The prevalence and effects of Adult Attention-Deficit/hyperactivity Disorder (ADHD) on the performance of workers: Results from the WHO World Mental Health Survey Initiative

Ron de Graaf ¹, Ronald C Kessler ^2*, John Fayyad ³, Margaret ten Have ¹, Jordi Alonso ⁴, Matthias Angermeyer ⁵, Guilherme Borges ⁶, Koen Demyttenaere ⁷, Isabelle Gasquet ⁸, Giovanni de Girolamo ⁹, Josep Maria Haro ¹⁰, Robert Jin ², Elie G Karam ¹¹, Johan Ormel ¹² and Jose Posada-Villa ¹³

¹ Netherlands Institute of Mental Health and Addiction, Netherlands
² Harvard Medical School, United States
³ Belamand University, Lebanon
⁴ Health Services Research Unit, Institut Municipal d'Investigació Medica (IMIM), Spain
⁵ University of Leipzig, Germany
⁶ Universidad Autonoma Metropolitana-Xochimilco Calzada, Mexico
⁷ University Hospitals Gasthuisberg, Belgium
⁸ Hopitaux de Paris, France
⁹ Regional Health Care Agency Emilia-Ronanga Region, Italy
¹⁰ Sant Joan de Deu-SSM, Spain
¹¹ Balamand University, Lebanon
¹² University of Groningen, Netherlands
¹³ Centro Medico de la Sabana, Colombia

^* To whom correspondence should be addressed. E-mail: kessler{at}hcp.med.harvard.edu.

Accepted 20 March 2008

Abstract

Objectives: To estimate the prevalence and workplace consequences of adult attention-deficit/hyperactivity disorder (ADHD).

Methods: Ann ADHD screen was administered to 18-44 year-old respondents in ten national surveys in the WHO World Mental Health (WMH) Survey Initiative (n = 7075 in paid or self employment; response rate 45.9-87.7% across countries). Blinded clinical reappraisal interviews were administered in the US to calibrate the screen.. Days out of role were measured in the WHO Disability Assessment Schedule (WHO-DAS). Questions were also asked about ADHD treatment.

Results: An average of 3.5% of workers in the ten countries was estimated to meet DSM-IV criteria for adult ADHD (inter-quartile range: 1.3-4.9%). ADHD was more common among males than females and less common among professionals than other workers. ADHD was associated with a statistically significant 22.1 annual days of excess lost role performance compared to otherwise similar respondents without ADHD. No difference in the magnitude of this effect was found by occupation, education, age, gender, or partner status. This effect was most pronounced in Colombia, Italy, Lebanon, and the US. Although only a small minority of workers with ADHD ever received treatment for this condition, higher proportions were treated for comorbid mental-substance disorders.

Conclusions: ADHD is a relatively common condition among working people in the countries studied and is associated with high work impairment in these countries. This impairment, in conjunction with the low treatment rate and the availability of cost-effective therapies, suggests that ADHD would be a good candidate for targeted workplace screening and treatment programs.