Outcome Continuous data	Pretreatment	Post-treatment	6-Month follow-up	Pretreatment to post-treatment comparison		Post-treatment to 6-month follow-up comparison		Pretreatment to 6-month follow-up comparison		Model p^a
Outcome Continuous data	Mean (SD)	Mean (SD)	Mean (SD)	Z	Cohen’s d† (95% CI)	Z	Cohen’s d† (95% CI)	Z	Cohen’s d† (95% CI)
DSHI-v	3.01 (1.82)	2.23 (2.02)	1.67 (1.76)	3.67***	0.41 (0.19 to 0.63)	2.86**	0.24 (0.07 to 0.42)	5.65***	0.65 (0.40 to 0.89)	<0.001
DERS	125.98 (19.37)	108.17 (27.52)	104.66 (27.40)	6.56***	0.91 (0.63 to 1.20)	1.00	0.12 (−0.09 to 0.43)	7.13***	1.03 (0.69 to 1.38)	<0.001
IIP-BPD	2.05 (0.72)	1.98 (0.71)	1.78 (0.76)	1.08	0.10 (−0.06 to 0.29)	2.43*	0.24 (0.06 to 0.43)	3.46***	0.34 (0.13 to 0.59)	0.002
DASS-D	25.35 (10.28)	20.11 (11.80)	19.95 (11.92)	4.37***	0.50 (0.29 to 0.75)	0.41	0.05 (−0.22 to 0.30)	3.91***	0.55 (0.27 to 0.85)	<0.001
DASS-A	17.14 (8.98)	16.30 (9.97)	14.54 (9.58)	0.85	0.08 (−0.10 to 0.27)	1.59	0.17 (−0.05 to 0.41)	2.11*	0.25 (0.01 to 0.49)	0.024
DASS-S	25.77 (7.95)	23.34 (9.21)	21.19 (10.34)	2.46*	0.30 (0.06 to 0.54)	1.95*	0.26 (0.01 to 0.52)	4.30***	0.56 (0.26 to 0.86)	<0.001
SDS	18.44 (6.99)	18.59 (7.05)	16.01 (8.41)	−0.25	−0.03 (−0.22 to 0.16)	2.71**	0.32 (0.07 to 0.60)	2.51*	0.29 (0.04 to 0.59)	0.013

Test statistics are based on negative binomial generalised mixed models for count data and linear mixed models analyses for continuous data. CIs for effect sizes are based on 5000 bootstrap replications.
BSL, Borderline Symptom List, behaviour supplement; DASS-A, Depression Anxiety and Stress Scales-21 Anxiety; DASS-D, Depression Anxiety and Stress Scales-21 Depression; DASS-S, Depression Anxiety and Stress Scales-21 Stress; DERS, Difficulties in Emotion Regulation Scale; DSHI-f, Deliberate Self-Harm Inventory-frequency; DSHI-v, Deliberate Self-Harm Inventory-versatility; IIP-BPD, BPD-related composite of the Inventory of Interpersonal Problems; SDS, Sheehan Disability Scales.
a (p-value of log-likelihood ratio comparison with null model including no fixed effects and only random intercept)
*p<.05 **p<0.01, ***p<0.001.
†Effect size estimates for DSHI frequency and BSL are reported as per cent change across time, and effect sizes for the remaining continuous outcomes are reported as Cohen’s d.