An individual participant data meta-analysis (IPDMA) is a specific type of meta-analysis, for which the original data for each participant in a study are collected, checked, and re-analyzed in a systematic way. The IPDMA has also been described as the gold standard of systematic reviews because it can improve the completeness and quality of data and the breadth and flexibility of analysis.
We aim to gain more insight into psychosocial interventions for children and adolescents with ADHD and disruptive behaviors.
We are currently conducting systematic reviews to identify which studies are relevant to incorporate individual participant data into our IPDMA.

Read more about the latest IPDMA publication and results:

Results IPDMA

Goal of the project

Many well-designed studies have been performed to investigate the effectiveness of psychosocial interventions for ADHD and disruptive behavior. However, most studies did not have the opportunity to conduct well-powered moderator analysis. If all studies in this field are combined, we can look into factors influencing treatment efficacy and identify subgroups of families who respond better or worse to specific types of interventions. Hopefully this will lead to great advances in personalized care for children with ADHD and disruptive behaviors.

Why perform an IPDMA?

An IPDMA differs from aggregated data meta-analysis in that it uses the original participant data instead of results described in research articles. With this method it is possible to look whether a treatment is effective. Individual participant data has several advantages to aggregated data meta-analysis. First, statistical methods can be standardized across studies, reducing noise across studies. Second, moderators of treatment effects and effects in subgroups can be explored in a much more reliable way than in individual studies (because of the larger sample size) or aggregated data meta-analysis (because of the greater power compared to meta-regression). Third, with IPDMA missing data can be handled in the same way across trials. Importantly, IPDMA can contribute considerably to the development of personalized treatment for ADHD and disruptive behaviors.

What do we ask from the participants?

Once we identify all eligible studies, we will contact the corresponding authors to ask for their participation in the IPDMA. Principal investigators of eligible trials will be requested to send raw, anonymous data of all included participants, from all eligible conditions (i.e., intervention and control conditions) and all assessment points. Only the transfer of individual trial data is necessary for participation in the IPDMA.

Future plans

We plan to establish a large individual participant database that includes a worldwide range of parenting intervention studies (not yet covered in our current IPDMAs) on the broad group of referred children with externalizing behavior problems, including both children with and without an ADHD, ODD, or CD diagnosis. Specifically, we will include any type of intervention that focuses their efforts on parents as the main agents of change in child behavior. The aim is to gain more insight into the differential effectiveness of parenting interventions and identify optimal program content for individual children with externalizing problems.

Contact or Questionas?

If you have any questions please feel free to contact a.groenman@accare.nl or c.psyllou@accare.nl

The researchers

Prof. dr. Barbara van den Hoofdakker
Accare Child Study Center

Dr. Annabeth Groenman
Accare Child Study Center

Dr. Patty Leijten
Accare Child Study Center

Dr. Marjolein Luman
Accare Child Study Center

Constantina Psyllou
Accare Child Study Center

More about the researchers

Latest publications

Attachment in children with ADHD

July 18th, 2022|0 Comments

In the general population, externalising behaviour seems to be associated with insecure attachment and lack of trust in caregiver support. Some studies in ADHD populations have shown that children with ADHD are more likely to [...]

Other Projects


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In PAINT-IPDMA, an individual participant data meta-analysis is being conducted on psychosocial treatments for children and adolescents with ADHD. In the follow-up IPDMA study, the psychosocial treatments for children and adolescents with behavioural problems are investigated.


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