More than 45,000 NHS staff members a day report sick, according to the first national audit of working patterns within the health service.

The sickness rate is one-and-a-half times that of the private sector in general, while NHS workers were also found to have high average levels of obesity, smoking and poor mental health, affecting patient care.

The report by Dr Steve Boorman, an expert in occupational health who was commissioned by ministers to conduct six months of staff surveys and data analysis, concludes that hospitals with worse staff health levels tend to have higher rates of infection and more patient deaths.

Excerpts of the report, initial findings of which are being published today, were reported in the Times. Boorman told the paper: "It is ironic that the NHS is trying to focus on the public health agenda yet not making it available to its own staff, because staff should be exemplars.

"The key finding of this review is that health and wellbeing of staff is very important to the quality of patient care, and there are good reasons for prioritising investment in it."

Other findings include that 20% of the roughly 1 million staff members smoke, with around 40,000 NHS workers consuming more than 20 cigarettes a day. About 40% of staff exercise fewer than three times a week.

It found that more than a third of staff have moderate to very poor mental health, with many expressing concern about intimidation from patients and relatives. More than 75% of NHS workers believe that the state of their health affects patient care.

The audit comes as figures show the number of claims against the NHS for clinical negligence has risen by 11%.

The health department said the report was an "important initiative" and that its final findings were due in the autumn.

"In the meantime, the Department of Health and NHS will need to consider very carefully the implications of the findings so far and the impact that staff health and well-being has on NHS productivity and quality of care," a spokesman said.