According to the latest CBI/Pfizer Absence and Workplace Health Survey, the rate of absence is the lowest since the survey began in 1987, and down slightly from 6.7 days per employee in 2007.
A small improvement in the public-sector absence rate helps explain the fall, but it remains significantly higher than the private-sector rate.
In the public sector, employees took more sick days, with an average of 8.3 days per year, which is 43% higher than the private-sector figure of 5.8 days. The public-sector's record improved since the last CBI absence survey covering 2007, when the average was nine days.
It is estimated the180 million sick days cost employers about £16.8 billion in 2009, plus indirect costs like reductions in customer service and delays to teamwork.
The senior HR staff surveyed at 241 public and private-sector organisations estimated that around 15%, or 27 million sick days weren't genuine, and cost the country £2.5 billion a year.
Katja Hall, CBI director of employment policy, said: "The rate of employee absence has come down, but it still costs the economy billions of pounds a year. If absence levels across the board could be reduced by 10%, the economy would see annual savings of just under £1.7 billion.
"Unfortunately, bogus sick days remain a problem, and are unfair on hard-working colleagues and employers alike."
Long-term absence is a particular problem. Although it only accounted for 5% of absences, the longer periods meant that it accounted for 20% of lost days in the private sector and 36% in the public sector. Back pain and mental health issues are key causes of long-term absence, according to the survey.
Berkeley Phillips, UK medical director, Pfizer, said: "We have long known that mental health, back pain and other musculoskeletal disorders are the leading causes of long-term absence, and this year's CBI report reinforces this. While employers view loss of productivity as the main impact of absence, as this report highlights, the economic consequences stretch much further and, as such, we as a society, need to do more to advance health and wellness at every stage of life."
Companies are increasingly using rehabilitation plans and support in which getting staff back to work sooner and productively are major objectives. Evidence suggests that this is good for the company and employees' health alike. The survey showed that 95% of organisations had a formal absence policy - a rise of 10 percentage points compared with 2007.
