Comorbid Diagnosis

For other diagnoses we collect see Admit Diagnosis or Acquired Diagnosis / Complication.

Comorbid Diagnoses are for diseases the patient has had for some time. Comorbidities can be a factor in increasing the patient risk of dying; see Charlson Comorbidity Index.

Collection Instructions

• This "bin" of diagnoses is exclusively for CHRONIC conditions.
• So, an ACUTE condition (even if recurrent) that is ABSENT between recurrences should NOT be coded here.
  • e.g. Recurrent pneumonia -- although one can be left with chronic sequelae of pneumonia (e.g. a pneumatocele or a region of emphysema or a bulla), in between these infections, there IS NO pneumonia
  • e.g. Recurrent severe sepsis -- same as above
  • e.g. Asthma that is not currently in an exacerbation -- this IS a chronic disease whose nature is intermittent symptoms, but in between those symptoms the person still has asthma.
• So, for chronic conditions that are at their baseline at admission, code those in this bin -- e.g. COPD.
  • This "baseline" could include either of: not currently getting any treatment; getting maintenance/control treatment.
  • Obviously, if the chronic condition (e.g. COPD) is in exacerbation at admission, then it should be listed under the bin Admit Diagnosis -- e.g COPD, acute exacerbation
• A good example of coding a diagnosis that is important as a comorbid, but no longer an acute issue is an old, presumably cured, cancer
• An issue in coding chronic comorbid conditions is that in addition to the "usual" ICD10 diagnoses of conditions that could be listed there, ICD10 has a bunch of codes that indicate explicitly either "Past history of X" or "Artifical opening, has one". These are included in here:

Past history codes:

When to use Comorbid Diagnosis vs Admit Diagnosis or neither

When not to code a dx at all

• Dx was present in the past but that problem is resolved AND does not fit into one of the Category: Past medical history codes
  • To be clear on this -- do NOT code past problems that are fully resolved unless they are one of the Category: Past medical history codes
• Do not code diagnoses that occur during this admission as a comorbid diagnoses. If they have completely resolved then do not code as a comorbid diagnosis until the next admission if applicable. ie. surgical ward had a COVID pneumonia resolved prior to ICU admission. Do not code Past history of Covid-19 infection until the next hospital admission.

Regular comorbid rules exception: Strokes (of any sort, ischemic or hemorrhagic) -- code even resolved strokes with no current sequelae as comorbid diagnoses. If a patient has a past history of stroke, use the regular stroke codes to identify this, even if the patient does not have any residual deficits we will now capture ANY past history of stroke. This is contrary to the usual rules about Comorbid_Diagnosis#When_not_to_code_a_dx_at_all.

Example:

Patient had the left lung removed 7 years ago. Dont code the removal of the lung CCI, but instead code Past history, removal of all or part of lung For someone who had a Cardiac arrest in the past, don't code that as a Comorbid Diagnosis 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 Diagnosis. Patient had ARDS (noncardiogenic pulmonary edema) a few years ago, and while ARDS is only an acute problem and thus is no longer active, his lungs never fully recovered and he has Respiratory failure (insufficiency), chronic which should be coded as a Comorbid Diagnosis. Chronic and ongoing old conditions should be coded -- as a Comorbid Diagnosis if not part of the reason for this admission.

Some diagnoses can/should be coded as BOTH Admit Diagnosis and Comorbid Diagnosis

If a dx is chronic but also actively treated during this admission, code it as both Admit Diagnosis and Comorbid Diagnosis.

Example:

ex1: 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" Comorbid Diagnosis. ex2: Patient has a past history of CHF and thus it should be coded as a Comorbid Diagnosis. And if the CHF is worse at admission and it is part of the reason for admission, then CHF should also be an Admit Diagnosis.

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:

Ex1: 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:

Ex2: 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 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.

Controlling Dx Type for ICD10 codes

This wiki page talks about which ICD10 codes are allowed to be Comorbid Diagnosis vs. Admit Diagnosis vs. Acquired Diagnosis Dx Type. See Controlling Dx Type for ICD10 codes for a discussion about cross-checks for these.

Legacy - did not use to code Comorbid Diagnoses only discovered during this admission

see how this used to be coded...

As of June 25, 2020, the rules were revised for coding as Comorbid Diagnoses those diagnosed during the current hospitalization (either at admission or thereafter) but which virtually certainly were present pre-admission.

Dx_Priority

You will need to enter priorities for comorbids to group them for Combined ICD10 codes. Don't worry about actually prioritizing them in any order of importance, for comorbids the priorities will only be used for related grouping.

Patient has no comorbidities

If a patient has no comorbidities, enter No Comorbidities (ICD10 code).

Transfer of Comorbids on transfer between wards

Hi Tina is there any way that our comorbid diagnosis in the NEW ICD 10 collection can be transferred with the patient when they are discharged to another ward rather than readmitting and entering them ? (Shirley) This question has come up in the past and there are unresolved questions at Patient copier button. All collectors, please contribute there... Ttenbergen 09:24, 2018 June 19 (CDT)

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