ICD-10-CM specificity: The sky isn't falling

Part 1 of 2 about the transition

ICD-10-CM allows much greater specificity of diagnosis codes, it will require little more from physicians than ICD-9

Rumor has it that the International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM), will impose a nightmare of excessive documentation requirements, forcing physicians to use new, unfamiliar clinical terminology and to document excessive detail.

Nothing could be further from the truth. ICD-10-CM will impose no such conditions, and the documentation specificity that physicians provide under ICD-9 will change very little for ICD-10-CM when it takes effect on Oct. 1, 2015.

Photo by Thinkstock
Photo by Thinkstock

ICD-10-CM is the United States' version of ICD-10, the system currently used throughout the world for the assignment of diagnosis codes. Beginning October 1, virtually all clinicians and payers in the country will be required to use ICD-10-CM diagnostic codes in all health care transactions. Physicians will continue using the American Medical Association's familiar Current Procedural Terminology, 4th Edition (CPT-4), for coding of all physician services including procedures.

ICD-10-CM allows the capture of much greater detail in coded clinical data, which will permit more comprehensive analysis of valuable clinical information. The greater specificity of physician documentation permitted by ICD-10-CM is almost limitless. But is it required? In most cases, no. Documenting with greater specificity can be useful clinically and for research, but it is not a necessity unless greater specificity has a significant impact on such things as reimbursement, quality, outcomes, or pay-for-performance measures.

Performance measures are risk adjusted to account for the overall severity of illness of a clinician's patient population. Risk adjustment is used to “level the playing field” so that clinicians caring for sicker patients are not unfairly penalized.

Severity of illness is determined by the specific codes submitted on claims by hospitals and clinicians. In some instances, common clinical documentation terminology does not precisely translate into codes reflecting the actual severity of illness of a patient's condition. In these situations, greater specificity is often needed to allow the correct code to be assigned.

There are currently a limited number of diagnoses where greater specificity impacts reimbursement and performance measures. These are already very familiar to most hospitalists, who are regularly asked to provide greater diagnostic specificity for conditions like sepsis, suspected organisms likely causing health care-associated pneumonia, encephalopathy, acute kidney injury, and the systolic or diastolic nature of heart failure. The same needs will continue with ICD-10-CM together with a handful of new ones, such as the need to specify the severity of major depressive disorder.

Take, for example, the impact of documenting congestive heart failure (CHF) as systolic or diastolic. This distinction is clinically important and has therapeutic implications. In terms of quality and reimbursement, the code for a diagnosis of “CHF” alone may contribute little or nothing to risk adjustment even if it is acutely decompensated. On the other hand, specifying the systolic or diastolic nature of CHF results in code assignment that contributes significantly to severity of illness, and when specified as “acute” even more so.

Now consider the example of greater specificity for acute respiratory failure available in ICD-10-CM (see Table). ICD-10-CM provides codes to distinguish between acute hypoxic and acute hypercapnic respiratory failure, which were not contained in ICD-9, but also retains codes for respiratory failure unspecified as hypoxic or hypercapnic. All of the ICD-10-CM codes for respiratory failure are classified as major comorbidities comparable to the current nonspecific ICD-9 code (518.81) and therefore have the same severity of illness impact.

Would documentation of hypoxic and hypercapnic respiratory failure be valuable? Most certainly it would for our health care database. These conditions are clinically distinct, having different causes, characteristics, and management considerations. Analysis of the more specific data permitted by ICD-10-CM may reveal significant differences in costs of care, length of stay, and outcomes among patients with these conditions. Is this specificity necessary for accurate reimbursement and performance measures? No, since all the ICD-10-CM codes for respiratory failure have the same severity of illness impact as the ICD-9 code. Documenting this distinction is useful but not a necessity. Down the road this may change, but all clinicians will have advance notice with ample time to modify their documentation practices—just as we do now.

Fortunately, ICD-10-CM coding guidelines and rules permit coders in many cases to add additional specificity for documented diagnoses from medical record sources other than physician documentation. Some examples are the location of a stroke taken from an MRI, the specific site involved in a fractured bone from an X-ray, or the part of the heart involved in an acute myocardial infarction from the electrocardiogram. This saves the physician from documenting extensive diagnostic specificity that may not have an impact apart from data quality.

In summary, although ICD-10-CM allows much greater specificity of diagnosis codes, it will require little more from physicians than ICD-9.