May 27 (Bloomberg) -- Employees suffering from attention deficit and hyperactivity do a month less work a year than staff without the condition, according to a World Health Organization survey.

The findings suggest it may be cost-effective for companies to screen workers and offer treatment programs for the disorder as a way to recoup time lost and improve workplace performance, said researchers led by Ron de Graaf from the Institute of Mental Health and Addiction in Utrecht, the Netherlands.

An average 3.5 percent of employees have adult attention- deficit hyperactivity disorder, or ADHD, which causes problems with concentration and makes people hyperactive, easily distracted, forgetful or impulsive. The condition is more prevalent in men than women, and in workers in developed rather than developing countries, the scientists found. The research was published today in the Occupational and Environmental Medicine journal.

``ADHD among workers has non-trivial prevalence, high impairment and a low rate of treatment,'' said de Graaf in the report. ``It might be cost-effective from the employer perspective to implement workplace screening programs and provide treatment for workers with ADHD.''

Researchers screened 7,075 employed and self-employed workers, aged 18 to 44 years, for ADHD as part of the WHO World Mental Health Survey Initiative. They also asked the workers from Belgium, Colombia, France, Germany, Italy, Lebanon, Mexico, the Netherlands, Spain and the U.S. about their performance in the last month.

Less Productive

The results showed that people with ADHD spent 22.1 more days not doing work than other workers per year. This included 8.4 days when they were unable to work or carry out their normal activities, 21.7 days of reduced work quantity and 13.6 days of reduced work quality, according to the researchers, who are part of a WHO research grouping at Harvard Medical School.

Researchers need to evaluate programs and treatment that may have a ``positive return-on-investment for employers,'' de Graaf wrote in the paper. ``Only a small minority of these workers are treated for ADHD despite evidence that such treatment can be quite effective in improving their functioning.''

Physicians mainly prescribe stimulants including Novartis AG's Ritalin or Shire Ltd.'s Adderall to treat ADHD in children and adults. Eli Lilly & Co.'s non-stimulating drug Strattera also has U.S. regulatory approval to treat ADHD symptoms.

Diagnosing Children

Lilly funded the WHO research with a grant and drugmakers including GlaxoSmithKline Plc, Bristol-Myers Squibb Co., Ortho- McNeil Pharmaceutical Inc. and the Pfizer Foundation supported the WHO World Mental Health Survey Initiative.

Unlike adults, whose condition often goes undetected, children with ADHD are being increasingly diagnosed because they are more likely to be tested for the disorder if they have problems with their schoolwork. About 2 million children in the U.S. have ADHD, according to the National Institutes of Health.

As many as 70 percent of children with ADHD continue to have symptoms as adults. Such adults often have problems getting organized, seeing tasks through or keeping appointments. Getting to work on time and being productive on the job may be major challenges.

Most of the time lost to ADHD-related leave was due to reduced work quantity and quality. Many employers estimate one day of lost productivity a month as part of the cost of doing business, and have mechanisms in place to reduce financial losses.

``Employers typically expect their workers to be working when they are on the job,'' de Graaf wrote.

To contact the reporter on this story: Chantal Britt at cbritt@bloomberg.net

Last Updated: May 27, 2008 01:50 EDT