Functional health status, chronic medical conditions, and disorders of mood
Surtees PG, Wainwright NW, Khaw KT and Day NE;
Commented by , 27 Oct 2003
Aim of the Study
To assess how depression and anxiety effects health status compared to chronic medical illness.
Method
The population studied was derived from a larger community sample involved in a prospective study into cancer. As part of this wider study, 20,921 men and women aged 40 – 74 from Norfolk, England completed the Health and Life Experiences Questionnaire (HLEQ), a response of 73 % from the total eligible sample.
This instrument includes a structured self-assessment approach to lifelong diagnosis of depression and anxiety – DSM-IV criteria, - and the Medical Outcomes Study Short Form 36 (SF-36), a generic measure of subjective health status.
Subjects with cancer, diabetes, myocardial infarction or stroke were compared with those with major depressive disorder and generalised anxiety disorder. Statistical analysis allowing for age and gender was performed using linear regression.
Results
The mean age of participants was 61 years (standard deviation 9.3 years). 1,953 (9.3 %) reported at least 1 of the 4 chronic medical conditions; 1,328 (6.3 %) reported prevalent major depression or generalised anxiety disorder. Depression was reported more than twice as commonly as anxiety, 231 reported both conditions. Depression and anxiety were both 1.5 times more common in women.
The key finding was that the degree of subjective physical functional impairment arising from depression and anxiety is substantial, and of approximately equal or greater size to that arising from chronic serious medical conditions. The reduction in physical functioning (arising from mood disorders) was calculated as equivalent to being 12 years older. By contrast, chronic medical conditions had a modest impact on mental functioning.
Subjects with generalised anxiety disorder reported particularly high functional impairment – even more so than those with depression and serious medical illnesses. Of the medical illnesses, stroke had the greatest impact on physical functioning, cancer the least.
Discussion
It is known that depression and anxiety have a substantial impact on functional health status, but previous studies have examined patient populations; this study was derived from a community sample.
This study therefore provides evidence to support what most health professionals already know: chronic disabling medical and psychiatric conditions combine to impair functional status, but the psychiatric component is particularly important in improving functional status in that it is potentially treatable.
Naturally, this questionnaire based study has limitations, not least because only 45 % of eligible participants (from the original study) completed all parts. Participants therefore did not represent a truly random sample and the HLEQ is not a perfect instrument for detecting all cases of depression and anxiety.
The study was cross-sectional, and therefore could not be sensitive to fluctuating symptoms through the course of a (physical or mental) illness, particularly those suffering with cancer.
Nonetheless, this study provides further evidence of the burden that common treatable mental illnesses place on society.