Suicide Prevention Research Unit, Centre for Mental Health Studies, Faculty of Health, University of Newcastle, New South Wales, and Department of Consultation-Liaison Psychiatry, Newcastle Mater Hospital, Newcastle
Suicide Prevention Research Unit, Centre for Mental Health Studies, and Faculty of Health, University of Newcastle
Discipline of Clinical Pharmacology, Faculty of Health, University of Newcastle, and Department of Clinical Toxicology and Pharmacology, Newcastle Mater Hospital, Newcastle
Discipline of Clinical Pharmacology, Faculty of Health, University of Newcastle, Australia, and South Asian Clinical Toxicology Research Collaboration University of Peradeniya, Sri Lanka
Centre for Clinical Epidemiology and Biostatistics, Faculty of Health, University of Newcastle, and Centre for Military and Veterans' Health, University of Queensland, Brisbane, Australia
Correspondence: Dr Gregory Carter, Department of Consultation-Liaison Psychiatry, Locked Bag 7, Hunter Region Mail Centre, NSW 2310, Australia. Tel: + 61 2 4921 1283; fax: + 61 2 4921 1870; email: Gregory.Carter{at}newcastle.edu.au
|
|
|---|
Aims To report the 24-month outcomes of a non-obligatory postcard intervention (plus treatment as usual) compared with treatment as usual.
Method In a randomised-controlled trial (Zelen design) conducted in Newcastle, Australia, eight postcards were sent to participants over a 12-month period. The principal outcomes were the proportion of participants with one or more repeat episodes of self-poisoning and the number of repeat episodes per person.
Results No significant reduction was observed in the proportion of
people repeating self-poisoning in the intervention group (21.2%, 95% CI
17.0-25.3) compared with the control group (22.8%, 95% CI 18.7-27.0;
2=0.32, d.f.=1, P=0.57); the difference between
groups was –1.7% (95% CI –7.5 to 4.2). There was a significant
reduction in the rate of repetition, with an incidence risk ratio of 0.49 (95%
CI 0.33-0.73).
Conclusions A postcard intervention maintained the halving of the rate of repetition of hospital-treated self-poisoning events over a 2-year period, although it did not significantly reduce the proportion of individuals who repeated self-poisoning.
|
|
|---|
|
|
|---|
Setting
The Hunter Area Toxicology Service (HATS) is a regional toxicology unit at
the Newcastle Mater Misericordiae Hospital, New South Wales, Australia,
serving a primary referral population of 385 000 adults and a tertiary
referral population of a further 170 000. All poisoning presentations to
emergency departments in the greater Newcastle region are either admitted to
HATS or notified to HATS and entered prospectively into a clinical database
(Whyte et al, 1997,
2002). The HATS model of
service delivery means that in (virtually) all cases of self-poisoning in the
catchment area the person is brought to the Newcastle Mater Hospital for
treatment and in all cases the person is formally admitted under the care of
HATS. The psychiatry department sees all such patients for assessment and
diagnosis, and to determine discharge destination and follow-up. Details of
the model of service for these patients have been described by Whyte et
al (1997).
Study population
Patients aged 16 years or over who presented to HATS during the recruitment
period (April 1998 to December 2001) were potentially eligible. Inclusion
criteria were that the patient must be capable of informed consent, not
considered to pose a threat to an interviewer, not of `no fixed address' and
with sufficient English to complete a structured interview.
Variables
The two dependent variables were the proportion of individuals who had one
or more readmissions for self-poisoning and the number of readmissions for
self-poisoning per individual, over 24 months. Descriptive variables were
obtained from the standardised clinical assessment of the patients
(Buckley et al, 1999)
and extracted from the HATS database. The categorical variables were gender,
marital status (married, including de facto relationships,
v. never married, separated, divorced or widowed), employment
(full-time or part-time v. unemployed, pensioner, student or other),
intensive care unit admission, time of admission (09.00–17.00 weekdays
v. out of hours) and discharge destination (psychiatric hospital
v. all others). The continuous variables were age, length of stay in
hours, median number of previous admissions to HATS for self-poisoning and
number of psychiatric diagnoses from clinical assessment.
Study design
A randomised consent (Zelen: single consent version) design was used
(Zelen, 1979,
1990). This design is a
variation on the standard randomised controlled experimental design, in which
participants were randomised to control or intervention before consent was
sought. In the single consent version, written informed consent to receive the
intervention (eight non-obligatory postcards) was sought only from
participants randomised to the intervention. The outcomes were assessed by an
intention-to-treat analysis based on randomisation status.
The Hunter Area Health Research Ethics Committee approved this study, including the randomised consent design.
Randomisation
Randomisation was by database (HanD-Base version 2.0; DDH Software,
Wellington, Florida, USA) on a personal digital assistant (Palm III; Palm,
Inc., Sunnyvale, California, USA) which was populated with a pre-generated
randomisation schedule (in blocks of ten) and carried by the duty
toxicologist. To avoid recruiting patients more than once, identification
information was searched in this database before enrolment. To maintain
masking to allocation status during recruitment, randomisation was not
revealed until after all information was entered and eligibility determined.
Randomisation status was then revealed in order to obtain patient consent. To
monitor any potential alterations (interference) a duplicate record was kept
in a hidden field of the database and a copy held on a separate computer for
later verification of correct randomisation status.
All other clinical and research staff were unaware of allocation.
Intervention
A new intervention was developed based on the study by Jerome Motto, which
demonstrated reduced death by suicide in a psychiatric hospital in-patient
population (Motto, 1976;
Motto & Bostrom, 2001).
The new intervention was a series of eight `postcards' sent in a sealed
envelope in months 1, 2, 3, 4, 6, 8, 10 and 12 after discharge (the postcard
is shown in the online supplement to this paper). All participants received
treatment as usual.
Sample size
During study planning several sample sizes were calculated based on
different estimates of possible effects for the 12-month outcomes
(Carter et al, 1999).
A difference in proportions (5% significance level, 80% power) of 15% to 10%
required 1364 participants, 20% to 10% required 392 participants and 30% to
20% required 293 participants. On the basis of clinical experience and
previous research it was anticipated that 15–30% of the control group
would self-poison again within 12 months, with an average of two episodes,
meaning overall self-poisoning rates of 30–60%. A sample of 400 per
group would allow detection of absolute differences between groups of
10–15% (5% significance level, 80% power) and 12–17% (5%
significance level, 90% power), yielding relative risks of 0.67–0.75 and
0.60–0.72 (80% and 90% power respectively). This sample size would be
adequate to detect differences in the proportion of participants who had any
episode of self-poisoning of 7–9% (80% power) and 8–10% (90% power
and 5% significance level), which we considered would represent a clinically
significant reduction.
![]() View larger version (20K): [in a new window] [as a PowerPoint slide] |
Fig. 1 Study profile (TAU, treatment as usual).
|
2 analyses. For the number of readmissions per individual, a
negative binomial regression was undertaken to compare the risk of
self-poisoning events per individual in the postcard group relative to the
control group and is reported as incidence risk ratio (IRR) with 95%
confidence intervals. Two subgroup analyses, using negative binomial models,
were undertaken for the treatment effect for male and female groups, since a
post hoc analysis of 12-month outcomes suggested a gender effect
(Carter et al,
2005).
Intent to treat
We assessed 922 patients for eligibility, of whom 150 (16%) were ineligible
(Fig. 1), leaving 772 potential
participants (control group n=394 intervention group n=378).
Among the intervention group, 76 refused the intervention, 1 missed the
intervention as planned and 32 did not receive the full intervention (this was
due to these people being unavailable, their postcards being returned `not
known at this address - return to sender'). Twenty people in the control group
received the intervention owing to clerical errors, but were retained in the
control group as data were analysed as intention to treat, based on
randomisation.
|
|
|---|
|
View this table: [in a new window] |
Table 1 Characteristics of the study sample
|
Proportion of sample repeating self-poisoning
In the intervention group 21.2% (80/378; 95% CI 17.0–25.3) had one or
more readmissions for self-poisoning compared with 22.8% (90/394; 95% CI
18.7–27.0) in the control group 24 months after baseline, a
non-significant difference (
2=0.317, d.f.=1, P=0.57),
the difference between groups being –1.7% (95% CI –7.5 to
4.2).
Number of repeat admissions
There were 310 cumulative readmissions in the control group and 145 in the
intervention group (Fig. 2).
Table 2 shows the relative
risks for the intervention group compared with the control group from the
negative binomial regressions. The risk of repetition was statistically
significantly lower in the intervention group (IRR=0.49, 0.49, 95% CI
0.33–0.73). Separate subgroup analyses by gender showed the treatment
was effective for women (IRR=0.49, 95% CI 0.30–0.80) but not for men
(IRR=0.97, 95% CI 0.50–1.88. Readmissions by intervention group and
gender are shown in Table
3.
![]() View larger version (14K): [in a new window] [as a PowerPoint slide] |
Fig. 2 Cumulative readmissions to hospital for treatment of self-poisoning (24
months; unadjusted for multiple admissions).
|
|
View this table: [in a new window] |
Table 2 Negative binomial models for 24-month outcomes for intervention effect on
number of readmissions for self-poisoning and for subgroup analyses by
gender
|
|
View this table: [in a new window] |
Table 3 Number of repetitions of self-poisoning by gender and experimental
group
|
|
|
|---|
There were some limitations to consider for this study and caution needs to be used when interpreting the results. Less than a quarter of the participants self-poisoned a second time, and a subgroup showed a highly skewed pattern of more than one repeat episode. It is not known to what extent the HATS referral population and model of clinical service (Whyte et al, 1997) would be generalisable to other settings. This study investigated patients who self-poisoned and the results cannot necessarily be generalised to patients with other forms of self-harm. We do not currently have data available on mortality and suicide outcomes for the study participants. A previous longitudinal study in our centre found a 1% suicide rate after 24 months and nearly 2% suicide rate after 5 years, which would translate to 8 suicide deaths and 16 suicide deaths respectively (Reith et al, 2004). These suicide rates are lower than the 12-month 1.8% rate reported in a recent meta-analysis of psychosocial interventions after self-harm (Crawford et al, 2007). We intend to be able to report the mortality and suicide outcomes for the 5-year follow-up of the Postcards from the EDge project in the future.
Replications of this study and additional effectiveness trials would be necessary before widespread implementation could be considered. The decision to include a subgroup analysis based on gender was a post hoc one based on the findings from the primary outcomes at 12 months. Caution should always be used in interpreting such subgroup analyses because of (unplanned) reduced sample sizes, and judgement needs to be exercised regarding the biological plausibility of such analyses. There may also have been a conservative estimate of treatment effect because 20 persons in the control group were inadvertently exposed to the intervention, whereas 76 persons in the treatment group did not consent to receive the intervention and a further 32 persons were not exposed to the intervention.
Implications of the study
The simple postcard intervention used in this study was previously shown to
have nearly halved the number of readmissions for self-poisoning within 12
months: IRR=0.55, 95% CI (0.35-0.87)
(Carter et al, 2005).
This study of 24-month outcomes showed that this benefit was maintained for a
further 12 months after the final contact by postcard: IRR=0.49, 95% CI
0.33–0.73. There were 422 bed-days used by the control group and 183
bed-days used by the postcard group, a total of 239 bed-days saved. This
represented a considerable ongoing saving in opportunity costs, availability
of hospital beds and decrease in emergency department workload. This low-cost
intervention seems to have substantial cost-effectiveness. The simplicity of
the intervention means that it could be delivered from hospitals that do not
have extensive resources. The difference in total readmissions for
self-poisoning came from one main source – women with three or more
repeat admissions (see Table 3)
– which accounted for a difference of 165 repeat admissions (210 in the
control group and 45 in the intervention group).
Benefit of treatment beyond the treatment phase
One other study (n=101) has shown a significant reduction in
self-harm over a 24-month period (12 months after treatment cessation): 23%
v. 46% (Linehan et al,
2006). That study used dialectical behaviour therapy to treat
women with recent self-harming behaviour who met criteria for borderline
personality disorder. This therapy is an important form of treatment for a
subset of patients who self-harm, although it is not applicable universally to
the hospital-treated population. One further study (n=44) has shown a
sustained reduction in self-mutilation (23% v. 68%) and suicide
gesture (18% v. 63%) over 36 months, 18 months after treatment
cessation (Bateman & Fonagy,
2001). That study used a psychoanalytically informed day hospital
programme in patients with borderline personality disorder. Both of these
studies suggested that longer-term alternative behaviours to self-harm were
learned, such as improvement in coping strategies, emotion regulation, impulse
control, self-understanding or relationship quality, which resulted in the
maintenance of the beneficial effects
(Bateman & Fonagy, 2001;
Linehan et al, 2006).
A third study of self-poisoning patients (n=119), using a brief,
nurse-led psychological intervention in the patient's home, found the
intervention group less likely to report repeated attempts to harm themselves
at the 6-month follow-up (9% v. 28%;
Guthrie et al, 2001).
Beneficial effects on repetition sustained beyond the duration of the
intervention might have been mediated by other beneficial effects on suicidal
ideation and treatment satisfaction. All three of these studies used highly
selected subgroups within the hospital-treated self-harm population, either
people with borderline personality disorder
(Bateman & Fonagy, 2001;
Linehan et al, 2006)
or a group of only 119 participants from an initial sample of 587 patients
presenting with self-poisoning (Guthrie
et al, 2001), which makes comparison with our study more
difficult. However, these four studies taken together suggest that if some
impact on reduction of repetition of self-harm or self-poisoning behaviour can
be made, then perhaps the effects might be sustained over a period beyond that
of the intervention.
Although it may also be inferred that some participants in our study learned sustained alternative behaviours to self-poisoning, there was no particular component of the intervention that aimed to induce these specific behavioural changes. The mechanism for the long-term benefits in the Postcards from the EDge study remains speculative. We have planned a qualitative study to explore the question of what mechanisms might have contributed to this. We also do not know whether there was any change in the pattern of psychiatric hospital, psychiatric community service or primary care service use that might have been a mediating factor in the difference in repetition events, but we hope to be able to explore some of these possibilities in the planned 5-year follow-up study.
Comparison with other brief interventions
There are other brief interventions for repetition of hospital-treated
self-harm or self-poisoning that can be considered. One of the best-known
low-cost interventions for self-harm in the UK was the green card study and
the subsequent crisis telephone card study, which showed no difference in the
proportion of those repeating self-harm at 6 months
(Evans et al, 1999) or
at 12 months (Morgan et al,
1993; Evans et al,
2005). The first of these studies (n=212) was
underpowered and included only those presenting for the first time with
self-harm, who subsequently showed a repeat rate of self-harm of only 8%
(Morgan et al, 1993).
The second variation (n=827) was adequately powered, used a self-harm
case register to define repetition, and found no difference in proportions of
those repeating self-harm, with a 12-month repetition rate of 20%
(Evans et al, 2005).
In France, a telephone contact intervention delivered either 1 month or 3
months after an episode of self-poisoning showed no difference in the
proportion of a combined `adverse effects' outcome or proportion of
self-reported suicide attempt (Vaiva
et al, 2006). That study (n=605) was adequately
powered, used a stratified (based on more than four suicide attempts in 3
years), three-arm design and had a 12-month repeat attempted suicide rate of
17%. A multicentre UK study used a manual-assisted cognitive–behavioural
therapy intervention for established cases of repeated self-harm and showed no
difference in proportion of those with self-reported repeat parasuicide
(Tyrer et al, 2003).
This study (n=480) was adequately powered (for an expected repetition
rate of 45%), used a stratified (based on parasuicide score) design and had a
12-month parasuicide rate of 43%. The comparison condition for these studies
was standard treatment or treatment as usual and for the Postcards from the
EDge study it was postcards plus treatment as usual v. usual
treatment alone. Each of these studies showed a similar non-significant
reduction in the proportion of those repeating self-harm (patient rate) of
2.2–7.0% (Crawford & Kumar,
2007). However, none of these studies of brief, low-cost
interventions analysed the number of episodes of repeated self-harm (event
rates) as an outcome, and most used different definitions of the primary
outcome and different methods of estimating the rates of that outcome, so
comparison with the beneficial finding from the Postcards from the EDge study
is difficult despite the similarities of intent underlying the
interventions.
Concluding remarks
This study of hospital-treated self-poisoning showed that a low-cost
postcard intervention was effective in reducing the number of events per
individual by a relative reduction of more than 50%, which was clinically and
statistically significant. The postcard intervention continued to be effective
in reducing repeat episodes of hospital-treated self-poisoning for 1 year
after the intervention ceased.
|
|
|---|
|
|
|---|
Related articles in BJP:
This article has been cited by other articles:
![]() |
M. Kripalani, A. Gash, and J. Reilly Cognitive-behavioural therapy for self-harm The British Journal of Psychiatry, July 1, 2008; 193(1): 80 - 80. [Full Text] [PDF] |
||||
Read all eLetters
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||