The proportion of disabled people is rising and now represents 1 billion people – 15% of the global population – according to the first official global report on disability.

An ageing population and an increase in chronic health conditions, such as cardiovascular and respiratory diseases, mean the proportion has grown from an estimated 10% in the 1970s.

But, despite a robust disability rights movement and a shift towards inclusion, disabled people remain second-class citizens, according to the report by the World Health Organisation and the World Bank. One in five experience "significant difficulties".

In developed countries, disabled people are three times more likely to be denied healthcare than other people. Children with disabilities are less likely to start or stay in school than other children, while employment rates are at 44%, compared with 75% for people without disabilities in OECD countries, the report found.

Barriers include stigma, discrimination, lack of adequate healthcare and rehabilitation services, and inaccessible transport, buildings and information. In developing countries the picture is even worse.

Tom Shakespeare, one of the authors of the World Report on Disability, said: "The clear message from the report is that there is no country that has got it right. Italy is a world leader in terms of inclusive education and de-institutionalisation of people with mental health problems but in other areas it is not. In the US the access is phenomenal – it is a civil rights issue. However, if you are looking at poverty and employment it is not good.

"Disabled people do not need to be poor and excluded; they do not need to be segregated. They do not need to be second class citizens."

One of the most "shocking and powerful" issues to come out of the report, according to Shakespeare, was the discrimination in healthcare.

Dr Margaret Chan, director general of the WHO, said disability was part of the human condition. "Almost every one of us will be permanently or temporarily disabled at some point in life. We must do more to break the barriers which segregate people with disabilities, in many cases forcing them to the margins of society."

Professor Eric Emerson, of the Centre for Disability Research at Lancaster University, said the findings on healthcare were not surprising.

"In the UK, there have been numerous independent reports documenting the systemic discrimination faced by people with disabilities, particularly people with learning disabilities. The health and wellbeing of disabled people is not simply as a direct result of their impairment. It's a result of the way that people with impairments are treated by society."

Last year, the Life Opportunities Survey found many disabled people in Britain were isolated, cash-strapped and struggling to participate in normal activities, with a fifth saying they suffered from so much anxiety and lack of confidence that they lacked the ability to work.

The WHO report, which did not compare countries directly but highlighted best practice, singled out the UK's Disability Discrimination Act 2005, which places a duty on public bodies to promote equality and its direct payment policies for disabled people as an example of good practice.

But Shakespeare said: "The UK has done very well, due to its direct payment mechanisms, and benefits like independent living allowance and access to work. It appears that many of these developments are under threat. The axing of the independent living fund and other changes to benefit appear to move away from what was a good situation."

Liz Sayce, of the disability campaigning organisation Radar, said: "The UK has made some real progress and it's good to be reminded that there's something to celebrate, but the employment rate of disabled people has crept up by only 6% in recent years to 47%. But it is still only 47% and many people are working below their potential."

Tim Wainwright, of ADD (Action on Disability and Development) International, said: "We welcome the fact that there's a lot more clarity on the figures. It confirms that disabled people are the world's largest minority. Great strides have been made in making sure that women are included in international development programmes. The next biggest group is disabled people."