For someone who had a Cardiac arrest in the past, don't code that as a comorbid in future admissions, but instead DO code the cause of the cardiac arrest, e.g. an arrythmia, or coronary artery disease, etc.
Patient has hypertension for which she takes medications and it is well controlled, but not related to the reasons for admission. Code this, because even if not part of the reason for the current admission, the hypertension IS relevant to this person's chronic medical situation and thus SHOULD be coded, as a comorbid.
Distinction between admit and acquired diagnoses relate to the START of a database record. As of October 2020, a single record may span direct transfers between different locations and even between different services. Accordingly, an admit diagnosis only relates to the very start of a database record. Diagnoses that occur after the start of a database record will be acquired diagnoses.
Dx was present prior to the start of the record.
Example -- patient's care is taken over by Medicine service while he is still in ED. The admission diagnosis is DKA. He remains on Medicine service in ED (due to lack of ward beds) for 2 days, after which he finally gets up to the Medicine ward and then has a stroke. The stroke is an acquired diagnosis, and would still be acquired even if it had occurred during those 2 days in ED.
AND
Dx is relevant to this admission in that it is either:
(a) an acute or exacerbated condition (as opposed to a chronic, stable condition -- e.g. stable diabetes), OR
(b) it is a condition not directly related to the reason(s) for admission, but its treatment is being actively managed -- and by actively we mean that during this admission changes are made to the management.
Examples:
Example:
Patient with TB has been treated for the past 5 (of his 9 expected) months admitted now for acute MI.
Scenario#1:No changes made in his TB treatment ---> so NOT an admit dx (but this active TB is a comorbid dx)
Scenario#2:Changes are made to his TB treatment during this admission ---> so IS an admit dx too
As of June 25, 2020, the rules were revised for coding as comorbid conditions those diagnosed during the current hospitalization (either at admission or thereafter) but which virtually certainly were present pre-admission.
In this situation, code it as a comorbid diagnosis if it is a chronic, NONINFECTIOUS condition -- e.g. a cancer, collagen-vascular disease (such as Systemic lupus erythematosis (SLE, lupus)), COPD, diabetes
But do NOT code it as comorbid if it is a chronic INFECTIOUS condition -- such as Tuberculosis or AIDS (disease due to HIV) (which if first discovered/identified during the current admission would qualify as an admit diagnosis).
Note that this rule does not impact on coding as a comorbid an infection which is still present but WAS known pre-admission --- e.g. an osteomyelitis being treated at home with iv antibiotics.
Some diagnoses can/should be coded as BOTH admit and comorbid
example: Patient who has been, and still is, being treated for active pulmonary TB as an outpatient, and is admitted for an acute MI. Here since on the current admission the TB is still being actively treated, it qualifies as an admit diagnosis, as above. But because it has been present from long before this admission, it also qualifies as an "active" comorbidity.
example: Patient has a past history of CHF and thus it should be coded as a comorbid. And if the CHF is worse at admission and it is part of the reason for admission, then CHF should also be an admit code too.
Recurrent conditions
Do not code a recurrent condition that is NOT currently present -- if currently active, include as Admit Diagnosis, otherwise don't code it
Example:
Recurrent pneumonia -- in between the infections, there IS NO pneumonia
Do code conditions that by nature have intermittent rather than continuous symptoms, but where the underlying condition doesn't go away.
Example:
Asthma, without acute exacerbation -- this 'is a chronic disease whose nature is intermittent symptoms, but in between those symptoms the person still has asthma.
Past medical history
Past medical history codes
Past medical history codes should only be captured as Comorbid Diagnoses that represent previous procedures or medical situations. Their names usually follow the pattern "Past history of X" or "X, has one". See Category:Past medical history for a list.
Diagnosis categories in relation to patients moving around the hospital
This section explains rules for how to categorize diagnoses as a patient moves from place to place within a hospital -- i.e. during a single hospitalization. In this section we'll refer to a person who moves from A to B to C (e.g. A and C are ICU while B is ward; so 3 separate records in the database)
Rule#1: Situation where a diagnosis is NEW to this hospitalization [i.e. either it: (a) was an admit diagnosis to location A that was not a chronic, pre-existing disorder before hospitalization, OR (b) developed after admission, as an acquired diagnosis while in location A], then:
when you start records B or C do NOT include that diagnosis as a comorbid
if by the time they are transferred to the subsequent location it is resolved and no longer being treated, then it should not show up as any kind of diagnosis for that subsequent record
if by the time they are transferred to the subsequent location it is still being dealt with medically, and indeed is part of the reasons they are going to the new location, then it should be listed as an admit diagnosis for that subsequent record
Rule#2: The group of diagnoses that represent "past history" (e.g. Past history, loss of limb(s) are also guided by Rule#1.
Rule#3: The "duration" of a diagnostic event (e.g. pneumonia vs. an arrythmia) has no role in decision-making about how these diagnoses are listed (or not)
Rules 1 and 2 are clear, could rule 3 be further clarified
This wiki page talks about which ICD10 codes are allowed to be Comorbid vs. Acute vs. Acquired diagnosis type. See Controlling Dx Type for ICD10 codes for a discussion about cross-checks for these.