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The impact of study design and diagnostic approach in a large multi-centre ADHD study. Part 1: ADHD symptom patterns

The impact of study design and diagnostic approach in a large multi-centre ADHD study. Part 1: ADHD symptom patterns
The impact of study design and diagnostic approach in a large multi-centre ADHD study. Part 1: ADHD symptom patterns
Background: The International Multi-centre ADHD Genetics (IMAGE) project with 11 participating centres from 7 European countries and Israel has collected a large behavioural and genetic database for present and future research. Behavioural data were collected from 1068 probands with the combined type of attention deficit/hyperactivity disorder (ADHD-CT) and 1446 'unselected' siblings. The aim was to analyse the IMAGE sample with respect to demographic features (gender, age, family status, and recruiting centres) and psychopathological characteristics (diagnostic subtype, symptom frequencies, age at symptom detection, and comorbidities). A particular focus was on the effects of the study design and the diagnostic procedure on the homogeneity of the sample in terms of symptom-based behavioural data, and potential consequences for further analyses based on these data.

Methods: Diagnosis was based on the Parental Account of Childhood Symptoms (PACS) interview and the DSM-IV items of the Conners' teacher questionnaire. Demographics of the full sample and the homogeneity of a subsample (all probands) were analysed by using robust statistical procedures which were adjusted for unequal sample sizes and skewed distributions. These procedures included multi-way analyses based on trimmed means and winsorised variances as well as bootstrapping.

Results: Age and proband/sibling ratios differed between participating centres. There was no significant difference in the distribution of gender between centres. There was a significant interaction between age and centre for number of inattentive, but not number of hyperactive symptoms. Higher ADHD symptom frequencies were reported by parents than teachers. The diagnostic symptoms differed from each other in their frequencies. The face-to-face interview was more sensitive than the questionnaire. The differentiation between ADHD-CT probands and unaffected siblings was mainly due to differences in hyperactive/impulsive symptoms.

Conclusions: Despite a symptom-based standardized inclusion procedure according to DSM-IV criteria with defined symptom thresholds, centres may differ markedly in probands' ADHD symptom frequencies. Both the diagnostic procedure and the multi-centre design influence the behavioural characteristics of a sample and, thus, may bias statistical analyses, particularly in genetic or neurobehavioral studies.

adhd, multi-centre study, sibling design, informant effects, centre effects
1471-244X
54
Müller, Ueli C.
966b8269-faa1-4d9c-b4e5-df81a9c5be89
Asherson, Philip
a734c1f6-f31a-450b-81c3-ba7bb373e147
Banaschewski, Tobias
4627c589-04cc-4f5b-ac2d-05f547f63dfd
Buitelaar, Jan K.
a2e08a14-4de4-419e-9ea8-1e97ebbdddba
Ebstein, Richard P.
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Eisenberg, Jaques
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Gill, Michael
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Manor, Iris
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Miranda, Ana
e416878c-5ff3-4892-bb8f-17e8de0884ac
Oades, Robert D.
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Roeyers, Herbert
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Rothenberger, Aribert
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Sergeant, Joseph A.
fca17df1-498d-4009-b445-dc6033711ab0
Sonuga-Barke, Edmund J.S.
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Thompson, Margaret
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Faraone, Stephen V.
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Steinhausen, Hans-Christoph
991ad7f9-c5d1-4c61-8118-3d4895d2706d
Müller, Ueli C.
966b8269-faa1-4d9c-b4e5-df81a9c5be89
Asherson, Philip
a734c1f6-f31a-450b-81c3-ba7bb373e147
Banaschewski, Tobias
4627c589-04cc-4f5b-ac2d-05f547f63dfd
Buitelaar, Jan K.
a2e08a14-4de4-419e-9ea8-1e97ebbdddba
Ebstein, Richard P.
b7b70774-d400-4f33-84bf-11a21bc83170
Eisenberg, Jaques
4a898cb4-b86d-43d9-970b-240c370e9b6f
Gill, Michael
408d1dfa-5205-4e50-8130-7b26aa8288e8
Manor, Iris
786b2370-0f31-4448-a3b3-484204b3b7e2
Miranda, Ana
e416878c-5ff3-4892-bb8f-17e8de0884ac
Oades, Robert D.
85d7ca21-1a76-458d-a3e3-69d4b13232db
Roeyers, Herbert
3554b6b3-e364-4a6a-9e8b-64f5188a6d60
Rothenberger, Aribert
736981ca-a16d-44b3-8312-2067dc792a6d
Sergeant, Joseph A.
fca17df1-498d-4009-b445-dc6033711ab0
Sonuga-Barke, Edmund J.S.
bc80bf95-6cf9-4c76-a09d-eaaf0b717635
Thompson, Margaret
bfe8522c-b252-4771-8036-744e93357c67
Faraone, Stephen V.
bd307516-e8db-4d38-b649-9d7d7caafe93
Steinhausen, Hans-Christoph
991ad7f9-c5d1-4c61-8118-3d4895d2706d

Müller, Ueli C., Asherson, Philip, Banaschewski, Tobias, Buitelaar, Jan K., Ebstein, Richard P., Eisenberg, Jaques, Gill, Michael, Manor, Iris, Miranda, Ana, Oades, Robert D., Roeyers, Herbert, Rothenberger, Aribert, Sergeant, Joseph A., Sonuga-Barke, Edmund J.S., Thompson, Margaret, Faraone, Stephen V. and Steinhausen, Hans-Christoph (2011) The impact of study design and diagnostic approach in a large multi-centre ADHD study. Part 1: ADHD symptom patterns. BMC Psychiatry, 11 (1), 54. (doi:10.1186/1471-244X-11-54). (PMID:21473745)

Record type: Article

Abstract

Background: The International Multi-centre ADHD Genetics (IMAGE) project with 11 participating centres from 7 European countries and Israel has collected a large behavioural and genetic database for present and future research. Behavioural data were collected from 1068 probands with the combined type of attention deficit/hyperactivity disorder (ADHD-CT) and 1446 'unselected' siblings. The aim was to analyse the IMAGE sample with respect to demographic features (gender, age, family status, and recruiting centres) and psychopathological characteristics (diagnostic subtype, symptom frequencies, age at symptom detection, and comorbidities). A particular focus was on the effects of the study design and the diagnostic procedure on the homogeneity of the sample in terms of symptom-based behavioural data, and potential consequences for further analyses based on these data.

Methods: Diagnosis was based on the Parental Account of Childhood Symptoms (PACS) interview and the DSM-IV items of the Conners' teacher questionnaire. Demographics of the full sample and the homogeneity of a subsample (all probands) were analysed by using robust statistical procedures which were adjusted for unequal sample sizes and skewed distributions. These procedures included multi-way analyses based on trimmed means and winsorised variances as well as bootstrapping.

Results: Age and proband/sibling ratios differed between participating centres. There was no significant difference in the distribution of gender between centres. There was a significant interaction between age and centre for number of inattentive, but not number of hyperactive symptoms. Higher ADHD symptom frequencies were reported by parents than teachers. The diagnostic symptoms differed from each other in their frequencies. The face-to-face interview was more sensitive than the questionnaire. The differentiation between ADHD-CT probands and unaffected siblings was mainly due to differences in hyperactive/impulsive symptoms.

Conclusions: Despite a symptom-based standardized inclusion procedure according to DSM-IV criteria with defined symptom thresholds, centres may differ markedly in probands' ADHD symptom frequencies. Both the diagnostic procedure and the multi-centre design influence the behavioural characteristics of a sample and, thus, may bias statistical analyses, particularly in genetic or neurobehavioral studies.

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More information

Published date: 7 April 2011
Keywords: adhd, multi-centre study, sibling design, informant effects, centre effects

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Local EPrints ID: 186231
URI: http://eprints.soton.ac.uk/id/eprint/186231
ISSN: 1471-244X
PURE UUID: 514ea5bb-0884-47b2-bc02-382bbaee3dee

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Date deposited: 12 May 2011 15:34
Last modified: 14 Mar 2024 03:19

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Contributors

Author: Ueli C. Müller
Author: Philip Asherson
Author: Tobias Banaschewski
Author: Jan K. Buitelaar
Author: Richard P. Ebstein
Author: Jaques Eisenberg
Author: Michael Gill
Author: Iris Manor
Author: Ana Miranda
Author: Robert D. Oades
Author: Herbert Roeyers
Author: Aribert Rothenberger
Author: Joseph A. Sergeant
Author: Edmund J.S. Sonuga-Barke
Author: Margaret Thompson
Author: Stephen V. Faraone
Author: Hans-Christoph Steinhausen

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