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. 2018 Nov 5;2018(11):CD012324. doi: 10.1002/14651858.CD012324.pub2

Howlin 2007.

Methods Design: cluster‐randomised‐controlled trial with school as the randomisation unit (schools randomised into 3 groups: immediate treatment group (ITG), delayed treatment group (DTG), and no treatment group (NTG))
Date of study: not stated but study published in 2007
Duration of study:

  1. ITG: time point 1‐time point 3 mean 17.9 months (SD 0.5)

  2. DTG: time point 1‐time point 3 mean 14.6 months (SD 1.9)

  3. NTG: time point 1‐time point 3 mean 15.3 months (SD 0.7)


Setting: greater London and South East England, UK. A total of 17 classes with > 4 children in each class were enrolled in the study. All children were attending autism‐specific classes or units. Most had child:adult ratio of 2:1. All classes followed the national curriculum. Teaching approaches differed but most took an eclectic approach utilising pictures and visuals and structured teaching.
Participants Sample size: 84 (note, n = 88 after randomisation but one ITG class (n = 4) withdrew before baseline assessment)

  1. ITG: 5 classes, n = 26

  2. DTG: 6 classes, n = 30

  3. NTG: 6 classes, n = 28


Withdrawals: 1 class withdrew after randomisation. 1 child withdrawn from NTG (failed to meet diagnostic criteria after baseline assessments done), and 1 child joined the DTG. 1 child form ITG moved away following intervention and before final assessment. 7 children moved out of DTG pre‐intervention but completed final assessments.
Sex:

  1. ITG: 21 boys, 5 girls

  2. DTG: 27 boys, 3 girls

  3. NTG: 25 boys, 3 girls


Age:

  1. ITG: mean 73.1 months (SD 15.8, range 47.3–106.3)

  2. DTG: mean 86.6 months (SD 12.7, range 62.0–113.5)

  3. NTG: mean 85.6 months (SD 13.6, range 61.0–122.1)


Inclusion criteria*:

  1. Children with a formal clinical diagnosis of autism (meets criteria for ASD on ADOS)

  2. Little or no functional language (i.e. not exceeding single words/productions)

  3. No evidence of sensory impairment

  4. Aged between 4 years and 11 years

  5. Not using PECS beyond phase 1 (i.e. can only exchange symbols with prompting)


*Each class required minimum of 3 children meeting the above criteria
Exclusion criteria:

  1. Children without a diagnosis of ASD

  2. Children who were in a classroom where there were fewer than 3 children meeting inclusion criteria
Interventions Intervention: PECS

  1. ITG: 7.6 months (approximately 2 terms) of PECS training followed by a 10.4 month follow‐up period

  2. DTG: 7.5 months of no treatment/baseline followed by 7.1 months of PECS training


Control: NTG; 15.3 months with no PECS training
Administration: intervention and assessments occurred in the school setting. Teachers and parents received PECS training (2‐day workshop or 13 h) followed by consultation. The active intervention period began about 1 week after training. PECS consultants conducted 6 half‐day consultations with each class once per month over 5 months. The consultants recommended and demonstrated strategies to improve children's use of PECS in the classroom, monitored teachers' progress and provided systematic feedback on implementation of PECS. Note, classroom teachers were not completely naïve to PECS, but generally the use of this was minimal and limited to phase I scaffolded requesting.
Outcomes Primary outcomes
Researchers videotaped daily snack session for maximum of 15 min. Three variables were coded:

  1. Frequency of child communicative initiations

  2. Frequency of use of PECS symbols

  3. Frequency of speech (including non‐word vocalisations); frequencies expressed as rates per minute


Secondary outcomes
These included standardised measures: Expressive One Word Picture Vocabulary Test, British Picture Vocabulary Scales completed 3 times through the study. The Communication and Reciprocal Social Interaction Domain scores of the ADOS‐G were also used.
Timing of outcome measurement: children were filmed/assessed at baseline, after the end of the first intervention period, and after the end of the second intervention period
Notes Comment: none
Funding source: supported by the Three Guineas Trust. Pyramid UK also supported the project (by providing the PECS consultants). It is unclear if these consultants were paid.
Risk of bias
Bias Authors' judgement Support for judgement
Random sequence generation (selection bias) Low risk Comment: 15/18 class groups excluded due to fewer than 3 eligible children in the same classroom. Classes were stratified according to size. In each stratum, classes were randomly allocated to 1 of the 3 conditions using an online randomisation programme (www.random.org).
Allocation concealment (selection bias) Unclear risk Comment: study does not mention how allocation was performed
Blinding of participants and personnel (performance bias) 
 All outcomes High risk Comment: participants and personnel were aware of allocation. It is not possible to perform blinding as placebo not possible for this type of trial
Quote: "Because of financial and personnel limitations… assessors (and videotape coders, see below) were not blind to group assignment" (p 476)
Blinding of outcome assessment (detection bias) 
 All outcomes High risk Comment: staff conducting assessments or coding (or both) were not blinded to group assignment. See directly above.
Incomplete outcome data (attrition bias) 
 All outcomes Low risk Comment: 1 child from the immediate treatment group moved away after the trial started, and 7 children in the delayed treatment group moved out of classes prior to the intervention starting. Analyses were conducted on an intention‐to‐treat basis. Did not compare those who dropped out to those who remained in terms of characteristics
Selective reporting (reporting bias) Low risk Comment: all measures reported in the published trial protocol were reported in the Results section. Does not state whether adverse outcomes were collected in protocol or paper
Other bias Unclear risk Comment: PECS may have been used to some extent in the control group. Also, there may be bias due to the cluster‐randomised control design of the study; however, the extent of this bias is unclear (see Risk of bias in included studies for more details).
Quote: "it was not possible to collect ongoing measures of treatment fidelity… [but] this is of less importance for pragmatic effectiveness studies than for efficacy studies." (p 479)