Ten trusts had a higher than expected mortality rate during 2011-12, in comparison to 14 during the previous year, latest data reveals.

Summary hospital mortality indicator is published quarterly and groups acute NHS trusts into those with mortality rates “higher than expected”, “as expected” and “lower than expected”.

Data for the second full year was published last week by the NHS Information Centre. Four trusts have had a higher than expected mortality rate in each of the five data sets published so far. They are: Blackpool Teaching Hospitals Foundation Trust, George Eliot Hospital Trust, East and North Hertfordshire Trust and Tameside Hospital Trust.

Blackpool medical director Mark O’Donnell said the trust had worked with the Advancing Quality Alliance, a north-west based improvement organisation, and was assured there were “no areas of clinical concern” and “no issues around the care we give our patients”.

He said the work had also highlighted the need to take into account deprivation, a factor the SHMI does not adjust for, unlike some other mortality rates.

However, data on deprivation published alongside the SHMI for the first time appeared to show a limited correlation between deprivation and high mortality rates. The average proportion of patients in the most deprived quartile under the index of multiple deprivation was 25.7 per cent in trusts the “higher than expected” band and 21.4 per cent in the “lower than expected” band.

Of 142 acute trusts, Blackpool had the 37th highest number of patient spells where the patient was in the most deprived quartile.

East and North Herts and George Eliot both pointed out their SHMI was improving. A spokesman for George Eliot said actions taken included an analysis of patient flows to reduce the number of times patents are moved during their stay from 3.6 to 2.2 as well as moves resulting in big reductions in falls and pressure sores.

The use of hospital-wide mortality rates as an indicator of poor patient care remains controversial. A recent paper from Birmingham University, whose academics have been long standing critics of their use, argued case mix adjusted mortality rates are a “poor proxy” for the proportion of preventable deaths.