Spurious precision : variability in procedural validity of diagnostic procedures in psychotic disorders and implications for research and treatment

Very few studies have quantified the level of agreement among alternative diagnostic procedures that use a common set of fixed operational criteria. The authors examined the procedural validity of four independent methods of assigning DSM-III-R diagnoses of psychotic disorders. METHOD: The research was conducted as a satellite study to the DSM-IV Field Trial for Schizophrenia and Related Psychotic Disorders. The setting was the National Health and Medical Research Council Schizophrenia Research Unit's Early Psychosis Prevention and Intervention Centre, which focuses on first-episode psychosis. Consecutively admitted patients (N = 50) were assessed by independent raters who used four different procedures to determine a DSM-III-R diagnosis. These procedures were 1) the diagnostic instrument developed for the DSM-IV field trial, 2) the Royal Park Multidiagnostic Instrument for Psychosis, 3) the Munich Diagnostic Checklists, and 4) a consensus DSM-III-R diagnosis assigned by a team of clinician researchers who were expert in the use of diagnostic criteria. RESULTS: Concordance between pairs of diagnostic procedures was only moderate. Corresponding levels of percent agreement, however, ranged from 66% to 76%, with converse misclassification rates of 24%-34% (assuming one procedure to be "correct"). CONCLUSIONS: These findings have significant research and clinical implications. Despite the introduction of operationally defined diagnoses, there remained an appreciable level of differential classification or misclassification arising from variability in the method of assigning the diagnostic criteria rather than the criteria themselves. Such misclassification may impede neurobiological research and have harmful clinical effects on patients with first-episode psychosis.

Evaluation of Bayesian belief networks for diagnosis of psychotic disorders

The thesis examined the inter-rater reliability and procedural validity of four computerised Bayesian belief networks (BBNs) which were developed to assist with the diagnosis of psychotic disorders. The results of this research indicated that BBNs can significantly improve diagnostic reliability and may represent an important advance over current diagnostic methods. The professional portfolio investigated, through the presentation of case studies and review of literature relevant to each case study, how comorbidity and context of depression may impact on cognitive behavioural therapy treatment.

'Better health choices' by telephone: a feasibility trial of improving diet and physical activity in people diagnosed with psychotic disorders

The study objective was to evaluate the feasibility of a telephone delivered intervention consisting of motivational interviewing and cognitive behavioural strategies aimed at improving diet and physical activity in people diagnosed with psychotic disorders. Twenty participants diagnosed with a non-acute psychotic disorder were recruited. The intervention consisted of eight telephone delivered sessions targeting fruit and vegetable (F&V) consumption and leisure screen time, as well as smoking and alcohol use (as appropriate). F&V frequency and variety, and overall diet quality (measured by the Australian Recommended Food Score, ARFS), leisure screen time, overall sitting and walking time, smoking, alcohol consumption, mood, quality of life, and global functioning were examined before and 4-weeks post-treatment. Nineteen participants (95%) completed all intervention sessions, and 17 (85%) completed follow-up assessments. Significant increases from baseline to post-treatment were seen in ARFS fruit, vegetable and overall diet quality scores, quality of life and global functioning. Significant reductions in leisure screen time and overall sitting time were also seen. Results indicated that a telephone delivered intervention targeting key cardiovascular disease risk behaviours appears to be feasible and relatively effective in the short-term for people diagnosed with psychosis. A randomized controlled trial is warranted to replicate and extend these findings.

The specificity of platelet glutamate receptor supersensitivity in psychotic disorders.

Hypoglutamatergic function is implicated in the pathogenesis of schizophrenia, and supersensitivity of platelet NMDA receptors has been reported in schizophrenia. The aim of this study was to examine the platelet glutamate receptor sensitivity in patients with schizophrenia (n=12), mania with psychotic features (n=10) and depression with psychotic features (n=10) and matched controls (n=12) in order to assess if this is a marker of schizophrenia or occurs in other psychotic conditions. Glutamate receptor sensitivity was assessed using the intracellular calcium response to glutamate measured with spectrofluorometry. The percentage response of the schizophrenic and depressed psychotic subjects to glutamate stimulation was significantly greater than control subjects (p<0.005). The mania with psychotic features group was not significantly different to controls. This data suggests that platelet glutamate receptors may be supersensitive in schizophrenia and depression with psychotic features. Furthermore, the platelet may be a possible peripheral marker of glutamate function in schizophrenia and depression with psychotic features.

A comparison of olanzapine with haloperidol in cannabis-induced psychotic disorder: a double-blind randomized controlled trial

Little controlled data exist on the treatment of substance induced psychotic disorders. In this study, 30 patients meeting DSM-IV criteria for cannabis induced psychotic disorder were randomly allocated to receive either olanzapine or haloperidol in a 4-week double-blind clinical trial. There were no significant outcome differences between the two groups on any of the primary outcome measures, the Brief Psychiatric Rating Scale (haloperidol 25.7; olanzapine 27.1; P = 0.70); Clinical Global Impression (CGI) severity scale (haloperidol 1.8, olanzapine 2.3; P = 0.21) or the CGI improvement scale (haloperidol 1.3, olanzapine 1.7; P = 0.16). The haloperidol group however, developed significantly more extrapyramidal side-effects as measured by the Simpson Angus Scale (haloperidol 11.4, olanzapine 2.5; P = 0.014). Significantly (P = 0.027) more biperidin was used for extrapyramidal side-effects in the haloperidol (7.143 mg) than in the olanzapine (0.357 mg) group. Olanzapine appears to be as effective as haloperidol in the treatment of cannabis induced psychotic disorder, but is associated with a lower rate of extrapyramidal side-effects.

Parents with psychosis : a pilot study examining self-report measures related to family functioning

The aims of this study were to examine the utility of various self-report instruments related to family functioning in families where a parent has a psychotic disorder, and to explore associations between these instruments and symptoms in the parent. Twenty-one parents with a psychotic disorders participated in the study. All participants were able to complete the questionnaires and the majority of parents reported levels of parental competence in the average range. Most parents (90%) perceived themselves to be effective parents, however 30% reported low levels of satisfaction with the parenting role. There were significant associations between objective measures of negative symptoms and self-report scores related to problems in ways of coping, and problems with parent-child interactions. Many individuals with psychosis were able to report areas of perceived need related to their role as parents and to the functioning of their families, however there are several limitations in the use of these instruments in this setting.

Is early intervention in psychosis cost-effective over the long term?

Objective: This study assesses the long-term cost-effectiveness of a comprehensive model of mental health care for first-episode psychosis. The study is an extension of a previous economic evaluation of the Early Psychosis Prevention and Intervention Centre (EPPIC) that assessed the first-year costs and outcomes of treatment.

Method: The current study used a matched, historical control group design with a follow-up of approximately 8 years. Complete follow-up data were available for 65 of the original 102 participants. Direct public mental health service costs incurred subsequent to the first year of treatment and symptomatic and functional outcomes of 32 participants initially treated for up to 2 years at EPPIC were compared with a matched cohort of 33 participants initially treated by generic mental health services. Treatment-related resource use was measured and valued using Australian published prices.

Results: Almost 8 years after initial treatment, EPPIC subjects displayed lower levels of positive psychotic symptoms (P = .007), were more likely to be in remission (P = .008), and had a more favorable course of illness (P = .011) than the controls. Fifty-six percent of the EPPIC cohort were in paid employment over the last 2 years compared with 33% of controls (P = .083). Each EPPIC patient costs on average A$3445 per annum to treat compared with controls, who each costs A$9503 per annum.

Conclusions: Specialized early psychosis programs can deliver a higher recovery rate at one-third the cost of standard public mental health services. Residual methodological limitations and limited sample size indicate that further research is required to verify this finding.

The procedural validity of retrospective case note diagnosis

Objective: Deriving diagnoses from retrospective case note examination is a common practice in psychiatric research. The Operational Criteria (OPCRIT) diagnostic checklist is essentially a checklist built up of operational criteria defined by a comprehensive glossary and is designed to assign reliable diagnoses from case notes. However, the validity of such a procedure compared with procedures involving prospective assessment has never been tested. We examined the procedural validity of the OPCRIT diagnostic system in relation to four other diagnostic procedures mostly employing prospectively gathered information.

Method: Three experienced psychopathology raters rated the case notes and clinical abstracts, using the OPCRIT method of diagnostic assignment, of 50 subjects who had participated in an early procedural validity study as an adjunct to the DSM-IV Field Trial for psychotic disorders. The setting was the Early Psychosis Prevention and Intervention Centre (EPPIC), which focuses on first episode psychosis.

Results: The pairwise concordance with the other procedures for DSM-III-R diagnoses assigned by OPCRIT using ratings derived from either the clinical abstracts or the case notes was found to be only poor to moderate when compared with the pairwise concordance of the four other procedures. The per cent agreement between OPCRIT clinical abstracts diagnoses and the other procedures ranged from 49% to 60% with kappa values between 0.30 and 0.45, and for OPCRIT case note diagnoses and the other procedures the per cent agreement range was between 44% and 57% and the kappa values were between 0.35 and 0.49.

Conclusions: The procedural validity of diagnoses assigned via the application of checklists of operational criteria to case notes and clinical abstracts alone is unacceptably poor. Such sources need to be buttressed by other data, particularly direct patient interview and informant material.