Assessment of physical etiologies for mood and anxiety disorders in structured diagnostic interviews

The association between chronic illness, multimorbidity and depressive symptoms in an Australian primary care cohort

PURPOSE

To assess the link between multimorbidity, type of chronic physical health problems and depressive symptoms

METHOD

The study was a cross-sectional postal survey conducted in 30 General Practices in Victoria, Australia as part of the diamond longitudinal study. Participants included 7,620 primary care attendees; 66% were females; age range from 18 to 76 years (mean = 51 years SD = 14); 81% were born in Australia; 64% were married and 67% lived in an urban area. The main outcome measures include the Centre for Epidemiologic Studies Depression Scale (CES-D) and a study-specific self-report check list of 12 common chronic physical health problems.

RESULTS

The prevalence of probable depression increased with increasing number of chronic physical conditions (1 condition: 23%; 2 conditions: 27%; 3 conditions: 30%; 4 conditions: 31%; 5 or more conditions: 41%). Only 16% of those with no listed physical conditions recorded CES-D scores of 16 or above. Across the listed physical conditions the prevalence of 'probable depression' ranged from 24% for hypertension; 35% for emphysema; 35% for dermatitis to 36% for stroke. The dose-response relationship is reduced when functional limitations and self-rated health are taken into account, suggesting that these factors mediate the relationship.

CONCLUSIONS

A clear dose-response relationship exists between the number of chronic physical problems and depressive symptoms. The relationship between multimorbidity and depression appears to be mediated via self-perceived health related quality of life. Primary care practitioners will identify more cases of depression if they focus on those with more than one chronic health problem, no matter what the problems may be, being especially aware in the group who rate their health as poor/fair.

The role of comorbidity in the detection of psychiatric disorders with checklists for mental and physical symptoms in primary care

OBJECTIVE

To examine the contribution of a mental and physical symptom count to the detection of single or comorbid anxiety, depressive and somatoform disorders.

METHOD

In primary care 1,046 consulting patients completed the Hospital Anxiety and Depression Scale (HADS) and the Physical Symptom Checklist (PSC-51). In a stratified sample of 473 patients DSM-IV psychiatric disorders were assessed using the WHO-SCAN interview. The diagnostic value of the HADS total score and the PSC-51 symptom count was examined with ROC-analyses.

RESULTS

The discriminative power of PSC-51 and HADS was highest for patients with both a somatoform disorder and an anxiety or depressive disorder, with an AUC of 0.86 (95% CI: 0.81-0.91) and 0.91 (95% CI: 0.87-0.94) respectively. Using both symptom counts together did not increase the diagnostic value for the detection of the psychiatric disorders.

CONCLUSION

Both symptom counts preferentially detected patients with comorbid disorders. When interpreting diagnostic values of screening questionnaires one should keep in mind that the validity of these values can be dependent of the presence of comorbid disorders.

Impact of substance-induced and general medical condition exclusion criteria on the prevalence of common mental disorders as defined by the CIDI

OBJECTIVES

It has been previously argued that the methodology used by the Composite International Diagnostic Interview version 2.1 to assess the substance-induced and general medical condition exclusion criteria are inadequate. As a result prevalence estimates generated from epidemiological studies using this interview may be underestimated. The purpose of the current study was to examine the substance-induced and general medical condition exclusion criteria in the Australian National Survey for Mental Health and Well-being and determine the impact that they have on prevalence estimates of the common mental disorders.

METHOD

Data from the 1997 Australian National Survey of Mental Health and Well-being were analysed. Frequencies were generated as an indication of how many respondents believed that their psychiatric symptoms were always due to a substance or general medical condition. New DSM-IV prevalence estimates were calculated ignoring the application of the substance-induced and general medical condition exclusion criteria and compared to standard DSM-IV prevalence estimates.

RESULTS

The effect of the substance-induced and general medical condition exclusion criteria on final prevalence rates were minimal, with approximately a 0.1% increase when the exclusions were ignored. This equates to a relative difference ranging from no difference for generalized anxiety disorder to an increase of 12% of the base prevalence estimate for agoraphobia.

CONCLUSIONS

In surveys that use the Composite International Diagnostic Interview version 2.1 the substance-induced and general medical condition exclusion criteria have a minor impact on determining final case definition in the majority of mental disorders.