Irritable Bowel Syndrome Message Boards | Diagnostic Yield of Alarm Features in Irritable Bowel Syndrome

Diagnostic Yield of Alarm Features in Irritable Bowel Syndrome and Functional Dyspepsia

Hammer J, Eslick GD, Howell SC, Altiparmak E, Talley NJ
Gut. 2004;53(5):666-672

Objective: The diagnostic value of the addition of alarm symptoms in distinguishing functional from organic gastrointestinal disease remains uncertain. We aimed to establish the value of alarm features in differentiating between organic disease and irritable bowel syndrome (IBS) and functional dyspepsia (FD).
Methods: A total of 568 consecutive patients (63% female; mean age 44.7 years) completed a detailed symptom questionnaire and then received a complete diagnostic workup, as required. Questionnaire data were collected prospectively and audited retrospectively; the treating physician was blinded to the results of the questionnaires. Patients were coded and allocated to the following diagnostic groups: IBS, FD, organic diseases of the upper gastrointestinal tract, or organic diseases of the lower gastrointestinal tract. Logistic regression was used to identify the best subset of symptoms that discriminated organic disease from functional illness. Separate models compared IBS (n = 214) with diseases of the lower gastrointestinal tract (n = 66), and FD (n = 70) with diseases of the upper gastrointestinal tract (n = 250).
Results: Age (50 years at symptom onset: odds ratio (OR) 2.65 (95% confidence interval 1.4�5.0); p = 0.002) and blood on the toilet paper (OR 2.7 (1.4�5.1);p = 0.002) emerged as alarm features that discriminated IBS from lower gastrointestinal illness. A diagnosis of IBS was typically associated with female sex (OR 2.5 (1.3�4.6); p = 0.004), pain on six or more occasions in the previous year (OR 5.0 (2.2�11.1); p<0.001), pain that radiated outside of the abdomen (OR 2.9 (1.4�6.3); p = 0.006), and pain associated with looser bowel motions (OR 2.1 (1.1�4.2); p = 0.03). A model incorporating three Manning criteria and alarm features yielded a correct diagnosis of IBS in 96% and a correct diagnosis of organic disease in 52% of cases. Alarm features did not discriminate FD from upper gastrointestinal disease. Patients with FD were significantly more likely to report upper abdominal pain (OR 3.7 (1.7�8.3); p = 0.002) and significantly less likely to report aspirin use (OR 0.26 (0.1�0.6); p = 0.001). The predictive value of symptoms in diagnosing FD was only 17%.
Conclusions: Symptoms plus alarm features have a high predictive value for diagnosing IBS but the predictive value for a diagnosis of FD remains poor. Current criteria for the diagnosis of IBS should incorporate relevant alarm features to improve the diagnostic yield.

Summary: With the burgeoning costs of healthcare, there is ever-increasing pressure placed on the healthcare provider to use the most cost-effective strategy to diagnose and treat a particular health problem. Irritable bowel syndrome (IBS) and functional dyspepsia (FD) are among the most common diagnostic problems presenting the gastroenterologist with the conundrum of whether to perform extensive diagnostic testing or to treat empirically. However, the accuracy of the latter option (a diagnosis based purely on the presenting gastrointestinal symptoms) potentially places a considerable liability on the practitioner, who is subject to the level of confidence that can be placed in the diagnosis that is suspected. Many clinicians have suggested that the presence of "alarm features," such as bleeding, dysphagia, weight loss, vomiting, or later age at onset, may be more suggestive of the need for early diagnostic testing for organic disease. Therefore, the working hypothesis for this present study conducted by Hammer and colleagues was that taking an accurate history to evaluate the presence of alarm features and symptoms would increase the diagnostic potential and avoid unnecessary diagnostic procedures in patients with functional disease. The aim thereby was to further evaluate the yield of these "alarm features" that might suggest that functional disease (eg, IBS and FD) is less likely.

A total of 806 patients consulting a gastroenterology practice in Australia were studied. These patients were prospectively asked to fill out a questionnaire and data were retrospectively analyzed. Although there were no sample-size calculations performed for this study initially, the study authors provided a creditable effort to justify the power of the study by post hoc calculations, which suggest that the sample size was more than appropriate. All functional disorders were diagnosed based on the history and physical examination, as well as on the appropriate exclusionary diagnostic tests, including upper and lower endoscopy. The treating physicians were blinded to the results of the questionnaire. All results were then reviewed by at least one other gastroenterologist. If there were disparate opinions, the diagnosis was established by consensus.

Alarm features that discriminated IBS from organic disease were as follows: onset of symptoms at age > 50 years (odds ratio [OR], 2.7; 95% confidence interval [CI] 1.4-5.0; P = .002) and blood on the toilet paper (OR, 2.7; 95% CI, 1.4-5.1; P = .004). Factors predictive of IBS were: female sex (OR, 2.5; 95% CI, 1.3-4.6; P = .004), pain occurring 6 or more times in a year (OR, 5.0, 95% CI, 2.2-11.1; P < .001), pain radiation out of the abdomen (OR, 2.9; 95% CI, 1.4-6.3; P = .006), and pain associated with loose bowel movements (OR, 2.1; 95% CI, 1.1-4.2; P = .03). A model formulated incorporating the Manning criteria (abdominal pain relieved with bowel movements, pain associated with more frequent stools, sensation of incomplete evacuation, passage of mucus, abdominal distension) and alarm features yielded a correct diagnosis of IBS in 96% and organic disease in 52% of cases.

Only 1 of 16 alarm features discriminated upper gastrointestinal disease from FD. Patients with organic upper gastrointestinal disease were less likely to report decreased appetite (OR, 0.49; 95% CI, 0.26-0.91; P = .02). Patients with FD were more likely to report upper abdominal pain (OR, 3.7; 95% CI, 1.7-8.3; P = .002), and reported less aspirin use (OR, 0.26, 95% CI, 0.1-0.6; P = .001). The predictive value of symptoms in diagnosing FD was only 17%. The study authors concluded that alarm features have a high predictive value for the diagnosis of IBS, but not for FD.

Commentary: So what does this all mean? For IBS, it means that alarm features are the most important factors for establishing the diagnosis. In this study, the absence of alarm features correctly identified IBS in 93% of patients, while the addition of the Manning criteria improved this statistic by only an additional 3%. It is puzzling to me why the investigators used the Manning criteria (developed back in 1978). Clearly, attempts have been made to improve the diagnostic accuracy of IBS through the development of, and revisions in, the Rome criteria (Rome I and II). The clinician reader should be aware that this study may have some limitations. First, there were very few cancers identified, a finding that may reflect a referral bias to the evaluation site. Additionally, the study authors did not fully evaluate all alarm features, rather only those listed on the validated questionnaire employed in this study.

For the dyspepsia portion of this report, data presented suggest that a symptom-based diagnosis had a very poor predictive value. Hence, evaluation of alarm features fails to satisfactorily improve the diagnostic yield of symptoms of FD.

The work group for Rome III revisions will begin late in 2004. It is likely, as based on this study, that the Rome criteria will need to be expanded to include key alarm features for both IBS and FD. Although this should help the diagnostic accuracy for IBS, in contrast, the diagnosis of FD will likely remain as a diagnosis of exclusion. This study provides very weighted support for the recommendation that testing is generally not required in patients with positive symptom criteria for IBS and an absence of alarm features. For the diagnosis of FD, however, it remains caveat emptor.

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David A. Johnson, MD, FACG, FACP, Professor of Medicine, Chief of Gastroenterology, Eastern Virginia School of Medicine, Norfolk, Virginia

Disclosure: David A. Johnson, MD, FACG, FACP, has disclosed that he has received grants for clinical research from AstraZeneca, Wyeth, TAP, BSC, and Novartis.

Medscape Gastroenterology 6(1), 2004. � 2004 Medscape

http://www.medscape.com/viewarticle/479783#a2

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