TABLE 2.
Effect Sizes in Meta-Analysis of Studies Comparing Interpersonal Psychotherapy With Control Conditions, Pharmacotherapy, and other Psychotherapiesa
| Comparison | Number of Comparisons |
d | 95% CI | Hetero- geneityb |
pc | Number Needed to Treat |
|---|---|---|---|---|---|---|
| IPT versus control condition | ||||||
| All studies | 16 | 0.63*** | 0.36 to 0.90 | 82.96*** | 2.91 | |
| Outlier removedd | 15 | 0.52*** | 0.36 to 0.68 | 42.84* | 3.50 | |
| HAM-D only | 9 | 0.60*** | 0.39 to 0.81 | 40.47 | 3.05 | |
| BDI only | 7 | 0.60*** | 0.32 to 0.89 | 59.62* | 3.05 | |
| Subgroup analysese | ||||||
| Adapted manual | ||||||
| No | 5 | 0.29 | 0.12 to 0.47 | 0.00 | 0.004 | 6.17 |
| Yes | 10 | 0.67 | 0.48 to 0.85 | 27.52 | 2.75 | |
| Target group | ||||||
| Adults in general | 3 | 0.37** | 0.15 to 0.58 | 0.00 | 0.214 | 4.85 |
| Adolescents | 5 | 0.63*** | 0.43 to 0.82 | 0.00 | 2.91 | |
| Specific target group | 7 | 0.53** | 0.19 to 0.87 | 68.11** | 3.42 | |
| Basis of diagnosis | ||||||
| Diagnostic interview | 12 | 0.57*** | 0.40 to 0.73 | 29.74 | 0.424 | 3.18 |
| Self-report | 3 | 0.38 | −0.04 to 0.80 | 67.73* | 4.72 | |
| Control group | ||||||
| Usual care | 6 | 0.50*** | 0.28 to 0.72 | 32.20 | 0.182 | 3.62 |
| Waiting list | 3 | 0.81*** | 0.42 to 1.20 | 59.63 | 2.30 | |
| Other | 5 | 0.38** | 0.14 to 0.62 | 0.00 | 4.72 | |
| Intent-to-treat analysis | ||||||
| Yes | 10 | 0.57*** | 0.38 to 0.76 | 51.56* | 0.718 | 3.18 |
| No | 4 | 0.50** | 0.16 to 0.84 | 12.97 | 3.62 | |
| IPT versus other psychotherapyf | ||||||
| All studies | 13 | 0.04 | −0.14 to 0.21 | 39.81 | 45.45 | |
| One effect size per study (highest) | 10 | 0.01 | −0.20 to 0.21 | 44.59 | 166.67 | |
| One effect size per study (lowest) | 10 | 0.00 | −0.20 to 0.19 | 41.11 | – | |
| HAM-D only | 10 | 0.12 | −0.07 to 0.31 | 19.04 | 14.71 | |
| BDI only | 7 | 0.28 | −0.02 to 0.57 | 45.46 | 6.41 | |
| Studies on dysthymia excluded | 11 | 0.01 | −0.18 to 0.20 | 42.09 | 166.67 | |
| Subgroup analysese | ||||||
| Adapted manual | ||||||
| Yes | 7 | −0.09 | −0.25 to 0.07 | 0.00 | 0.098 | 20.00 |
| No | 6 | 0.25 | −0.12 to 0.63 | 62.27* | 7.14 | |
| Comparison group | ||||||
| CBT | 9 | −0.04 | −0.23 to 0.16 | 39.72 | 0.113 | 45.45 |
| Other psychotherapy | 4 | 0.27 | −0.06 to 0.59 | 4.68 | 6.58 | |
| Target group | ||||||
| Adults | 8 | −0.08 | −0.24 to 0.08 | 0.00 | 0.116 | 21.74 |
| More specific group | 5 | 0.31 | −0.15 to 0.77 | 69.51* | 5.75 | |
| Intent-to-treat analysis | ||||||
| Yes | 9 | 0.16 | −0.06 to 0.38 | 35.74 | 0.106 | 11.11 |
| No | 3 | −0.13 | −0.40 to 0.15 | 0.00 | 13.51 | |
| IPT versus pharmacotherapyf | ||||||
| All studies | 10 | −0.12 | −0.36 to 0.12 | 61.98** | 14.71 | |
| Outlier removedg | 9 | −0.19* | −0.38 to −0.01 | 30.95 | 9.43 | |
| HAM-D only | 8 | −0.16 | −0.43 to 0.11 | 57.39* | 11.11 | |
| BDI only | 3 | −0.31 | −0.72 to 0.09 | 40.39 | 5.75 | |
| Studies on dysthymia excluded | 7 | −0.12 | −0.33 to 0.09 | 23.78 | 14.71 | |
| Subgroup analysese | ||||||
| Medicationh | ||||||
| SSRI or SNRI | 3 | −0.39** | −0.68 to −0.11 | 14.18 | 0.037 | 4.59 |
| Tricyclic antidepressant | 4 | −0.02 | −0.22 to 0.19 | 0.00 | 83.33 | |
| Intent-to-treat analysis | ||||||
| Yes | 5 | −0.15 | −0.42 to 0.13 | 45.10 | 0.450 | 11.90 |
| No | 4 | −0.28* | −0.50 to −0.06 | 0.00 | 6.41 | |
| Pharmacotherapy versus combination treatmenti |
||||||
| All studies | 10 | 0.16 | −0.03 to 0.36 | 39.26 | 11.11 | |
| HAM-D only | 8 | 0.21 | −0.11 to 0.52 | 64.64** | 8.47 | |
| BDI only | 2 | 0.10 | −0.20 to 0.41 | 0.00 | 17.86 | |
| Studies on dysthymia excluded | 7 | 0.22 | −0.03 to 0.47 | 44.17 | 8.06 | |
| Subgroup analyses | ||||||
| Adapted manual | ||||||
| Yes | 5 | 0.23 | −0.04 to 0.51 | 50.15 | 0.494 | 7.69 |
| No | 5 | 0.08 | −0.25 to 0.41 | 40.50 | 21.74 | |
| Medication | ||||||
| SSRI | 5 | 0.07 | −0.27 to 0.41 | 64.96* | 0.562 | 25.00 |
| Tricyclic antidepressant | 2 | 0.33 | −0.11 to 0.76 | 0.00 | 5.43 | |
| Other/protocol | 3 | 0.27 | −0.00 to 0.54 | 0.00 | 6.58 | |
| Target group | ||||||
| Adults | 5 | 0.07 | −0.12 to 0.27 | 0.00 | 0.569 | 25.00 |
| More specific group | 5 | 0.19 | −0.16 to 0.54 | 61.35* | 9.43 | |
| Intent-to-treat analysis | ||||||
| Yes | 6 | 0.12 | −0.10 to 0.34 | 23.03 | 0.391 | 14.71 |
| No | 4 | 0.35 | −0.12 to 0.82 | 63.84* | 5.10 |
These data are from analysis using the random effects model. BDI=Beck Depression Inventory; HAM-D=Hamilton Depression Rating Scale; IPT=interpersonal psychotherapy; SNRI=serotonin/norepinephrine reuptake inhibitor; SSRI=selective serotonin reuptake inhibitor.
Variance between studies as a proportion of the total variance; heterogeneity tested using the I2 statistic. Low heterogeneity=25%; moderate heterogeneity=50%; high heterogeneity=75%. The p values indicated in this column refer to whether the Q statistic is significant (the I2 statistic does not include a test of significance).
The p values in this column indicate whether the difference between the effect sizes in the subgroups is significant.
Bolton et al. (39).
Subgroup analyses are conducted without outliers.
Positive effect sizes indicate superior effects of IPT.
Finkenzeller et al. (44).
Two studies in which other pharmacotherapies were used (nefazodone, protocolized treatment) were excluded from these analyses.
Positive effect sizes indicate superior effects of combination treatment.
p<0.05.
p<0.01.
p<0.001.