Relationship between antidepressant sales and secular trends in suicide rates in the Nordic countries
Reseland S, Bray I, Gunnell D;
Commented by , 23 May 2006
Background
There are increasing concerns that selective serotonin reuptake inhibitors (SSRIs) may precipitate suicidal behaviour in some individuals. In the UK, the Medicines and Healthcare products Regulatory Agency recently concluded that a modest increase in the risk of self-harm in SSRI users could not be ruled out, but that there was too little evidence available to assess the suicide risk.
Method
Data on suicide rates were compared with data on sale of antidepressants for four Nordic countries. Data on suicide were available from 1961 to 2001 and data on total antidepressant and SSRI prescribing were available from 1974 for Norway, from 1977 for Sweden, from 1990 for Denmark and from 1985 for Finland.
Results
Suicide rates declined in all four countries during the 1990s, whereas antidepressant sales increased by 3- to 4-fold. Decreasing suicide rates in Sweden and Denmark preceded the rise in antidepressant sales by over 10 years, although the reductions accelerated between 1988 and 1990.
In Norway, a modest but short-lived decline in suicide rates began around the time of the increase in antidepressant sales. In Finland, decreases in suicide rates began around the time of increased antidepressant sales.
The authors conclude that there is mixed evidence that increases in antidepressant sales have coincided with a reduction in the number of suicides in the Nordic countries.
Professor Kessing's comments
As discussed by the authors, many complex factors may influence on national suicide rates, including the availability of lethal methods of suicide, changing social and economic conditions, changing levels of substance misuse, etc. and these factors may be strongly correlated with each other. The main limitation is however, that the study employed an ecological study design. Thus, the study has not investigated the influence of antidepressant treatment on suicide risk.
Another recently published study by Sondergard et al. (ref. 1) investigated the relationship between treatment with antidepressants and suicide on individualized data from the same Danish nationwide databases with linkage of registers of all prescribed antidepressants and recorded suicides in Denmark during the period 1995–99. Patients who continued treatment with SSRIs (i.e. who purchased SSRIs twice or more) had a decreased rate of suicide compared with patients who purchased SSRIs once only.
Furthermore, the rate of suicide decreased consistently with the number of prescriptions. Similarly, among patients treated with newer antidepressants other than SSRIs, the rate of suicide was decreased compared with the rate for patients who purchased other newer antidepressants once only.
Thus, a number of factors as mentioned above may have been associated with the decrease in suicide rate before the 1990’s and the increasing use of antidepressants during the 1990’s seems to have accelerated the ongoing decrease in the suicide rate.
References
1. Sondergard L, Kvist K, Andersen PK, Kessing LV. Do antidepressants prevent suicide? International Clinical Psychopharmacology; 21 (4); 211-218