Table 1.
General information on studies included in the meta-analysis
| Author year | Country | Na | Nb | % w. GD | % female | mean age | Intervention groups | Control groups | Primary outcomes | Secondary outcomes | Pre-Post (weeks) | FUc (months) | RoB |
| Sylvain et al. (1997) | Canada | 40 | 29 | 100 | 0.0 | 40.2 | 1) CBT face-to-face, individually | 1) WL | DSM-III SOGS |
– | – | 6 12 |
High |
| Ladouceur et al. (2001) | Canada | 88 | 64 | 100 | 19.3 | 41.7 | 1) CBT face-to-face, individually | 1) WL | DSM-IV SOGS |
– | 12 | 6 12 |
High |
| Ladouceur et al. (2003) | Canada | 71 | 59 | 100 | 22.0 | 43.3 | 1) CBT face-to-face, group | 1) WL | DSM-IV | – | 16 | 6 12 24 |
High |
| Melville et al. (2004) (1) | USA | 13 | 13 | 100 | 61.5 | – | 1) CBT face-to-face, group 2) CBT (extended) face-to-face, group |
1) WL | DSM-IV | – | 8 | 8 | High |
| Melville et al. (2004) (2) | USA | 19 | 19 | 100 | 84.2 | – | 1) CBT face-to-face, group | 1) WL | DSM-IV | BAI BDI-II |
8 | 8 | High |
| Petry et al. (2006) | USA | 231 | 231 | 100 | 45.0 | 44.9 | 1) CBT self-help, no therapist guidance (GA referral) 2) CBT face-to-face, individually (GA referral) |
1) AO (GA referral) | SOGS DSM-IV ASI-G |
– | 8 | 6 12 |
High |
| Dowling et al. (2007)* | Australia | 56 | 56 | 100 | 100 | 43.6 | 1) CBT face-to-face, individually 2) CBT face-to-face, group |
1) WL | DSM-IV | STAI-T STAI-S BDI-II |
12 | 6 | High |
| Carlbring and Smit (2008) | Sweden | 66 | 66 | 100 | 6.0 | 31.9 | 1) MI/CBT self-help, no therapist guidance | 1) WL | NODS | HADS-A HADS-D |
12 | 6 18 36 |
High |
| Korman et al. (2008) | Canada | 42 | 42 | 100 | 14.3 | 47.6 | 1) DBT face-to-face, individually | 1) TAU | PGSI | – | 14 | 6.5 | SC |
| Petry, Weinstock, Ledgerwood, and Morasco (2008) | USA | 180 | 172 | 52.8 | 40.0 | 43.5 | 1) MI face-to-face, individually 2) MI/CBT face-to-face, individually |
1) AO 2) PFI |
SOGS ASI-G |
– | 6 | 9 | High |
| Grant et al. (2009) | USA | 68 | 68 | 100 | 38.2 | 48.7 | 1) CBT/MI face-to-face, individually | 1) GA referral | PG-YBOCS G-SAS |
HAM-A HAM-D |
8 | 6 | High |
| Myrseth, Litlere, Støylen, and Pallesen (2009) | Norway | 14 | 14 | 100 | 21.4 | 37.4 | 1) CBT face-to-face, individually | 1) WL | DSM-IV | BAI MADRS |
7 | 4.75 | High |
| Petry, Weinstock, Morasco, and Ledgerwood (2009) | USA | 117 | 114 | – | 15.4 | 20.4 | 1) MI face-to-face, individually 2) MI/CBT face-to-face, individually |
1) AO 2) PFI |
SOGS | – | 6 | 9 | High |
| Larimer et al. (2011)* | USA | 147 | 111 | 10.2 | 34.7 | 21.2 | 1) MI face-to-face, individually 2) CBT face-to-face, group |
1) AO | NODS | BACS | 24 | – | High |
| Marceaux and Melville (2011) | USA | 49 | 33 | 100 | 65.3 | 47.8 | 1) 12-step (TSF) face-to-face, group 2) CBT face-to-face, group |
1) WL | DSM-IV SOGS |
BAI BDI-II |
8 | 6 | High |
| Lee and Awosoga (2015) | Canada | 18 | 16 | 100 | 34.0 | 49.3 | 1) CCT face-to-face, couple | 1) AO | G-SAS | DAS | 12 | 5 | High |
| Wong, Chung, Wu, Tang, and Lau (2015) | China | 40 | 31 | 83.9 | 0.0 | – | 1) CBT face-to-face, group | 1) AO | SOGS | GRCS DASS-21 A DASS-21 D |
10 | – | High |
| Luquiens et al. (2016) | France | 1,122 | 144 | 8.0 | 7.9 | 34.7 | 1) CBT self-help, no therapist guidance 2) CBT self-help, therapist guidance |
1) WL | PGSI | – | 6 | 3 | High |
| McIntosh et al. (2016) | Australia | 77 | 77 | 98.7 | 28.6 | 38.5 | 1) CBT (and MBCT) face-to-face, individually 2) CBT (and MBCT) face-to-face, individually |
1) TAU | DSM-5 SOGS |
– | 13 | 6.25 9.25 |
High |
| Petry et al. (2016) | USA | 217 | 217 | 86.2 | 31.3 | 42.0 | 1) MI/CBT face-to-face, individually | 1) WL, AC 2) PFI |
SOGS | – | 8 | 5 8 12 16 20 24 |
High |
| Abbott et al. (2017) | New Zealand | 462 | 346 | 95.0 | 52.6 | 39.2 | 1) MI phone 2) MI phone + CBT self-help 3) MI phone + CBT self-help/phone |
1) TAU | PGSI | – | 12 | 6 12 36 |
Low |
| Boudreault et al. (2017) | Canada | 62 | 54 | 82.3 | 38.7 | 51.5 | 1) MI phone + CBT self-help | 1) WL, AC | DSM-5 | BAI BDI-II |
11 | 3.75 8.75 14.75 |
High |
| Casey et al. (2017) | Australia | 174 | 174 | 100 | 59.2 | 44.4 | 1) CBT internet program, no therapist guidance 2) MFS internet program, therapist guidance |
1) WL | SOGS G-SAS |
GRCS DASS-21 A DASS-21 D |
6 | – | High |
| Oei et al. (2017) | Australia | 110 | 55 | – | 50.9 | 49.4 | 1) CBT self-help, no therapist guidance | 1) WL | CPGI | GRCS DASS-21 A DASS-21 D |
6 | – | High |
| Cunningham, Godinho, and Hodgins (2019) | Canada/USA | 321 | 278 | 58.6 | 55.1 | 36.5 | 1) CBT internet program, no therapist guidance | 1) WL, AC | NODS G-SAS |
– | 6 | 6 | SC |
| Hodgins, Cunningham, Murray, and Hagopian (2019) | Canada | 187 | 187 | 89.0 | 47.1 | 46.8 | 1) CBT internet program, no therapist guidance | 1) PFI | NODS PGSI |
– | 12 | 6 12 |
Low |
| Jonas et al. (2020) | Germany | 167 | 167 | 98.2 | 28.1 | 33.5 | 1) Solution focused/self-regulation/MI internet program, therapist guidance 2) Solution focused/self-regulation/MI, no therapist guidance |
1) WL | PGSI | – | 12 | 6 12 |
High |
| McAfee et al. (2020) | USA | 255 | 255 | 15.3 | 38.0 | 22.2 | 1) PFI/CBT text messages | 1) AO 2) PFI |
PGSI/CPGI | GRCS | 4 | 6 | High |
| So et al. (2020) | Japan | 254 | 185 | – | 20.8 | 36.3 | 1) CBT text messages | 1) AO | PGSI G-SAS |
– | 4 | – | Low |
| Bücker, Gehlenborg, Moritz, and Westermann (2021) | Germany | 156 | 65 | 99.3 | 32.7 | 35.0 | 1) CBT (third wave elements) internet program, no therapist guidance (TAU allowed) | 1) WL (TAU allowed) | SOGS PG-YBOCS |
GABS-15 PHQ-9 |
8 | – | SC |
Abbreviations: AO, assessment only; AC, attention control; ASI-G, Addiction Severity Index for Gambling; BAI, Beck Anxiety Inventory; BDI, Beck Depression Inventory; BDI-II, Beck Depression Inventory II; CBT, cognitive behavioral therapy; CPGI, Canadian Problem Gambling Index; DAS, Dyadic Adjustment Scale; DASS-21, Depression, Anxiety and Stress Scale 21; DBT, dialectical behavior therapy; FU, Follow-up; GA, Gambler Anonymous; GAD-7, Generalized Anxiety Disorder Questionnaire 7; GD, Gambling Disorder; G-SAS, Gambling Symptom Assessment Scale; HADS-A, Hospital Anxiety and Depression Scale-Anxiety; HADS-D, Hospital Anxiety and Depression Scale-Depression; HAM-A, Hamilton Anxiety Rating Scale; HAM-D, Hamilton Depression Rating Scale; MADRS, Montgomery & Åsberg Depression Rating Scale; MFS, monitoring, feedback and support; MI, motivational intervention; NODS, NORC Diagnostic Screen for Gambling Problems; PFI, personalized feedback intervention; PGSI, Problem Gambling Severity Index; PG-YBOCS, Yale Brown Obsessive Compulsive Scale adapted for Pathological Gambling; PHQ-9, Patient Health Questionnaire 9; RAS-G, Relation Assessment Scale Generic; RoB, Risk of Bias assessment According to the revised Cochrane risk-of-bias assessment tool for randomized trials (RoB2)39; SC, some concerns; SOGS, South Oaks Gambling Screen; STAI-S, State-Trait Anxiety Inventory, State-anxiety; STAI-T, State-Trait Anxiety Inventory, Trait-anxiety; TAU, treatment as usual; TSF, Twelve-step Facilitated therapy; VGS, Victorian Gambling Screen; WL, waiting list; WSAS, Work and Social Adjustment Scale. a) Number of participants randomized, b) number of participants represented in our analysis on primary outcome gambling severity post intervention, c) In a majority of studies, follow-up data were only available for the intervention group, and no comparisons were possible, *not included in post-intervention estimate on primary outcomes.