Coding guidelines have long reflected a causal relationship between HTN and CKD, and coders are accustomed (and permitted) to linking these conditions and coding I12.- and the appropriate stage of CKD (in this case, N18.4).  But when the PCP links the CKD to the DM2 and not to the HTN or to both, coding guidelines state coders may “not assign a code from I12 when provider documentation indicates the CKD is attributable to another cause.”

So, the answer depends on what the PCP charted.

• If he or she selected, for example, E11.22, N18.4 & I12.9, that is permissible because the PCP is conveying that both conditions are linked to the kidney disease.
• If he or she coded E11.22, I10 & N18.4, the coder cannot automatically substitute I12.9 for the HTN without querying the provider.

From a risk adjusted standpoint, however, there is no impact to the HCCs from linking HTN to CKD in this example.