In the context of healthcare, “coding” refers to the process of converting words or phrases from the medical record into standardized codes that capture the conditions of a patient (diagnosis codes) and what we did to treat those conditions (procedure codes). In the inpatient world, these codes are analyzed to yield a single Diagnosis Related Group (DRG), which is the basis of reimbursement for Medicare, Medicaid, and many other payers. The codes are also used for various types of research, e.g. on outcomes and other measures of quality. The current code set is ICD-9 (ICD stands for International Classification of Diseases), and the next version will be ICD-10.

A tool called an encoder helps the coder to arrive at each diagnosis or procedure code by asking them a series of questions about the case. Next, another tool called a grouper analyzes the codes to yield a DRG for that inpatient discharge. Because the DRG is the basis for how we get paid, getting the ICD codes correct is vital to ensure appropriate reimbursement.

Dual coding refers to the assignment of both ICD-9 and ICD-10 codes to a given patient visit during a single coding session. Because ICD-10 is almost always more complex than ICD-9, the encoder provides additional prompts to the coder in order to gain the additional information that is required to produce ICD-10 codes.

Dual coding is a transition-period function that will help us prepare for ICD-10. Some motivating factors for dual coding are listed below. As part of the ICD-10 project, NYP has coded more than 5,000 inpatient cases and hundreds more outpatient cases in ICD-10 to satisfy these goals.

1. Coder practice and proficiency. NYP employs dozens of coding professionals to translate the care documented in patients’ medical records into billable and reimbursable diagnosis and procedure codes. This group is as affected by the transition to ICD-10 as any in the organization. The more time they are provided to practice and master coding actual claims in ICD-10, the greater chance for NYP success.
2. System and interface testing. Dual coding allows us to determine whether our systems and interfaces are capable of handling ICD-10 codes, and to take corrective action if there are issues. This applies to both our internal systems and to external systems used by payers, clearinghouses, registries, etc.
3. Financial impact analysis. Dual coding a case generates two DRGs – one for ICD-9 and one for ICD-10.   If the DRGs (or other metrics such as Severity of Illness, or SOI) don’t match, further investigation is warranted. Sometimes a DRG shift is due to human error, and so highlights an educational opportunity. Other times, correctly coding the chart in ICD-9 and ICD-10 results in two different DRGs, which means our reimbursement could change. In these cases, we may comment to Medicare to request that they alter their methodology.
4. Claims testing. We want to be sure that our payers are ready to process ICD-10 coded claims, and that they get the same DRGs that we do. If our DRGs don’t match, we need to explore why.
5. Quality metrics drift. Dual coding cases that fall within the metric population for various quality metrics, e.g. core measures and patient safety indicators, allows us to see whether the metric population may shift under ICD-10, which could result in changes to our performance on those metrics.
6. Medical Necessity testing. Dual coding can help to identify cases that met medical necessity in ICD-9 but do not in ICD-10, or vice versa.
7. Clinical documentation improvement. The best way to prepare providers for the additional document requirements of ICD-10 is with actual examples. When the coder is responding to the encoder’s prompts during a dual coding session, if they are not able to respond to a question because of inadequate documentation, this indicates an opportunity to provide education to providers.