Download Scale for Lifetime Course of Psychotic Illness

Scale for Lifetime Course of Psychotic Illness: A longitudinal scale for psychotic
illnesses
Dr V Balain1, Dr L Palaniyappan1, Dr R Dangi2, Prof P Liddle1
1. University of Nottingham
2. Nottinghamshire Healthcare NHS Trust
Background: Quantifying psychiatric signs and symptoms in psychotic illness has
always been a challenge. The care provided to patients with psychiatric illnesses has
changed with time. Pioneers of classification of psychiatric illnesses (Kahlbaum,
Kraepelin, Bleular) observed patients in asylums over long periods of time. In the last
thirty years asylum care has given way to community based care. Most of the patients
with chronic psychotic illnesses who would have earlier been in asylums are now cared
for in the community or residential settings under the care of rehabilitation services.
Mental health professionals practicing today are not able to observe patients in the
community over long periods as patients are reviewed at specific intervals or at the time
of crisis. Most rating scales currently available for psychotic illnesses are cross sectional
e.g. Positive and Negative Symptom Scale (PANSS; Kay 1991), Scale for Assessment of
Negative Symptoms (SANS ; Andreason 1984a), Brief Psychiatric rating Scale (BPRS;
Overall & Gorham 1962). Although they can be repeated over a period of time to
measure change in symptomatology, they fail to provide longitudinal picture of various
symptoms which patients with psychotic illnesses experience. Particular challenge has
been to devise a scale which measures lifetime prevalence of signs and symptoms in
patients with psychotic illnesses. We aim to develop and test a new scale which can
inform clinicians working in rehabilitation services about the persistence of symptom
factors of psychotic symptoms over the lifetime course of illness.
Kraepelinian dichotomy has dominated the classification of psychotic illness and has
provided the foundation for classification for over a century. Current evidence fails to
provide a point of rarity between psychotic illnesses (Peralta et al 2007; Craddock et al
2005; Crow 1995). Therefore the move is towards dimensional approach to psychotic
illnesses, away from concepts of Kraepelinian dichotomy. We aim to develop this scale
for patients with a diagnosis of schizophrenia, schizoaffective and bipolar affective
disorder type 1, based on continuum diagnosis of psychotic illnesses. These patients
constitute majority of patients under the care of rehabilitation services.
Aim: To test inter-rater reliability and external validity of the new Scale for Lifetime
Course of Psychotic Illness (Addendum 1). We aim to study whether the total persistence
scores or persistence of individual symptom factors can predict cognitive impairment
(speed of processing) and subtle thought disorder during period of stability. We also aim
to investigate if persistence of psychotic symptoms predicts structural changes in the
brain by using VBM (Voxel Based Morphometry) to measure loss of grey matter.
Method: We used factor analysis data for nineteen psychotic symptoms which are
included in the scale- Signs and Symptoms in Psychotic Illness (SSPI; Liddle et al 2002).
Factor analysis of these symptoms revealed five symptom factors which accounted for
loading of these symptoms and were included in our scale. The five symptom factors
are- Anxiety/depression, Psychomotor poverty,
Disorganisation, Reality distortion and Psychomotor excitation. Loss of Insight was added
as the sixth symptom factor (Addendum 1).
70 patients with a DSM-IV diagnosis of schizophrenia, schizoaffective and bipolar
affective disorder Type 1 disorders were recruited in stable phase of illness. Stability was
defined as no change in Global Assessment of Functioning (GAF of DSM-IV; American
Psychiatric Association 1994) score for at least 6 weeks. Diagnosis was established by
discussions in consensus meetings of co-investigators and using computer programme
OPCRIT (McGuffin & Farmer 1991). Their case notes were used to score individual
episodes (0, 1, 2 or 9) and persistence of these symptom factors over lifetime (0 to 6,
Total 0-36) (Addendum 1). Social and Occupational Functioning Assessment Scale
(SOFAS; Goldman et al 1992) was used to assess their social functioning, Digit- symbol
test for cognitive functioning and Thought & Language Index (TLI; Liddle et al 2002) to
identify subtle thought disorder. Structural 3 Tesla MRI scans of these patients were
performed on the day of study participation.
Inter-rater reliability was established for total persistence score and individual symptom
factors using intraclass correlation (ICC). Two raters scored 25 cases independently after
attending training and consensus meetings for scoring. SOFAS score was obtained from
videos of patients. Two raters independently scored the videos to establish inter-rater
reliability for SOFAS score. Intraclass correlation (ICC) was used to establish interrater
reliability. Interrater reliability was achieved using ICC for TLI scores with four
independent raters.
Data was analysed for distribution and where it was found to be non-normal, log
transformation was used and kurtosis & skewness of distribution analysed. To establish
external validity Pearson correlation coefficients were calculated for relationship between
total persistence & individual symptom factor persistence scores with SOFAS.
Correlations were calculated to rule out possible confounding variables (duration of
illness & chlorpromazine equivalent doses). Multiple regression was used to identify
symptom factors which independently influenced SOFAS scores. Similar analysis was
performed to test the hypothesis that persistence of psychotic symptoms leads to
impaired cognitive performance (Digit Symbol test score) and subtle thought disorder
(TLI scores).
Voxel Based Morphometry analysis was done using SPM 8 (Friston 2007) to reorient
images, normalise anatomical data and to segment grey matter, white matter &
cerebrospinal fluid. Spatial smoothing was applied and an explicit masking technique was
used for image analysis. Intracranial volume was introduced as a confounding variable.
Grey matter differences were calculated using Total persistence and individual symptom
factors as covariates.
Results:
Interrater reliability analysis- Intraclass correlation (ICC) for six symptom factors and
total persistence score ranged from 0.68 to 0.90. ICC for SOFAS was 0.83. This indicated
that the scale was reliable.
External validity analysis- SOFAS score was significantly correlated with Total persistence
and Psychomotor poverty, Disorganisation, Reality distortion & Loss of Insight symptom
factors. Multiple
regression revealed that Psychomotor poverty and Loss of insight independently had
negative relationship with SOFAS scores.
The above analysis proves that the scale is reliable and valid measure of persistence of
psychotic symptoms.
Cognitive impairment analysis (Digit-Symbol test scores) – Correlation coefficient for
Total persistence was -0.22 (p=0.033). Multiple regression revealed higher Psychomotor
poverty (-0.248 p=0.034) and Reality Distortion (-0.244 p=0.036) predicted poorer
performance on cognitive task.
Subtle thought disorder (TLI) - Multiple regression showed that there was a negative
association between Total persistence and persistence scores of Disorganistion & Loss of
insight symptom factors and subtle thought disorder.
VBM analysis-Patients with greater persistence scores, with chlorpromazine doses as a
nuisance covariate, have less grey matter in frontal lobe, mid cingulate and medial
parietal lobe (pFDR=0.048 T =3.14). Greater loss of grey matter is found in midcingulate, medial parietal and temporal lobe in patients with higher scores for
Kraepelinian persistence (Disorganisation, Psychomotor poverty, and Reality distortion).
Discussion: Scale for Lifetime Course of Psychotic Illness is a reliable scale and also
achieved external validity. The persistence scores obtained confirm the importance of
negative symptoms (Milev et al 2005) and loss of insight (Sitzer et al 2008) as being the
predictors of social functioning. The scores were also informative in predicting the
cognitive functioning (Puig et al 2008) and subtle thought disorder (Bowie et al 2008).
The scale also informs us about structural changes in the brain related to persistence of
psychotic symptoms.
This scale can be used to develop better understanding of not only the persistence of
psychotic symptoms over lifetime. It also provides individual relapse episode symptom
factor data, medications used and duration of these episodes. It is a helpful scale to
predict the prognosis and assist clinicians in biopsychosocial recovery of patient. Its use
is particularly relevant for rehabilitation psychiatry professionals as it provides a
longitudinal picture for patients with often long history of various symptoms of psychotic
illness. This scale helps in providing information about their illness to patients and a
relative in a non-stigmatising way as it does not use any diagnostic ‘pigeon holes’.