Current Diagnostic Strategies and Pharmacologic Treatment Options for Irritable Bowel Syndrome

INTRODUCTION Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal (GI) disorder with an estimated prevalence of up to 20% in the United States (1). Although few individuals with IBS seek medical treatment for their symptoms (1), IBS is the most frequent diagnosis made by gastroenterologists (2). Individuals with IBS have reduced health-related quality of life, substantially decreased work productivity, and an increased number of missed workdays compared with healthy individuals (3). Furthermore, the economic Anthony J. Lembo, M.D., Director, GI Motility Laboratory, Beth Israel Deaconess Medical Center, Boston, MA. The pathophysiologic mechanisms underlying irritable bowel syndrome (IBS) may involve altered small bowel motility, visceral hypersensitivity, and immune activation in the gastrointestinal tract. These mechanisms are not mutually exclusive and may vary among individuals, leading to a complex heterogeneity of symptoms that can make accurate diagnosis and optimal management of IBS challenging. Because no known biochemical markers identify IBS, diagnosis is determined by symptom-based criteria. These criteria have proven beneficial for clinical research purposes, but validation in clinical practice is limited. Current approaches to treatment of IBS include symptombased pharmacologic interventions as well as therapies that target putative underlying mechanisms. However, few therapeutic agents have been rigorously evaluated in high-quality clinical trials. Furthermore, clinical studies of IBS therapies have a high placebo response rate, making conclusions about treatment efficacy difficult. Given these challenging issues, current diagnostic strategies and optimal treatment options for individuals with IBS are discussed.