Wednesday, August 18, 2010

Making autism research history: The Preschool Autism Communication Trial
Some months ago, Jonathan Green and his colleagues simultaneously published (in the Lancet) and presented (at IMFAR 2010) their multi-site RCT of an early autism intervention. In conducting and reporting the Preschool Autism Communication Trial, they have made autism research history. They have done so simply by applying to autistics scientific standards that are well-established in non-autism non-ABA areas. The upshot is an autism early intervention trial whose results are worth serious consideration and which is unprecedented in this respect.

Via the PACT website, you can find the Lancet paper reporting the PACT RCT, the peer-reviewed PACT intervention "manual" (which refers to another, more detailed manual), the PACT RCT protocols, references for related papers including a 2004 pilot RCT, a list of investigators and funders, and so on.

I've previously written about the PACT as an anomaly in autism intervention research. The PACT entails an early autism intervention that was not widely promoted as effective or essential before it was fairly tested. That is a first in the history of autism research. It may also be the largest RCT of any kind of autism intervention ever published (if I'm wrong, I'm sure someone will tell me).

In short the PACT RCT is an internationally-registered multi-site trial of a manualized intervention targeting the parents of preschool (ages 2-5yrs) autistic children. The PACT intervention spans one year and involves 12 twice-monthly 2hr clinic-based sessions followed by 6 monthly sessions. Parents are expected to apply what they learn, in interacting with their autistic child, for half an hour per day.

For the PACT RCT, 152 children who met criteria for the specific diagnosis of autism were randomly assigned to receive either the PACT intervention plus treatment as usual or TAU alone. PACT and TAU children were well-matched at intake across several measures, and finished well-matched in other treatments received. Parents were not as well-matched. A detailed description of the PACT intervention is here.

Dr Green and colleagues were successful both in recruiting an unprecedentedly large number of preschool autistic children for an RCT--in fact, expectations for recruitment were exceeded--and in minimizing drop-outs. In the Lancet, you will find an outstandingly clear CONSORT flowchart of participants as well as an intention to treat analysis and mixed results.

Results favouring the PACT group were mainly in the area of parent-child interaction, as assessed through videos. The PACT group also outperformed the TAU children in parent-reported vocabulary and social measures, results carefully downplayed by Green et al. due to the parents not being blinded to intervention status. Post-treatment-only measures of adaptive behaviour reported by teachers did not differ between groups.

The main measure was the ADOS used as a scale, and here too there was no result. In my view, using the ADOS as the main measure is a major error but an informative one. The ADOS, as used here (awkward tweaks and all), has thresholds only and doesn't work like a scale. And where is the evidence that lower ADOS scores in very young autistic children in themselves lead to better eventual outcomes? On the other hand, the strong design of the PACT RCT is such that it calls into question what exactly the ADOS is assessing--a result which deserves a lot of attention.

Using ADOS thresholds, 27% of the 146 children who completed their assigned treatment had migrated from the specific diagnosis of autism to the lower-threshold "ASD" category, while an additional 6% no longer met criteria for any autistic spectrum diagnosis. No group differences were found. These findings lend perspective to the widely-publicized diagnostic category results from another recent RCT involving a small sample of much younger children receiving more than two years of intervention.

As with all studies, it's possible to list a range of flaws, potential concerns, and caveats. The ADOS is not only wrongly used as a measure, it is incorrectly used to stratify the sample for randomization. The ADI-R is used in a slightly unconventional way, possibly to accommodate children who otherwise would be excluded by its limitations. There was no screening ergo no exclusion for genetic syndromes, which arguably makes the findings more difficult to interpret. There was poor agreement between raters for two of the three parent-child interaction measures, which in my view is fascinating and telling: nonautistic raters are not good at agreeing about what child initiation and shared attention consist of, when a child is autistic. If you look at the Lancet paper, depending on how your brain works, you should rapidly find at least one minor error in the data (I can't help it...).

The PACT intervention itself has questionable aspects. The fundamental idea is sound: train parents to better respond to their autistic children's communication. But the PACT is a rigidly developmental six-step approach based on how nonautistics develop. In addition, and like so many other autism interventions, the PACT imposes extreme rationing of information and materials. Everything is cleared and shut away except a few toys or items. Anything in which autistics regardless manage to show strong interest will be taken away and replaced with something less interesting. What this does to an autistic child's communication and learning is not considered. The PACT explicitly requires every effort to identify and cater to the parents' different ways of learning, but no such consideration is extended to the autistic children.

The above is a not-close-to-complete list of the PACT's strengths, many of them unique, and its weaknesses--which due to its strengths serve as important information for the future of autism intervention research. Because the trial is so strongly designed compared to the rest of the literature, it is that much more important to learn from and build on. This may not serve the interests of various lobby groups or service providers or political leaders or advocates, but it will serve the interests of autistics. Here is a suggestion from Dr Green and colleagues in the Lancet:
These findings suggest that the optimistic results from other studies should be reassessed.
Yes--good experimental design means that you risk not having your biases confirmed. But taking this risk is currently the only demonstrated way to fairly test interventions and treatments, and for this reason, the only way to conduct ethical research.

There is a Lancet editorial about the PACT RCT, written by two NIH scientists. Here is one thing they point out:
Thus, in a field in which minimum study standards have made it difficult to even look for literature to answer what works for autism, this study is an achievement.
Here is another, and they get the last word:
This study furthers the field by setting a new bar for the minimum standards of rigorous methodology needed in trials that have potentially far-reaching service and policy implications.


Green, J., Charman, T., McConachie, H., Aldred, C., Slonims, V., Howlin, P., Le Couteur, A., Leadbitter, K., Hudry, K., & Byford, S. (2010). Parent-mediated communication-focused treatment in children with autism (PACT): a randomised controlled trial The Lancet, 375 (9732), 2152-2160 DOI: 10.1016/S0140-6736(10)60587-9

Spence, S., & Thurm, A. (2010). Testing autism interventions: trials and tribulations The Lancet, 375 (9732), 2124-2125 DOI: 10.1016/S0140-6736(10)60757-X