By Paloma Migone of NZPA

Wellington, July 21 NZPA - Only half of New Zealand prisoners suffering from serious mental health illness are being treated, despite there being room to accommodate them.

The shortcomings are due to an "identification issue," not a capacity issue, Parliament's health committee was told today.

Health Ministry mental health director David Chaplow said there was room to treat all prisoners suffering from severe mental health problems, but not all those needing services were detected.

"We do know that at the moment we are seeing about five percent and we know that probably we should be seeing 10 percent," he said.

"It's a moving target so you can have a person who is quite acutely unwell and a week later they have sort of adjusted to that."

Dr Chaplow said a new initial screening process aimed at improving detection was being considered.

It was trialled in 2007 in a joint effort by the Corrections Department, Ministry of Health, and Regional Forensic Psychiatric Services (RFPS) staff.

Corrections national health manager Deborah Alleyne told NZPA though the current initial health assessment was useful for identifying individuals with acute need, it is not sufficiently specific to allow for the detection of many mild to moderate mental health issues.

The trial was done as a response to research showing a higher level of mental disorder amongst prisons population at 50 percent, including mild and moderate health issues, compared to 20 percent in the community within a 12-month period.

The screening process was piloted at Christchurch Men's Prison and Auckland Central Remand Prison to test its effectiveness -- 1292 screens were completed.

"The pilot demonstrated that the [trial] was more effective in identifying mental disorder, with 30 percent of new male arrivals requiring referral to Forensic Services for further assessment," Ms Alleyne said.

"Of these nine percent were referred to a psychiatrist with the remainder being either referred back to prison health services for follow up or assessed as not requiring ongoing care."

The trial was funded jointly by Corrections and the ministry.

Ms Alleyne said "identifying and treating prisoners with mental health needs means that they are more able to engage in rehabilitation activities that support their reintegration back into the community, and therefore less likely to re-offend."

Dr Chaplow said the new screening process has been approved in principal and he is meeting Corrections next week to discuss funding.