Table 2 Single trial results

Trials including participants with major depressive disorder^a

Trial characteristics

Primary review outcomes

Secondary review outcomes

Trialists’ own conclusions

Trial ID

Shorter-term intervention

Longer-term intervention

Quality of Life

Serious Adverse Events

Symptom severity

Suicide/Suicide attempts

Self-harm

Level of functioning

Barkham et al. 1996 [40]

8 sessions CBT (8 weeks)

16 sessions CBT (18 weeks)

-

-

-

-

-

-

Clients given 16 sessions showed a statistically significant advantage over clients given 8 sessions on some measures at some assessments

8 sessions psychodynamic-interpersonal therapy (8 weeks)

16 sessions psychodynamic-interpersonal therapy (18 weeks)

Bruijniks et al. 2020 [39]

20 sessions CBT (24 weeks)

20 sessions CBT (16 weeks)

CBT: The mean RAND-36 scores at EoT were 50.13 (22.20) for the short-term group (n = 49) and 51.53 (22.36) for the long-term group (n = 39) (p = 0.77)

IPT: The mean RAND-36 scores at EoT were 46.8 (20.46) in the short-term group (n = 36) and 53.46 (20.67) in the long-term group (n = 47) (p = 0.14)

-

CBT: The mean (SD) BDI scores at EoT were 24.16 (15.09) for the short-term group (n = 37) and 21.25 (12.90) for the long-term group (n = 35) (p = 0.38)

IPT: The mean (SD) BDI scores at EoT were 22.91 (14.75) for the short-term group (n = 34) and 20.02 (16.05) for the long-term group (n = 39) (p = 0.42)

-

-

-

In clinical practice settings, delivery of twice weekly sessions of CBT and IPT for depression was superior to once weekly sessions when assessing depression outcomes

20 sessions interpersonal therapy (24 weeks)

20 sessions interpersonal therapy (16 weeks)

Christensen 2006 [43]

Brief online CBT and problem solving (unclear duration)

Extended online CBT and problem solving (unclear duration)

-

-

-

-

-

-

Brief CBT-based interventions are not as effective as extended interventions

Dekker et al. 2005 [44]

8 sessions short psychodynamic supportive psychotherapy (8 weeks)

16 sessions short psychodynamic supportive psychotherapy (24 weeks)

The mean (SD) QLDS scores at EoT were 22.6 (8.6) for the short-term group (n = 45) and 22.8 (8.3) for the long-term group (n = 45) (p = 0.911)

-

The mean (SD) HDRS scores at EoT were 11.1 (6.8) for the short-term group (n = 45) and 12.1 (7.6) for the long-term group (n = 45) (p = 0.512)

-

-

-

Eight or 16 psychotherapy sessions in addition to 8 sessions of pharmacotherapy over a period of 6 months would appear to be equally effective in terms of dealing with symptoms

Shapiro et al. 1994 [41]

8 sessions CBT (8 weeks)

16 sessions CBT (18 weeks)

-

-

-

-

-

-

There is no added benefit from 16 treatment sessions compared with 8

8 sessions psychodynamic-relationship-oriented therapy (8 weeks)

16 sessions of psychodynamic-relationship-oriented therapy (18 weeks)

Trials including participants with anxiety disorders^a

Trial characteristics

Primary review outcomes

Secondary review outcomes

Trialists’ own conclusions

Trial ID

Shorter-term intervention

Longer-term intervention

Quality of Life

Serious Adverse Events

Symptom severity

Suicide/Suicide attempts

Self-harm

Level of functioning

Bohni et al. 2009 [42]

8 sessions CBT (3 weeks)

13 sessions CBT (13 weeks)

-

-

-

-

-

-

Patients in massed CBT achieved their results at a faster rate than patients in spaced CBT, with outcomes after 3 weeks in massed CBT comparable with those achieved after approximately 3 months in spaced CBT

Clark et al. 1999 [37]

5 sessions CBT (12 weeks)

12 sessions CBT (12 weeks)

-

-

The mean (SD) BAI scores at EoT were 9.8 (6.7) for the short-term group (n = 14) and 8.4 (8.0) for the long-term group (n = 15) (p = 0.615). This result is included in a meta-analysis

-

-

-

Brief CT did not differ from full CT at posttreatment or at follow-up, and effect sizes were essentially the same

Herbert et al. 2004 [36]

12 sessions CBT (12 weeks)

12 sessions CBT (18 weeks)

-

-

The mean (SD) SPAI-SP scores at EoT were 76.71 (47.18) for the short-term group (n = 15) and 113.77 (39.56) for the long-term group (n = 19) (p = 0.018). This result is included in a meta-analysis

-

-

-

The results revealed that the standard treatment program in which therapy was provided over 12 successive weeks resulted in more rapid symptom reduction and lower dropout relative to the extended treatment delivered over 18 weeks

Kenardy et al. 2003 [48]

6 sessions CBT (6 weeks)

12 sessions CBT (12 weeks)

-

-

The mean (SD) STAI-T scores at EoT were 47.86 (12.31) for the short-term group (n = 39) and 41.10 (13.14) for the long-term group (n = 42) (p = 0.0195). This result is included in a meta-analysis

-

-

-

A brief version performs significantly worse than the standard duration treatment at posttreatment

Roberge et al. 2008 [38]

7 sessions CBT (16 weeks)

14 sessions CBT (15 weeks)

-

-

The mean (SD) PAS scores at EoT were 10.2 (8.8) for the short-term group (n = 32) and 9.5 (10.3) for the long-term group (n = 33) (p = 0.77). This result is included in a meta-analysis

-

-

-

Brief CBT effectiveness appears comparable to standard CBT in the short term

Trials including participants with mood- and anxiety disorders^a

Trial characteristics

Primary review outcomes

Secondary review outcomes

Trialists’ own conclusions

Trial ID

Shorter-term intervention

Longer-term intervention

Quality of Life

Serious Adverse Events

Symptom severity

Suicide/Suicide attempts

Self-harm

Level of functioning

Knekt et al. 2008 [34]

Short-term psychodynamic therapy

Long-term psychodynamic therapy

-

-

The mean (SD) HDRS scores at EoT were 10.8 (5.65) for the short-term group (n = 83) and 9.0 (6.0) for the long-term group (n = 107) (p = 0.037)

-

-

The mean (SD) SAS-work scores at EoT were 1.88 (0.55) for the short-term group (n = 83) and 1.72 (0.62) for the long-term group (n = 107). (p = 0.066). This result is included in a meta-analysis

Patients receiving short-term psychodynamic psychotherapy recovered faster from both depressive and anxiety symptoms during the first year of follow-up. During the following 2 years, the symptoms persisted at the level reached in the brief therapy group, whereas in the long-term psychodynamic psychotherapy group the improvement continued during the entire 3-year period. In the long run, long-term psychodynamic psychotherapy thus gave greater benefits than those achieved by the brief therapies

Lorentzen et al. 2013 [35]

Short-term psychodynamic group therapy

Long-term psychodynamic group therapy

-

-

-

There were 0/77 suicides or suicide attempts in the short-term group compared to 0/90 in the long-term group (p = not applicable)

-

The mean (SD) GAF scores at EoT were 67.8 (11.7) for the short-term group (n = 71) and 68.1 (14.2) for the long-term group (n = 79) (p = 0.889). This result is included in a meta-analysis

We observed that short- and long-term therapy were equally effective across 3 years, using IIP, GAF-S and GAF-F as the outcome variables. However, there was a trend in favour of long-term therapy (P = 0.10) using GAF-S as the outcome variable

Hadjistavropoulos et al. 2022 [50]

Internet-based CBT (8 weeks)

Internet-based CBT (8 weeks + 3 booster sessions)

The mean (SD) EQ-5D-5L scores at EoT were 71.92 (18.93) for the short-term group (n = 79) and 71.36 (21.34) for the long-term group (n = 87) (p = 0.858)

-

The mean (SD) PHQ-9 scores at EoT were 7.93 (5.36) for the short-term group (n = 79) and 5.84 (5.07) for the long-term group (n = 87) (p = 0.01)

The mean (SD) GAD-7 scores at EoT were 7.56 (5.37) for the short-term group (n = 79) and 5.56 (4.60) for the long-term group (n = 87) (p = 0–01)

-

-

The mean (SD) SDS scores at EoT were 13.86 (7.86) for the short-term group (n = 79) and 10.66 (8.7) for the long-term group (n = 87) (p = 0.01)

No significant group differences were found in this study

Internet-based CBT (12 weeks)

Internet-based CBT (12 weeks + 3 booster sessions)

The mean (SD) EQ-5D-5L scores at EoT were 74.06 (15.94) for the short-term group (n = 87) and 69.13 (21.93) for the long-term group (n = 91) (p = 0.089)

-

The mean (SD) PHQ-9 scores at EoT were 6.52 (5.23) for the short-term group (n = 87) and 7.55 (6.24) for the long-term group (n = 91) (p = 0.235)

The mean (SD) GAD-7 scores at EoT were 6.33 (5.19) for the short-term group (n = 87) and 6.96 (5.8) for the long-term group (n = 91) (p = 0.446)

-

-

The mean (SD) SDS scores at EoT were 10.29 (8.01) for the short-term group (n = 87) and 11.39 (8.46) for the long-term group (n = 91) (p = 0.374)

Trials including participants with post-traumatic stress disorder^a

Trial characteristics

Primary review outcomes

Secondary review outcomes

Trialists’ own conclusions

Trial ID

Shorter-term intervention

Longer-term intervention

Quality of Life

Serious Adverse Events

Symptom severity

Suicide/Suicide attempts

Self-harm

Level of functioning

Böttche et al. 2021 [51]

6 sessions internet-based CBT (3 weeks)

10 sessions internet-based CBT (5 weeks)

The mean (SD) EUROHIS-QOL-8 scores at EoT were 5.53 (0.83) for the short-term group (n = unclear) and 5.11 (1.02) for the long-term group (n = unclear) (p = 0.75)

-

The mean (SD) PDS change scores at EoT were -14.73 (1.45) for the short-term group (n = unclear) and -15.03 (1.64) for the long-term group (n = unclear) (p = 0.89)

-

-

-

The shorter condition results in the same symptom change and dropout rate as the longer condition

Dell et al. 2022 [49]

Massed prolonged expoure

Standard prolonged exposure

-

0 events

The mean (SD) CAPS scores at EoT were 27.69 (18.42) for the short-term group (n = 63) and 25.68 (16.59) for the long-term group (n = 71) (p = 0.664)

0 events

-

-

Massed prolonged exposure was non-inferior to standard prolonged exposure in reducing symptoms of PTSD

Ehlers et al. 2014 [45]

Intensive cognitive therapy

Standard cognitive therapy

The mean (SD) Q-LES-Q scores at EoT were 52.67 (20.21) for the short-term group (n = 30) and 62.93 (21.70) for the long-term group (n = 31) (p = 0.061)

-

The mean (SD) CAPS scores at EoT were 32.22 (27.20) for the short-term group (n = 30) and 26.97 (28.68) for the long-term group (n = 31) (p = 0.466)

-

-

The mean (SD) SDS scores at EoT were 9.30 (8.20) for the short-term group (n = 30) and 10.02 (9.76) for the long-term group (n = 31) (p = 0.757)

A novel 7-day intensive version of cognitive therapy for PTSD was well tolerated, achieved faster symptom reduction, and led to comparable overall outcomes as the standard once-weekly cognitive therapy delivered over 3 months

Foa et al. 2018 [46]

Massed prolonged exposure

Extended prolonged exposure

-

-

The mean (SD) PSS-I scores at EoT were 18.88 (no SD reported) for the short-term group (n = 110) and 18.34 (no SD reported) for the long-term group (n = 110) (p = not applicable)

-

-

-

Among active duty military personnel with PTSD, massed prolonged exposure therapy (10 sessions delivered over 2 weeks) was noninferior to spaced pro- longed exposure therapy (10 sessions delivered over 8 weeks)

Nacasch et al. 2015 [47]

60 min sessions of prolonged exposure

90 min sessions of prolonged exposure

-

-

The mean (SD) PSS-I scores at EoT were 13.3 (9.52) for the short-term group (n = 20) and 12.24 (8.02) for the long-term group (n = 17) (p = 0.719)

-

-

-

In sum, 20-min imaginal exposure within 60-min sessions yielded noninferior outcomes in PTSD symptoms and posttraumatic negative cognitions at posttreatment and follow-up to the 40-min imaginal exposures and 90-min sessions

Trials including participants with borderline personality disorder^a

Trial characteristics

Primary review outcomes

Secondary review outcomes

Trialists’ own conclusions

Trial

Shorter-term intervention

Longer-term intervention

Quality of Life

Serious Adverse Events

Symptom severity

Suicide/Suicide attempts

Self-harm

Level of functioning

McMain et al. 2022 [52] (McMain S: The effectiveness of 6 versus 12-months of dialectical behaviour therapy for borderline personality disorder: the feasibility of a shorter treatment and evaluating responses (FASTER) trial, Unpublished)

6 months of DBT

12 months of DBT

The mean (SD) overall EQ5DL scores at EoT were 60.7 (21.43) for the short-term group (n = 91) compared with 61.41 (23.17) in the long-term group (n = 90) (p = 0.831)

2 / 90 participants had one or more serious adverse events in the short-term group at EoT compared with 2 / 93 in the long-term group (p = 1) (based on suicide/ suicide attempt data only)

The mean (SD) BSL scores at EoT were 38.6 (22.4) for the short-term group (n = 90) compared with 39.3 (22.2) in the long-term group (n = 91) (p = 0.833)

2 / 90 participants had one suicide or suicide-attempts in the short-term group at EoT compared with 2 / 93 in the long-term group (p = 1)

28 / 90 participants had one or more deliberate self-harm incidents in the short-term group at EoT compared with 37/ 93 in the long-term group (p = 0.28)

The mean (SD) SAS scores at EoT were 2.51 (0.58) for the short-term group (n = 90) compared with 2.54 (0.59) in the long-term group (n = 91) (p = 0.731)

Half the dose of the standard DBT yielded noninferior improvements across time points for the primary outcome, total self-harm frequency, as well as several clinical outcomes