The difficult art of diagnostic coding

As doctors we are trained to diagnose. We are engaged in a systematic search for explanations of illness and disease, and we hope in the end to put a name on the disorder for each patient. When we know, or strongly suspect, what the problem can be, we may or may not be able to offer a treatment. This is the Aristotelean influence on medicine, although medicine today is equipped with more tools today than for nearly 2500 years ago. As diagnosis often comes in many forms and variations, diagnosis has become increasingly more complex. There may exist a number of sub-diagnoses even within a specific condition. Myocardial infarction is a good example, there are more than 20 modern sub-diagnoses, and many consider this not detailed enough. The quest for making a classification system from the various diagnosis and causes of death has a more than 150-year history. Some claim that it started with the systematic observations by Florence Nightingale. In 1899, the first international conference about diagnostic codes was held in Oslo (then called Christiania), and was planned to be revised every 10th year. In 1948, after the establishment of UN, the World Health Organization (WHO) continued this task with the 7th version of the code manual. We now have the 10th version of the International Statistical Classification of Diseases and Related Health Problems, abbreviated to: International Classification of diseases (ICD). This has become an invaluable tool for worldwide statistics on morbidity and mortality. The work towards ICD-11 is ongoing, and that version is expected to be launched in 2018. Most of us will agree that having such a classification of diseases, which is in common for the whole world, is beneficial. Some problems may arise when the diagnostic codes are used as an instrument in health care financing, which has happened with the diagnosis-related groups (DRG). These were presented in the 1970s to help to facilitate the financial reimbursement for health care service in USA. This system has since spread around the globe. In the Nordic countries, there is a strong collaboration about DRG coding as all countries with the exception of Iceland, use this system for reimbursement purposes in public health care. This is currently a deviation from the traditional diagnosis of patients, and this is the use of diagnostic codes for statistical and economical purposes. The transition has happened very fast, and only recently this topic was introduced in medical schools in Norway. Physician knowledge in use of ICD codes and the DRG system is often rudimentary, and is not usually given a high priority in medical training. That is why the DRG system in many hospitals is managed by non-medical professions, although supported by medical supervisors. How well do the diagnostic coding (ICD-10) and the procedure coding (NCMP) suit our specialty, anaesthesia and intensive care medicine? In particular, within intensive care, this has been a major issue, as the main source of ICU reimbursement, in Norway at least at the moment, is the procedure for tracheostomy. It may be that some of the increased frequency we have witnessed for this procedure, the last 15– 20 years also, is driven by its high impact DRG. Another issue of importance for critical