Table 5. Means, standard deviations and effect sizes of primary and secondary outcomes.
| Unadjusted mean (standard deviation) {valid n} | Effect size; p-value | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Pre-treatment | Post-treatment | 3-month f/up | 12-month f/up | Within-group | Within-group | Between-group | Within-group | Within-group | |
| pre to post | pre to f/up | ICBT vs. WL | post to 3 f/up | 3 to 12 f/up | |||||
| ADIS CSRprim | |||||||||
| ICBT | 6.69 (0.68) {35} | 3.83 (2.65) {35} | 3.88 (2.56) {33} | d = 1.48, p < .001 | d = 1.50, p < .001a | d = .65, p = .022 | d = -.02, p = .495 | ||
| WL | 6.54 (0.92) {35} | 5.09 (2.29) {32} | d = .83, p = .001 | ||||||
| ADIS CSRall | |||||||||
| ICBT | 13.17 (5.28) {35} | 6.89 (4.56) {35} | 6.39 (4.64) {33} | d = 1.27, p < .001 | d = 1.36, p < .001a | d = .83, p = .002 | d = .11, p = .482 | ||
| WL | 11.17 (4.42) {35} | 9.28 (4.13) {32} | d = .44, p = .012 | ||||||
| SCAS-Cadol | |||||||||
| ICBT | 47.29 (15.38) {35} | 31.88 (16.06) {32} | 28.74 (16.08) {27} | 33.36 (12.64) {25} | d = .98, p < .001 | d = .99, p < .001b | d = .68, p < .001 | d = .20, p = .054 | d = -.32, p = .056 |
| WL | 45.60 (15.79) {35} | 40.19 (19.90) {31} | d = .30, p = .038 | ||||||
| SCAS-Pmother | |||||||||
| ICBT | 48.23 (17.28) {35} | 29.43 (13.60) {35} | 28.73 (16.57) {33} | 28.58 (18.58) {31} | d = 1.21, p < .001 | d = 1.10, p < .001b | d = 1.12, p < .001 | d = .05, p = .548 | d = .01, p = .849 |
| WL | 42.71 (14.85) {35} | 41.31 (17.54) {32} | d = .09, p = .632 | ||||||
| SCAS-Pfather | |||||||||
| ICBT | 41.45 (19.18) {31} | 32.46 (17.29) {26} | 28.33 (15.33) {24} | 23.55 (18.77) {22} | d = .49, p = .001 | d = .94, p < .001b | d = .46, p = .011 | d = .25, p = .007 | d = .28, p = .484 |
| WL | 37.41 (12.75) {32} | 36.96 (14.35) {27} | d = .03, p = .579 | ||||||
| CALISadol | |||||||||
| ICBT | 13.54 (6.56) {35} | 10.59 (7.65) {32} | 8.93 (7.63) {27} | 9.72 (8.55) {25} | d = .41, p = .007 | d = .50, p = .002b | d = .21, p = .254 | d = .22, p = .183 | d = -.10, p = .663 |
| WL | 13.97 (6.73) {35} | 12.42 (8.65) {31} | d = .20, p = .180 | ||||||
| CALISmother | |||||||||
| ICBT | 32.14 (11.36) {35} | 22.49 (12.67) {35} | 23.21 (16.33) {33} | 20.61 (14.96) {31} | d = .80, p < .001 | d = .87, p < .001b | d = .93, p < .001 | d = -.05, p = .856 | d = .17, p = .450 |
| WL | 33.71 (11.91) {35} | 35.34 (13.47) {32} | d = -.13, p = .513 | ||||||
| CALISfather | |||||||||
| ICBT | 29.42 (14.07) {31} | 25.89 (15.58) {27} | 24.21 (14.53) {24} | 16.59 (13.50) {22} | d = .24, p = .049 | d = .93, p < .001b | d = .20, p = .227 | d = .11, p = .195 | d = .54, p = .044 |
| WL | 28.91 (9.74) {32} | 28.52 (13.00) {27} | d = .03, p = .574 | ||||||
| WHO-5 | |||||||||
| ICBT | 44.69 (21.44) {35} | 49.50 (21.69) {32} | 55.85 (25.21) {27} | 48.48 (25.98) {25} | d = .22, p = .143 | d = .16, p = .129b | d = -.04, p = .945 | d = .27, p = .100 | d = -.29, p = .105 |
| WL | 48.91 (19.19) {35} | 54.06 (20.39) {31} | d = .26, p = .135 | ||||||
| S-MFQadolescent | |||||||||
| ICBT | 10.46 (6.47) {35} | 8.06 (7.77) {32} | d = .34, p = .014 | d = -.11, p = .932 | |||||
| WL | 10.94 (7.07) {35} | 7.77 (7.14) {31} | d = .45, p = .010 | ||||||
| S-MFQmother | |||||||||
| ICBT | 9.91 (5.79) {35} | 5.77 (5.25) {35} | d = .75, p < .001 | d = .60, p = .008 | |||||
| WL | 10.43 (6.15) {35} | 9.47 (6.37) {32} | d = .15, p = .360 | ||||||
| S-MFQfather | |||||||||
| ICBT | 8.26 (5.43) {31} | 7.15 (5.86) {27} | d = .20, p = .103 | d = .07, p = .813 | |||||
| WL | 7.88 (4.89) {32} | 6.56 (4.85) {27} | d = .27, p = .229 | ||||||
| SEQ-Ctotal | |||||||||
| ICBT | 70.71 (13.88) {35} | 75.25 (16.55) {32} | d = .30, p = .008 | d = .12, p = .367 | |||||
| WL | 71.23 (15.76) {35} | 74.00 (16.27) {31} | d = .17, p = .174 | ||||||
| SEQ-Cacademic | |||||||||
| ICBT | 27.17 (7.14) {35} | 27.13 (8.04) {32} | d = -.01, p = .970 | d = -.08, p = .449 | |||||
| WL | 26.11 (8.49) {35} | 26.71 (7.84) {31} | d = .07, p = .270 | ||||||
| SEQ-Csocial | |||||||||
| ICBT | 25.09 (5.46) {35} | 26.06 (6.11) {32} | d = .17, p = .133 | d = .04, p = .668 | |||||
| WL | 26.20 (6.79) {35} | 27.06 (6.32) {31} | d = .13, p = .412 | ||||||
| SEQ-Cemotional | |||||||||
| ICBT | 18.46 (5.92) {35} | 22.06 (5.87) {32} | d = .61, p < .001 | d = .38, p = .026 | |||||
| WL | 18.91 (5.26) {35} | 20.23 (6.35) {31} | d = .23, p = .205 | ||||||
Note. ADIS: Anxiety Disorder Interview Schedule for DSM-IV; CSR: Clinical Severity Rating; SCAS-C/P: Spence Children’s Anxiety Scale Child/Parent version; CALIS: Child Anxiety Life Inference Scale; WHO-5: WHO-5 Well-being Index Questionnaire; S-MFQ: short version of the Moods and Feelings Questionnaire; SEQ-C: The Self-Efficacy Questionnaire for Children; f/up: follow-up.
a Pre to 3-month follow-up
b Pre to 12-month follow-up. For the SCAS, CALIS and S-MFQ, a family-wise Bonferroni-corrected significance level of p = 0.017 was deployed. Effect size calculations based on observed values and expressed as Cohen’s d. Positive effect sizes indicate improvement.