This study found that Chinese IBS-D patients could accurately experience and report abdominal pain, most patients described abdominal pain as spasm/cramping, but the feelings and descriptions of abdominal discomfort were varied. Most patients can distinguish between abdominal discomfort and abdominal pain. The degree of abdominal pain was severer than abdominal discomfort, but there was no significant difference in IBS-SSS, coexisting extra-intestinal pain, IBS-QOL, or psychological states between patients with abdominal pain and abdominal discomfort as the main symptom.
It is generally believed that abdominal pain is the most important symptom of IBS.19 However, the Rome Foundation Asia Working Team reported abdominal discomfort is secondly bothersome symptom only after abdominal pain in Asian patients with functional bowel disease.10 An online survey of patients with IBS with predominant constipation (IBS-C) conducted in the general population in Japan found that 64.3% of IBS-C patients had abdominal discomfort and 29.1% had abdominal pain, 15.3% of the patients considered abdominal discomfort and 4.5% considered abdominal pain as the most bothersome symptom, respectively.20 In addition, study in the United States reported that the proportion of abdominal pain and bloating-type discomfort in IBS patients was similar (60% vs 66%), 60% of the patients listed bloating-type discomfort and 29% listed abdominal pain as the most bothersome symptom, respectively.21 And the severity of abdominal discomfort was independently correlated with QOL damage in IBS patients.13
There is a lack of accurate definition of abdominal discomfort at present.2 Cultural background, socio-economic status, education level, and other factors will affect patients' feeling and expression of symptoms,22 which may be the main factors leading to the differences between results from eastern and western studies. Compared with diseases with clear biological basis, functional gastrointestinal diseases are more likely to be affected by cultural factors.23 Even in the same cultural and linguistic environment, the spectrum of abdominal discomfort reported by IBS patients in America is very broad.12,13 For Chinese IBS-D patients, only asking about "abdominal discomfort" can not obtain their accurate feelings. The descriptions of abdominal discomfort are varied, especially the use of Chinese dialects makes the connotation of abdominal discomfort more complicated. Among the patients with self-reported abdominal discomfort, 28% considered mild pain, bloating, flatulence and sense of defecation as abdominal discomfort. In a multilingual environment, doctors need to have the ability to understand various descriptions of abdominal discomfort.
Chinese IBS patients can accurately experience and report abdominal pain. Of 65.7% patients described abdominal pain as spasm/cramping, and other descriptions were associated with pain, which is similar to American patients,12 indicating that the cognition, experience and description of abdominal pain of IBS patients are relatively clear and consistent in different cultures. Some patients in American considered abdominal discomfort being a kind of mild pain.11,13 Fang et al. compared the characteristics of abdominal pain and abdominal discomfort in patients with Rome III-IBS in China. They found the degree of abdominal pain and abdominal discomfort was moderate in most patients, and 22.3% of patients with abdominal pain alone had severe abdominal pain, while 10.8% of patients with abdominal discomfort alone had severe abdominal discomfort (P = 0.007). And there was no significant difference in frequency of abdominal pain/discomfort, number of bowel movements or stool form during symptom onset, extra-intestinal pain, depression or anxiety state, or quality of life between the two groups.7 We found that the score of abdominal pain was higher than abdominal discomfort after cognitive interviews (4.73 ± 1.4 vs 3.62 ± 1.0), but both in moderate degree. Also, there was no significant difference in frequency, duration of abdominal pain/discomfort, or IBS-SSS between the two groups. Thus, although the degree of abdominal discomfort is less severe than abdominal pain, patients with abdominal discomfort alone are not IBS with mild symptoms because of the overall severity and the effect of abdominal discomfort on quality of life.
According to reports, 13.9%~29% of IBS patients have both abdominal pain and abdominal discomfort.7,13 In this study, 15 patients (17%) reported both abdominal pain and abdominal discomfort associated with defecation. After the explanation of the definitions of abdominal pain and abdominal discomfort, most patients could distinguish two symptoms. They considered abdominal pain and abdominal discomfort would cause different functional damage, and abdominal pain had a greater impact on life. It shows that Chinese IBS patients can accurately distinguish between abdominal pain and abdominal discomfort, and the significant difference in the description of abdominal discomfort reflects the diversity and complexity of the pathophysiological mechanism of abdominal discomfort to some extent.
Abdominal pain in patients with IBS is associated with visceral hypersensitivity caused by a variety of mechanisms, including diet, low-grade intestinal inflammation, changes in intestinal microbiota and psychological abnormality.24 Spasm/cramping in patients with IBS is associated with intestinal spasmodic contraction.25 Abdominal discomfort is more common in patients with IBS-C,20 Japanese scholars speculate that abdominal discomfort may be related to abnormal intestinal motility. At present, there is a lack of studies comparing the difference of pathophysiological mechanisms between abdominal pain and abdominal discomfort. Clinical analysis suggests that abdominal pain and abdominal discomfort are probably different experiences and feelings of similar stimuli.7,13,21 Meta analysis showed that female IBS patients were more likely to report abdominal pain.26 Anterior cingulate cortex (ACC) of brain is import in pain processing, and the thickness of bilateral subgenual anterior cingulate cortex (sgACC) in female IBS patients became thinner and correlated with the severity of abdominal pain.27 In this study, most patients with abdominal discomfort alone were male, indicating that gender may affect the experience and report of symptoms. Our brain imaging study found that visceral hypersensitivity was more prominent in patients with abdominal discomfort alone, and the occurrence of discomfort primarily related with the regions responsible for complex cognitive function and fear regulation (dorsal ACC).28 It is necessary to compare the pathophysiological mechanisms of abdominal pain and abdominal discomfort from the perspective of gut-brain interaction.
The study limitations
IBS-D is the main subtype in China, other subtypes weren’t included in this study. Cases with both abdominal pain and abdominal discomfort were relatively few. Considering the possible effects of depression and anxiety on symptom experience and report, patients with obvious psychological abnormalities were excluded, and the results could not reflect the condition of these patients.