International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM)

The International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) is the standard coding system currently used to describe a patient’s condition, injury, illness, disease, or other reasons the patient is receiving health care services. ICD-9-CM is also used by hospitals to describe significant procedures performed during a hospital inpatient stay. Diseases listed in the ICD-9 were primarily acute and related to conditions resulting from infectious diseases found in Europe. The types of conditions seen in Europe were different from those in the United States. Medical and technological advances led to new knowledge about diseases, which was not incorporated into the ICD-9. A modification to the ICD-9 was required to include more detailed information regarding diseases and procedures that would be more reflective of the conditions seen in the United States.

ICD was “clinically” modified to enhance the classification and collection of morbidity data and for indexing medical records. The World Health Organization (WHO) permitted the United States to clinically modify the ICD-9 to provide an adequate reflection of conditions seen in the United States. The Department of Health and Human Services (DHHS) published the modified version of the ICD-9, called the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM), in 1979. Despite this modification, the reality that ICD required further revisions and restructuring existed. The ICD-9 system did not have the capacity, numerically, to accommodate new or expanded codes that describe patient illness and treatments seen today. The ICD-9 system is clinically outdated and does not contain the specificity needed to adequately capture data regarding patient conditions and treatments reflective of today’s medicine that can be adopted internationally. The ICD-10 system was developed to address these issues. It was endorsed by the World Health Assembly in 1990.

International Classification of Diseases, 10th Revision (ICD-10)

The 10th revision of the ICD was originally named the International Statistical Classification of Diseases and Related Health Problems (ICD-10). This revision maintained the basic structure of ICD-9, but it included a higher level of clinical detail. In 1990, the Forty-third World Health Assembly endorsed ICD-10. The World Health Organization (WHO) published the newest version of the ICD with a new name, the International Classification of Diseases, 10th Revision (ICD-10), in 1993. ICD-10 has been implemented in many other countries including the United Kingdom, France, Australia, Germany, and Canada. WHO granted permission to the National Center for Health Statistics (NCHS), an agency under the Centers for Disease Control and Prevention (CDC), to clinically modify ICD-10 and to create a procedure coding system to replace ICD-9-CM Volume III. The Department of Health and Human Services (DHHS) published a final rule in 2009 adopting the International Classification of Diseases, 10th Revision (ICD-10) as the standard coding system for coding conditions and significant procedures performed during a hospital inpatient stay. ICD-10 will replace ICD-9-CM Volumes I-III. In accordance with Health Insurance Portability and Accountability Act (HIPAA) provisions, the compliance date for all covered entities was October 1, 2013. However, the Department of Health and Human Service (DHHS) has published a final rule that includes delaying the ICD-10 compliance date to October 1, 2014. ICD-9-CM contains diagnosis codes and procedure codes in one manual. ICD-10 consists of two different coding systems, ICD-10-CM and ICD-10-PCS, and they are in two separate manuals.

Documentation

Coding is the process of translating written descriptions of procedures, services, items, and patient conditions into numeric or alphanumeric codes. It involves the assignment of numeric or alphanumeric codes to all health care data elements of inpatient and outpatient care. Documentation is the term used to describe information recorded in the medical record regarding the patient’s condition, treatment, and response to treatment as illustrated in Figure 7-3. Information contained in the patient’s medical record is used to assign diagnosis and procedure codes that are submitted on a claim form. Diagnosis coding is the process of translating written descriptions of signs, symptoms, illness, injury, disease, and other reasons for health care services that are documented in the patient’s medical record into codes. Diagnosis coding is essential to explain why the patient is receiving health care services.

The transition to ICD-10-CM will require improved clinical documentation to allow the coder to use the coding system effectively to accurately describe patient conditions or other reasons for health care services. ICD-10-CM is a coding system that provides a higher level of specificity, with more than 68,000 codes as opposed to approximately 13,000 codes in ICD-9-CM. Documentation must include the detail required to code to the highest level of specificity. Hospitals have formed clinical documentation improvement (CDI) committees to work with providers to ensure documentation includes information required to support coded services and patient conditions. ICD-10-CM incorporates many changes that will require clinical documentation improvement (CDI) in several areas:

When the patient arrives at the hospital with a health care issue(s) that requires attention, clinical personnel will record the reason for the visit and details regarding that condition. Chief complaint is the term used to describe the main reason (medical condition, injury, or symptom) why the patient is seeking health care services. This information is provided by the patient. A clinical interview is conducted with the patient for the purpose of obtaining information regarding the patient’s chief complaint and the history of the illness. Details about the chief complaint can include when the condition occurred, how bad the condition is, and if it gets worse during certain activities or at particular times. Information regarding other conditions that may relate to the main condition is also obtained. The physician or other provider will review the history, perform an examination, and prepare a plan of care. Other patient care services may be provided. Information regarding the patient’s condition and treatment are recorded in the medical record. The coder translates the written descriptions of medical conditions into diagnosis codes.

When coding medical conditions, it is necessary to read the record to identify the condition(s) that is being treated and the condition(s) that can affect treatment. A code(s) is then selected from the ICD-10-CM that accurately describes the statement in the medical record. Examples of information recorded in the patient’s medical record and the code assignments are illustrated in Figure 7-4. The challenge for coders is to be absolutely certain the code assignment represents what is in the record. The coder must follow the Golden Rule of coding: IF IT IS NOT DOCUMENTED, DO NOT CODE IT. It is important that the coder does not read into the scenario and code a condition that is not supported by the documentation. If the record lacks specific information required to select a code, the coder should pursue more specific information from the physician or other provider. Most hospitals have a physician query process for coders to clarify information.

Medical Necessity

Medical necessity is the term used to describe procedures or services performed that are considered reasonable and necessary to address the patient’s medical condition, based on standards of medical care. Payer guidelines regarding medical necessity will vary by payer. While the variation from payer to payer should not influence code selection, coded diagnosis data submitted on a claim form is used by the payer to determine whether medical necessity guidelines were met. ICD-10-CM codes selected should be at the highest level of specificity to completely describe the patient’s condition and to establish medical necessity. However, the documentation must contain the information needed to code to the highest level of specificity.

There are two areas where coding using ICD-10-CM should impact medical necessity. ICD-10-CM provides greater detail regarding patient conditions and the severity of those conditions and therefore enhances the ability to explain medical necessity. The higher degree of specificity of diagnosis data captured from claim forms should decrease the need to submit additional documentation. Another area of impact involves collection of meaningful data that is more reflective of conditions and treatments seen in medical practice today. The ability to monitor and assess patient conditions and required treatments for those conditions will be greatly improved with the ICD-10-CM data.

Claim Forms

Claim forms are used to submit charges for services rendered to payers for reimbursement. The CMS-1450 (UB-04) is the claim form primarily used to submit hospital services. There may be a situation where a payer requires the CMS-1500 for specified services. Codes that describe services and diagnoses are listed on the claim form. As illustrated on the CMS-1450 (UB-04), diagnosis codes explain the patient’s condition or other reason why the services were provided (Figure 7-5).

The implementation of ICD-10-CM required revision of claim forms. The CMS-1500 and CMS-1450 (UB-04) have been revised to accommodate the new ICD-10-CM codes that are three to seven characters as opposed to the ICD-9-CM codes that consist of three to five digits. The CMS-1450 (UB-04) contains a field designated to indicate which coding system was used: “9” for ICD-9-CM and “0” for ICD-10-CM. In accordance with HIPAA regulations, standard formats for electronic transactions, including submission of claims, have been adopted. The adopted standard formats were developed by the American National Standards Institute (ANSI). The standard transaction format for the CMS-1500 is the ANSI X12 837, and the format for the CMS-1450 (UB-04) is the ANSI X12 837I. The standard transaction formats contain elements found on the CMS-1500 and CMS-1450 (UB-04) paper claims. The new format incorporates changes required to accommodate ICD-10 codes. The current standard format, Version 5010, was adopted and implemented effective January 2012. The compliance date for all HIPAA-covered entities to transition to Version 5010 was January 1, 2012.

ICD-10-CM diagnosis codes will be reported on the claim form to describe the principal diagnosis, other secondary diagnosis, admitting diagnosis, patient’s reason diagnosis, or an external cause. Diagnosis codes are reported on the claim form in accordance with the ICD-10 Official Coding guidelines and payer specific guidelines based on the level of service: inpatient, outpatient, or non-patient.

Principal Diagnosis

The principal diagnosis is the condition determined after study to be chiefly responsible for admission of the patient to the hospital for care. Study refers to the examination and other diagnostic testing used to determine the diagnosis. For example, a patient is admitted to the hospital for chest pain. After diagnostic tests are performed, the physician records a diagnosis of arteriosclerosis. The principal diagnosis is the condition determined after study, therefore a code is assigned for arteriosclerosis (Figure 7-6). If the physician does not document a definitive diagnosis, then the principal diagnosis would be the same as the admitting diagnosis. This record provides an example of combination codes found in ICD-10. One code is assigned to explain the atherosclerotic heart disease and the symptom, angina pectoris.

Other Secondary Diagnoses

Additional diagnosis codes may be required to describe other conditions that are treated or those that affect treatment. Other diagnoses may describe a complication or comorbidity (CC).

Complication

A complication is a disease or condition that develops during the course of a hospital stay. Complications may prolong the patient’s length of stay, usually by 1 day in 75% of cases. Complications generally have an impact on the MS-DRG assignment. A postoperative infection is an example of a complication, since the surgical wound became infected. A code(s) is assigned to describe complications as illustrated in Figure 7-7.

Comorbidity

Comorbidity is a secondary condition that coexists with the condition for which the patient is seeking health care services. Comorbidities may also prolong the patient’s length of stay and therefore can affect the MS-DRG assignment. An example of comorbidity is a patient presenting with atherosclerosis of an extremity who also has malignant hypertension. Malignant hypertension would be coded as the secondary diagnosis (see Figure 7-7).

Admitting Diagnosis

The admitting diagnosis is the major most significant reason why the patient is being admitted for an inpatient stay. For example, a patient presents with a chief complaint of rapid heartbeat and fever. The attending physician decides to admit the patient after reviewing results from diagnostic tests. The admitting diagnosis would be rapid heartbeat (tachycardia) because it is the major most significant reason for the admission (Figure 7-8).

Reporting Diagnoses – CMS-1450 (UB-04)

It is important for coders to understand what diagnosis is required for the claim form, where the diagnosis code is recorded, and what coding guidelines apply to the patient case, as illustrated in Table 7-1. ICD-10-CM implementation has not changed the reporting requirements for diagnoses on the CMS-1450 (UB-04). The form is used to submit facility charges for outpatient, non-patient, and inpatient services provided by a hospital or other facility. The CMS-1450 (UB-04) contains 81 fields referred to as form locators (FL). The CMS-1450 (UB-04) claim form completion requirements include the reporting of all patient diagnoses to explain the medical reason for the admission and services provided. Figure 7-9 illustrates how ICD-10-CM diagnosis code(s) are recorded on the CMS-1450 (UB-04).

TABLE 7-1

Claim Variations for ICD-10-CM Diagnosis Codes

ICD-10-CM diagnosis codes will be used to report patient conditions or other reasons for the visit for all (inpatient, outpatient, or non-patient) services.
Diagnosis Coding	Inpatient	Outpatient/ Non-Patient	ICD-10-CM Official Guidelines
Principal Diagnosis
The condition determined after study to be chiefly responsible for admission of the patient to the hospital for care	Form Locator 67	Not applicable	Section I, II: General Coding, Chapter-Specific, Selection of Principal Diagnosis and Present on admission
Other Secondary Diagnosis
Secondary diagnosis Complications and comorbidities (coexisting conditions)	Form Locator 67A-Q	Form Locator 67A-Q	Section I, III: General Coding, Chapter-Specific, Reporting Additional Diagnoses and Present on admission
Admitting Diagnosis
The major most significant reason the patient is admitted	Form Locator 69	Not applicable	Section I, II: General Coding and Chapter Specific
Patient’s Reason for Visit Diagnosis
The major most significant reason for the outpatient visit	Not applicable	Form Locator 69	Section I, II, IV: General Coding, Chapter-Specific and Diagnostic Coding, and Reporting for Outpatient Services
External Cause of Injury
External causes of the injury or illness	Form Locator 72a-c	Form Locator 72a-c	Section I: General Coding and Chapter-Specific Note: Guidelines for reporting external causes vary by payer.

Note: Present on admission (POA) indicators are required for the principal and other secondary diagnoses and the external cause of injury codes.

The principal diagnosis is recorded in FL 67. The term principal diagnosis is generally used for facility claims. FL 67A–Q are used to record other secondary diagnosis codes representing complications, comorbidities, or other reasons for the admission. Inpatient claims require a POA indicator for principal and other secondary diagnoses. The admitting diagnosis is recorded in FL 69. The patient’s reason for visit diagnosis is recorded in FL 70 on outpatient claims. If there is an external cause of injury, the appropriate code to describe it is recorded in FL 72. The payer will carefully review the codes reported to determine whether the medical necessity requirements were met for the admission and services provided.

Reimbursement

Reimbursement is the term used to describe payment for health care services provided. Claim forms are submitted to third-party payers, such as insurance companies, Medicare, and other government payers, to obtain reimbursement for services provided. Diagnosis codes are recorded on the claim form to explain why the services were provided and to establish the medical necessity of services provided. Payers provide reimbursement for services that are covered by the patient’s plan and that are considered medically necessary based on standards of medical care. Therefore, it is critical to ensure that the codes submitted completely describe the patient’s medical condition(s) to explain why the services were necessary.

Reimbursement methodologies for services provided on an outpatient basis are determined by the procedure code submitted. The diagnosis code is needed to explain the medical necessity of services. Initially, ICD-10-CM may not have an impact on reimbursement for outpatient services since the payment is determined based on the procedure code(s) submitted. However, the diagnosis codes do explain medical necessity. Hospital inpatient services are reimbursed based on Medicare Severity-Diagnosis Related Groups (MS-DRG). The MS-DRG reimbursement is determined based on the patient’s diagnosis and treatment required. ICD-10-CM will have a direct impact on MS-DRG reimbursement. MS-DRG groups will be converted to ICD-10-CM, which may result in changes in the MS-DRG reimbursement system. Over time, the data captured using ICD-10-CM may be used to update and develop new reimbursement methodologies.

Research

Data from coding systems are used to research various patterns in diagnosis and treatment of conditions. ICD-10-CM provides a greater level of specificity regarding patient conditions and severity of those conditions, as well as detailed information regarding other reasons patients seek health care services. Researchers will be able to monitor various treatments provided for specific conditions to determine outcomes. Research data will also be used to study conditions and develop new treatments and technology. By monitoring ICD-10 data, researchers can identify various risk factors related to specific procedures, services, or items. Analysis of health care data is critical to predicting trends in the health care industry.

Education

Data from coding systems can be used to educate health care professionals, such as medical students, nurses, and doctors. Education of health care professionals can be further enhanced through knowledge gained by analyzing ICD-10-CM data related to conditions and treatments. For example, ICD-10-CM expands the detail of fractures to include the exact bone that was fractured and the shape and form of the fracture itself. This data will be very helpful in educating clinical professionals on fractures. New treatments, supplies, and medications can be monitored for assessment of outcomes, both positive and negative. The data can also be used to identify and target specific educational needs of the public, such as risk factors related to heart disease or breast cancer. Standards for the prevention and treatment of disease are developed as a result of research using data from various coding systems.