Just as psychiatrists are adapting to DSM-5, they have to cope with implementation of the 10th edition of the International Statistical Classification of Diseases and Related Health Problems (ICD-10). This challenge raises questions: What is the importance of understanding ICD-10? How will it affect the practice of psychiatry?
Furthermore, how does ICD-10 relate to DSM-5 and Current Procedural Terminology (CPT)? How does it differ from ICD-9? What are the ICD-10-Clinical Modification (CM) and ICD-10-Procedures (PCS)?Learning the essence of the changes, and understanding what impact they have on your clinical work, are necessary to ensure that your practice keeps pace with professional and legal standards of care. The effort involved is not onerous, however, and can improve the quality and efficiency of your care and how you document it.
In this article, we provide you with an overview of ICD-10; highlight major changes of the new classification; explain its relevance to clinical practice; and offer guidelines for implementing it effectively. We also emphasize that a good understanding of DSM-5 facilitates appreciation of ICD-10 and makes its implementation fairly easy and straightforward.
To begin, we provide a glossary of ICD-related terms and a review of additional definitions, distinctions, and dates (Box).1-6
Major changes from ICD-9
No question: ICD-10 is going to significantly influence your practice and your reimbursement. Furthermore, a number of revisions in ICD-10 have the potential to meaningfully improve clinical documentation and communication and to enhance your ability to precisely describe the complexity of your patients—with implications for billing.
ICD-10 differs from ICD-9 in organization, structure, code composition, and level of detail. In addition, ICD-10 makes some changes in terminology and definitions, with the goal of improving precision.
ICD-10 also is much larger than ICD-9.The total number of medical diagnostic codes has increased more than 5-fold—from approximately 13,000 to 69,000. This expansion allows for greater specificity in diagnosis and enables differentiation of an initial clinical encounter from a subsequent encounter.
To accommodate the expansion in the number of codes, the 5-digit numeric codes used in ICD-9 have been replaced in ICD-10 by 7-digit alphanumeric codes:
- the first digit always is a letter
- the second and third digits are numbers followed by a decimal point
- the fourth though seventh digits can be letters or numbers
- the first 3 digits denote the diagnostic category
- the fourth through sixth digits provide diagnostic detail
- the seventh digit provides information about the nature of the encounter (eg, initial, subsequent, or sequel, denoted respectively by “A,” “D,” and “S” in the seventh digit).
The number of 3-digit categories for psychiatric disorders has increased from 30 in ICD-9 (290-319) to 100 in ICD-10 (F00-F99). Only the first 5 digits are used for the section on mental disorders in ICD-10, with the first digit always “F” and the second digit a number denoting the broad type of disorders. The second and third digits in conjunction define the major category of the disorder; the fourth and fifth digits provide additional descriptive detail about the disorder (Table).
ICD-9 ‘V’ codes are out
What were called “V” codes in ICD-9—factors that influence health status and contact with health services—have been replaced by “Z” codes in ICD-10. These “Z” codes provide greater detail and precision than “V” codes provided.
Examples of “Z” codes relevant to psychiatry are:
Z00 General psychiatric examination (eg, of a person who does not have a complaint or diagnosis)
Z03 Examination for suspected mental and behavioral disorder
Z04 Examination for medicolegal or other purposes; Z04.8 is relevant laboratory testing, such as drug testing of urine or blood
Z50 Care involving rehabilitation (substance use disorder, etc.)
Z60 Problem related to social environment
Z61 Problem related to negative life events in childhood
Z63 Problem related to primary support group, including family circumstances
Z64-Z65 Problem related to other psychosocial circumstances
Z70-Z71 Condition requiring counseling, not elsewhere classified
Z73 Problem related to difficulty with life management (burnout, stress, role conflict, etc.)
Z75 Problem related to medical facilities and other aspects of health care (eg, awaiting admission)
Z81 Family history of mental or behavioral disorders
Z85-Z91 Personal history of various disorders (must be absent or in full remission at the moment); Z86.51, for example, refers to a history of combat and operational stress reaction.
Greater precision is now possible when coding for treatment-related adverse effects. A particular adverse effect now is coded under the relevant system, along with its attribution to the specific substance. Obesity attributable to antipsychotic treatment,7,8 for example, is coded as E66.1.
Integrating DSM-5 and ICD-10
Because DSM-5 lists corresponding ICD-10-CM codes for all disorders, you will find it much easier than other physicians to implement ICD-10. DSM-5 includes ICD-9-CM and ICD-10-CM codes for each DSM-5 disorder (for example, the ICD-9-CM code for schizophrenia is 295.x; the ICD-10-CM code is F20.9).9