*Any person who habitually consumes tobacco at the time of sample collection or ceased smoking during the last year will be considered a smoker (see the ‘Collection and processing of urine samples’ section).28

†The following factors involved in the development of kidney damage will be considered risk factors: diabetes mellitus, hypertension and/or frequent use of non-steroidal anti-inflammatory drugs (more than 3 days a week during the 3 months prior to sampling). When a cell is marked with ‘X’, it is considered that the group included smokers (according to the previous definition*) or patients with at least one of the risk factors mentioned depending on the column considered.