et al (2021)12 | Brazil | Mindfulness-based training | 8 | Simple randomised experiment* | 170 TG=88 CG=82 | 6 | Good | HADS |
*Trials included a waitlist control group.
BRS, Brief Resilience Scale; CD-RISC, Connor-Davidson Resilience Scale; DASS-21, Depression, Anxiety and Stress Scales-21; ERS, Ego-Resiliency Scale; GAD-7, Generalised Anxiety Disorder 7-item Scale; HADS, Hospital Anxiety and Depression Scale; OSI, Occupational Stress Inventory; PGWBI, Psychological General Well-being Index; PHQ-9, Patient Health Questionnaire-9; POMS-SH, Profile of Mood States-Short Form; POQA, Personal and Organisational Quality Assessment; PROMIS, Patient-Reported Outcomes Measurement Information System; PSQ, Police Stress Questionnaire; PSS, Perceived Stress Scale; VAS, Visual Analogue Scale.