Original Article
An international study comparing the effect of medically explained and unexplained somatic symptoms on psychosocial outcome

https://doi.org/10.1016/j.jpsychores.2005.06.064Get rights and content

Abstract

Objective

Cross-sectional studies show an association between somatic symptoms and psychiatric morbidity in primary care. However, medically explained and unexplained symptoms have been considered separately as distinct and unrelated. In addition, data on outcome in primary care are equivocal. We compare the effect of both constructs (medically explained and unexplained symptoms) on psychiatric morbidity and disability (social and physical) at 1 year follow-up.

Method

Of 5447 patients presenting for primary care in 14 countries, 3201 participants were followed up (72% compliance). We measured physical, psychiatric, and social status using standardised instruments.

Results

Patients with five or more somatic symptoms had increased psychosocial morbidity and physical disability at follow-up, even after controlling for confounders such as sociodemographics and recognition or treatment by general practitioners. There was little difference in outcome between medically explained and unexplained symptoms.

Conclusions

Somatic symptoms–irrespective of aetiology–are associated with adverse psychosocial and functional outcome in diverse cultures.

Introduction

Somatoform disorders are common in primary care; 20% of patients present with medically unexplained somatic symptoms (MUS), and the proportion is higher in certain countries [1], [2], [3]. Traditional thinking regarding somatoform disorders has considered physical symptoms as either distinctly physical or distinctly psychological phenomena. Those with well-defined medical conditions are thought to have medically explained physical symptoms. Unexplained symptoms are thought to indicate a mental disorder, often anxiety or depression.

Some previous research supports this distinction between medically explained somatic symptoms (MES) and MUS. A World Health Organization (WHO) study of 15 centres reported that patients with MUS were significantly younger, had greater psychiatric morbidity, were at greater risk of harmful use of alcohol, and reported greater social disability than did those with a medical explanation for their somatic symptoms [3]. This effect was most apparent with five or more somatic symptoms. Studies in hospital settings suggest that patients with MUS have a worse outcome than do those with medically explained symptoms [5], [6]. The same international WHO study demonstrated that physical ill-health, defined by medically explained symptom count, reduced recovery from psychiatric illness 1 year later [7], [8]. However, the study also showed little difference in recovery rates between patients with medically explained and unexplained symptoms.

This study compares the effect of MES and MUS on psychiatric outcome for the entire cohort and not just those who were psychiatric cases at baseline. It also looks at differences in a wider range of outcomes including social and physical disability and health service use.

Section snippets

Baseline data collection

This research formed part of the WHO Collaborative Study of Psychological Disorders in General Health Care Settings (PPGHC). The prevalence, management, and outcome of common psychological disorders in primary care patients were investigated in 15 centres in 14 countries. Participating centres included Ankara, Athens, Bangalore, Berlin, Groningen, Ibadan, Mainz, Manchester, Nagasaki, Paris, Rio de Janeiro, Santiago, Seattle, Shanghai, and Verona in Italy. The overall study methods, including

Sociodemographic and clinical features

Three thousand two hundred one interviews were successfully completed. A further 1243 participants who were eligible for follow-up could not be interviewed. This gave a follow-up rate of 72%. Two thirds of the sample was female (n=2119). Two thousand (62%) had at least one medically explained somatic symptom and 2189 (68%) at least one medically unexplained symptom.

The patients who were lost to follow-up did not differ from participants who completed the follow-up interview in terms of the

Strengths of the study

There is a large literature on the association between MUS and psychopathology. There is also another large literature on the association between medical illness and psychopathology in terms of both increased prevalence of psychiatric disorder and poorer prognosis. However, papers have usually considered medically explained and unexplained symptoms separately as if they are distinct and unrelated. This is the first study to combine both constructs and investigate the effect of medically

Acknowledgments

This paper is based on the data and experience obtained during the WHO project on Psychological Problems in General Health Care, a project sponsored by the World Health Organization and the participating field research centres.

References (19)

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    Sometimes you or your doctor may have an idea about what causes these difficult-to-diagnose symptoms, but for this survey we will call them medically unexplained symptoms, or MUS. Previous research has found that physician diagnosis is not necessary to identify MUS [33,34], and we were most interested in understanding veterans’ experiences with care when they perceived that they had a medically unexplained symptom/syndrome. The term “MUS” is consistent with research on patients’ preferred terms for MUS [35].

  • Deployment, combat, and risk of multiple physical symptoms in the US military: A prospective cohort study

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    The longitudinal increases in probabilities of developing MPS associated with noncombat and combat deployment found in this study may appear small, but they have significant implications when applied across an entire military population of over 2.2 million active duty, Reserve, and National Guard members [43]. Several studies have shown that MPS is associated with significant increases in morbidity, mortality, and health care use [3–10], suggesting that the increase in MPS observed among deployed individuals may not only have adverse long-term effects on service member health and well-being, but also on the entire force readiness and later the civilian work force as these individuals separate from military service. Indeed, despite the rigorous health criteria required for entrance into the military, there is evidence that veterans and military service members are experiencing physical health declines faster than age-adjusted population norms in the years after deployment [44].

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