Absenteeism costs the Canadian economy more than $16 billion a year, according to a study by the Conference Board of Canada.

The report, released Monday, says the average full-time Canadian worker was absent for 9.3 days in 2011 -- the latest year for which figures are available -- with the highest absenteeism rates found in the health-care and social assistance sector.

The workplace absences resulted in the economy losing an estimated 2.4 per cent of the gross annual payroll, or an estimated $16.6 billion based on 2012 incomes, the study said.

The estimate does not include any indirect costs associated with a worker being away, like finding a replacement, delays and missed deadlines and a reduction in employee morale.

"Absenteeism is more than a human resources issue," wrote author Nicole Stewart in the 12-page report called Missing in Action: Absenteeism Trends in Canadian Organizations. "It costs the Canadian economy billions of dollars each year."

Using Statistics Canada figures from 2011 and results of a 2012 Conference Board survey of 401 medium- to large-sized companies, the report noted that the reasons given for the missed work ranged from illness to long-term leave of absences.

Workers in health-care and social assistance had an average of 14 missed days, which the report says, may be attributed to the industry being commonly known for shift work, overtime, high stress and workers coming in contact with the sick.

Those in the professional, scientific and technical services industries had the lowest rates of absenteeism, with an average of 5.8 days. These industries were also likely not be unionized, noted the report.

It also found differences among those who work in the public sector, with the average number of absences coming in at 12.9 days compared with an average of 8.2 days for those employed in the private sector.

Unionized workers also had a higher absenteeism rate of 13.2 days compared with 7.5 days for non-unionized workers.

The report explained this difference could be due to public sector and union employees typically being entitled to a higher number of sick days than those who work in the private sector.

The Canadian Labour Congress said there is little difference between the number of sick days taken among public and private sector workers when you take into account differences in age, gender and union status.

"Our position on that partly is that the reason why unionized workers take more days off is because they can, and that non-unionized workers, if they could, they would, and going into work sicka that it is dangerous for the people themselves and their coworkers," said Angella MacEwen, an economist with the CLC.

"We think there is a benefit to having negotiated sick days, so you can take those days when you're sick and when you need them."

MacEwen points out that the report does not touch on the cost of lost productivity when someone goes into the office sick and can't perform their work or if others have to take time off because they've come into contact with someone who was contagious.

The Conference Board research showed that women had higher rates of absences then men, with the average female employee absent from the workplace for 11.4 days compared with 7.7 days for male workers.

"Currently there is no definitive explanation on why the gap exists," said the report.

Young workers also had fewer absences than older workers, according to the study. Those aged 20 to 24 years old missed an average of 5.9 days, compared with 10.3 days for those between 45 to 54 years old. Workers between 55 and 64 years old clocked in an average of 13.2 days.

"The incidence of physical chronic disease increases with age, which contributes to increased illness and disability among this group," said the report.

Employees from large companies also missed more days at the office than those in smaller companies. The number of absences for those in organizations with more than 500 workers averaged 11.1 days, compared with 7.5 days for those in offices with less than 20 people.

"In smaller organizations, there are fewer people (often no one) to cover in the event of an employee absence, and it is more obvious when an employee is absent. Smaller organizations are also less likely to be unionized," the report said.

There were also regional differences. Workers in Saskatchewan had the highest absenteeism rates, averaging 11 days, followed by those in New Brunswick, Nova Scotia and Quebec at 10.8 days. Alberta and Ontario had the lowest rates, coming in at about eight days.

The report also noted that despite the cost of the absences, only 46 per cent of employers admitted to tracking the number of days workers are absent and the reasons why.

"By looking at absences patterns and identifying the causes of absences, organizations can put in place programs and policies to reduce absenteeism," wrote Stewart.

The Conference Board of Canada is an independent, not-for-profit research organization based in Ottawa.