disease” (IHD) – a disorder characterised by muscle aches and pains, fever and an itchy rash on the hands and
feet. Itchy hand disease is thought to have a higher incidence in older persons and smokers. Dr Boisty was
interested in determining whether healthcare workers were more at risk of developing IHD than were workers
in other sectors and decided to investigate this issue.
Five hundred health care workers were recruited into the study. They were compared to 700 office workers.
Both groups were followed for six months. During follow-up, any presentation to a doctor was notified to the
study team, who contacted the doctor to find out what the diagnosis was. The outcome of interest was IHD. Of
the 500 health care workers, 43 developed IHD during the study. Of the 700 office workers, 23 developed IHD
during the study.
Dr Boisty knew that many members of the community liked to take a supplement called Herbal Extract X (‘HEX’)
to try to “boost their immune system”. Herbal Extract X was also suspected of causing IHD. So, Dr Boisty
collected information on the use of HEX by the study participants.
Of the health care workers, 400 used HEX; 39 of these developed IHD. Of the office workers, 300 used HEX; 15
of these developed IHD.