The long-term outlook for schizophrenic patients is highly dependent on what antipsychotic medicine they are offered, a new study has found.

The three year Schizophrenia Outpatient Health Outcomes (SOHO) trial - the world's largest - studied the health outcomes associated with antipsychotic treatment.

The first six month results appear to show that, although people with schizophrenia treated with atypical antipsychotics experienced marked improvement in their clinical status in the short-term, various treatments differed in terms of effectiveness.

Those treated with the newer generation of atypical antipsychotics such as olanzapine and clozapine experienced more dependable control of their symptoms. Although the atypical drugs were not without their side-effects, such as weight gain, patients were much less likely to experience the debilitating and sometimes permanent side effects - such as extrapyramidal side-effects (EPS) - over the long-term compared to those treated with other antipsychotics.

"SOHO is excellent news for people with schizophrenia - it could provide vital evidence about how people can be treated more successfully and their quality of life enhanced," said Chief Executive of mental health charity SANE, Marjorie Wallace. "What matters is that people enduring this cruel illness are given a choice of effective, tolerated medications and other treatments at an early stage so that long term effects are less damaging and they can move their lives forward."

Carried out in an out-patient, community or ambulatory setting, patients who took part had to be initiating or changing antipsychotic treatment. An additional qualification was that any treatment decisions had to have been made prior to enrolment.

As an observational study conducted in a natural "real world" setting, SOHO is particularly important because it is more reflective of true patient experience. The trial involved 10,800 out-patients throughout 10 countries with 1,000 investigators providing study results. Of these, 334 UK patients were involved from 70 sites.

The SOHO study is likely to bolster NICE guidance which called last year for NHS patients to be offered the more expensive atypical antipsychotics as a "first choice option".