Christchurch's February earthquake may have contributed to more deaths than the official toll of 182.

The 182 are believed to have died within the first 24 hours – but the earthquake may also also have contributed to a "small number" of deaths during the following days.

Professor Michael Ardagh is chairing a research group which is looking into the health implications from the February 22 quake.

"While the official death toll remains at 182, if the indirect consequences of the earthquake were included the toll would be higher," Ardagh said.

"There were deaths in elderly people transferred out of Christchurch possibly contributed to by the stress of the transfer, and deaths on the road contributed to by earthquake road damage.

"These numbers are small but they are not included in the official death toll as they are not directly due to earthquake-caused injuries."

When frail, elderly people break a hip or other bones, the stress can sometimes be too much for them to cope with, Ardagh said.

"They die of renal failure, or heart attacks, or respiratory problems, or some complication of underlying diseases.

"So, while the fracture is the 'final straw', it is not directly the cause of death."

Christchurch Emergency Department nurse Viki Robinson is working with Ardagh and co-ordinating the research group Rhise.

Robinson, a nurse for 16 years, was researching the day of the quake but returned to work in the emergency department after it struck.

The Rhise group includes representatives from the Canterbury District Health Board, universities and polytechnics, St John, Pegasus Health and primary health organisations.

Rhise had to get permission from the Upper South A Regional Ethics Committee so information could be shared on a database and be available to researchers. Rhise, which stands for Researching the Health Implications of Seismic Events, has found 6659 people were injured within the first 24 hours of the February quake.

The most common injuries were lumbar (lower back) sprains, which were probably caused by falls, Robinson said.

General sprains and contusions (bruising), general wounds and dental injuries were also common.

While patients would usually go to Christchurch Hospital, "on this occasion people sought treatment from wherever they could".

Those places included Burwood, Princess Margaret and Southern Cross hospitals, the after-hours surgery, general practitioners and the emergency triage centre set up in Latimer Square.

The group secured a contract with the Health Research Council of New Zealand as a partnership programme with the Canterbury Medical Research Foundation and is only in its initial stages of research.

It will research the health implications from all the major quakes, including the latest on December 23.

The group hopes that by sharing information between health researchers and organisations that people will be able to learn the best way to manage a similar event in the future – in Canterbury, nationally and internationally.

"If another event like this occurs then people can be better prepared, and maybe we can prevent injuries and further deaths," Robinson said.