There isn't one source to get the scale of the problem

Jim Wade Report author

Relationship difficulties with parents or partners are the most common reasons.

A high proportion of those who disappear spend some time sleeping rough.

And only one in five traced and found alive returned to their family.

But the University of York's Social Work Research and Development Unit, which compiled the report, say there are no reliable estimates of the scale of the problem.

'Pool information'

Only 14 police forces routinely report cases to the helpline.

The report made a number of recommendations, including promoting greater public awareness of what it means to be missing and a better understanding of groups at risk.

Jim Wade, a senior research fellow at the university and co-author of the report, said why the research showed it was important to pool information.

"There needs to be an accurate database and there are two at present - the National Missing Persons Helpline and the Police National Missing Persons Bureau," he said.

"The two don't connect together so there isn't one source to get the scale of the problem."