The CIRS App is an interactive tool to measure comorbidity. It was developed to provide healthcare professionals with information on the 'Cumulative Illness Rating Scale for Geriatrics' (commonly abbreviated to CIRS-G), and to help them calculate a patient's biological fitness based on a ratified CIRS-G scoring assessment. The app is for guidance only, does not replace expert medical opinion and is not deemed to be a medical device within the terms of the Medical Devices Directive 93/42/EEC.