Tim Slade

Interpreting scores on the Kessler Psychological Distress Scale (K10).

Objective: To provide normative data on the Kessler Psychological Distress Scale (K10), a scale that is being increasingly used for clinical and epidemiological purposes.

The performance of the K6 and K10 screening scales for psychological distress in the Australian National Survey of Mental Health and Well-Being

BACKGROUND Two new screening scales for psychological distress, the K6 and K10, have been developed but their relative efficiency has not been evaluated in comparison with existing scales. METHOD The Australian National Survey of Mental Health and Well-Being, a nationally representative household survey, administered the WHO Composite International Diagnostic Interview (CIDI) to assess 30-day DSM-IV disorders. The K6 and K10 were also administered along with the General Health Questionnaire (GHQ-12), the current de facto standard of mental health screening. Performance of the three screening scales in detecting CIDI/DSM-IV mood and anxiety disorders was assessed by calculating the areas under receiver operating characteristic curves (AUCs). Stratum-Specific Likelihood Ratios (SSLRs) were computed to help produce individual-level predicted probabilities of being a case from screening scale scores in other samples. RESULTS The K10 was marginally better than the K6 in screening for CIDI/DSM-IV mood and anxiety disorders (K10 AUC: 0.90, 95%CI: 0.89-0.91 versus K6 AUC: 0.89, 95%CI: 0.88-0.90), while both were significantly better than the GHQ-12 (AUC: 0.80, 95%CI: 0.78-0.82). The SSLRs of the K10 and K6 were more informative in ruling in or out the target disorders than those of the GHQ-12 at both ends of the population spectrum. The K6 was more robust than the K10 to subsample variation. CONCLUSIONS While the K10 might outperform the K6 in screening for severe disorders, the K6 is preferred in screening for any DSM-IV mood or anxiety disorder because of its brevity and consistency across subsamples. Precision of individual-level prediction is greatly improved by using polychotomous rather than dichotomous classification.

2007 National Survey of Mental Health and Wellbeing: methods and key findings.

Objective: To provide a description of the methods and key findings of the 2007 Australian National Survey of Mental Health and Wellbeing. Method: A national face-to-face household survey of 8841 (60% response rate) community residents aged between 16 and 85 years was carried out using the World Mental Health Survey Initiative version of the Composite International Diagnostic Interview. Diagnoses were made according to ICD-10. Key findings include the prevalence of mental disorder, sex and age distributions of mental disorders, severity of mental disorders, comorbidity among mental disorders, and the extent of disability and health service use associated with mental disorders. Results: The prevalence of any lifetime mental disorder was 45.5%. The prevalence of any 12 month mental disorder was 20.0%, with anxiety disorders (14.4%) the most common class of mental disorder followed by affective disorders (6.2%) and substance use disorders (5.1%). Mental disorders, particularly affective disorders, were disabling. One in four people (25.4%) with 12 month mental disorders had more than one class of mental disorder. One-third (34.9%) of people with a mental disorder used health services for mental health problems in the 12 months prior to the interview. Conclusions: Mental disorders are common in Australia. Many people have more than one class of mental disorder. Mental disorders are associated with substantial disability, yet many people with mental disorders do not seek help for their mental health problems.

The structure of common DSM-IV and ICD-10 mental disorders in the Australian general population.

BACKGROUND Patterns of co-occurrence among the common mental disorders may provide information about underlying dimensions of psychopathology. The aim of the current study was to determine which of four models best fits the pattern of co-occurrence between 10 common DSM-IV and 11 common ICD-10 mental disorders. METHOD Data were from the Australian National Survey of Mental Health and Well-Being (NSMHWB), a large-scale community epidemiological survey of mental disorders. Participants consisted of a random population-based sample of 10641 community volunteers, representing a response rate of 78%. DSM-IV and ICD-10 mental disorder diagnoses were obtained using the Composite International Diagnostic Interview (CIDI), version 2.0. Confirmatory factor analysis (CFA) was used to assess the relative fit of competing models. RESULTS A hierarchical three-factor variation of a two-factor model demonstrated the best fit to the correlations among the mental disorders. This model included a distress factor with high loadings on major depression, dysthymia, generalized anxiety disorder (GAD), post-traumatic stress disorder (PTSD) and neurasthenia (ICD-10 only); a fear factor with high loadings on social phobia, panic disorder, agoraphobia and obsessive-compulsive disorder (OCD); and an externalizing factor with high loadings on alcohol and drug dependence. The distress and fear factors were best conceptualized as subfactors of a higher order internalizing factor. CONCLUSIONS A greater focus on underlying dimensions of distress, fear and externalization is warranted.

Lifetime prevalence of gender-based violence in women and the relationship with mental disorders and psychosocial function.

CONTEXT Intimate partner physical violence, rape, sexual assault, and stalking are pervasive and co-occurring forms of gender-based violence (GBV). An association between these forms of abuse and lifetime mental disorder and psychosocial disability among women needs to be examined. OBJECTIVES To assess the association of GBV and mental disorder, its severity and comorbidity, and psychosocial functioning among women. DESIGN, SETTING, AND PARTICIPANTS A cross-sectional study based on the Australian National Mental Health and Well-being Survey in 2007, of 4451 women (65% response rate) aged 16 to 85 years. MAIN OUTCOME MEASURES The Composite International Diagnostic Interview version 3.0 of the World Health Organizations World Mental Health Survey Initiative was used to assess lifetime prevalence of any mental disorder, anxiety, mood disorder, substance use disorder, and posttraumatic stress disorder (PTSD). Also included were indices of lifetime trauma exposure, including GBV, sociodemographic characteristics, economic status, family history of mental disorder, social supports, general mental and physical functioning, quality of life, and overall disability. RESULTS A total of 1218 women (27.4%) reported experiencing at least 1 type of GBV. For women exposed to 3 or 4 types of GBV (n = 139), the rates of mental disorders were 77.3% (odds ratio [OR], 10.06; 95% confidence interval [CI], 5.85-17.30) for anxiety disorders, 52.5% (OR, 3.59; 95% CI, 2.31-5.60) for mood disorder, 47.1% (OR, 5.61; 95% CI, 3.46-9.10) for substance use disorder, 56.2% (OR, 15.90; 95% CI, 8.32-30.20) for PTSD, 89.4% (OR, 11.00; 95% CI, 5.46-22.17) for any mental disorder, and 34.7% (OR, 14.80; 95% CI, 6.89-31.60) for suicide attempts. Gender-based violence was associated with more severe current mental disorder (OR, 4.60; 95% CI, 2.93-7.22), higher rates of 3 or more lifetime disorders (OR, 7.79; 95% CI, 6.10-9.95), physical disability (OR, 4.00; 95% CI, 1.82-8.82), mental disability (OR, 7.14; 95% CI, 2.87-17.75), impaired quality of life (OR, 2.96; 95% CI, 1.60-5.47), an increase in disability days (OR, 3.14; 95% CI, 2.43-4.05), and overall disability (OR, 2.73; 95% CI, 1.99-3.75). CONCLUSION Among a nationally representative sample of Australian women, GBV was significantly associated with mental health disorder, dysfunction, and disability.

Service use for mental health problems: findings from the 2007 National Survey of Mental Health and Wellbeing

Objectives: To provide an overview of 12 month rates of service use for mental health problems and mental disorders by the general Australian adult population. Method: Data came from the 2007 National Survey of Mental Health and Wellbeing (2007 NSMHWB), a nationally representative household survey of 8841 individuals aged between 16 and 85 years. Results: Overall, 11.9% of the general Australian adult population made use of any services for mental health problems in a 12 month period. Approximately one-third of people (34.9%) meeting criteria for a mental disorder did so. Female subjects with mental disorders were more likely to use services than male subjects (40.7% vs 27.5%). People in the youngest age group made relatively less use of services than older adults. Those with affective disorders were most likely to make use of services (58.6%), followed by those with anxiety (37.8%) and substance use disorders (24.0%), respectively. Mental health hospitalizations were less common than consultations with community-based providers (2.6%), whereas 34.6% consulted a community-based provider – particularly general practitioners (24.7%) and psychologists (13.2%). There was a clear dose-response effect between severity of disorders and rates of community-based service use: 63.5% of those with severe mental disorders used community-based services, compared with 40.2% and 17.7% of those with moderate and mild mental disorders, respectively. There was also a relationship between comorbidity of mental disorders and service use. Conclusions: Rates of service use for mental health problems among those with mental disorders in Australia are less than optimal. Little international guidance is available regarding appropriate levels of treatment coverage and other comparable countries face similar difficulties. Further work is required to determine what an appropriate rate of service use is, and to set targets to reach that rate. Australia has demonstrated that concerted policy efforts can improve rates of service use. These efforts should be expanded.

Prevalence and correlates of DSM-IV major depression in an Australian national survey

BACKGROUND Community surveys have reported prevalence of depressive disorders in adult populations since the 1970s. Until recently, no epidemiological studies of the same magnitude have been conducted to provide a profile of the adult population in Australia. This study examines the current (30-day) prevalence and correlates of major depression in the adult Australian population using data from the National Survey of Mental Health and Well-being, and compares the results with other national studies. METHODS Data were derived from a national sample of 10,641 people 18-75+ years of age surveyed using the computerised version of the Composite International Diagnostic Interview Version 2.1. RESULTS The overall weighted prevalence of current (30-day) major depression was 3.2% with the highest rate (5.2%) being found in females in mid life. This rate is between those of the USA National Comorbidity Survey and the Epidemiological Catchment Area study, and similar to the British Psychiatric Morbidity Survey. The strongest correlates for reported current major depression include being unemployed, smoking, having a medical condition, followed by being in mid life, previously married, and female. Living with a partner and drinking 1 to 2 glasses of alcohol per day were least correlated. Some correlates of major depression relate to social disadvantage and lifestyle issues. LIMITATIONS The study design does not allow definition of direction of causality. CONCLUSION Lowering the prevalence rate of major depression will require close attention to public health approaches to address the relationships between smoking, social isolation, poor health, mood and physical well-being. The best focus for this approach may be primary care settings.

Why does the burden of disease persist? Relating the burden of anxiety and depression to effectiveness of treatment

Why does the burden of mental disorders persist in established market economies? There are four possibilities: the burden estimates are wrong; there are no effective treatments; people do not receive treatment; or people do not receive effective treatments. Data from the Australian National Survey of Mental Health and Wellbeing about the two commonest mental disorders, generalized anxiety disorder and depression, have been used in examining these issues. The burden of mental disorders in Australia is third in importance after heart disease and cancer, and anxiety and depressive disorders account for more than half of that burden. The efficacy of treatments for both disorders has been established. However, of those surveyed, 40% with current disorders did not seek treatment in the previous year and only 45% were offered a treatment that could have been beneficial. Treatment was not predictive of disorders that remitted during the year. The burden therefore persists for two reasons: too many people do not seek treatment and, when they do, efficacious treatments are not always used effectively.

The structure of psychopathology: Toward an expanded quantitative empirical model

There has been substantial recent interest in the development of a quantitative, empirically based model of psychopathology. However, the majority of pertinent research has focused on analyses of diagnoses, as described in current official nosologies. This is a significant limitation because existing diagnostic categories are often heterogeneous. In the current research, we aimed to redress this limitation of the existing literature, and to directly compare the fit of categorical, continuous, and hybrid (i.e., combined categorical and continuous) models of syndromes derived from indicators more fine-grained than diagnoses. We analyzed data from a large representative epidemiologic sample (the 2007 Australian National Survey of Mental Health and Wellbeing; N = 8,841). Continuous models provided the best fit for each syndrome we observed (distress, obsessive compulsivity, fear, alcohol problems, drug problems, and psychotic experiences). In addition, the best fitting higher-order model of these syndromes grouped them into three broad spectra: Internalizing, Externalizing, and Psychotic Experiences. We discuss these results in terms of future efforts to refine emerging empirically based, dimensional-spectrum model of psychopathology, and to use the model to frame psychopathology research more broadly.

Kessler Psychological Distress Scale: normative data from the 2007 Australian National Survey of Mental Health and Wellbeing

Objective: To present Australian normative data on the ten-item Kessler Psychological Distress Scale (K10). Method: Analysis of cross-sectional data from the 2007 Australian National Survey of Mental Health and Wellbeing, a nationally representative household survey of 8841 adults. Mean K10 scores and K10 scores at selected percentiles of the K10 score distribution are presented by sex, age, the presence of mental disorders and the presence of physical conditions. Stratum-specific likelihood ratios were computed to help clinicians and researchers calculate predicted probabilities of mental disorder given scores on the K10. Results: Scores on the K10 were generally higher in women compared to men, in people with a mental disorder compared to without a mental disorder and in people with affective disorders compared to people with substance use disorders. The SSLRs were informative in ruling in a diagnosis of mental disorder, particularly at the high or very high end of the psychological distress spectrum. Conclusions: These data may be helpful for clinicians and researchers alike in understanding the likelihood of mental disorder in a given individual or sample.