Coding dictionaries

Coding capability What are the coding capabilities Does it support MedDRA dictionary Does it support other coding dictionaries ... 

Adverse events need to be coded consistently with respect to letter case. Problems can occur when there is discordant coding using all capital letters, all lower-case letters, or combinations thereof, as computer software will interpret these capitalization variations as different events. Letter case sensitivity can be important when two or more words are used to describe an adverse event. For example, some databases utilizing the Medical Dictionary for Regulatory Activities (MedDRA) coding dictionary employ a coding system in which only the first letter of the first word of an adverse event is capitalized (e.g., Atrioventricular block complete ). Failing to adhere to uniform letter case conventions across the data can result in severe errors in data analysis. 

Again, the free-text CRF format is useful in that it allows for explicit description of the historical condition, whereas the pre-categorized CRF format omits that detail. However, the free-text list format necessitates coding with a coding dictionary such as MedDRA in order to be useful for analyses. The pre-categorized format is useful here, as only medical history relevant to the investigational therapy can be captured and the cost of additional coding of the history data is eliminated entirely. 

There are hundreds of proprietary medical dictionaries in circulation. Fortunately, a number of medical dictionaries are headed for retirement. The pharmaceutical industry along with regulators and standards groups is actively working to reduce the number of coding dictionaries. So we will discuss MedDRA for adverse events and WHODrug for... 

Note that by changing the aesev variable to the aerel variable throughout Program 5.4, you can easily change the previous adverse event summary to a summary of adverse events by maximum drug relatedness. Also, if you remove the maximum severity steps, you get a typical overall summary of adverse events by body system and preferred term. Since patient medical history data are also often coded with MedDRA, patient medical history data may be summarized much like an overall summary of adverse events. However, frequently medical histories are collected in a checklist/checkbox format so that using a coding dictionary is unnecessary. 

Medical Term Coding Dictionaries. It is logical to deal with AEs, indications, diseases, surgeries and procedures using one system for the following reasons ... 

The genetic code dictionary was originally established from studies on the bacterium E. coli. It is now known to be the same for all organisms i.e., it is universal. The only exceptions occur for a few codons in mitochondria from a number of species. 

The original vocabulary used by the investigator to describe adverse experiences should be used in listings of the individual final study reports. These should indicate which terms in the coding dictionaries were used for the original terms. These dictionaries will contain a preferred word and usually summarize the adverse experiences by body system. 

The management and use of the system, and related reference data (e.g., laboratory reference ranges and coding dictionaries), should be controlled by Standard Operating Procedures. Such procedures should include taking data extracts, possibly as predefined reports. Extracts should be validated to demonstrate they correctly identify, combine/merge, and report data requested. At the system level the functionality of a reporting system should ensure that ... 

Perry, J. W., Kent, Allen, Tools for Machine Literature Searching (Semantic Code Dictionary, Equipment, Procedures), Interscience, New York, 1958. 

Pharmaceutical companies, individual regulatory authorities and the WHO have databases which facilitate this overview. The use of a standard coding dictionary of adverse event terms is essential for this sort of analysis, and one, MedDRA (Medical Dictionary for Regulatory Activities) has been accepted as the gold standard to be used. Nevertheless, routine review of individual cases by responsible, experienced reviewers is the most essential factor in identifying new signals and ensuring patient protection. 

Similar analysis approaches are used to describe the risk, in both the absolute and relative (comparative) sense, of individuals reporting specific AEs. These analyses are much more useful clinically because not all AEs are created equal. One example is to estimate the proportion of individuals in a given group who reported a headache. To do this in a standardized manner it is necessary to "code" the AE descriptions (for example, "tension headache", "achy head"). The use of the MedDRA coding dictionary for this purpose is now widely accepted, and in some instances may be required. Coding is performed before statistical analysis and the "coded" terms are used in statistical summaries that require counting of participants reporting each event. 

The fragments that have been chosen to act as screens are listed in a fragment coding dictionary. When a query or a new molecule is to be processed, the corresponding connection table is analyzed to identify those screens from the coding dictionary that are present in the structure. A database structure or query substructure is then represented by a fixed-length bit string... 

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