Unit of Analysis

The unit of analysis is the hospital stay rather than the patient. All discharges have been weighted to produce national estimates.

Coding Diagnoses and Procedures

Diagnoses and procedures associated with an inpatient hospitalization can be defined using several different medical condition classification systems. The Clinical Classifications Software (CCS) was used predominantly within this report to identify specific diagnoses and procedures. CCS is based on the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM), a uniform and standardized coding system containing over 13,600 diagnosis codes and 3,700 procedure codes. Each discharge record in the NIS is associated with one or more ICD-9-CM diagnosis code(s) and may contain one or more ICD-9-CM procedure code(s) if a procedure was performed during that hospitalization. Each hospital stay can have multiple CCS diagnoses and multiple CCS procedures.

In the CCS, ICD-9-CM codes are clustered into a smaller number of clinically meaningful categories that are sometimes more useful for presenting descriptive statistics than are individual ICD-9-CM codes. CCS codes are used extensively in this report to define groups of diagnoses and procedures for analysis. The CCS codes allow the reader to quickly and easily recognize patterns and trends in broad categories of hospital utilization. More information on CCS can be found online (http://www.hcup-us.ahrq.gov/toolssoftware/ccs/ccs.jsp). Specific CCS conditions or diagnoses can also be summarized into CCS body system or condition categories, which are broad groups of CCS conditions, such as Neoplasms, Mental Disorders, and Diseases of the Circulatory System.

Exhibit Diagnoses and Procedures

Throughout this report, combinations of diagnostic and procedure codes are used to isolate specific conditions or procedures. These codes are defined below by exhibit number.

SECTION 1—OVERVIEW STATISTICS FOR INPATIENT HOSPITAL STAYS

EXHIBIT 1.3

Principal CCS by body system or condition categories are summarized from specific CCS conditions using the multi-level CCS tool (http://www.hcup-us.ahrq.gov/toolssoftware/ccs/ccs.jsp). Mental health and substance abuse conditions are identified using the CCS-MHSA tool (http://www.hcup-us.ahrq.gov/toolssoftware/mhsa/mhsa.jsp). (For more information on the ICD-9-CM codes that comprise each CCS, refer to http://www.hcup-us.ahrq.gov/toolssoftware/ccs/AppendixASingleDX.txt for diagnoses and http://www.hcup-us.ahrq.gov/toolssoftware/ccs/AppendixBSinglePR.txt for procedures.) The body system or condition category, CCS code and category name are listed below.

SECTION 2—INPATIENT HOSPITAL STAYS BY DIAGNOSIS

EXHIBIT 2.1

Chronic conditions were identified using the Chronic Conditions Indicator, an HCUP tool used to categorize ICD-9-CM diagnosis codes into one of two categories: chronic or not chronic (acute). Diagnosis codes for this tool are based on the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM), Fifth Edition. Additional information can be found at http://www.hcup-us.ahrq.gov/toolssoftware/chronic/chronic.jsp.

Maternal CCS categories not listed on the exhibit table but included in total maternal discharges:

Infant CCS categories not listed on the exhibit table but included in total maternal discharges:

EXHIBIT 2.4

Comorbidities were defined using the Comorbidity software, an HCUP tool that assigns variables that identify comorbidities in hospital discharge records using the diagnosis coding of ICD-9-CM (International Classification of Diseases, Ninth Edition, Clinical Modifications). For more information, see http://www.hcup-us.ahrq.gov/toolssoftware/comorbidity/comorbidity.jsp.

SECTION 3—INPATIENT HOSPITAL STAYS BY PROCEDURE

EXHIBIT 3.1

Two steps were used to define maternal and infant procedures. First, all maternal and newborn stays were identified using the following codes:

Maternal stays were identified using the Major Diagnostic Code 14: Pregnancy, childbirth and the puerperium.

Newborn stays were identified using the following CCS diagnostic codes:

Second, maternal and newborn stays were examined for the following CCS all-listed procedures that were typically associated with maternal and infant stays:

Maternal procedures:

Infant procedures:

SECTION 4—SPENDING FOR INPATIENT HOSPITAL STAYS

EXHIBIT 4.1

See definition for CCS Body System and Condition Categories under Exhibit 1.3 above.

SECTION 5—PAYERS FOR INPATIENT HOSPITAL STAYS

EXHIBIT 5.5

See definition of maternal stays under Exhibit 3.1 above.

EXHIBIT 5.8 and 5.9

See definition for CCS Body System and Condition Categories under Exhibit 1.3 above.

Previous  Next