SSRI Study Released
18 May 2007
Press Release: Ministry of Health
Scoop Independent News
A study of a particular class of antidepressant used in New Zealand suggests that their use appears to be linked with fewer suicide deaths but slightly more hospitalisations for self harm.
The study looked at SSRIs (Selective Seratonin Reuptake Inhibitors), a class of antidepressants which are thought to be safer for treating depression because the drugs themselves can't be easily used for suicide unlike some other classes of antidepressants.
Over time that has led to an increase in use of SSRIs, which has in turn prompted debate and study about whether these medicines are actually safer or just thought to be safer.
There is considerable debate both in New Zealand and overseas about the possible link between SSRIs and suicide. The issue is complicated by depression being a risk factor for suicide. Depression is an illness that antidepressants are most commonly prescribed for.
The study was unable to answer the question of whether SSRIs are more strongly linked with suicide, though on balance researchers believe the study does seem to provide some support for the view that SSRIs do seem to be a safer option in terms of preventing deaths.
Researchers say that limitations to this latest study combined with the relative rarity of suicide in New Zealand mean that a clear answer on the issue is unlikely to be found here.
Study author Dr John Wren said the study found significant differences in prescribing rates around the country, with one in every 11 people in Canturbury taking SSRIs compared with one in every 27 in South Auckland.
He said the finding prompts a number of questions which may be able to be answered with further research, such as whether the levels of prescribing in the population represent under or over prescribing between the regions, and what should be regarded as an optimal level of prescribing in the population.
Dr Wren said the study's findings about the slight increase in risk of hospitalisations for self-harm also serves as a useful reminder to health professionals. "Individuals first prescribed SSRIs should be monitored for the early period after intial prescribing when the risk of harm or suicide was thought to be higher due to the way the drugs work."
Well-known SSRIs include nortriptyline (Norpress), paroxetine (Aropax) and fluoxetine (Prozac).
Questions and Answers - report methods and findings
Why was the research undertaken, and what did the research aim to achieve?
Many clinicians consider improved antidepressant drug utilisation an important means of intervention for both suicide prevention and improved mental health. The safety and efficacy of antidepressants is subject to much international debate. Given the debate and the new policy initiatives aimed at suicide prevention and mental health promotion, it was timely to undertake research that investigated whether a relationship can be observed between antidepressant prescribing (particularly SSRIs) in New Zealand and suicide related outcomes. A secondary objective of the study was to examine the usefulness of the national data sets –in particular the Pharmhouse data - to inform research into questions about the safety and efficacy of drug use in New Zealand.
How was the study undertaken?
Three research methods were used to explore the issue of antidepressant prescribing and suicide related outcomes in New Zealand.
1) Pharmaco-epidemiological study describing patterns and trends in antidepressant prescribing in New Zealand and by DHB between 1997 and 2005, and pattern of mental health diagnosis and drug treatment in 2005
2) Statistical modelling of interactions between intensity of antidepressant drug prescribing (DDD and PDD), population-level variables (eg, age group, sex, deprivation, DHB), and hospitalisation for intentional self-harm outcomes as a proxy for suicide attempt in 2005
3) Literature review of the debate about whether there is an increased risk of suicide-related outcomes from the prescribing of antidepressants, particularly SSRIs
What is a Pharmaco-epidemiological / ecological study?
A Pharmacoepidemiological study is population level observational research on the use of drugs and their effects in the population. The study uses data from national data sets, and internationally accepted drug utilisation methods. It provides information describing the patterns of antidepressant prescribing in New Zealand over time, examines whether a relationship can be observed between the patterns of prescribing and suicide related harm – in particular hospitalisations for intentional self-harm, and a review of the international literature on the issue.
What did the study find?
- statistically significant (95% confidence level) differences between DHBs in the proportion of people in the population prescribed an antidepressant
o The DHB with the highest proportion of the population prescribed an antidepressant was Canterbury, where 8.9 of the population is being prescribed an antidepressant compared to lowest DHB which was Counties-Manukau at 3.7 percent.
- statistically significant, observed, small increased risk (Odds Ratio ranging from 1.25 to 1.63) between increased prescribing in the population of nortriptyline, paroxetine and fluoxetine and increased hospitalisations for deliberate self-harm events
- that prescribed daily doses tend to be at the low end of what is thought to be a therapeutic dose recommended by regulatory authorities.
- while the results are statistically significant this does not necessarily mean that they are clinically significant at the individual treatment level because of limitations in the study design.
What are the explanations for the findings?
A number of explanations for the findings have been examined. On the evidence examined the most likely explanation is that the differences between DHBs reflect real differences in regional clinical prescribing practice and not underlying regional population factors.
The findings of a very small increased risk maybe due to a range of explanations including:
- prescribing practices
- patient non-compliance with their doctor’s instructions, and
- that because of the way the drugs work, patients at the start of their antidepressant drug treatment are for a short period of time at an increased risk of acting on their suicidal thoughts before the full therapeutic effects of the drugs become fully effective.
How do these results compare with international findings?
The findings are generally comparable with similar studies reported in the international literature. However there is significant debate in the literature about the meaning and value of the various studies.
What is the value of this study?
This study provides a robust description of the patterns of antidepressant prescribing in New Zealand, an understanding of the uses and limits of existing national datasets, and a description and consideration of the range of explanations and debates that exist around the topic of antidepressant use and suicide related outcomes in the international literature.
The study is unable to resolve the debate about the risks and benefits of using antidepressants because of the study design and limitations in the data sets used.
What advice does the Ministry provide to those being prescribed an antidepressant?
On the evidence reviewed and presented in this study and elsewhere, the Ministry would like to remind clinicians to follow the advice issued by Medsafe on 19 October 2004 about the prescribing of antidepressants.
Patients using antidepressants should continue their use.
Those experiencing suicidal thoughts while taking antidepressants should seek further help from their prescriber or other professional counsellor.
What should I do if I’m concerned someone may be suicidal?
If you are concerned about someone who may be suicidal or is very distressed, you can approach the following services for advice:
- primary health care professional or general practitioner (GP)
- community mental health service
- Mâori community health service
- counselling services
- helplines such as Lifeline (0800 111 777), Samaritans (0800 726 666) or Youthline (0800 376 633)
In an emergency you should:
- contact the nearest hospital or psychiatric emergency service/mental health crisis assessment team
- ring 111 and ask for ambulance or police
- remain with the person until appropriate support arrives
- remove any obvious means of suicide (guns, medication, cars, knives, rope, etc).