A major finding of the study is the alarmingly high rate of suicide attempts and precursors to suicide among IDUs in New Delhi. As well, suicidal ideation and suicide attempts did not decrease over the study period; rather these measures remained constant throughout while the number of participants reporting suicide plan increased over the study period despite access to a broad range of health and IDU-risk reduction intervention services. These included nutrition, health education, oral buprenorphine substitution, regular health check ups, medical referrals, and detoxification and rehabilitation facilities. However, since we did not examine uptake of these services, we cannot definitively conclude that they did not improve the mental health of the suicidal participants. Also, the study period may not have been long enough to mark changes in mental health state of the participants. Despite these limitations, we can tentatively suggest that suicidal ideation did not decrease over a period that saw the introduction of several interventions including the provision of nutritious food which is generally found to be associated with high utilization. With regard to suicide plan, we did find a difference in proportion across the study period with an increasing number of respondents responding affirmatively to the question on suicide plan. Thus, what this suggests is that despite the services offered, more and more participants were reporting plans to commit suicide. Studies based in India demonstrate that unemployment, marginalization, financial difficulties, and the inability to buy food is associated with suicide [31–33]. Other studies have found homelessness to be a major factor in depression and other forms of psychopathology among IDUs [13, 34]. Since most of our study participants are homeless, marginalized and suffer from an inability to buy food, using drugs in addition perhaps exacerbate the symptoms, thus necessitating mental health intervention through active referrals in harm reduction programs.
The fact that the majority of those with suicidal ideation reported attempting suicide, and that nineteen of these consistently reported attempts at all 3 time periods suggest, firstly, that suicidal ideation, in this population, can be a precursor of a suicide attempt  and secondly, that there is a small pool who consistently attempted suicide. Although a number of deaths occurred in the cohort during the study period (reported as adverse events to the IRB), we do not know whether they included suicides. However, the possibility cannot be ruled out, as there is no proper system of ascertaining the cause of death in India . At least in one case, field workers verified that a study participant did commit suicide based on his earlier actions and statements which were witnessed by many.
We also saw that suicidal ideation and risk behaviors were associated consistently over the study period, albeit the modest effect sizes. Our findings find support with other studies that have shown a correlation between suicidal thoughts and risk behaviours, such as using syringes used by another , injecting more frequently , and sharing needles and syringes [12, 25–27]. A harm reduction intervention has been operational for many years in Delhi, which is separate from the research study. The gains accrued in HIV prevention behaviours among IDUs subsequent to harm reduction interventions may very well be diluted if attention is not paid to this special section of the IDU population who present with suicidal behavior. In the context of comprehensive harm reduction programming, therefore, this would require an enhanced intervention targeting suicidal IDUs, as they continue with unsafe behaviours that make them and others vulnerable to infectious diseases.
Our study has a number of limitations. Since we could not determine if suicide is the cause of death among 8% of the cohort who died during the course of the study it leads us to propose that there is very real need for examining causes of mortality among this population, with the goal of prevention. We did not examine the uptake of services by suicidal IDUs, thus making it difficult for us to conclude that there is no improvement in mental health despite a broad array of services.
The findings tentatively suggest that HIV prevention efforts alone may not lead to reduction in behavioral risks among a certain group of IDUs. It may be necessary to provide services that ameliorate the conditions that lead to depressive symptoms and suicide which negatively influences HIV risk related behaviours. Linking harm reduction programmes with employment and income generating opportunities can help in mitigating economic hardships of IDUs, as well ensure stability in their lives. Furthermore, as drug use may also be contributing to their poor mental health, it is essential that the quality of detoxification and rehabilitation services be improved in order that IDUs may volunteer for such services. Additionally, it will be beneficial to have proper referral systems in place whereby IDUs exhibiting suicidal ideation and/or depression symptoms can access mental health services. Given the significance of the findings, it may be useful to develop simple mental health assessments that could be used in the context of harm reduction prgrammes to facilitate such referrals.