Impact of screening for risk of suicide: randomised controlled trial. 
Concerns have been expressed about the impact that screening for risk of suicide may have on a person's mental health.  To examine whether screening for suicidal ideation among people who attend primary care services and have signs of depression increases the short-term incidence of feeling that life is not worth living.  In a multicentre, single-blind, randomised controlled trial, 443 patients in four general practices were randomised to screening for suicidal ideation or control questions on health and lifestyle (trial registration: ISRCTN84692657).  The primary outcome was thinking that life is not worth living measured 10-14 days after randomisation.  Secondary outcome measures comprised other aspects of suicidal ideation and behaviour.  A total of 443 participants were randomised to early (n = 230) or delayed screening (n = 213).  Their mean age was 48.5 years (s.d.  = 18.4, range 16-92) and 137 (30.9%) were male.  The adjusted odds of experiencing thoughts that life was not worth living at follow-up among those randomised to early compared with delayed screening was 0.88 (95% CI 0.66-1.18).  Differences in secondary outcomes between the two groups were not seen.  Among those randomised to early screening, 37 people (22.3%) reported thinking about taking their life at baseline and 24 (14.6%) that they had this thought 2 weeks later.  Screening for suicidal ideation in primary care among people who have signs of depression does not appear to induce feelings that life is not worth living.