Subthreshold affective disorders: a useful concept in psychiatric epidemiology?

Panic agoraphobic spectrum in psychiatrically healthy subjects: Impact on quality of life

Several studies have evaluated the quality of life (QOL) in patients with Panic Disorder (PD). For instance, the Epidemiological Catchment Area Study (ECA) assessed the quality of life (QoL) using the subjective evaluation of health, psychosocial functioning and financial status as parameters (Regier et al., 1984). Among the general population, people with PD or panic attacks reported a low level of physical health in 35% of cases and a low degree of mental health in 38% of cases, similarly to people suffering from Major Depressive Disorder (29% and 39% respectively), but more frequently than the in individuals not affected by any disorder (24% and 12% respectively). Furthermore, 27% of patients with PD were in need of some form of social or financial support in contrast to 16% of people suffering from depression and 12% of unaffected people. The National Comorbidity Survey (NCS) (Magee et al., 1996) found serious interference in activities in 27% of agoraphobic patients. For instance, the agoraphobic subjects reported an average of 1.1 days of work lost in the previous month due to their psychopathology. Several Authors have studied the relationship between PD and a worse quality of life and/or a worse ability to function. In a review on the topic, Mendlowicz & Stein (2000) provided an integrated view of the issue of quality of life in patients with anxiety disorders and concluded that the existing studies almost uniformly show a marked impairment of quality-of-life and psychosocial functioning in individuals with anxiety disorders. However, as noted by the Authors above, “despite the growing number of studies undertaken during the past 15 years, the investigation of quality of life in individuals with anxiety disorders is still in its infancy.” Rucci et al. (1993) evaluated the prevalence of subthreshold psychiatric disorders in primary care and their association with the patients health perception, disability in daily activities and psychological distress Subjects with subthreshold disorders reported levels of psychological distress, disability in daily activities and perceived health comparable to those of patients with full-fledged ICD-10 disorders. Despite the scientific and clinical importance of the topic, relatively few studies have evaluated the prevalence and impact of subthreshold affective disorders in general (Schotte & Cooper, 1999) and panic symptoms in particular (for instance Bellini & Galverni, 2003) in non psychiatric populations. Moreover, the literature on the relationship between sub-threshold or residual PD and quality of life is scant. To this end, we decided to investigate the impact of panic-agoraphobic “spectrum” on the quality of life of subjects who did not meet the criteria for a full blown PD. We adopted the definition of “spectrum” developed by Cassano and colleagues (Cassano & Pini, 2000; Rucci & Maser, 2000), which refers to a dimensional view of psychopathology that includes a broad array of manifestations of the target disorder, including its most severe symptoms as well as a range of more subtle features related to the core condition, which may include temperamental traits, prodromal indicators, or residual symptoms. Although they are frequently associated with specific DSM-IV disorders, these conditions are also found in individuals who have never met full DSM-IV diagnostic criteria. Our hypothesis for this study was that the presence of subthreshold panic-agoraphobic symptomatologies in otherwise healthy individuals would significantly impair the quality of life despite the absence of a full-blown PD diagnosis.

A dimensional versus a categorical approach to diagnosis: anxiety and depression in the HUNT 2 study

The aim of this study was to compare a dimensional and a categorical approach to diagnosis, using as an illustration co-occurring symptoms of anxiety and depression concerning description, associations and predictive power. We analysed data from 60 869 individuals with valid ratings on the Hospital Anxiety and Depression Scale (HADS) and on mental impairment in the age range of 20 to 89 years of the cross-sectional Nord-Trøndelag Health Study 1995-1997. There was a wide variation of the dimensional symptom level (subscale scores) within both diagnostic categories (cut-offs > > or = 8 on both subscales), as is usually true with categorical and dimensional diagnosis. The dimensional (Spearman) correlation coefficients between anxiety and depression was 0.51 compared to 0.38 for the categorical. The power to predict impairment was weaker with the categorical than with the dimensional approach of the HADS, showing fewer statistically significant coefficients in the logistic regression models and lower area under curve (0.82 versus 0.87). This is an example illustrating the impact use of dimensional diagnoses would have on research and clinical practice.

[Epidemology and treatment of depressive disorders]

5-10% of the general population suffer from depressive disorders, one third of which are chronic. Depression impairs the quality of life, and 30.8% of patients show reduced working capacity. Patients are on average 10.9 days per month on sick leave. About half of the depressed patients undergo treatment, contacting general practitioners at an average of 14.5 times, psychotherapists 2 times and psychiatrists 1.4 times per year. Approximately 100 million daily doses of specific antidepressants are prescribed per year in Germany, an amount enough to treat 1% of the general population, which is indicative of an insufficient treatment rate. Pharmacotherapy has been found to be more effective than psychotherapy in acute episodes. However, psychotherapy patients show better long term results in respect to relapses and social adaptation. Due to the large number of depressed patients, general practitioners are the primary therapists. Referral to psychiatrists or psychotherapists is indicated in cases of chronic and complicated courses.

Instrument development in the Italy-USA Collaborative Spectrum Project

SCOPE

The Collaborative Spectrum Project aims to define subthreshold and atyical conditions not sufficiently characterized in the current diagnostic nomenclature and for which adequate assessment instruments are not available. This paper reports on the development and validation of new instruments to assess the spectrum of five psychiatric disorders.

DESIGN

Three multicenter studies and one single-site study were conducted in Italy to assess the validity and reliability of the five spectrum interviews. Another cross-sectional study to validate the panic-agoraphobia spectrum has been conducted in Pittsburgh.

SETTING

Outpatients attending various university clinics, university students and, in one Italian study, gym attenders were recruited for the studies.

MAIN OUTCOME MEASURES

Five structured clinical interview to assess the spectrum of panic-agoraphobia (SCI-PAS), mood (SCI-MOODS), social phobia (SCI-SHY), and the obsessive-compulsive (SCI-OBS) and eating disorder spectra (SCI-ABS) were administered along with a diagnostic interview and a number of self-report and interviewer-rated instruments.

RESULTS

All the domains of the interview showed high test-retest reliability (intraclass correlation coefficient > 0.61) and satisfactory internal consistency. Mean domain scores were significantly higher in cases than in controls and in patients with the disorder of interest than in patients with other disorders. Convergent validity was satisfactory for panic-agoraphobia, social phobia and obsessive-compulsive spectrum domains. Differences emerged between SCI-ABS and self-report instruments assessing eating disorders. A cut-off score for the panic-agoraphobia spectrum was defined and its clinical validity was tested.

CONCLUSIONS

The psychometric properties of the five spectrum interviews are very satisfactory, and studies are currently ongoing to test the clinical validity of all the spectra. Subthreshold and atypical symptoms deserve attention in epidemiological investigation.