Intervention fidelity
Group sessions were audio recorded to assess intervention fidelity. Two research assistants not conducting the intervention retrospectively listened to 25% (42 h) of sessions. AP group fidelity was assessed in terms of whether intervention components were delivered. Given the nature of the AE group, general principles (e.g., not discussing planning activities outside of sessions) rather than specific content were used to evaluate fidelity (see Additional File Listen to audiorecording and assess fidelity together;Listen to audiorecording together and assess fidelity separately;Listen to audiorecording separately and assess fidelity separately.Following steps 2 and 3, raters compared their scores and resolved discrepancies, if any. Sufficient agreement was considered reached once raters had less than 10% discrepant items, after which ratings were completed independently. All rating checklist items were summed and given percent scores per checklist, per group. Percent scores were then averaged for a total estimate.