For home health coders, the real challenge is not understanding coding rules—it is applying them strategically to balance compliance and reimbursement under PDGM. While primary diagnoses capture the main reason for care, secondary diagnoses play a vital role in reflecting the full clinical picture of the patient and significantly impact reimbursement values.
Here are practical tips and best practices for coding secondary diagnoses and maximizing comorbidity adjustment in home health:
1. Capture All Active Conditions That Affect Care
Secondary diagnoses only matter if they are influencing care. Do not waste code slots on inactive history conditions—but don’t undercode either. The subtle catch is often in the documentation: a clinician may not explicitly link hypertension or CKD to the plan of care, but if the nurse is monitoring vitals or labs, the condition qualifies.
Tip: Scrutinize the OASIS and orders for evidence of monitoring or teaching. Many comorbidities are lost not from lack of presence but lack of documentation support.
2. Leverage Comorbidity Pairings
Under PDGM, missing one half of a comorbidity subgroup is a wasted adjustment. CHF + diabetes, obesity + hypertension—these pairings matter. Missing one condition from a qualifying pair could mean missing a higher comorbidity adjustment.
Tip: Keep a current crosswalk of PDGM comorbidity subgroups. It pays to double-check when coding cases with multiple chronic conditions.
3. Don’t Miss Combination Codes
Combination codes are still an underutilized tool. Coders who default to separate codes risk missing severity and adjustment opportunities. Think diabetic complications (neuropathy, CKD, retinopathy) or hypertensive heart disease.
Tip: Always check the “with” guidelines and index notes before finalizing. ICD-10 tends to reward combination coding with better specificity and, often, higher PDGM capture.
4. Sync Coding With OASIS
OASIS responses and coding should align. For example, if the OASIS indicates that the patient is insulin-dependent, but the coding lists only unspecified diabetes, this creates inconsistency and may affect both compliance and reimbursement.
Tip: Encourage collaboration between clinicians completing OASIS and coders to ensure both documentation and diagnosis coding fully reflect the patient’s condition. Develop concise, template-based queries that clinicians can respond to quickly. Do a quick side-by-side of OASIS functional items and your coded diagnoses before locking the chart.
5. Use Provider Queries Wisely
If documentation is vague—for example, an unspecified type of diabetes—send a concise, compliant query to the referring physician or provider. Many comorbidities are undercoded simply because documentation is incomplete.
Tip: Maintain close collaboration with clinicians and the intake team to coordinate queries and obtain the supporting documentation needed to substantiate coding.
6. Keep Up With Annual ICD-10-CM and PDGM Updates
CMS updates comorbidity groupings and ICD-10-CM codes every year. A diagnosis that triggered a comorbidity adjustment last year may not in the current year—and new codes may qualify for adjustment.
Tip: Stay current with official coding updates, but don’t just skim the guidelines. Make sure to use updated resources and revise your quick-reference tools and query templates.
Coding secondary diagnoses is not about coding more—it’s more about coding smarter to maximize comorbidity adjustment. Beyond that, it ensures patients’ conditions are fully represented while optimizing reimbursement under PDGM.
The best coders aren’t just accurate—they’re strategic. By carefully reviewing documentation, understanding comorbidity groupings, and collaborating with clinicians and intake, home health agencies can prevent missed opportunities and achieve improvements in both clinical quality and financial performance.
