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Background: Evidence of incidence of functional somatic disorders (FSD) is hampered by unclear delimitations of the conditions and little is known about the possible interchangeability between syndromes. Further, knowledge on remission and persistence of FSD in the general population is limited. We aimed to assess the natural course of various FSD over 5 years in the general population., Methods: A follow-up study (Danish Study of Functional Disorders-DanFunD) was conducted in a random sample of the general population comprising 5,738 participants aged 18-76 years at baseline. Both at baseline and five-year follow-up, participants filled in validated questionnaires on symptoms to delimitate two approaches of FSD, the bodily distress syndrome (BDS) and four functional somatic syndromes (FSS): irritable bowel (IB), chronic fatigue (CF), chronic widespread pain (CWP), and multiple chemical sensitivity (MCS)., Results: Both BDS and FSS showed a five-year incidence around 11%. Incidence of the individual FSS varied from 0.8% (MCS) to 5.7% (CF). BDS and FSS showed a remission proportion close to 50%. We found a high degree of interchangeability between each FSS varying from 15.0% to 23.4%., Conclusion: We identified a marked fluctuation pattern of FSD during a five-year period, with a high degree of interchangeability between each FSS. The study stresses the importance of large population-based cohorts with transparent delimitation of FSD in future research to understand these complex conditions., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Schovsbo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Objectives: It has been hypothesised that functional somatic disorders (FSD) could be initiated by sympathetic predominance in the autonomic nervous system as measured by low heart rate variability (HRV). Earlier studies on the association between HRV and FSD are small case-control studies hampered by selection bias and do not consider the great overlap between the various FSDs. The aim of the present study is to assess any associations between HRV and various FSDs and whether chronic stress confounds such an association., Design: A cross-sectional general population-based study., Setting: The Danish Study of Functional Somatic Disorders conducted 2013-2015 in 10 municipalities in the western part of Greater Copenhagen, Denmark., Participants: A total of 6891 men and women aged 18-72 years were included in the analyses after exclusion of 602 persons with missing HRV data. Various delimitations of FSD (chronic fatigue, chronic widespread pain, irritable bowel and bodily distress syndrome) were identified by validated questionnaires and diagnostic interviews. HRV parameters in time and frequency domains were calculated from successive beat-to-beat heart rate (HR) data using the 'E-motion' HR monitor device during 7 min of supine rest. Chronic stress was assessed by Cohen's self-perceived stress scale., Outcome Measures: Logistic regression analyses were used to calculate possible associations between the various delimitations of FSD and HRV adjusting for chronic stress., Results: Persons with FSD had a slightly higher mean HR and lower HRV as measured by time domain parameters, whereas associations with frequency domain parameters were not consistent. Adjusting for chronic stress attenuated associations slightly., Conclusion: The study supports a sympathetic predominance in persons with FSD, which could not be entirely explained by chronic stress. However, it is not possible to conclude whether the association is a causal factor to or a consequence of FSD., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objectives: Earlier studies on the association between plasma lipid profiles and functional somatic disorders (FSD) are mainly small case control studies hampered by selection bias and do not consider the great overlap between the various FSDs. The aim of the present study was to investigate the associations between various FSDs and plasma lipid profiles (total cholesterol, HDL cholesterol, non-HDL cholesterol and triglycerides) in a large, unselected population., Design: A cross-sectional general population-based study., Setting: The Danish Study of Functional Somatic Disorders (DanFunD) conducted in 2011-2015 in 10 municipalities in the western part of greater Copenhagen, Denmark., Participants: A total of 8,608 men and women aged 18-76 years were included in the analyses. Various delimitations of FSD such as chronic fatigue, chronic widespread pain, irritable bowel, and bodily distress syndrome were measured using validated self-administrated questionnaires. Lipid parameters were measured from fasting plasma samples using colorimetric slide methods with Vitros 4600/5600 Ortho Clinical Diagnostics., Outcome Measures: Logistic regression analyses were used to calculate possible associations between plasma lipids and the various delimitations of FSD. Associations are presented by OR (95% CI) and shown in boxplots., Results: We found a positive association between bodily distress syndrome and triglycerides and non-HDL cholesterol and a negative association with HDL-cholesterol, but no consistent association with total cholesterol. A similar pattern was observed for persons with chronic fatigue, and to some degree for persons with chronic widespread pain, whereas persons with irritable bowel did not show a clear association with the lipid profiles., Conclusion: This is the first major study on plasma lipid profiles and FSD indicating an association between some delimitations of FSD and an unfavorable lipid profile. Due to the cross-sectional design, it cannot be determined whether the findings are consequences or determinants of FSD. Further studies-preferable prospective studies-are needed., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Jørgensen et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Objectives: Multiple chemical sensitivity (MCS) is a rare multisystem and poly-symptomatic disease characterised by a report of various somatic symptoms attributed to inhalation of volatile chemicals in usually harmless doses. The aim was to explore four selected social factors and the risk of MCS in the general Danish population., Design: A cross-sectional general population-based study., Setting: The Danish Study of Functional Disorders was conducted from 2011 to 2015 which included 9656 participants., Participants: A total of 8800 participants were included in analyses after observations with missing data on exposure and/or outcome were excluded. A total of 164 cases fulfilled the questionnaire criteria for MCS. Of the 164 MCS cases, 101 reported no comorbid functional somatic disorder (FSD) and were included in a subgroup analysis. A total of 63 MCS cases fulfilled the criteria for at least one additional FSD, this subgroup was not included in further analysis. The remaining study population without MCS or any FSD were regarded as controls., Outcome Measures: We used adjusted logistic regression to calculate OR and 95% CIs of MCS and MCS without FSD comorbidities for each social variable separately including education, employment, cohabitation and subjective social status., Results: We found an increased risk of MCS among the unemployed (OR: 2.95, 95% CI: 1.75 to 4.97), and a twofold increased risk of MCS among individuals with low subjective social status (OR: 2.00, 95% CI: 1.08 to 3.70). At the same time, 4 years or more of vocational training were protective of MCS. No significant associations were observed among MCS cases with no comorbid FSD., Conclusion: Lower socioeconomic status was found to be associated with a higher risk of having MCS but not with MCS without FSD comorbidities. Due to the cross-sectional design of the study, we cannot determine whether social status is a determinant or a consequence of MCS., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background and Aim: It is generally accepted that functional somatic disorders (FSDs) are a product of biological, psychological, and social factors. Social position might be part of this complex, but the literature on this issue is currently heterogeneous and inconsistent. The aim of the present study was - in a population-based cohort - to test the hypothesis that lower social position would be associated with higher a risk of FSD., Method: The association between social position and FSD was examined in a cross-sectional study with various measures of social position (education as measured by vocational training; employment; cohabitation; subjective social status) and delimitations of FSD (irritable bowel syndrome, chronic fatigue syndrome, fibromyalgia, bodily distress syndrome, and symptom profiles). The associations were analyzed using logistic regressions to calculate odds ratios and 95% confidence intervals. Each social measure was analyzed independently and was adjusted for age and sex., Results: Lower levels of vocational training, being unemployed, and living alone were associated with higher risk of FSD, regardless of the FSD delimitation. There was also a significant negative association between subjective evaluated social status and FSD. The associations remained after multiple adjustments, and seemed to be strongest for the more severe FSD-types., Conclusions: Lower social position is associated with higher risk of FSD, especially the more severe FSD delimitations, which might constitute an especially vulnerable group. However, the mechanisms behind the relations remain unknown.

Objectives: It has been suggested that infections can trigger functional somatic disorders (FSD). However, current evidence is limited by inconsistent findings in smaller studies conducted in clinical settings within selected populations and short follow-up times. We aimed to test the hypothesis that former infections are associated with FSD using data from nationwide registries and a large population-based cohort study, the Danish Study of Functional Disorders study., Design: FSD cases were identified in a cross-sectional population-based cohort and linked retrospectively to former hospital contacts with infections identified in the Danish National Patient Registry. The associations between FSD and former infections within 17 years were analysed using logistic regressions to calculate ORs and 95% CIs adjusted for age, sex and subjective social status., Setting: A population-based cohort in Denmark examined between 2011 and 2015., Participants: A total of 9656 men and women aged 18-76 years., Main Outcome Measures: FSD measured by various delimitations, including bodily distress syndrome (BDS), irritable bowel (IB), chronic fatigue (CF), chronic widespread pain (CWP), and multiple chemical sensitivity (MCS)., Results: Overall, infections were associated with increased risk of all delimitations of FSD. The associations were more pronounced for multisystemic FSD. The number of prior infections increased the risk in a dose-response manner (p<0.0001). Bacterial but not viral infections were significantly associated with BDS (OR 1.69 (95% CI 1.46 to 1.96)), IB (OR 1.41 (95% CI 1.06 to 1.88)), CWP (OR 1.47 (95% CI 1.13 to 1.90)) and CF (OR 1.62 (95% CI 1.34 to 1.96)), but not MCS., Conclusion: Former infections leading to hospital contacts were associated with a higher risk of having FSD. These associations were more pronounced for bacterial than viral infections, and more infections increased the risk in a dose-response manner. These results tend to support the idea that severe infections could play a role in FSD., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Adverse experiences in childhood are a major public health concern, promoting social inequality in health through biopsychosocial mechanisms. So far, no known measures comprehend the complexity and variations of severity of adverse events. This study aims to develop and validate a new index: the Weighted Index for Childhood Adverse Conditions (WICAC)., Methods: The population consists of 7493 randomly invited men and women aged 18-72 years. Data were collected in 2012-2015 as part of the Danish Study of Functional Disorders (DanFunD). Content and construct validation of the WICAC was performed with the hypothesis testing of multiple biopsychosocial outcomes: cardiovascular disease, cancer, poor health, back pain, BMI, obesity, anxiety, depression, low vitality, subjective social status, lower education, smoking, and alcohol consumption. Data were analysed with binominal and linear regression models with risk ratios (RR) and mean differences (MD)., Results: Content validation is fitting for WICAC. The strongest associations observed were for most severe adversity: Poor Health RR = 2.16 (1.19-2.91), Anxiety RR = 3.32 (2.32-4.74), Heavy Drinking RR = 4.09 (1.85-9.04), and Subjective Social Status MD = -0.481 (-0.721-(-0.241)). Similar results were found for the remaining outcomes. Discriminative validation was undecided., Conclusions: WICAC is an adequate instrument for measuring cumulative adverse life events in childhood and adolescence for research purposes.