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Specimen New Style Paper IIA
October 2014
Question
You are working in a public health department covering a population of 250,000. Your area has a
very deep water-filled gorge, spanned by a suspension bridge that is over 75 metres high. Every
year there are a number of suicide jumps from the bridge with a case fatality of 95%. The
director of a national charity which counsels people at high risk of suicide has written to you
requesting that action is urgently taken to erect a barrier at the bridge. The director points out
the high case fatality and states that there is strong evidence that preventing access to lethal
means is a highly effective measure to reduce acts of suicides. You have recently read the
following published paper:
Sinyor M, Levitt AJ. Effect of a barrier at Bloor Street Viaduct on suicide rates in
Toronto: natural experiment. BMJ 2010;341:c2884. doi:10.1136/bmj.c2884
Please note that the Abstract and the section on the strength and limitations have
been redacted.
1. In approximately 600 words, write the strengths and limitations section for inclusion in
the discussion section of this article.
[Please note that the strengths and limitations are not necessarily equal in number.
Candidates will not be penalised for exceeding the word limit which should be used
as a guide.]
(50% of marks)
2. In the analysis the researchers carried out t tests for continuous variables and χ2 tests for
categorical variables. Explain what is meant by categorical and continuous variables.
(10% of marks)
3. Outline in detail the key points you would include in a letter of response to the national
charity. Include consideration of the main findings of the published BMJ paper as well as
relevant local policy issues.
(20% of marks)
4. A decision is made to consider safety measures at the bridge for the prevention of
suicide by jumping. Who would you invite to join a working group to discuss this and
what information would you prepare ahead of the meeting to present to the working
group?
(20% of marks)
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Key points
1. Strengths and limitations (50% of marks)
Candidates have been asked to draft the strengths and limitations for inclusion in the discussion
section of the journal article. The expectation is that it will be written in prose and not in bullet
point format.
For brevity the key points are given here in bullet point format.
Strengths:
 The erection of the barrier at Bloor Street Viaduct is an opportunity for a fascinating
‘natural experiment’ comparing before and after data.
 It provides what is perhaps the best scenario for testing whether such barriers are
effective because the bridge had the second highest yearly rate of suicides after the
Golden Gate Bridge.
 Unlike other locations such as San Francisco, no bridges in Toronto span large bodies of
water, meaning that essentially all suicides by jumping in Toronto come to the attention
of the coroner and are recorded i.e. all bodies are recovered and thus data on the actual
deaths are complete.
 Demographic data for people who completed suicide by jumping from Bloor Street
Viaduct (median age 36, 79% male) were similar to data recently reported for people
who jumped at the Golden Gate Bridge (median age 40, 74% male) indicating to some
extent the generalisability of findings.
Limitations:
 As in any natural experiment, however, this research has many uncontrolled variables;
however, whilst there are methodological limitations there is not an alternative obvious
methodology which could be used to address the question of whether barriers reduce
suicide.
 Despite the relatively high rate of suicides by jumping at Bloor Street Viaduct, the
absolute numbers may have been too low to achieve adequate power in a study of this
kind; there was no power calculation given in the methods.
 Despite the relative comprehensiveness of the chief coroner’s records, it is possible that
suicide rates by all causes were overestimated or underestimated in the period before or
after the barrier owing to incompleteness or inaccuracy of records.
 The coroner’s records might be prone to bias because people found dead beneath certain
bridges or after falling from any bridge or building are more likely to have been ruled as
having died by suicide than by causes such as homicide or unintentional death/accident.
 Due to the large number of deaths from other causes, such as accidents, homicide and
undetermined causes, it was not possible for the researchers to examine all these deaths
to exclude the possibility of bias in the assignment of cause of death.
 It is possible that an ‘ecological fallacy’ is operating. Suicide in itself is a rare event and
suicides by jumping are uncommon to an even greater extent. Despite the remarkably
stable number of suicides by jumping in Toronto before the barrier, the possibility that
rates of suicide at other bridges increased after the barrier for reasons other than
substitution of location cannot be discounted. These reasons might include chance
fluctuations in rates, economic changes, social changes, or other interventions to restrict
the means of completing suicide. It is conceivable that the barrier led to a reduction in
suicides but that this was masked by one or more of these uncontrolled variables i.e.
uncontrolled confounding.
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2. Technical question (10% marks)
A categorical variable is any variable made up of data that can be divided into groups
(categories) e.g. sex, race, socioeconomic status.
Continuous variables represent measurements on some continuous scale, e.g. blood
pressure, height, weight, income, age.
3. Letter of response (20% of marks)
Because candidates have been asked to outline points they can do this in bullet point
format, however, single word answers will not be sufficient and an explanation of the
each point will need to be given to attract the full marks.

Use of appropriate language for correspondence.

Thank the charity for their interest and acknowledge the local problem.

Acknowledge the often public nature of a death by jumping (distress to witnesses who
can be traumatically affected).

Give a brief summary of findings highlighting the key points (not just copying the answer
from the paper) and results: consider how applicable this is to the local situation, any key
limitations, discuss any practical issues re implementation.

Consider paying more attention to the results of other favourable studies, if your local
bridge is regarded as a ‘suicide magnate.’

Point out that other interventions have had a major impact (e.g. restriction on
paracetamol pack sizes).

Suggest undertaking an audit of all suicide sites and methods, not just at the suspension
bridge e.g. railways.
4. Working group (20% of marks)
Given the nature of the question this can be a bullet point list or series of short answers.
Consider inviting:
Identify key players and the importance of engaging appropriate professionals and other
interested parties/how to engage them.
Chair of group – possibly DPH or PH consultant; structural engineer; architect; senior police
officer (negotiating team); ambulance; local psychiatric unit; A&E; trustee/manager of the
bridge; local government representative; local (or national if none locally) third sector
organisation reps (preferably more than one and suggest including the director of the national
charity who wrote the original letter).
Recognise the challenge of having a manageable sized group to take work forward/versus
engaging all interested parties. One suggestion might be to have a ‘workshop’ to start the
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work/gather ideas about local issues then identify a smaller working group to develop a possible
action plan etc.
Preparing for the meeting

Write a short briefing paper outlining the context and the key findings from the paper for
the meeting.

Include any relevant local information.

Give the results of any local audits including suicides from other causes.

Draft a set of terms of reference for the group.

Decide on the suggested timescale for the work of the group.