The King's Fund think tank said this pent-up demand for help across England will soon force the health care system to deal with a "capacity crunch".
Between January and March, 11,672 patients in the NHS Derby and Derbyshire CCG area who had needed GP appointments over the last 12 months were asked if they had avoided booking them, and the reasons why.
Of these patients, 2,310 (20%) said they put off seeing their GP because they did not want to place a burden on the NHS – the most common reason given.
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Meanwhile, 15% said they did not make an appointment as they were worried about the risk of catching Covid-19, and 11% because it was too difficult.
Of patients who needed appointments, 41% said they avoided making one for any reason – in line with the average across England.
The figures come from the 2021 GP Patient Survey, which provides an overview of patients’ experiences with primary care services .
The Royal College of GPs said many patients, particularly at the start of the coronavirus pandemic, did not seek medical attention when they were unwell.
Professor Martin Marshall, chairman of the Royal College of GPs, said: "GP services have been available throughout the pandemic, and GPs and our teams are now making record numbers of patient consultations alongside delivering the vast majority of the vaccination programme.
"Nevertheless, we continue to urge patients, if they are unwell or have symptoms that could be signs of serious illness such as cancer, to seek medical assistance."
He added that GP teams are working under "intense workload and workforce pressures" and called on the Government to recruit more staff to address the problem.
Beccy Baird, senior fellow at The King’s Fund, said: "As this pent-up demand starts to come back into the system many GPs, and other parts of the health and care system, are facing a capacity crunch.
"The Government and NHS leaders need to consider how general practice will be supported to work with other NHS and care services to make sure that people continue to be able to access the care they need.”
Despite hundreds of thousands of patients across England avoiding seeing their doctor, there was a slight rise in patient satisfaction with GP services in general.
Around 83% said they had a good overall experience of their local practice, compared to 82% the previous year.
Ms Baird said although reassuring, the results are not spread evenly, with people in deprived areas more likely to report negative experiences.
In Derby and Derbyshire, 85% of patients described their experience as good – up from 84% the year before.
The Department of Health and Social Care said GP practices continue to provide care at the forefront of the pandemic response, alongside the vaccine rollout.
A spokeswoman added: "We need to learn to live with this virus and we are supporting practices in expanding capacity, by making £270 million available so they can continue to provide support for those in need.”