More than a million people suffering from asthma are missing out on key yearly checks, a charity has warned.
New analysis by charity Asthma UK found that 31% of asthma patients did not receive an "essential" annual review to check whether they are on the right medicine and can use their inhalers properly.
The charity said that its review of GP data for 2012/13 showed that there were 3,359,612 people in England who should have received an asthma review but 1,025,539 patients missed out.
NHS guidance suggests that everyone with asthma should get an annual review, an asthma action plan and their inhaler technique checked.
"The fact that over one million people with asthma aren't getting their medicines checked at their annual review is no doubt contributing to the rising NHS spend on asthma and putting people's lives at risk," said Asthma UK's deputy chief executive Dr Samantha Walker.
"With the worrying scale of prescribing errors identified by the National Review of Asthma Deaths, it's vital that doctors and nurses do everything they can to follow up with patients to review their medicines, especially as asthma can vary hugely over the year.
"There is also an unacceptably large variation in the numbers of people attending annual reviews, which ranges from only 52% to 79% across the UK. We're worried this variation is only the tip of the iceberg in terms of differences in routine care."