| Report | Type | Additional eligibility criteria a | Persisting | Recovered | Follow-up length | Confounding | Clinical characteristic reported |
|---|---|---|---|---|---|---|---|
| California - Long Beach | |||||||
| Ryan (2001) | PR | 7 (4 M) | 15 (10 M) | 2–10 years | NR | S, [SS], [RV], [GL], [SF] | |
| 50 mo. (11) | |||||||
| Early Language in Victoria Study | |||||||
| Kefalianos et al. (2017) | PR | 36 (24 M) | 67 (37 M) | At least 3 years | Adjusted values reported | S, EV, FH, T | |
| 48 mo. | 48 mo. | ||||||
| Erasmus University Medical Centre Study | |||||||
| Franken et al. (2018) | PR | 4 (4 M) | 11 (6 M) | At least 9 years | N/A | S, A, FH, FH-P, FH-R, PSS, CSS, SF | |
| 52.25 mo. (7.0) | 43.36 mo. (8.6) | ||||||
| Illinois Stuttering Research Project | |||||||
| Watkins et al. (1999) | PR | 22 (18 M) | 62 (40 M) | At least 4 years | Data stratified by age | S, MLU, NDW,* NTW,* DSS | |
| 43 mo. | 39 mo. | ||||||
| Yairi & Ambrose (2005) | BK | Within 12 mo. of onset | 19 (15 M) | 70 (49 M) | At least 4 years | Multiple methods reported | S, SS, b EL, EV, FH, FH-P, [PSS], [CSS], SF |
| 43.16 mo. (9.52) | 36.87 mo. (7.66) | ||||||
| Netherlands – High Risk | |||||||
| Kloth et al. (1999) | PR | 7 (5 M) | 16 (7 M) | At least 4 years | NR | S, EL, RL, MLU | |
| 40 mo. (6.45) | 36 mo. (9.8) | ||||||
| Outcomes of Children with Hearing Loss | |||||||
| Arenas et al. (2017) | PR | 7 | 11 | At least 2 years or until 8 years old | NR | S, SS, EL, RL | |
| Purdue Stuttering Project | |||||||
| Bostian (2017) | UP | 4–5 years old at entry | 19 (14 M) | 29 (22 M) | N/A | S, SF, OD, PW, SW, DP, MR,* CSS | |
| 58.05 mo. (1.71) | 53.58 mo. (1.04) | ||||||
| Leech et al. (2017) | PR | 28 (15 M) | 22 (11 M) | 2 years | Age and SES not statistically different | S, A, SS, RL, EL, NRT,* IPSYN | |
| 62 mo. | 57 mo. | ||||||
| Roehl (2018) | UP | 16 (12 M) | 26 (17 M) | 2–5 years | NR | S, A, EL, RL, SF, CSS, PSS | |
| 57.72 mo. (1.7) | 54.84 mo. (1.3) | ||||||
| Spencer & Weber-Fox (2014) | PR | 19 (15 M) | 21 (14 M) | 12–48 months | Age, nonverbal reasoning, SES matching | S, SS, EL, RL, NRT* | |
| 57.11 mo. (6.71) | 53.33 mo. (5.36) | ||||||
| Walsh et al. (2018) c | PR | 31 (26 M) | 32 (21 M) | S, FH, d FH-P, d FH-R d | |||
| Subtypes and Risk Factors | |||||||
| Ambrose et al. (2015) | PR | 19 (12 M) | 39 (27 M) | up to 5 years | NR | S, A, EL, RL, EV, EL, [SS], [MLU], CSS, PSS, SF, PW, SW, DP, RU,* T | |
| 43.63 mo. (11.96) | 38.18 mo. (7.57) | ||||||
| Buhr (2007) | UP | Language skills within normal limits | 4 | 4 | 2 years | NR | GL,* DSS, MLU, SF, OD |
| 49 mo. | 50 mo. | ||||||
| Hollister et al. (2017) | PR | Excluded children > 43 months or if speech sample < 100 utterances | 8 | 5 | 2 years | Age not statistically different | EL, RL, EV, RV, SF, CSS, IPSYN, MLU |
| 37.1 mo. (4.6) | 35.2 mo. (5.8) | ||||||
| Twins Early Development Study | |||||||
| Dworzynski et al. (2007) | PR | 135 (100 M) | 950 (521 M) | N/A | S | ||
| The Ulm Study | |||||||
| Rommel et al. (2001) | UP | 19 (16 M) | 46 (33 M) | 3 years | NR | S, [A], FH, [RV], [L], [MLU], [NDW], | |
| 62.4 mo. | 58.8 mo. | ||||||
| Vanderbilt Developmental Stuttering Project | |||||||
| Erdemir et al. (2018) | PR | 10 (9 M) | 10 (9 M) | 2–2.5 years | Sex, age, and language matched | S, A, SF, CSS | |
| 46.9 mo. (4.5) | 46.1 mo. (6.9) | ||||||
| Singer et al. (2020) | PR | Under 5;0 years at entry | 10 (9 M) | 32 (23 M) | At least 2 years | Age and SES not statistically different | S, CSS, SF, SS, EL, RL, EV, RL |
| 46.6 mo. (4.5) | 45.0 mo. (6.8) | ||||||
| Zengin-Bolatkale et al. (2018) | PR | 9 (8 M) | 23 (17 M) | 16–32 months | Age not statistically different | S, CSS, SF, SS, EL, RL, EV, RV, CRS,* T | |
| 45.11 mo. (6.23) | 47.11 mo. (6.84) | ||||||
Note. Bold indicates data were extracted for this study; brackets indicate data could not be used to estimate an effect size; asterisk indicates data not reported in another study. PR = published report; M = male; NR = not reported; S = sex; SS = speech sound accuracy; RV = receptive vocabulary; GL = global language; SF = stuttered-like disfluency frequency; mo. = months; EV = expressive vocabulary; FH = family history of stuttering; T = temperament; N/A = not available; A = age at onset; FH-P = family history of persistent stuttering; FH-R = family history of recovered stuttering; PSS = parent-rated stuttering severity; CSS = clinician-rated stuttering severity; MLU = mean length of utterance; NDW = number of different words; NTW = number of total words; DSS = Developmental Sentence Scoring (Lee & Canter, 1971); BK = book; EL = expressive language; RL = receptive language; UP = unpublished; OD = other disfluencies; PW = part-word repetition frequency; SW= single-word repetition frequency; DP = dysrhythmic phonation frequency; MR = max repetition units; NRT = nonword repetition task; SES = socioeconomic status; IPSYN = Index of Productive Syntax (Scarborough, 1990); RU = repetition units (mean); L = language; CRS = child response to stuttering.
Criteria adopted in addition to the study-wide criteria.
Reported for 19 persistent children and 65 recovered children.
Additional data for calculated effect sizes collected through personal communication via e-mail with the first author (Walsh, personal communication, April 24, 2019).
Reported for 17 persistent children and 28 recovered children.