Developing the diagnostic and statistical manual V: what will "statistical" mean in DSM-V?

Lifetime Psychiatric Comorbidity and Diagnostic Trajectories in an Italian Psychiatric Sample

OBJECTIVE

Comorbidity in psychiatric patients has been widely examined in the literature, enucleating the role in misinterpretation of symptom's root in a multi-disease background, as well as the impact on the quality of life, outcome, and health-care effects. This research aimed to examine, in an Italian population of psychiatric patients, the diagnostic continuum in the context of lifetime psychiatric comorbidity, assessing possible differences related to the onset disorder.

METHOD

A retrospective analysis of medical records of 458 subjects, in which various psychiatric diagnoses were represented and categorized in 16 nosographic classes, was conducted.

RESULTS

Results showed that "Bipolar disorder" (22.06%) was the most frequent diagnosis, "Eating disorder" had the earliest age onset (Mean age years = 16 ± 1.41), and "Schizophrenia" showed the longest disease duration (Mean years = 24.20±12.76). Moreover, 54,4% of the final sample presented at least one psychiatric comorbidity in disease history, while "Other personality disorders" was the most comorbidity-associated diagnosis, representing 29% of all the cases with more than 3 past diagnoses. Heterotypic transition was observed in fairly all considered onset diagnoses, exception made for "Schizophrenia" with 75% of the subjects showing homotypic progression.

CONCLUSIONS

Our results suggest a tendency to make multiple diagnoses over psychiatric patients' lifetime in the majority of cases, often escaping from the original onset nosographic domain. More generally, our findings agree with a broad consensus that describes psychiatric symptomatic dimensions rather overlapped and correlated with each other, leading to a more transdiagnostic clinical approach.

Future Directions for the Examination of Mediators of Treatment Outcomes in Youth

How do psychological therapies work? How can we enhance treatment to improve outcomes? Questions of mediation lie at the heart of these inquiries. However, within the child and adolescent treatment literature, studies of mediation often rely on methodological and statistical approaches that limit the inferences that can be drawn from study findings. This future directions review delineates some of these issues and suggests improvements through two interrelated paths. We propose that mediation studies in the youth treatment literature will be enhanced (a) by adopting best practices in nomothetic (group-based) methodologies for assessing putative mediating variables and conducting appropriate statistical analyses and (b) by increasing the use of idiographic (individual-focused) approaches to youth outcome research through mediation studies that use innovative designs, data collection techniques, and analytic methods. We discuss the applicability of findings using these approaches to the treatment of youth in particular.

The DSM revision process: needing to keep an eye on the empirical ball

From DSM-III onward, successive DSM editions have strived to ground the diagnostic definitions in empirical evidence. DSM-IV established a three-stage process of empirical review, consisting of comprehensive and systematic literature reviews, secondary analyses of datasets, and field trials to provide reliability and validity data for the most substantial or controversial proposals. DSM-IV Work Group members were required to review the empirical literature to document explicitly the evidence supporting the text and criteria published in DSM-IV. As noted by Kendler and Solomon (2016), in contrast to the emphasis on systematic reviews in medicine which is a manifestation of the evidence-based medicine movement, such systematic evidence-based reviews have not been consistently integrated into the development of DSM-5, raising questions about empirical rigor underlying the DSM-5 revision. It is likely that this regression in terms of anchoring the revision process in a comprehensive review of empirical data stemmed from the emphasis during the DSM-5 revision process on trying to move DSM-5 from its categorical descriptive approach towards a more etiological dimensional approach. Although such a shift ultimately did not occur, the effort spent on trying to achieve a paradigm shift likely came at the expense of the hard work of conducting systematic empirical reviews. For the DSM to continue to remain credible in the current era of evidence-based medicine, it is essential that the developers of future editions of the DSM avoid taking their eye off the empirical ball and insure that the manual remains grounded in solid empirical evidence.

The Troubled History of Psychiatry's Quest for Specificity

Over the course of the nineteenth century, medical disciplines replaced holistic conceptions of body and mind with specific diagnoses that were unrelated to the qualities and circumstances of the individuals who harbored them. Despite periodic attempts from the late nineteenth through the mid-twentieth centuries to implement diagnostic systems based on the principle of specificity, psychiatric diagnoses remained undifferentiated, overlapping, and capacious. The need for medical legitimacy, compatibility with a biomedical model, and conditions that third parties would reimburse led psychiatry to replace the psychodynamically oriented DSM-I and DSM-II with the radically empiricist DSM-III in 1980. This manual emphasized explicit measurement, symptom-based entities, and homogeneous categories that were compatible with the specific disorders embraced in the rest of medicine. Yet the diagnostic system that the DSM-III launched was incongruent with the underlying nature of the continuous, fluid, and intersecting conditions with which psychiatry deals. The widespread institutionalization of the specific diagnostic system in psychiatric practice, however, prevented any thoroughgoing revisions when the DSM-5 was published in 2013. The result is an impasse between psychiatry's classificatory system and the need for scientific progress in understanding the causes of and treatments for mental disorders.

Psychiatric comorbidity and causal disease models

In psychiatry, comorbidity is the rule rather than the exception. Up to 45% of all patients are classified as having more than one psychiatric disorder. These high rates of comorbidity have led to a debate concerning the interpretation of this phenomenon. Some authors emphasize the problematic character of the high rates of comorbidity because they indicate absent zones of rarities. Others consider comorbid conditions to be a validator for a particular reclassification of diseases. In this paper we will show that those at first sight contrasting interpretations of comorbidity are based on similar assumptions about disease models. The underlying ideas are that firstly high rates of comorbidity are the result of the absence of causally defined diseases in psychiatry, and second that causal disease models are preferable to non-causal disease models. We will argue that there are good reasons to seek after causal understanding of psychiatric disorders, but that causal disease models will not rule out high rates of comorbidity--neither in psychiatry, nor in medicine in general. By bringing to the fore these underlying assumptions, we hope to clear the ground for a different understanding of comorbidity, and of models for psychiatric diseases.

Auxiliary marker-assisted classification in the absence of class identifiers

Constructing classification rules for accurate diagnosis of a disorder is an important goal in medical practice. In many clinical applications, there is no clinically significant anatomical or physiological deviation exists to identify the gold standard disease status to inform development of classification algorithms. Despite absence of perfect disease class identifiers, there are usually one or more disease-informative auxiliary markers along with feature variables comprising known symptoms. Existing statistical learning approaches do not effectively draw information from auxiliary prognostic markers. We propose a large margin classification method, with particular emphasis on the support vector machine (SVM), assisted by available informative markers in order to classify disease without knowing a subject's true disease status. We view this task as statistical learning in the presence of missing data, and introduce a pseudo-EM algorithm to the classification. A major distinction with a regular EM algorithm is that we do not model the distribution of missing data given the observed feature variables either parametrically or semiparametrically. We also propose a sparse variable selection method embedded in the pseudo-EM algorithm. Theoretical examination shows that the proposed classification rule is Fisher consistent, and that under a linear rule, the proposed selection has an oracle variable selection property and the estimated coefficients are asymptotically normal. We apply the methods to build decision rules for including subjects in clinical trials of a new psychiatric disorder and present four applications to data available at the UCI Machine Learning Repository.

A study of the dimensionality and measurement precision of the SCL-90-R using item response theory

We used item response theory (IRT) to (a) investigate the dimensionality of the Symptom Checklist-90-Revised (SCL-90-R) in a severely disturbed patient group, (b) improve the subscales in a meaningful way and (c) investigate the measurement precision of the improved scales. The total sample comprised 3078 patients (72% women, mean age=35±9) admitted to 14 different day hospitals participating in the Norwegian Network of Personality-focused Treatment Programmes. Mokken Scale Analysis was used to investigate the dimensionality of the SCL-90-R and improve the subscales. This analysis was theory-driven: the scales were built on two start items that reflected the content of the disorder that corresponds with the specific scale. The Graded Response Model was employed to determine measurement precision. Our theory-driven IRT approach resulted in a new seven-factor solution including 60 of the 90 items clustered in seven scales: depression, agoraphobia, physical complaints, obsessive-compulsive, hostility (unchanged), distrust and psychoticism. Most of the new scales discriminated reliably between patients with moderately low scores to moderately high scores. In conclusion, we found support for the multidimensionality of the SCL-90-R in a large sample of severely disturbed patients.

Comparing autism, PDD-NOS, and other developmental disabilities on parent-reported behavior problems: little evidence for ASD subtype validity

Studies on the distinction between Autistic Disorder (AD) and Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS) have been inconclusive. This study examined the validity of PDD-NOS by comparing it to AD and other developmental disorders (DD) on parent-reported behavior problems. Fifty-four children with PDD-NOS were individually matched on age and non-verbal IQ to 54 children with AD and 54 children with DD. Groups were compared on select subscales of the Child Behavior Checklist. High rates of psychopathology were observed in both ASD groups. The only difference between PDD-NOS and AD groups was higher scores in the PDD-NOS group on two items measuring Anxiety/Depression. Cognitive functioning may be a more salient variable than subtype when studying psychopathology in individuals with ASDs.

Informing the symptom profile of complicated grief

BACKGROUND

Complicated Grief (CG) is under consideration as a new diagnosis in DSM5. We sought to add empirical support to the current dialogue by examining the commonly used Inventory of Complicated Grief (ICG) scale completed by 782 bereaved individuals.

METHODS

We employed IRT analyses, factor analyses, and sensitivity and specificity analyses utilizing our full sample (n = 782), and also compared confirmed CG cases (n = 288) to noncases (n = 377). Confirmed CG cases were defined as individuals bereaved at least 6 months who were seeking care for CG, had an ICG ≥ 30, and received a structured clinical interview for CG by a certified clinician confirming CG as their primary illness. Noncases were bereaved individuals who did not present with CG as a primary complaint (including those with depression, bipolar disorder, anxiety disorders, and controls) and had an ICG<25.

RESULTS

IRT analyses provided guidance about the most informative individual items and their association with CG severity. Factor analyses demonstrated a single factor solution when the full sample was considered, but within CG cases, six symptom clusters emerged: (1) yearning and preoccupation with the deceased, (2) anger and bitterness, (3) shock and disbelief, (4) estrangement from others, (5) hallucinations of the deceased, and (6) behavior change, including avoidance and proximity seeking. The presence of at least one symptom from three different symptom clusters optimized sensitivity (94.8%) and specificity (98.1%).

CONCLUSIONS

These data, derived from a diverse and predominantly clinical help seeking population, add an important perspective to existing suggestions for DSM5 criteria for CG.

The dimensionality of alcohol use disorders and alcohol consumption in a cross-national perspective

AIMS

To replicate the finding that there is a single dimension trait in alcohol use disorders and to test whether the usual 5+ drinks for men and 4+ drinks for women and other measures of alcohol consumption help to improve alcohol use disorder criteria in a series of diverse patients from emergency departments (EDs) in four countries.

DESIGN

Cross-sectional surveys of patients aged 18 years and older that reflected consecutive arrival at the ED. The Composite International Diagnostic Interview Core was used to obtain a diagnosis of DSM-IV alcohol dependence and alcohol abuse; quantity and frequency of drinking and drunkenness as well as usual number of drinks consumed during the last year.

SETTING

Participants were 5195 injured and non-injured patients attending seven EDs in four countries: Argentina, Mexico, Poland and the United States (between 1995-2001).

FINDINGS

Using exploratory factor analyses alcohol use disorders can be described as a single, unidimensional continuum without any clear-cut distinction between the criteria for dependence and abuse in all sites.

RESULTS

from item response theory analyses showed that the current DSM-IV criteria tap people in the middle-upper end of the alcohol use disorder continuum. Alcohol consumption (amount and frequency of use) can be used in all EDs with the current DSM-IV diagnostic criteria to help tap the middle-lower part of this continuum. Even though some specific diagnostic criteria and some alcohol consumption variables showed differential item function across sites, test response curves were invariant for ED sites and their inclusion would not impact the final (total) performance of the diagnostic system.

CONCLUSIONS

DSM-IV abuse and dependence form a unidimensional continuum in ED patients regardless of country of survey. Alcohol consumption variables, if added, would help to tap patients with more moderate severity. The DSM diagnostic system for alcohol use disorders showed invariance and performed extremely well in these samples.

Population prevalence of depression and mean Beck Depression Inventory score

BACKGROUND

For some phenomena the mean of population distributions predicts the proportion of people exceeding a threshold value.

AIMS

To investigate whether in depression, too, the population mean predicts the number of individuals at the extreme end of the distribution.

METHOD

We used data from the European Outcome in Depression International Network (ODIN) study from populations in Finland, Norway and the UK to create models that predicted the prevalence of depression based on the mean Beck Depression Inventory (BDI) score. The models were tested on data from Ireland and Spain.

RESULTS

Mean BDI score correlated well with the prevalence of depression determined by clinical interviews. A model based on the beta distribution best fitted the BDI distribution. Both models predicted the depression prevalence in Ireland and Spain fairly well.

CONCLUSIONS

The mean of a continuous population distribution of mood predicts the prevalence of depression. Characteristics of both individuals and populations determine depression rates.

Evidence-based medicine evaluation of electrophysiological studies of the anxiety disorders

We provide a systematic, evidence-based medicine (EBM) review of the field of electrophysiology in the anxiety disorders. Presently, electrophysiological studies of anxiety focus primarily on etiological aspects of brain dysfunction. The review highlights many functional similarities across studies, but also identifies patterns that clearly differentiate disorder classifications. Such measures offer clinical utility as reliable and objective indicators of brain dysfunction in individuals and indicate potential as biomarkers for the improvement of diagnostic specificity and for informing treatment decisions and prognostic assessments. Common to most of the anxiety disorders is basal instability in cortical arousal, as reflected in measures of quantitative electroencephalography (qEEG). Resting electroencephalographic (EEG) measures tend to correlate with symptom sub-patterns and be exacerbated by condition-specific stimulation. Also common to most of the anxiety disorders are condition-specific difficulties with sensory gating and the allocation and deployment of attention. These are clearly evident from evoked potential (EP) and event-related potential (ERP) electrical measures of information processing in obsessive compulsive disorder (OCD), post-traumatic stress disorder (PTSD), panic disorder (PD), generalized anxiety disorder (GAD) and the phobias. Other'ERP measures clearly differentiate the disorders. However, there is considerable variation across studies, with inclusion and exclusion criteria, medication status and control group selection not standardized within condition or across studies. Study numbers generally preclude analysis for confound removal or for the derivation of diagnostic biomarker patterns at this time. The current trend towards development of databases of brain and cognitive function is likely to obviate these difficulties. In particular, electrophysiological measures of function are likely to play a significant role in the development and subsequent adaptations of DSM-V and assist critically in securing improvements in nosological and treatment specificity.

Reducing the burden of depression

OBJECTIVE

To consider why the burden of depression persists.

METHOD

The epidemiology and disability associated with depression were reviewed to consider whether depression persists because: the causes are overwhelming, prevention is ineffective, the disease is difficult to detect or diagnose, the condition remits and recurs, treatments do not work, individuals do not seek treatment, or effective care is not provided when they do seek it.

RESULTS

The first 5 possibilities were not considered significant reasons for the persistence of the burden.

CONCLUSION

The burden persists because individuals do not seek treatment for their depression when they relapse and effective proactive treatment is not always provided when they do seek it.

Acceptable terminology and subgroups in schizophrenia: an exploratory study

There is general agreement that "the group of schizophrenias" comprises a very heterogeneous group of patients with diverse problems. Schizophrenia itself is a highly stigmatised term and yet has continued in use for nearly one hundred years. The development of cognitive behaviour therapy for psychosis and psychosocial epidemiological research has led to increased interest in finding alternative ways of conceptualisation. This study investigated attitudes of patients, care coordinators and consultant psychiatrists to the term, schizophrenia, and to psychosocial alternatives. It found that 63% of patients expressed negative attitudes to schizophrenia compared to 19% to the alternatives. However, concordance between the terms selected by patients, psychiatrists and care coordinators with those of the researchers was low. Such terms and subgroups may be more acceptable to patients but further work is needed on establishing their reliability and validity.