Mapping & Computer Algorithm
Once the data collector has coded all of the Collaborative Staging System elements for a case (the input values), the coded values can be passed to a computer program that then generates the correct stage for the case in three systems: AJCC TNM, 6th edition; Summary Stage 1977; and Summary Stage 2000. The program returns output values for a set of output items.
The output values are returned as a set of numeric codes designed for storage in the computerized abstract. Each of the numeric codes is also provided with a display value, or English language character string that shows the meaning of the code. For example, a returned value of 12 for T means T1a, and a 15 means T1b.
The computer algorithm that generates the stages is based on the values in the Mapping columns for each of the Collaborative Staging System data elements. Mapping is provided from each code to the appropriate category in TNM and each summary stage. Some schemes require reference to two or more tables to determine the appropriate category. The mapping column either contains the category or a pointer to a further table where the category can be determined. Once each of the categories is determined, a further step is done. Although the data collector does not code the stage groups directly, the rules by which the stages are derived are explicit in all of the tables, and the logic that the computer program follows should be fully evident from the tables available to the data collector.