Being admitted to hospital in England at the weekend is risky, experts say. Research company Dr Foster came to this conclusion after identifying a \"worrying\" 10% spike in deaths compared to weekdays across 147 hospital trusts. It said some deaths could have been avoided with better staffing and access to services such as diagnostics. The review also looked at performance overall, warning death rates appeared to be higher than they should be in more than a quarter of trusts. Dr Foster, which works closely with the Department of Health, said the findings needed to be investigated urgently. The data was published in the group\'s Hospital Guide, which has been produced yearly for the past decade. Pretty stark\' Dr Foster looked at death rates using four measures - deaths in hospital, deaths in hospital and within 30 days of discharge, deaths linked to low-risk conditions and deaths after surgery. In total, 42 trusts had higher than expected mortality rates on at least one measure, of which at least 22 were flagged up in two categories and two in three. As part of the analysis of weekend performance, Dr Foster carried out a review of staffing ratios. Researchers said they found a \"pretty stark\" link with hospitals which had more senior doctors working having lower death rates. Access to key services like diagnostics was also highlighted as a factor. However, it was acknowledged that some of the deaths were unavoidable as people who were at the end of life were more likely to be admitted to hospital at the weekend. This is because community services which they would have relied on if they had been close to death during the week would not be available. Overall, 8.1% of those admitted at weekends died compared to 7.4% from Monday to Friday, once those having elective operations such as hip and knee replacements were discounted. The report concluded weekend treatment was \"risky\". Roger Taylor, director of research at Dr Foster, added: \"A safe NHS is an NHS that provides care 24/7. This year\'s guide shows we are some way from that target.\" Richard Hamblin, of the Care Quality Commission, which regulates standards in the NHS, said it was \"too simplistic\" to conclude high death rates were definitely down to poor care. But he agreed trusts needed to look at their performance on the back of this report. \"Trust boards should use it to ask themselves serious questions about the quality of their services,\" he said. Katherine Murphy, chief executive of the Patients Association, said she was \"appalled\" by the findings. \"Patients deserve safe, effective care no matter what the time of day is. They deserve nothing less,\" she added.