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Observation Code Systems


The reason that an exposure occurred.

Code Display
voluntary The subject voluntarily subjects him or herself to the exposure, for example, smoking or using a drug recreationally.
addiction The subject is addicted to the substance.
self_prescribed The subject takes a non-prescription substance to address health issues or for prevention, e.g. herbal remedy for depression.
occupational Exposure in a workplace setting.
home Exposure in home setting.
passive The exposure occurred or occurs involuntarily, e.g., exposure to second-hand smoke.
accidental The exposure as a result of an accident.


An explanation of why the observation was not made (or ordered), i.e., why test was not ordered, or why a question was not asked. Since an observation is really a type of procedure, reasons that an observation was not carried out are similar to reasons any procedure might not be carried out.

Code Display
not_applicable The question or data element is not applicable, or based on other answers, no answer to this question is required.
contraindicated The test or observation is contraindicated, i.e., the subject is intolerant or at risk of an adverse reaction if subjected to the test or observation.
redundant The observation has made previously, or a previous test result is available, a new test or observation would be redundant.
cost The observation would be too costly.
refused The subject refused the observation.