Hong Kong J Psychiatry 2006;16:33-35
COMMENTARY
JYW Cheng
Dr Jackie Ying-Wai Cheng, MBBS, Department of Psychiatry, Queen Mary Hospital, Pokfulam Road, Hong Kong, China.
This article was written in response to: Yip PSF. A public health approach to suicide prevention. Hong Kong J Psychiatry. 2005;15:29-31.
Address for correspondence: Dr Jackie Ying-Wai Cheng, Department
of Psychiatry, Queen Mary Hospital, Pokfulam Road, Hong Kong, China.
Tel: (852) 2855 4486; Fax: (852) 2855 1345;
E-mail: jackieyg@gmail.com
Submitted: 28 June 2006; Accepted: 3 July 2006
Introduction
Public health is defined by the Acheson Report as: "The art and science of preventing disease, prolonging life, and promoting health through organized efforts of society."1 Beaglehole and Bonita stated that such art and science will only work if it has:
- a focus on whole populations
- an emphasis on prevention, especially primary prevention
- a concern for the underlying socio-economic determinants of health and disease, as well as the more proximal risk factors.2
This commentary will consider some general aspects of the formulation of public health interventions in relation to suicide prevention and treatment.
Epidemiology and Characteristics of Suicide
Psychiatric epidemiological studies are confronted with the same paradigmatic tensions as the field of psychiatry itself, namely that psychiatric disorders tend to be characterised by the lack of demonstrable organic lesions, and that the construction of psychiatric illnesses tends to change over time as a result of sociocultural changes in values and norms. This poses a problem for the comparison of psychiatric dis- orders across time, place, and cultures. National suicide rates reported to the World Health Organization (WHO) do not include all countries, and surveillance systems and meth- ods of defining suicide (determined by a coroner to have clear evidence of suicide) differ between countries. Terms and definitions related to suicide-related behaviours are varied, which makes comparisons between research studies difficult. For defining a public health problem, a good report- ing system must be present to provide complete, accurate, representative, and timely statistics.
Screening is also an integral part of prevention in public health since it is "the systematic application of a test or in- quiry, to identify individuals at sufficient risk or a specific disorder to benefit from further investigation or direct pre- vention action, among persons who have not sought medi- cal attention on account of symptoms of that disorder."3 According to the modified WHO criteria for screening, the disease should have a detectable preclinical phase, there should be a valid screening test available, the disease should be treatable, and there should be a recognised treatment for lesions identified following screening.4
Two-thirds of people who commit suicide consulted their general practitioner in the previous month, 40% in the previous week, and one-quarter were seeing a psychi- atrist, of whom half had seen the psychiatrist in the previous month, suggesting that suicide prevention is plausible.5 However, no formal and reliable suicide prediction in- strument has been developed and suicide risk assessment is not foolproof, even for the most experienced psychiatrists. Furthermore, most successful suicides are planned and precautions against discovery are taken, which makes detection even more difficult.
The incidence of suicide is comparatively low; Lithuania has the highest suicide rate in the world at 41.9/100,000 population.6 The positive predictive value of any screening test can only be high if the prevalence of the condition is in the range of 40% to 60%. In the case of suicide, any screen- ing test will be doomed to failure since the false-positive rate will be high due to the low prevalence.
Geoffrey Rose and Public Health
The Rose Theorem is: "A large number of people exposed to a small risk may generate many more cases than a small number exposed to a high risk."7 The 'shifting of the risk curve' is such that the reduction of the general risk level in the population will result in a shift of the curve such that a large proportion of people will benefit. These theoretical constructions have tremendous influence in modern public health and should be convincing and appealing to anyone proposing population intervention at a grand scale.
The Cost of Prevention
Another important theory by Rose is the prevention para- dox: "A preventive measure that brings large benefits to the community affords little to each participating individual."1 Since high-risk individuals in the population are also likely to gain more as a result of intervention, the choice to divert resources away from those few high-risk individuals and to devote them to a large number of low-risk individuals who are less likely to gain as much brings a dilemma: should we target the high-risk populations or use a broad population approach? Another pertinent question is: why not simply shift the whole population curve out of the risk zones? The inevitable problem is that of limited resources and the sustainability of suicide prevention and treatment pro- grammes. The next question then is: is suicide prevention cost effective? Before answering this question, we have to consider yet another question.
Evidence-based Suicide Prevention and Treatment: an Oxymoron?
A search through the Cochrane database using the key words 'suicide' and 'self-harm', yielded only 1 review article, which stated plainly: "More evidence is required to determine the most effective treatment for deliberate self- harm patients."8 In a WHO document on the effectiveness of strategies of suicide prevention, one of the conclusions was: "Limited evidence indicates that no single interven- tion appeared to be effective in reducing the suicide rate."9 A commentary published on a review paper on suicide intervention in young people, concluded, "Research is lacking about interventions to prevent suicide in young people."10
A search through PsychInfo and PubMed yielded no re- view articles on the cost-effectiveness of suicide prevention or treatment. The conceptual problem appears to be that if little evidence points to the effectiveness of suicide preven- tion and treatment, the cost-effectiveness ratio will be infini- tely large since effectiveness is small.
Prevention and Treatment
Considering the lack of reliable statistics due to the cultural stigma of reporting suicide, coroners' under-reporting sui- cide unless clear evidence is present, and under-reporting to the WHO, it is difficult to characterise this self-harm phenomenon. The problem is further compounded by its ill-defined course, difficulty of detection, and high false- positive rates upon detection. There is also limited evidence for the effectiveness of treatment and prevention. All of these factors go against the principles of screening and the practice of public health. Where is the evidence for this public health approach?
References
- Public health in England: the report of the Committee of Inquiry into the Future Development of the Public Health Function. London: HMSO; 1988.
- Beaglehole R, Bonita R. Public health at the crossroads. Cambridge: Cambridge University Press; 1997.
- Wald NJ. Guidance on terminology. J Med Screen. 2001;8:56.
- Goel V. Appraising organised screening programmes for testing for genetic susceptibility to cancer. Br Med J. 2001;322:1174-78.
- Barraclough B, Bunch J, Nelson B, Sainsbury P. A hundred cases of suicide: clinical aspects. Br J Psychiatry. 1974;125:355-73.
- World Health Organization. Facts and figures about suicide. Geneva: World Health Organization; 1999.
- Rose G. The strategy of preventive medicine. Oxford: Oxford Univer- sity Press; 1992.
- Hawton K, Townsend E, Arensman E, et al. Psychosocial versus phar- macological treatments for deliberate self harm. Cochrane Database Syst Rev. 2000;2:CD001764.
- For which strategies of suicide prevention is there evidence of effectiveness? Geneva: WHO Regional Office for Europe's Health Evidence Network (HEN); 2004.
- Gould MS, Greenberg T, Velting DM, Shaffer D. Youth suicide risk and preventive interventions: a review of the past 10 years. J Am Acad Child Adolesc Psychiatry. 2003;42:385-405.
