I'm still on a break, but wanted to briefly mention a study that exemplifies the kind of suicide prevention I fully support. The study, published in the Archives of Opthalmology (July 2008), links suicide with low vision - but only when health is poor in general. Risk of suicide is elevated (though not statistically significantly) for individuals with low vision only, but is significantly elevated for individuals who are in poor health and have visual impairment - well above the increased risk for individuals with poor health alone.
The intervention proposed by the authors of the study is not to lock up everyone with low vision, or to have their doctors ask them humiliating questions to check for depression, but, shockingly, "better treatments for the underlying conditions that cause visual impairment." (The authors also encourage eye doctors to be aware of the increased risk and provide appropriate referrals, but the primary recommendation of the study seems to be better treatment of visual problems.)
This is the kind of suicide prevention that even one who believes strongly in a right to suicide can support. This sort of study identifies specific types of suffering that lead to suicide, and recommends actually relieving the specific types of suffering. If this type of intervention were implemented - if old, sick people got better vision care - suicides would likely be prevented, but they wouldn't be the suicides of people determined to die, people whose true end is death. The suicides averted by this type of intervention would be bad suicides - suicides by people who value their lives but suffer so greatly from a specific problem (or problems) that they choose to end their lives. There is nothing humiliating or coercive about better vision care. I would love to see more studies like this, and more interventions of this type.