Should psychological formulation replace diagnosis for psychiatrists?
Summary
Psychological formulation has been promoted as a replacement
for diagnosis in mental health. This does not take into account the time
pressures facing psychiatrists and their needs in clinical practice. Using an
example of a published psychological formulation for psychosis it can be
demonstrated that psychological formulation is inferior to psychiatric
diagnosis for clinical functions (prognosis and choosing treatments). It is
also inferior for research (classifying participants) and social roles
(including access to welfare and administrative integration with the rest of
healthcare). For psychiatrists, diagnosis is still superior but should be supplemented
by diagnostic formulation which can incorporate psychological mechanisms.
Declaration of Interest
The author has written a book awaiting publication which has
large sections focussed on the value of diagnosis in mental health.
Introduction
Psychological formulation – sometimes called case
formulation - has been promoted to replace diagnosis in clinical practice 1,2
particularly to increase understanding of the patient and choosing
appropriate interventions 2.
Psychological formulation involves the organising of
relevant clinical material to map out and summarise a patient’s problems – in
collaboration with the patient over the course of clinical work - using
psychological theories and knowledge to understand the patterns of difficulties
and suggest ways forward to resolve these problems 2,3,4.
Statements on the superiority of psychological formulation
compared to diagnosis tend to be made on the assumption that the clinician
works in a particular way – that they can spend a long time with relatively few
patients, will see these patients many times with short intervals between
sessions (for example weekly), often in non-urgent situations at civilised
hours and that psychosocial interventions are the main therapeutic activity.
For their outpatient practice psychiatrists average 60
minutes for first appointments and 18 minutes for follow-up appointments5
(usually separated by weeks or months between appointments) carrying caseloads
up to ten times of their colleagues6. Emergencies/ overnight and
inpatient assessments are often similarly brief and patients may only be seen
once or twice by the same doctor. This makes providing psychosocial
interventions difficult and where effective medications are available these
tend to be used as these are usually taken outside of the assessments thus making
effective therapeutic interventions possible.
This paper briefly discusses the usefulness of psychological
formulation for psychiatrists in clinical, research and social functions.
Usefulness of psychological formulation for clinical practice
To evaluate the usefulness of psychological formulation for
clinical functions an example of psychological formulation will be used to
illustrate the points; the formulation used to understand ‘Dan’ and his
psychosis in Section 7 of ‘Understanding Psychosis and Schizophrenia’7.
This example is chosen for two reasons. Firstly, it is given as a good example
of psychological formulation to enable understanding of psychosis by the
Division of Clinical Psychology so has been given a stamp of approval by
professionals whose core professional skills include psychological formulation4.
Secondly, it is used for a case of psychosis and my main clinical work is with
patients with schizophrenia and other related conditions, so this is an example
I can relate to my clinical practice.
The ‘medical model’ relies on advising on and helping
deliver interventions that improve health based on the best possible evidence8.
For clinical practice, classification systems (such as diagnosis or
psychological formulation) utility is judged on whether they allow
communication of useful information between clinicians/patients/carers,
accurate conceptions of the nature of the problem, provide information on
prognosis (such as rates of relapse), aetiology/ causation, complications and
which interventions to use and their chances of success9,10,11,12. This
utility is context-sensitive (such as limitations imposed on the way the
professional works by resource demands including limited time)9.
This information is probabilistic in nature rather than giving absolute
certainty. Psychological formulation also aims to allow understanding of the
patient and their situation1,2,3,4.
Looking at the formulation of ‘Dan’7 it is about
150 words in boxes connected by of arrows linking past experiences, current
events, thoughts, beliefs, responses and feelings. It certainly communicates
information such as how these different aspects may be connected and lists
important aetiological factors for psychosis such as adverse childhood experiences
and substances.
The formulation plausibly links hypervigilance to childhood
bullying (but ignoring that this hypervigilance would presumably be directed
towards others and not his own body); somatic hypervigilance may lead to a
belief that there is a lump in the neck but does not explain why the patient believes
that this lump is transmitting thoughts. The lacunae in this formulation
reflects the gaps in the evidence for purely psychological mechanisms linking
adverse childhood experiences and psychotic symptoms content and nature13.
It is possible the substance misuse is more closely linked to the generation of
psychotic symptoms and the other factors such as childhood bullying are linked
to the substance misuse rather than as depicted in the formulation.
The formulation provides some prognostic information such as
substance use, childhood bullying and criminal activity being linked to worse
outcomes such as higher relapse rates or aggression. The formulation provides
useful pointers for psychotherapy such as addressing substance misuse or the
links between past experiences, current life difficulties and thoughts and
feelings.
On the other hand, this formulation has important
information gaps. It is not clear how severe the psychotic symptoms are and
whether they persist when substances are not being abused (such as psychosis
related to substance intoxication or relatively brief psychotic episodes
triggered by substance misuse) or whether the psychosis is caused by mood
problems caused by adverse childhood experiences and/or current life
difficulties – all these distinctions have clinical relevance not just for
prognosis but for appropriate interventions and treatment14. For
example, if the psychotic symptoms are only present during substance
intoxication or for short periods afterwards then prolonged antipsychotic
treatment is unlikely to be indicated.
In the text before the formulation of ‘Dan’ the diagnosis of
schizophrenia is mentioned. This diagnosis is associated with a great deal of
information such as factors associated with increased risk, associated
differences in biological or psychological factors and the effectiveness of
interventions15. Diagnostic constructs are associated with
information that is learned by the clinician that allows easier recall and use
of this information under time/ fatigue/ workload and other pressures in the
context of brief appointments or emergency/ overnight working practices of most
psychiatrists.
Schizophrenia as a diagnostic construct is defined by the
absence of known organic factors explaining the clinical picture, nevertheless
it is associated with multiple factors known to increase the risk of meeting the
diagnostic criteria such as childhood adverse experiences and cannabis16,17.
Like many general medical conditions there is no single fixed outcome but we
have evidence for a range of probable outcomes including recovery and their
likelihood18. We also have evidence for the likely effectiveness of
interventions in people meeting schizophrenia criteria such as antipsychotics19
and cognitive behavioural therapy for psychosis20 to guide choice of
therapeutic interventions.
An additional diagnosis – such as substance harmful use-
will need to be used to indicate the important role of substance use affecting
prognosis and to influence clinical management to include providing information
on the effect of substances to the patient and referring for a psychosocial
intervention to address the substance misuse. Two diagnostic constructs may
thus need to be used but the total word count is still far less than that of
the formulation. Although the diagnostic construct schizophrenia does not
explicitly state the causative factors of this case many general medical
diagnostic constructs - such as type 2 diabetes - do not state the causative
factors in their title and even when a necessary cause is included in the title
– such as tuberculosis – other important factors in the aetiology are not
included in the title (for instance the role of overcrowded housing in
tuberculosis)21. Psychosis is a very broad concept that some extend
to unusual experiences that cause little harm or dysfunction to more severe
states that can meet diagnostic criteria for schizophrenia or bipolar disorder22.
It is therefore useful to identify a more specific classification than
psychosis alone14 to provide more useful information to guide
clinical decision making for the individual patient.
Research and Social Functions
Psychological formulation – except psychodynamic formulation
- has disappointing reliability23 impairing its usefulness in
classifying participants in research. Conceptually as a classification system
for research, psychological formulation would have to be reduce the emphasis on
the individual-specific factors as they will vary a lot between individuals –
they will need to focus on a few common elements otherwise the number of
participants in each group would be too small and underpowered to detect
statistically significant differences between groups. Although not suitable as
a classification system for research, psychological formulation can be used as
part of an intervention in studies evaluating their effectiveness.
There are many social functions of a health classification
such as diagnosis – administrative (activity measurement and billing),
organisational (services organised according to diagnosis or group of
conditions), statistical (incidence/ prevalence and planning healthcare
provision on basis of need) and access to benefits or special educational
support24. Given the high word count of psychological formulation,
it’s highly individualised nature and the lack of horizontal integration with
general medical diagnostic systems it is not very suitable as system for
administrative, organisational, statistical or access to benefits or special
educational support. Most health activity involves payment from third parties
such as health insurance or government and providers are required to provide
activity data to justify their expenditure – psychological formulation would
not satisfy the requirements of third party funders as it would differ greatly
between individuals making counting categories difficult. Similar problems
apply for statistical and organisational purposes. Psychiatric diagnosis for
all its faults is the most convenient system to fulfil
administrative/statistical social functions25.
To gain access to benefits for example, a diagnosis – with
empirical evidence of association with impaired functioning and a recognised
classified entity in ICD10 for instance – with additional description of
impaired functioning in the individual is more likely to convince welfare
agencies of eligibility for benefits – it relies on empirical evidence (lacking
for psychological formulation in comparison to psychiatric diagnosis2)
and a standardised recognised
classification not just expert assertion and is compatible with existing
systems for general medical conditions.
Discussion
Psychological formulation is unable to replace psychiatric
diagnosis for psychiatrists’ clinical work for the contexts in which they work
– such as brief appointments or emergency/ night work – and requirements for
empirical-based advice and decision-making8 as much of the evidence
base is based on diagnostic classifications2. This statement carries
caveats. For those – including some psychiatrists – whose clinical work uses
primarily psychosocial interventions in the context of long appointments with
relatively few patients during routine hours may find psychological formulation
more useful. For some ‘organic’
conditions such as dementia or general medical conditions with psychological
problems then psychological formulation will be used to address specific
problems rather than overall management of the primary condition. Conversely
for conditions where medication has little benefit – such as where people meet
borderline personality disorder diagnostic criteria – then management plans
would preferably be based on psychological formulation rather than diagnosis.
This difference in clinical utility of psychological formulation depending on
presenting condition illustrates the usefulness of psychiatric diagnosis –
different conditions have different implications such as range of likely
outcomes, treatment responses and usefulness of psychological formulation.
For the social functions of classification – such as
administrative, statistical or access to benefits – diagnosis is superior to
psychological formulation. Psychological formulation would not easily used as a
classification system for participants in research making it harder to close
the evidence gap with diagnostic based research. Diagnostic formulations –
although disagreement exists as to what they should contain 26,27
and can exclude or include psychological theories3 including
incorporating psychological formulations from other professionals or their own
work – can incorporate both the diagnosis (and differential diagnosis) as well
as individual predisposing, precipitating, perpetuating and protective factors
in the patient3.
For general medical conditions it is common practice to use
additional information apart from the diagnosis to help with estimating
prognosis and guiding clinical decision-making such as the use of staging for
cancers, Glasgow Coma Scale for acute brain injury, DAS28 for rheumatoid
arthritis and Modified Blatchford Score in acute upper gastrointestinal
haemorrhage21.
Diagnostic formulation – beginning with a diagnosis then
expanding with further relevant individual information and can include
psychological theorising – is the best complex classification system for most
psychiatrists in the context of the way they work and their need to provide
evidence-based advice to the patient and to guide decision-making. It can build
on the empirical information attached to a diagnosis with further individual
and contextual factors (which may provide additional empirical evidence
affecting prognosis or clinical management or aid further understanding of the
patient and their predicament3). Diagnosis can also be combined with
psychological formulation as they provide supplementary information.
References
1. Division of
Clinical Psychology. Classification of
Behaviour and Experience in Relation to Functional Psychiatric Diagnoses: Time
for a Paradigm Shift. DCP Position Statement. British Psychological Society
2013
2. Macneil, CA, Hasty, MK, Conus, P. and Berk, M. Is
diagnosis enough to guide interventions in mental health? Using case
formulation in clinical practice. BMC
Medicine 2012; 10: p.111
3. Summers A., Boland B., Dave S., Gill H., Ingrams C. &
Padakarra S. Occasional Paper 103: Using
formulation in general psychiatric care: good practice. Royal College of
Psychiatrists, 2017
4. Division of Clinical Psychology. Good Practice Guidelines on the use of psychological formulation.
British Psychological Society 2011
5. Creed F. How consultants manage their time. BJPsych
Advances 1995; 1: 65-70
6. Tyrer P, Al Muderis O & Gulbrandsen G. Distribution
of case-load in community mental health teams. 2001; Psychiatric Bull 25: 10-12
7. Cooke, A., Basset, T., Bentall, R., Boyle, M., Cupitt, C.
and Dillon, J. Understanding psychosis
and schizophrenia. British Psychological Society, 2014
8. Shah, P & Mountain, D. The medical model is
dead--long live the medical model Br J of
Psychiatry 2007; 191: 375-377
9. Kendell R.E. & Jablensky A. Distinguishing between
validity and utility of psychiatric diagnoses. Am J Psychiatry 2003; 160:
4-12
10. Kendler KS. The Nosologic Validity of Paranoia (Simple
Delusional Disorder). Arch Gen Psychiatry 1980; 37: 699-706
11. First MB, Pincus HA, Levine JB, Williams JBW, Ustun B
and Peele R. Clinical utility as a criterion for revising psychiatric diagnoses. Am J
Psychiatry 2004; 161: 946-954
12. Tennant N & Thompson IE. Causes and Logic in
Epidemiological Psychiatry 2: Causal Models and Logical Inference. Br J Psychiatry 1980; 137: 579-582
13. Gibson, LE, Alloy, LB & Ellman, LM. Trauma and the
psychosis spectrum: A review of symptom specificity and explanatory mechanisms Clin Psychol Rev 2016; B: 92-105
14. Frances A. A report card on the utility of psychiatric
diagnosis. World Psychiatry 2016; 15: 32-3
15. Matheson, SL, Shepherd, AM & Carr, VJ. How much do
we know about schizophrenia and how well do we know it? Evidence from the
Schizophrenia Library Psychol Med
2014; 44: 3387-3405
16. Belbasis L, Köhler CA, Stefanis N, Stubbs B, van Os J,
Vieta E, Seeman MV, Arango C, Carvalho AF, Evangelou E. Risk factors and
peripheral biomarkers for schizophrenia spectrum disorders: an umbrella review
of meta‐analyses. Acta Psychiatr Scand 2018
Feb;137: 88-97.
17. Radua J, Ramella‐Cravaro V, Ioannidis JP, Reichenberg A,
Phiphopthatsanee N, Amir T, Yenn Thoo H, Oliver D, Davies C, Morgan C, McGuire
P. What causes psychosis? An umbrella review of risk and protective factors. World Psychiatry 2018;17: 49-66
18. Menezes, NM, Arenovich, T & Zipursky, RB. A systematic
review of longitudinal outcome studies of first-episode psychosis Psychol Med 2006; 36: 1349-1362
19. Leucht S, Leucht C, Huhn M, Chaimani A, Mavridis D,
Helfer B, Samara M, Rabaioli M, Bächer S, Cipriani A & Geddes JR. Sixty
years of placebo-controlled antipsychotic drug trials in acute schizophrenia:
systematic review, Bayesian meta-analysis, and meta-regression of efficacy
predictors. Am J Psychiatry 2017; 174:927-42
20. Jauhar S, McKenna PJ, Radua J, Fung E, Salvador R, Laws
KR. Cognitive–behavioural therapy for the symptoms of schizophrenia: systematic
review and meta-analysis with examination of potential bias. Br J of Psychiatry 2014; 204: 20-9
21. Walker BR, Colledge NR, Ralston SH & Penman I. Davidson’s Principles and Practice of
Medicine (22nd Edition), Churchill Livingstone (Elsevier) 2014
22. Van Os, J & Reininghaus, U. Psychosis as a transdiagnostic and extended
phenotype in the general population World
Psychiatry 2016; 15: 118-124
23. Flinn, L, Braham, L & Nair, R. How reliable are case
formulations? A systematic literature review. Br J Clin Psychol 2015; 54:
266-290
24. Rose, N. What is Diagnosis For? Lecture given at the Institute of Psychiatry
(London) in 2013. Transcript can be found at http://nikolasrose.com/wp-content/uploads/2013/07/Rose-2013-What-is-diagnosis-for-IoP-revised-July-2013.pdf
25. Boyle M. The problem with diagnosis. The Psychologist
2007; 20: 290-292
