Comorbidities of Patients with Functional Somatic Syndromes Before, During and After First Diagnosis: A Population-based Study using Bavarian Routine Data

Abstract

Functional somatic syndromes (FSS) are characterised by the presence of one or multiple chronic symptoms that cannot be attributed to a known somatic disease. They are thought to arise though a complex interaction of biological and psychosocial factors, but it is unclear whether they share a common aetiology. One hypothesis supported by recent studies is that the FSS are postinfectious disorders, as is widely recognised for a subset of patients with irritable bowel syndrome. Our study used claims data submitted by office-based physicians to compare groups of patients with different FSS in the five years before and after the point of first diagnosis. Even five years prior to diagnosis, FSS patients consulted more frequently for a range of psychological and somatic conditions than did controls. Following diagnosis, consultation rates increased further and remained persistently high. Five years after diagnosis, between 34% (somatization disorder) and 66% (fibromyalgia) of patients were still being treated for the condition. Both prior gastrointestinal and upper-respiratory infection were associated with an increased risk of developing an FSS. We therefore recommend that patients at risk should be identified at an early stage and the underlying psychosocial and somatic issues addressed to prevent progression of the condition.

Figure 1

Schematic diagram of the study flow.

Figure 2

Age distribution of cases and controls at the time of first diagnosis. Each histogram displays a subgroup of the cohort and is stacked to show the relative proportions of male and female patients for each two-year age interval.

Figure 3

Kaplan-Meier estimation of the time between the first and last recorded diagnosis of the FSS conditions.

Figure 4

Smoothed estimation of the percentage of patients consulting with various diagnoses in the 20 quarters before and after first FSS diagnosis.

Figure 5

Odds ratios for the diagnosis of prior gastrointestinal infection, gastrointestinal symptoms, psychological disorder and unspecific somatic symptoms in dependence on functional somatic syndrome, age group and gender.