Deaths by suicide compared to other causes

There's been quite a lot in the media recently about the spate of suicides in Dundee, Scotland; particularly because they occurred in younger people. Many people have been comparing the number of suicides to road deaths (suicides are higher). For example: "Every year in the United Kingdom around 5000 people die by suicide. This is twice the number who die on the roads, and suicide is the commonest cause of death among young people." This was from the British Medical Journal.

However, it's worth looking at this statement in a little more depth to understand what's really going on. At first reading, one might assume that suicide is becoming more common, particularly in young people. This isn't the case, however.

A recent paper looking at trends in suicide rates from 1861-2007 (Thomas, K., & Gunnell, D. (2010). Suicide in England and Wales 1861-2007: a time-trends analysis [In Press - DOI: 10.1093/ije/dyq094]. International Journal of Epidemiology) would indicate that suicide rates in all groups are the lowest they have been for over a hundred years.

Data published by the Department of Health confirms that the suicide rates in all age groups are generally trending downwards, and have been for the last 15 years or so. So why are more people dying by suicide than on the roads?

The simple answer is that over time, the rate of decrease in road deaths is greater than the rate of decrease in suicides. Cars are getting safer, speed cameras might be affecting driving behaviours in high-risk areas, public-health messages on drink-driving might be having an effect, etc. This can be seen in the figure below which uses data from the WHO Health For All (HFA) database; a great (and free) source of population data for European Countries.

The rates are very similar if you correct for changes in population over time (the data are available from National Statistics).


It's a similar situation to deaths from many cancers, which are often reported to be going up. They are going up relative to other causes of death not because they are becoming more common but because fewer people are dying of other causes. A hundred years ago, people were dying of diptheria, typhoid, tuberculosis, and a host of diseases that have been 'tamed' with the advent of vaccinations and modern therapies. If these diseases don't kill you, then you stand a good chance of living long enough to die of cancer.

Hospital SMRs in Scotland

A lot has been made of the publication of Hospital Standardised Mortality Ratios (HSMRs) by the NHS in England and Wales.  These were collated and published by Dr Foster in 2009.

Dr Foster have produced a useful guide to HSMRs here. To quote from the guide:

"The HSMR is a calculation used to monitor death rates in a trust. The HSMR is based on a subset of diagnoses which give rise to 80% of in-hospital deaths. HSMRs are based on the routinely collected administrative data often known as Hospital Episode Statistics (HES), Secondary Uses Service Data (SUS) or Commissioning Datasets (CDS). The HSMR was conceived by Professor Sir Brian Jarman, director of the Dr Foster Unit at Imperial College, London.

Measuring hospital performance is complex. Dr Foster understands that complexity and is clear that HSMRs should not be used in isolation, but rather considered with a basket of other indicators that give a well rounded view of hospital quality and activity."

HSMRs were first used in 2001 and Scotland have just produced their first published set of HSMRs, proudly announcing that "Unexpected deaths fall by six per cent." This is true, to some extent, but let's look at the figures which are available from the Information and Statistics Division (ISD) of NHS Scotland.

The most recent average HSMR is 0.936, which represents a six-percent reduction from the predicted hospital mortality. This figure comes from Apr-Jun 2009, and the comparison is made to the previous period when the rate was 0.992 - this is a reduction of 0.057, or 5.7%.

However, the change from one period to another is not as informative as trends over time. These are shown below:

As you can see, there is a very strange periodicity to the HSMR over time, with peaks during winter, and troughs during summer. Comparing the most recent HSMR with the same period one year ago, the reduction is 1.1% - likely to be insignificant. Quick tip: always choose the greatest differences between time points when you are wanting to look good. I'm pretty sure that the Scottish Government wouldn't have announced in December 2008 that hospital mortality had gone up by 7%!

The reason for this variation is not clear, although there are some possible contributing factors:

1. The increased morbidity in the population during the winter is reflected in increased mortality in those admitted to hospital.
2. The contribution of junior doctor changes is not obvious, but traditionally the changeover times (when new doctors start) were February and August. With changes in training, many doctors are now on 4-month, rather than 6-month rotations, and it isn't clear why doctors starting in February would increase mortality but doctors starting in August wouldn't.

What's also interesting is that this cyclical pattern is not seen in all hospitals, and is marked in others. For example, Arbroath Hospital shows a 100% variation depending on season, suggesting that mortality above the predicted rate doubles at certain times of the year.

Of course, these are new figures for NHS Scotland, and it is possible that there are errors in the data. One would hope that NHS Scotland wouldn't publish the figures unless they were reasonably confident in their reliability.

Finally, if you're interested in the hospitals with the highest HSMRs in the most recent reporting period, look no further. All of the following hospitals have a HSMR higher than the predicted rate. In order to understand that some hospitals may have made significant improvements, the change from baseline (Oct-Dec 2006) is also given. It's important to take the cyclical variations described above into account when interpreting this latter figure.

News of the World on ECT

News of the World (although there's rarely much world news, so it's clearly an ironic title) recently published a feature on the Coronation Street actress Bev Callard's experience of a severe depressive episode during which she received ECT. It was titled: "Frankenstein op saved me from suicide".

It's relatively rare for someone in the public spotlight to talk about their experiences of mental illness; less frequent for them to touch on treatments such as ECT. So, this is to be commended. It's a shame that the paper didn't really take much of an opportunity to provide the information that the average reader might have found helpful. Such as:

1. ECT is not always a "last-resort". Indeed, in this case, it seems as though it was suggested relatively early in a course of treatment.
2. For many people, ECT is offerred for a variety of reasons which include: a) a quick response is needed. This is the case when someone is at high risk of suicide, or they are not eating/ drinking; b) ECT has worked in the past and the person wishes to have it again because they know it works. For some people, ECT can be more effective than drugs, and in most cases will work more quickly. The most common reasons for giving ECT in Scotland are 'Previous Good response' and 'Resistance [to antidepressants]' (Scottish ECT Accreditation Network (SEAN) Annual Report, 2009).
3. Effects on memory are not uncommon, with approximately two-thirds of people experiencing some effect on autobiographical memory for the period in which they're receiving ECT. The vast majority of studies have found that memory returns to normal 2-3 months after a course of ECT, but memories from the period of treatment may always be hazy. However, the majority of people in hospital for severe depression do not report unbroken and clear autobiographical memory anyway.
4. Twelve treatments is the typical maximum number of treatments in a course, although some people might choose to stop after fewer, and other people (those with delayed response and chronic depression) might have more. Like most things, it's a discussion about risk versus benefit. Someone who has had 10 treatments with no benefit and memory problems might choose to stop. Another with partial improvement and few memory problems might choose to continue. In Scotland, the mean number of treatments per course is 7.6 (Scottish ECT Accreditation Network Annual Report, 2009).

The article does reflect some realities about ECT:

1. Most people will experience some sense of improvement after 3-4 treatments.
2. ECT can be very effective. Indeed, it is probably one of the most effective treatments in modern psychiatry. The SEAN Report 2009 indicates that 50% of people experienced a 75-100% improvement in depressive symptoms from baseline to end of treatment. A further 26% experienced a 50-74% improvement. In psychiatry, a 50% improvement in symptoms is usually classified as 'response' (not remission), so in Scotland approximately 75% of people respond to ECT.