TO THE EDITOR: We read the “Second Asian consensus on irritable bowel syndrome” by Gwee et al1 with interest. We would like to emphasize on the importance of correct diagnosis of the disorder. Generally, the diagnosis of irritable bowel syndrome (IBS) could be established based on clinical grounds if patients fulfill clinical criteria and have no alarm features.2,3 However, there are emerging evidences that colorectal cancer (CRC) may mimic IBS, and alarm features have unacceptably low sensitivity for CRC.
First, a Danish cohort study on 57 851 IBS patients reported 522 (0.9%) patients with CRC.4 In this study, there was a significantly increased risk of CRC in the first 3 months after an IBS diagnosis. Our study on 404 Vietnamese patients with IBS symptoms fulfilling the Rome III criteria found 2.2% of patients with CRC,5 and CRC was significantly associated with a short onset (≤ 2 years) of symptoms, but not with alarm features.
Second, alarm features are reported to have very low sensitivity for CRC in patients with lower gastrointestinal symptoms worldwide. A meta-analysis on 19 443 patients, mainly from Europe and United States of America, found that the sensitivity ranged from 5.0–64.0%.6 Similarly, a recent colonoscopy database review on 10 603 patients in China reported that the sensitivity was only 9.6%.7
Adjunctive tool, therefore, is crucial for daily practice. The Asia-Pacific Colorectal Screening (APCS) score is firstly developed to stratify risk for CRC in asymptomatic Asian subjects (Table).8 Our recent study6 found that it could be applied for patients with IBS symptoms. All of CRC patients with IBS symptoms who presented with no alarm features had high APCS scores. Besides, there were 4.7% of IBS patients with advanced colorectal adenomas. Compared to patients with an APCS score of 0 to 1, those with a score of 2 to 3 and 4 to 7 had 5.6-fold and 12.1-fold increase in odd for CRC or advanced colorectal adenomas, respectively. The APCS score, therefore, could be used to identify IBS patients with priority for colonoscopy. In the management of IBS, reassurance on the benign progression of the disease is important.1–3 But follow-up during the first 1 year to 2 years after IBS diagnosis should be considered for any change in symptoms, especially for patients with high APCS score who not yet undergo colonoscopy. Asking patients with IBS symptoms to revisit when alarm features develop may be too late.
Table.
The Asia Pacific Colorectal Screening Score
| Risk factor | Criteria | Points |
|---|---|---|
| Age (yr) | < 50 | 0 |
| 50–69 | 2 | |
| ≥ 70 | 3 | |
| Gender | Female | 0 |
| Male | 1 | |
| Family history of colorectal cancer in a first degree relative | Absent | 0 |
| Present | 2 | |
| Smoking | Never | 0 |
| Current or past | 1 |
A score of 0–1defines average risk, 2–3 moderate risk, and 4–7 high risk.
Footnotes
Financial support: None.
Conflicts of interest: None.
Author contributions: Duc T Quach initiated the study conception, wrote the draft, and submitted the study; and Duc T Quach and Toru Hiyama critically revised the manuscript. All authors approved the final version of the draft.
References
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