Luminary Learning Gastrointestinal Disorder- Issue 1

32  • LUMINARY LEARNING: GASTROINTESTINAL DISORDERS Indications for Colonoscopy In order to achieve good penetration of the target screening population while also remaining cost effective, it is of utmost importance to distinguish between screening of asymptomatic individuals and diagnostic workup for their appropriate use in regard to onset and duration of screening and frequency of repeat exams (Table 1). Risk Categories Approximately, 65–75% of the population are considered to be low or average risk, i.e., there are no identifiable risk factors including, a lack of first-degree relatives with CRC or advanced adenomata (Table 2). Another 20–30% are at an increased risk of CRC, based on having one first-degree relative with an age of less than 60 years or two or more first-degree relatives of any age with CRC or advanced polyps, or a respective personal history; there are also a number of ethnicities who have been associated with an increased risk of CRC, including African-Americans and Ashkenazi Jews [4]. Additionally, 6–8% of the population are linked to a high-risk constel- lation for developing CRC based on the presence of genetic mutations/syndromes such as famil- ial adenomatous polyposis (FAP) or its attenuated form (AFAP), Lynch syndrome (HNPCC), or MUTYH-associated polyposis (MAP), or based on the presence of chronic inflammatory bowel disease (IBD) [12]. Time for the First Screening In the asymptomatic average-risk individual, it is recommended to start screening colonoscopy at age 50, and if negative to repeat it every 10 years (Table 3). Data from larger cohort studies suggest Table 1: Distinction between and criteria for screening versus diagnostic colonoscopy. Setting Parameters Screening Absence of symptoms Defined risk categories (Table 2) Establishing the time for the first screening (Table 3) Quality assessment parameters for each test in general and in individual patient (Table 4) Establishing the appropriate repeat intervals depending on (Table 5):  • Basic risk profile  • Quality of the test performance  • Individual findings Diagnostic workup Symptom characterization Age Presence of age-independent risk factors Defining the appropriate role of other tests beyond colonoscopy