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.
The first record in a CSV file might represent the names of the following columns of data, and are generally referred to as column headers. Each record in a file with column headers may be have fewer fields in it than the number of column headers. If so, the left out fields' values should be considered empty.