Latent class analysis of functional somatic symptoms in a population-based sample of twins

Abstract

Objective-This study aimed to investigate empirically how and in what way individuals with symptoms of functional somatic syndromes should be classified. We also aimed to look into genetic and environmental influences on the classification.Method-A total of 28531 twins aged 41-64 underwent screening interviews via a computerassisted data collection system from 1998 to 2002. Nine functional somatic symptoms (abnormal tiredness, general muscular pain, recurrent abdominal discomfort, back pain, gastroesophageal reflux, recurrent headache, recurrent urinary problem, dizziness, breathlessness at rest) were assessed using structured questions in a blinded manner. Latent class analysis was applied to the data. Structural equation modeling was further performed in order to estimate the relative importance of genetic and environmental influences on class probability.Results-Latent class analysis resulted in a 5-class solution. Individuals in the first class did not show any health problems. Those assigned to the second, third, and fourth classes tended to have abnormal tiredness, gastrointestinal problems, and pain-related symptoms, respectively. Individuals in the fifth class had multiple symptoms to a greater extent than the other classes. All the five classes showed modest genetic influences (7 -29% of the total variation) with gender differences except Class 3; however, the majority of influences on the class membership derived from unique environmental effects. Conclusion-The findings suggested the necessity of re-defining the existing classification criteria for functional somatic syndromes in terms of single (uncomplicated) or multiple

Somatic symptom profiles in the general population: A latent class analysis in a Danish population-based health survey

“…The findings of symptom profiles with no/few symptoms and with multiple symptoms were comparable with previous findings, [9][10][11][12][13][14] while only two of the previous studies also found symptom profiles defined by specific symptoms. 11,12 However, the number and description of the profiles differed from our findings except for an MS/pain profile, 11,12 a GI profile, 11,12 and an MS + GI profile.…”

“…[9][10][11][12][13][14] Thus, 2, 13,14 3, 9,10 5, 12 and 11 11 profiles have been identified either based merely on numbers of symptoms 9,10,13,14 or based on number, site, and type of symptoms. 11,12 However, all the studies differed considerably in material and methods. Only two of the studies were conducted on a population-based sample, 12,14 while the others included more selected populations, eg, patients from primary or secondary care.…”

“…11,12 However, all the studies differed considerably in material and methods. Only two of the studies were conducted on a population-based sample, 12,14 while the others included more selected populations, eg, patients from primary or secondary care. This selection might have led to considerable bias in the identification of classes including higher symptom prevalence in the study population.…”

“…This selection might have led to considerable bias in the identification of classes including higher symptom prevalence in the study population. Furthermore, most of the studies included only few symptoms 12 or groups of symptoms [9][10][11] in their analyses on symptom profiles, which may have decreased the possibility of identifying nuanced and multiple profiles. Similarly, the relatively small study populations used in some of the studies may also have limited the nuances.…”

Treatment of fibromyalgia

“…4 While commonly co-occurring with mood and anxiety disorders, research suggests that, although functional somatic disorders are related and potentially interact with psychological conditions, they are independent. 5 The syndrome is characterised by its hallmark features of widespread somatic pain and deep tissue tenderness, which result from sensitisation of neural pain pathways.…”