to venlafaxine (Howell et al., 2007), (although Isbister (2009)
showed that cardiotoxicity was not a common feature of ven-
lafaxine overdose except where exposure exceeded 8 g). It may
be that guidance suggesting the careful prescription of SNRIs
for depressed patients, particularly patients with pre-existing
cardiac disease, may have aﬀected its use during the study
period (National Institute for Clinical Excellence, 2004).
Alternatively, it may be that the association is due to uniden-
tiﬁed confounding (e.g. more recently diagnosed psychiatric
illness). Further, the weak association between selective sero-
tonin reuptake inhibitors (SSRIs) and SUD is interesting.
Although paroxetine (an SSRI) was associated with a reduced
OR in the multivariate predictor model, SSRIs were not asso-
ciated with SUD in any other analyses. Similarly, trazodone
(a tricyclic-related drug) was associated with an increased risk
of SUD in the multivariate predictor model, although the
association did not reach signiﬁcance in the unadjusted or
adjusted analyses. Further investigation of the association
between SUD and antidepressants is warranted.
Physical health problems, speciﬁcally a history of CV
disease and respiratory disease, resulted in approximately a
two-fold increase in the risk of SUD. To help reduce the
occurrence of SUD on psychiatric in-patient wards, mental
health services should seek to improve the physical health
care of mental health patients, with a particular emphasis
on patients with pre-existing CV and respiratory problems.
The association between primary diagnosis and SUD merits
discussion. The increased risk of SUD in patients with a
primary diagnosis of dementia may be the result of poorer
physical health of older patients.
We gratefully acknowledge the support of consultant psychiatrists,
members of the medical teams, and representatives from user and
carer organizations. We thank clinician Dr Phalaksh Walishetty for
his contribution to the validation of SUD cases.
This study was funded by the Department of Health, England and the
National Institute for Clinical Excellence, England. The National
Patient Safety Agency (NPSA) has funded the study since April 2005.
Declaration of interest
Louis Appleby was the National Director of Mental Health for
England and is now the National Director for Health and Criminal
The study was principally designed by L Appleby, J Shaw, T Amos,
G Lewis, S Thomas and N Ferrier, but all authors had input into
aspects of study design. Procurement of data from the NWCS and
HES and collection of questionnaire data was carried out by P
Turnbull, K Hadﬁeld, K Windfuhr, U Hiroeh, C Dixon, S Flynn,
and H Watkinson, supported by T Amos. Initial data manipulation
was carried out by P Turnbull, D While, K Windfuhr, U Hiroeh, C
Dixon, and S Flynn. Case validation was carried out by N Swinson,
H Mehta and H Watkinson, with supervision from N Kapur, S
Thomas, and N Ferrier. Data analysis was carried out by P
Turnbull, D While, U Hiroeh, and P Skapinakis with supervision
from N Kapur, G Lewis, and L Appleby. The manuscript was
prepared by K Windfuhr, P Turnbull, D While, and U Hiroeh with
supervision from N Kapur. All authors commented on drafts of the
paper and contributed to the ﬁnal version.
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