Table A1.
Follow up data used in the meta-analysis.
| Study | Outcome | Measure | Experimental Group | Control Group | ||||
|---|---|---|---|---|---|---|---|---|
| Mean | SD | N | Mean | SD | N | |||
| Aldred et al. (2004) [27] | Expressive | MCDI words post | 199.4 | 25.606 | 14 | 33.1 | 683 | 14 |
| Receptive | MCDI words post | 222.7 | 40.431 | 14 | 146.8 | 11,426 | 14 | |
| Communication | VABS post | 36.9 | 21.2 | 14 | 28.7 | 16.6 | 14 | |
| Brian et al. (2017) [28] | Expressive | MSEL follow up | 28.53 | 12.13 | 30 | 32 | 13.86 | 32 |
| Receptive | MSEL follow up | 29.07 | 13.17 | 30 | 30.87 | 14.51 | 32 | |
| Communication | VABS follow up | 75.63 | 13.18 | 30 | 78.34 | 13.42 | 32 | |
| Socialization | VABS follow up | 75.83 | 8.27 | 30 | 76.44 | 8.62 | 32 | |
| Cognitive Ability | MSEL | 65.2 | 16.23 | 30 | 69.81 | 21.57 | 32 | |
| Expressive | PLS-4 | 75.4 | 13.78 | 30 | 76.97 | 15.02 | 32 | |
| Receptive | PLS-4 | 70.33 | 17.7 | 30 | 68.91 | 19.21 | 32 | |
| Carter et al. (2011) [29] | Communication | VABS follow up | 76.14 | 13.85 | 32 | 76.43 | 14.05 | 30 |
| Socialization | VABS follow up | 71.42 | 7.07 | 32 | 70.7 | 6.89 | 30 | |
| Daily living skills | VABS follow up | 77.84 | 7.07 | 32 | 72.95 | 10.11 | 30 | |
| Motor skills | VABS follow up | 83.16 | 7.36 | 32 | 81.55 | 9.26 | 30 | |
| Cognitive Ability | MSEL follow up | 63.88 | 18.41 | 32 | 64.88 | 13.94 | 30 | |
| Receptive | MSEL | 15.52 | 6.93 | 32 | 17.48 | 8.33 | 30 | |
| Expressive | MSEL | 16.2 | 7.23 | 32 | 16.68 | 7.88 | 30 | |
| Dawson et al. (2010) [30] | Cognitive Ability | MSEL | 78.6 | 24.2 | 24 | 66.3 | 15.3 | 21 |
| Expressive | MSEL | 36.6 | 13.6 | 24 | 30 | 9.2 | 21 | |
| Receptive | MSEL | 40 | 16.3 | 24 | 31.5 | 10.6 | 21 | |
| Adaptive behaviour composite | VABS | 68.7 | 15.9 | 24 | 59.1 | 8.8 | 21 | |
| Communication | VABS | 82.1 | 21.8 | 24 | 69.4 | 15.8 | 21 | |
| Socialization | VABS | 69.2 | 11.6 | 24 | 63.1 | 9.3 | 21 | |
| Daily living skills | VABS | 64.7 | 12.4 | 24 | 58 | 8.1 | 21 | |
| Motor skills | VABS | 77.4 | 19.8 | 24 | 64.1 | 12.3 | 21 | |
| Divan et al. (2019) [31] | Adaptive behaviour composite | VABS | 65.00 | 12.69 | 19 | 60.53 | 12.98 | 21 |
| Communication | VABS | 60.93 | 17.88 | 19 | 55.90 | 14.15 | 21 | |
| Socialization | VABS | 68.47 | 10.26 | 19 | 63.25 | 11.45 | 21 | |
| Drew et al. (2002) [32] | Cognitive Ability | NVIQ | 77.9 | 14.8 | 12 | 66.1 | 17.1 | 12 |
| Expressive | MCDI words | 96.6 | 118.8 | 12 | 44 | 50.2 | 12 | |
| Expressive | MCDI gestures | 38.6 | 12.5 | 12 | 29.1 | 18.4 | 12 | |
| Receptive | MCDI words | 176.1 | 121.9 | 12 | 100.3 | 80.2 | 12 | |
| Estes et al. (2015) [33] | Cognitive Ability | MSEL follow up | 90.52 | 26.36 | 24 | 79.83 | 23.64 | 21 |
| Adaptive behaviour composite | VABS follow up | 81.41 | 17.27 | 17 | 72.06 | 13.86 | 16 | |
| Communication | VABS follow up | 88.35 | 19.76 | 17 | 79.71 | 18.53 | 17 | |
| Socialization | VABS follow up | 79.24 | 16.03 | 17 | 69.44 | 13.81 | 16 | |
| Daily living skills | VABS follow up | 83.06 | 21.56 | 17 | 77.71 | 16.4 | 17 | |
| Gengoux et al. (2019) [34] | Expressive | CDI 396 | 194.9 | 133.7 | 23 | 84.4 | 93.5 | 20 |
| Expressive | CDI 680 | 256.6 | 200.1 | 23 | 112.9 | 148.1 | 20 | |
| Expressive | VABS | 7.6 | 2.4 | 23 | 6.2 | 1.6 | 20 | |
| Expressive | PLS-5 | 58.7 | 10.2 | 23 | 56.9 | 10.5 | 20 | |
| Expressive | MSEL | 21 | 8.7 | 23 | 17.3 | 6.9 | 20 | |
| Communication | VABS | 63.8 | 14.8 | 23 | 62.5 | 11.6 | 20 | |
| Green et al. (2010) [35] | Expressive | PLS | 20 | 11.2 | 77 | 20 | 11.3 | 75 |
| Expressive | MCDI | 171.9 | 150.7 | 77 | 163.8 | 144.3 | 75 | |
| Receptive | PLS | 21.5 | 13 | 77 | 20.3 | 12.8 | 75 | |
| Receptive | MCDI | 233.7 | 129.6 | 77 | 209 | 131.3 | 75 | |
| Adaptive behaviour composite | VABS | 60.3 | 15.2 | 77 | 62.8 | 14.8 | 75 | |
| Communication | VABS | 6.6 | 3.3 | 77 | 6.7 | 3.2 | 75 | |
| Socialization | VABS | 9.2 | 3 | 77 | 9.8 | 2.9 | 75 | |
| Green et al. (2020) [36] | Expressive | PLS | 57.5 | 14.9 | 92 | 59.3 | 20 | 102 |
| Expressive | MCDI | 42.5 | 18.5 | 49 | 42 | 21.7 | 52 | |
| Receptive | PLS | 57.7 | 13.7 | 92 | 59.5 | 18.9 | 102 | |
| Receptive | MCDI | 43.2 | 20 | 39 | 42.2 | 21.9 | 42 | |
| Hampton et al. (2020) [37] | Expressive | PLS post | 25 | 5 | 34 | 25 | 5 | 34 |
| Expressive | PLS follow-up | 26 | 6 | 34 | 27 | 5 | 34 | |
| Receptive | PLS post | 26 | 7 | 34 | 25 | 6 | 34 | |
| Receptive | PLS follow-up | 28 | 8 | 34 | 28 | 7 | 34 | |
| Hardan et al. (2015) [38] | Expressive | CDI | 172.2 | 123.6 | 25 | 215 | 118.3 | 22 |
| Expressive | CDI | 289.1 | 181.9 | 25 | 239.9 | 187.1 | 22 | |
| Expressive | PLS | 63.9 | 11.6 | 25 | 63 | 13.4 | 22 | |
| Expressive | VABS | 41.7 | 14.7 | 25 | 34 | 18.9 | 22 | |
| Receptive | VABS | 21.5 | 14.7 | 25 | 18.9 | 6.5 | 22 | |
| Communication | VABS | 78.9 | 18.9 | 25 | 72.8 | 16.5 | 22 | |
| Socialization | SRS | 74.9 | 12.4 | 25 | 80.6 | 10.7 | 22 | |
| Kaale et al. (2014) [39] | Expressive | RDSL | 27.9 | 29.48 | 34 | 34.1 | 32.41 | 27 |
| Receptive | RDSL | 32.8 | 29.1 | 34 | 39.4 | 28.5 | 27 | |
| Communication | SCQ parents | 4.1 | 3.28 | 34 | 4.52 | 3.42 | 27 | |
| Communication | SCQ teachers | 4.88 | 3.28 | 34 | 4.12 | 3.22 | 27 | |
| Socialization | SCQ parents | 5.28 | 6.23 | 34 | 4.13 | 5.7 | 27 | |
| Socialization | SCQ teachers | 6.3 | 4.94 | 34 | 5.19 | 3.22 | 27 | |
| Kasari et al. (2015) [40] | Expressive | RDLS post | 18.42 | 8.03 | 43 | 19.83 | 7.84 | 43 |
| Expressive | RDLS follow up | 24.26 | 9.34 | 43 | 24.59 | 8.82 | 43 | |
| Receptive | RDLS post | 20.87 | 11.85 | 43 | 23.17 | 13.02 | 43 | |
| Receptive | RDLS follow up | 32.74 | 15.24 | 43 | 33.38 | 16 | 43 | |
| Landa et al. (2011) [41] | Non-verbal IQ | MSEL post | 36.75 | 14.54 | 24 | 32.24 | 14.07 | 24 |
| Non-verbal IQ | MSEL follow up | 34.44 | 16.67 | 24 | 30.28 | 16.62 | 24 | |
| Expressive | MSEL post | 34.08 | 14.59 | 24 | 31.92 | 13.67 | 24 | |
| Expressive | MSEL follow up | 34.52 | 12.33 | 24 | 31.36 | 12.12 | 24 | |
| Oosterling et al. (2010) [42] | Expressive | MCDI words | 182.3 | 201 | 34 | 157.8 | 206.96 | 31 |
| Expressive | MCDI gestures | 35.8 | 23.9 | 34 | 36.4 | 22.16 | 29 | |
| Receptive | MCDI words | 239.9 | 197.5 | 34 | 216.7 | 187.5 | 31 | |
| Parsons et al. (2019) [43] | Expressive | MSEL | 70.9 | 27.97 | 21 | 67.5 | 22.75 | 27 |
| Receptive | MSEL | 72.1 | 32.84 | 21 | 71.6 | 26.98 | 27 | |
| Fine motor | CSBS | 68.8 | 21.74 | 21 | 70.2 | 19.42 | 27 | |
| Socialization | MSEL | 36.2 | 7.07 | 21 | 31 | 8.4 | 27 | |
| Rahman et al. (2016) [44] | Expressive | MCDI | 6.69 | 2.51 | 29 | 6.97 | 2.11 | 30 |
| Receptive | MCDI | 9.24 | 2.65 | 29 | 9.47 | 2.54 | 30 | |
| Adaptive behaviour composite | VABS | 61.76 | 12.51 | 29 | 63.67 | 10.54 | 30 | |
| Communication | VABS | 60.28 | 13.84 | 29 | 60.73 | 13.84 | 30 | |
| Socialization | VABS | 61.41 | 9.02 | 29 | 61.73 | 8.07 | 30 | |
| Reitzel et al. (2013) [45] | Motor skills | VABS | 72.3 | 7.1 | 6 | 67.7 | 7 | 3 |
| Communication | VABS | 58 | 9.4 | 7 | 67 | 10.4 | 4 | |
| Socialization | VABS | 63.9 | 5.1 | 7 | 64.8 | 3.9 | 4 | |
| Daily living skills | VABS | 66.9 | 13.7 | 7 | 65.3 | 11 | 4 | |
| Adaptive behaviour composite | VABS | 62.7 | 6.8 | 7 | 63.3 | 5.7 | 4 | |
| Rickards et al. (2007) [46] | Cognitive Ability | Bayley/WPPSI-R | 57.2 | 21.9 | 18 | 48.6 | 17.5 | 21 |
| Roberts et al. (2011) [47] | Expressive | RDLS | 8.8 | 8.9 | 28 | 11.1 | 9.9 | 28 |
| Receptive | RDLS | 17.5 | 6.3 | 28 | 22 | 17.8 | 28 | |
| Communication | VABS | 68.4 | 15.6 | 28 | 74.2 | 15.5 | 28 | |
| Socialization | VABS | 66.4 | 7.7 | 28 | 73.1 | 10.8 | 28 | |
| Rogers et al. (2012) [48] | Expressive | MCDI | 42.27 | 61.99 | 49 | 38.87 | 73.71 | 49 |
| Receptive | MCDI | 106.51 | 96.81 | 49 | 125.72 | 106.39 | 49 | |
| Receptive | MCDI phrases | 12.73 | 9.11 | 49 | 14.77 | 8.14 | 49 | |
| Communication | VABS | 72.55 | 12.06 | 49 | 74.29 | 14.55 | 49 | |
| Socialization | VABS | 77.32 | 9.19 | 49 | 78.67 | 10.78 | 49 | |
| Daily living skills | VABS | 82.25 | 13.82 | 49 | 84.04 | 13.5 | 49 | |
| Rogers et al. (2019) [49] | Cognitive Ability | MSEL post | 72 | 18.55 | 51 | 69.4 | 17.77 | 52 |
| Cognitive Ability | MSEL follow up | 83.09 | 26.12 | 44 | 79.14 | 25.58 | 35 | |
| Adaptive behaviour composite | VABS post | 15.39 | 5.22 | 49 | 15.86 | 6.25 | 45 | |
| Adaptive behaviour composite | VABS follow up | 39.76 | 12.07 | 44 | 36.69 | 14.32 | 36 | |
| Scahill et al. (2016) [50] | Communication | VABS | 84.75 | 15.68 | 89 | 85.78 | 14.5 | 91 |
| Socialization | VABS | 76.46 | 13.51 | 89 | 76.63 | 12.28 | 91 | |
| Daily living skills | VABS | 82.39 | 14.61 | 89 | 79.6 | 15.39 | 91 | |
| Schertz et al. (2013) [51] | Expressive | MSEL | 33.27 | 15.79 | 11 | 27.17 | 11.21 | 12 |
| Receptive | MSEL | 28.27 | 11.35 | 11 | 25.33 | 8.52 | 12 | |
| Communication | VABS | 75.9 | 13.51 | 11 | 68.08 | 19.77 | 12 | |
| Siller et al. (2013) [52] | Expressive | MSEL post | 4.02 | 1.34 | 36 | 3.9 | 1.42 | 34 |
| Expressive | MSEL follow up | 4.38 | 1.42 | 36 | 4.17 | 1.42 | 34 | |
| Solomon et al. (2014) [53] | Expressive | MSEL | 52.82 | 28.1 | 52 | 48.33 | 29.08 | 47 |
| Expressive | MCDI gestures | 66.41 | 58.91 | 64 | 81.59 | 85.58 | 64 | |
| Expressive | MCDI sentences | 598.25 | 129.12 | 16 | 590.55 | 123.7 | 22 | |
| Receptive | MSEL | 59.1 | 31.76 | 52 | 53.84 | 29.97 | 47 | |
| Receptive | MCDI words | 285.2 | 123.98 | 64 | 276.2 | 128.51 | 64 | |
| Receptive | MCDI | 23.09 | 6.54 | 64 | 22.27 | 7.32 | 64 | |
| Motor skills | MSEL | 59.94 | 26.36 | 52 | 54.33 | 26.03 | 47 | |
| Strain & Bovey (2011) [54] | Cognitive Ability | MSEL | 68.5 | 7.5 | 177 | 61.4 | 9 | 117 |
| Expressive | MSEL | 38.7 | 6.4 | 177 | 35.9 | 4.4 | 117 | |
| Receptive | MSEL | 49.3 | 7.9 | 177 | 40.7 | 7.7 | 117 | |
| Fine motor skills | MSEL | 43.3 | 5.2 | 177 | 39.8 | 4.9 | 117 | |
| Tonge et al. (2014) [55] | Communication | VABS | 71.71 | 19.83 | 35 | 69.53 | 24.05 | 35 |
| Socialization | VABS | 73.31 | 16.59 | 35 | 67.35 | 16.7 | 35 | |
| Daily living skills | VABS | 68.26 | 16.46 | 35 | 60.09 | 18.59 | 35 | |
| Motor skills | VABS | 76.82 | 20.29 | 35 | 68.25 | 17.13 | 35 | |
| Cognitive Ability | PEP-R | 72.18 | 24.77 | 35 | 67.72 | 28.14 | 35 | |
| Expressive | RDLS | 17.17 | 17.07 | 35 | 18.24 | 20.65 | 35 | |
| Receptive | RDLS | 14.06 | 19.67 | 35 | 19.18 | 22.17 | 35 | |
| Turner-Brown et al. (2019) [56] | Cognitive Ability | MSEL | 67.10 | 23.39 | 32 | 70.33 | 23.16 | 17 |
| Valeri et al. (2020) [57] | Expressive | MCDI | 59.7 | 104.2 | 12 | 43.3 | 52.1 | 8 |
| Receptive | MCDI | 103.3 | 104.2 | 12 | 79.7 | 25.9 | 7 | |
| Vernon et al. (2019) [58] | Cognitive Ability | MSEL | 90.67 | 27.28 | 12 | 68.36 | 21.62 | 11 |
| Expressive | MSEL | 37.83 | 12.31 | 12 | 31.27 | 11.88 | 11 | |
| Receptive | MSEL | 47.17 | 14.79 | 12 | 31.91 | 14.83 | 11 | |
| Expressive | PLS | 87.50 | 15.75 | 12 | 74.27 | 17.39 | 11 | |
| Receptive | PLS | 90.17 | 27.78 | 12 | 73.27 | 20.99 | 11 | |
| Adaptive behaviour composite | VABS | 87.91 | 12.99 | 12 | 73.27 | 8.22 | 11 | |
| Communication | VABS | 88.45 | 16.23 | 12 | 70.91 | 11.59 | 11 | |
| Socialization | VABS | 85.18 | 10.56 | 12 | 74.27 | 10.21 | 11 | |
| Daily living skills | VABS | 92.45 | 10.08 | 12 | 80.45 | 10.62 | 11 | |
| Motor skills | VABS | 92.91 | 18.32 | 12 | 92.91 | 18.33 | 11 | |
| Welterlin et al. (2012) [59] | Cognitive Ability | MSEL | 63.7 | 17.4 | 10 | 58.1 | 25 | 10 |
| Expressive | MSEL | 58 | 21.9 | 10 | 62.4 | 32.6 | 10 | |
| Expressive | SIB | 16.2 | 7.1 | 10 | 14.2 | 7.1 | 10 | |
| Receptive | MSEL | 60.9 | 26.1 | 10 | 58.1 | 30.8 | 10 | |
| Receptive | SIB | 12 | 4.7 | 10 | 10.9 | 4.8 | 10 | |
| Socialization | SIB | 18.4 | 7.3 | 10 | 16 | 5 | 10 | |
VABS indicates Vineland Adaptive Behaviour Scale. MSEL indicates Mullen Scales of Early Learning. PLS-4 indicates Preschool Language scale. SCQ indicates Social Communication Questionnaire. RDLS indicates Reynell Developmental Language Scales. SRS indicates Social Responsiveness scale. WPPSI-R indicates Wechsler Preschool and Primary Scale of Intelligence-Revised. PEP-R indicates psycho-Educational Profile-Revised. SIB indicates Scales of Independent Behaviour scale.