Mapping principles: dual coding and transition tables

Measure the difference

Dual coding studies tell you what a transition will really change. Here is how they work.

Code the same episodes twice

Dual coding studies code the same episodes in two ICD versions and compare the results. They identify coding variations and predict the impact on the coder workforce and revenue, and they show the effect of crosswalks on trends, casemix and funding. They are easier for mortality, and less simple but possible for morbidity.

• What · Two versions · Coding the same mortality or morbidity episodes in two ICD versions and comparing the results.
• What it shows · Impact · Coding variations, the effect on the coder workforce and revenue, trends, casemix and funding.

Keep the old system running

WHO encourages maintaining the current classification for a defined period, with an overlap of at least eighteen months with the new system. That gives stability of reporting, data for dual coding studies, bridge coding between revisions, early detection of problems, and continuity of trained coders.

• Overlap · 18 months · Maintain the current classification for a defined period, with an overlap of at least 18 months with the new system.
• Benefits · Continuity · Data continuity, dual coding data, bridge coding, error detection and continuity of trained coders.

Provided with every version

Transition tables and materials showing the differences are provided with every version. Version identifiers are reported together with the codes. And WHO plans stable international versions every five years, with more detailed updates annually.

• Tables · Each version · Transition tables and materials showing the differences are provided with every version.
• Identifiers · Reporting · Version identifiers are used for reporting together with the codes.
• Cycles · Five years · Stable versions for international use are planned five-yearly; more detailed updates can be annual.

Check yourself

Pause and think. For how long does WHO encourage keeping the current classification running alongside the new one? The answer: At least eighteen months. WHO encourages maintaining the current classification for a defined period, with an overlap of at least eighteen months with the new system.

• At least eighteen months
• About one month
• Exactly six months
• Three years at most

Keep these in mind

Dual coding measures the impact. Overlap the old system by at least eighteen months. And report the version with the codes.

• Dual coding measures the impact
• Overlap the old system by at least 18 months
• Report the version with the codes