The search for biomarkers and endophenotypes in functional gastrointestinal disorders

Clinical associations of functional dyspepsia with gastric dysrhythmia on electrogastrography: A comprehensive systematic review and meta-analysis

BACKGROUND

Functional dyspepsia (FD) is a common gastroduodenal disorder, yet its pathophysiology remains poorly understood. Bioelectrical gastric slow-wave abnormalities are thought to contribute to its multifactorial pathophysiology. Electrogastrography (EGG) has been used to record gastric electrical activity; however, the clinical associations require further evaluation.

AIMS

This study aimed to systematically assess the clinical associations of EGG in FD.

METHODS

MEDLINE, EMBASE, and CENTRAL databases were systematically searched for articles using EGG in adults with FD. Primary outcomes were percentage normal versus abnormal rhythm (bradygastria, normogastria, and tachygastria). Secondary outcomes were dominant power, dominant frequency, percentage coupling, and the meal responses.

RESULTS

1751 FD patients and 555 controls from 47 studies were included. FD patients spent less time in normogastria while fasted (SMD -0.74; 95%CI -1.22 to -0.25) and postprandially (-0.86; 95%CI -1.35 to -0.37) compared with controls. FD patients also spent more fasted time in bradygastria (0.63; 95%CI 0.33-0.93) and tachygastria (0.45; 95%CI 0.12-0.78%). The power ratio (-0.17; 95%CI -0.83-0.48) and dominant frequency meal-response ratio (0.06; 95%CI -0.08-0.21) were not significantly different to controls. Correlations between EGG metrics and the presence and timing of FD symptoms were inconsistent. EGG methodologies were diverse and variably applied.

CONCLUSION

Abnormal gastric slow-wave rhythms are a consistent abnormality present in FD, as defined by EGG and, therefore, likely play a role in pathophysiology. The aberrant electrophysiology identified in FD warrants further investigation, including into underlying mechanisms, associated spatial patterns, and symptom correlations.

The common link between functional somatic syndromes may be central sensitisation

OBJECTIVES

Functional somatic syndromes are common and disabling conditions that all include chronic pain, and which may be related to central nervous system sensitisation. Here, we address the concept of central sensitisation as a physiological basis for the functional somatic syndromes.

METHODS

A narrative review of the current literature on central sensitisation and physiological studies in the functional somatic syndromes.

RESULTS

Central sensitisation may be a common neurophysiological process that is able to explain non-painful as well as painful symptoms in these disorders. Furthermore, central sensitisation may represent an endophenotypic vulnerability to the development of these syndromes that potentially explains why they cluster together.

CONCLUSIONS

Further research is needed to verify these findings, including prospective studies and the standardisation of combined methods of investigation in the study of central sensitisation in functional somatic syndromes. In turn, this may lead to new explanatory mechanisms and treatments being evaluated. Our conclusions add to the debate over the nomenclature of these syndromes but importantly also provide an explanation for our patients.

Diagnostic criteria in IBS: useful or not?

There are a number of reasons to establish the accurate diagnosis of irritable bowel syndrome (IBS): to relieve patient uncertainty; to avoid adverse effects of unnecessary medications or treatments; to avoid unnecessary diagnostic procedures and surgeries; to conserve limited healthcare resources; and, of course, to initiate the most appropriate treatment. However, making the diagnosis of IBS remains difficult because it is clinically heterogeneous, no biological marker to detect it exists, many other diseases share the same clinical manifestations and it is often difficult for both physicians and patients to accept the uncertainty of a symptom-based diagnosis. Different diagnostic criteria have been developed during the last 4 decades but none have proved to be an ideal method of accurately diagnosing IBS. Just as importantly, physicians are frequently unaware of published guidelines or consciously ignore these diagnostic criteria. Most clinicians still believe IBS is a diagnosis of exclusion and not a positive diagnosis based on history, physical examination, use of published diagnostic criteria such as the Rome III criteria, and the absence of alarm features. In the sections to follow we will address the inherent difficulties of diagnosing IBS, highlight the importance of symptom-based diagnoses to help reign in soaring healthcare costs, and discuss future strategies that may enable a more cost-efficient diagnosis of IBS.