Medically reviewed by Onikepe Adegbola, MD, PhD
A study published in Scientific Reports, a Nature.com peer-reviewed journal, showed that 49% of patients diagnosed with irritable bowel syndrome (IBS) and referred to secondary care tested positive for small intestinal bacterial overgrowth (SIBO) instead.
The same study found that people referred to secondary care diagnosed with IBS often have other non-cancerous gastrointestinal disorders, and needlessly suffer from conditions that could be treated if only they were properly diagnosed.
This study, “A systematic review and meta-analysis on the prevalence of non-malignant, organic gastrointestinal disorders misdiagnosed as irritable bowel syndrome,” was conducted by D. Poon, G. Law, G. Major, H. Jervoise, and N. Andreyevrty, focused on five organic gastrointestinal conditions, which doctors were misdiagnosing as IBS. The included disorders included bile acid diarrhea (BAD), carbohydrate malabsorption (CM), microscopic colitis (MC), pancreatic exocrine insufficiency (PEI), and small intestinal bacterial overgrowth (SIBO). The researchers retrieved the relevant data from the PubMed, EMBASE, and Cochrane medical databases from the years 1978 to 2020. The data were sorted and filtered for quality assurance purposes.
Using Q and I2 statistics, 2149 patients were included in a meta-analysis of 22 studies using a glucose breath test as a substrate (a foundation for the test). The crude pooled rate was 24.9% (range 0%–48.5%) and the estimated pooled rate was 19% (95% CI 13%–27%). This gives us a low range of 19% and a high of 25% of patients testing positive for SIBO.
Again, using Q and I2 statistics, this time, 4630 patients received a lactulose breath test in 36 studies as a substrate. The pooled rates for SIBO were 43.7% and 45.1% (range 0%–83.8%), respectively. The estimated pooled rates are 46% (95% CI 37%–55%) and 49% (95% CI 40%–57%). The lactulose section of the study included a group of patients who used six different diagnostic criteria to diagnose patients as positive for SIBO.
So, what is the takeaway from this meta-analysis of these studies? It is quite evident that patients presenting to either emergency care or their primary care physician with gastrointestinal symptoms are being misdiagnosed with IBS, and that in many cases an organic GI condition is to blame for their symptoms.
IBS is defined by what is known as a “cluster” of symptoms. The cluster has evolved over the years, but a diligent physician should have no problem diagnosing this disorder, which is marked by recurrent, defecation-associated abdominal pain. And when you consider that IBS affects 7%–21% of the global adult population, it is alarming to think that 49% of those people are going untreated when it is completely unnecessary.
The researchers in this study concluded that specialist-clinicians are too quick to diagnose IBS, and they question the current methods for diagnosing IBS in the ER and primary care settings. More research is needed to determine what it would cost to introduce more testing for people who present with IBS-like symptoms in the ER or primary care to avoid being misdiagnosed.
Dukowicz, A. C., Lacy, B. E., & Levine, G. M. (2007). Small intestinal bacterial overgrowth: a comprehensive review. Gastroenterology & hepatology, 3(2), 112–122.
Poon, D., Law, G. R., Major, G., & Andreyev, H. J. N. (2022, February 4). A systematic review and meta-analysis on the prevalence of non-malignant, organic gastrointestinal disorders misdiagnosed as irritable bowel syndrome. Nature News. Retrieved May 4, 2022, from https://www.nature.com/articles/s41598-022-05933-1#Sec1