In 2002, the National Kidney Foundation published treatment guidelines that identified five stages of Chronic Kidney Disease (CKD) based on declining GFR measurements. The guidelines recommend different actions based on the stage of kidney disease.
CSV (Comma Separated Value) was a file format devised to store tabular data. It uses commas to separate each entry in a row and the newline symbol to go to the next row. Excel is a more recent spreadsheet application from Microsoft and it saves the data with its own file format.
CSV is a delimited data format that has fields/columns separated by the comma character and records/rows terminated by newlines. A CSV file does not require a specific character encoding, byte order, or line terminator format (some software does not support all line-end variations). A record ends at a line terminator. However, line-terminators can be embedded as data within fields, so software must recognize quoted line-separators (see below) in order to correctly assemble an entire record from perhaps multiple lines.