Total Hip and Total Knee Replacement Inpatient (THKR-IP)

THKR-IP Initial Patient Population

The THKR measure set is unique in that there are two distinct strata within the measure set, each identified by a specific group of principal procedure codes, or lack thereof. The patients in each stratum are counted in the Initial Patient Population of multiple measures. The inpatient population is defined as a patient who is hospitalized overnight. ICD-10 PCS codes are utilized to bill inpatient and observation cases when the patient undergoes a procedure. Any patient who is listed as an inpatient or observation and has surgery that is billed using an ICD-10 PCS code should be assigned to the inpatient bucket to determine patient volumes and cases for abstraction within the THKR performance measures.

The population of the THKR measure set is identified using 6 data elements:

• ICD-10-PCS principal procedure code
• Admission Date
• Birthdate
• Discharge Date
• ICD-10-PCS Other procedure code
• ICD-10-CM Principal or Other Diagnosis Code

Patients admitted to the hospital for inpatient care are included in THKR-IP Measure set if they have:

An ICD-10-PCS Principal procedure Code as defined in Appendix A, Table 14.01a, 14.02a , a Patient Age (Admission Date minus Birthdate) greater than or equal to 18 years and a Length of Stay (Discharge Date minus Admission Date) less than or equal to 120 days, ICD-10-PCS Other procedure codes are all missing or none on Table 14.05a, 14.06a, 14.07a, and no ICD-10-CM Principal or Other Diagnosis Codes on Table 14.08, 14.09.

And are eligible to be sampled for:

1 – Stratum 1 – If patients have an ICD-10-PCS Principal Procedure Code as defined in Appendix A, Table 14.01a are included in the THKR stratum-1 and are eligible to be sampled.

2 – Stratum 2 – If patients have an ICD-10-PCS Principal Procedure Code as defined in Appendix A, Table 14.02a are included in the THKR stratum-2 and are eligible to be sampled.

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Initial Patient Population Algorithm

Total Hip and Total Knee Replacement Inpatient (THKR-IP) Initial Patient Population Algorithm Narrative

Variable Key: Patient Age, Initial Patient Population Reject Case Flag, and Length of Stay.

1. Start THKR Initial Patient Population logic sub-routine. Process all cases that have successfully reached the point in the Transmission Data Processing Flow: Clinical which calls this Initial Patient Population Algorithm. Do not process cases that have been rejected before this point in the Transmission Data Processing Flow: Clinical.
   
2. Check ICD-10-PCS Principal Procedure code
   
   1. If the ICD-10-PCS Principal Procedure code is not on Table 14.01a, 14.02a, the patient is not in the THKR Inpatient Initial Patient Population and is not eligible to be sampled for the THKR Inpatient measure set. Set the Initial Patient Population Reject Case Flag to equal Yes. Return to Transmission Data Processing Flow: Clinical in the Data Transmission section.
      
   2. If the ICD-10-PCS Principal Procedure code is on Table 14.01a, 14.02a, continue processing and proceed to Patient Age Calculation.
      
3. Calculate Patient Age. Patient Age, in years, is equal to the Admission Date minus the Birthdate. Use the month and day portion of admission date and birthdate to yield the most accurate age.
   
4. Check Patient Age:
   
   1. If the Patient Age is less than 18 years, the patient is not in the THKR Inpatient Initial Patient Population and is not eligible to be sampled for the THKR Inpatient measure set. Set the Initial Patient Population Reject Case Flag to equal Yes. Return to Transmission Data Processing Flow: Clinical in the Data Transmission section.
   2. If the Patient Age is greater than or equal to 18 years, continue processing and proceed to Length of Stay Calculation.
      
5. Calculate the Length of Stay. Length of Stay, in days, is equal to the Discharge Date minus the Admission Date.
   
6. Check Length of Stay:
   
   1. If the Length of Stay is greater than 120 days, the patient is not in the THKR Inpatient Initial Patient Population and is not eligible to be sampled for the THKR Inpatient measure set. Set the Initial Patient Population Reject Case Flag to equal Yes. Return to Transmission Data Processing Flow: Clinical in the Data Transmission section.
   2. If the Length of Stay is less than or equal to 120 days, continue processing and proceed to ICD- 10-PCS Other procedure code Check.
      
7. Check ICD-10-PCS Other procedure code
   
   1. If there is at least one ICD-10-PCS Other procedure code on Table 14.05a, 14.06a, 14.07a, the patient is not in the THKR Inpatient Initial Patient Population and is not eligible to be sampled for the THKR Inpatient measure set. Set the Initial Patient Population Reject Case Flag to equal Yes. Return to Transmission Data Processing Flow: Clinical in the Data Transmission section.
   2. If the ICD-10-PCS Other procedure code is all missing or none on Table 14.05a, 14.06a, 14.07a, continue processing and proceed to ICD-10-CM Principal or Other Diagnosis Code Check.
8. Check ICD-10-CM Principal or Other Diagnosis Code
   
   1. If there is at least one ICD-10-CM Principal or Other Diagnosis Code on Table 14.08, 14.09, the patient is not in the THKR Inpatient Initial Patient Population and is not eligible to be sampled for the THKR Inpatient measure set. Set the Initial Patient Population Reject Case Flag to equal Yes. Return to Transmission Data Processing Flow: Clinical in the Data Transmission section.
   2. If there is no ICD-10-CM Principal or Other Diagnosis Code on Table 14.08, 14.09, the patient is in the THKR Initial Patient Population. Set the Initial Patient Population Reject Case Flag to equal No. Proceed to ICD-10-PCS Principal procedure code check to determine the stratification.
      
9. Check ICD-10-PCS Principal procedure code
   
   1. If the ICD-10-PCS Principal procedure code on Table 14.01a, the patient is in the 1st THKR Inpatient stratum and patient is eligible to be sampled for the 1st THKR Inpatient Stratum. Include the patient in the Initial Patient Population for the appropriate measures. Return to Transmission Data Processing Flow: Clinical in the Data Transmission section.
   2. If the ICD-10-PCS Principal procedure code on Table14.02a, the patient is in the 2nd THKR Inpatient stratum and patient is eligible to be sampled for the 2nd THKR Inpatient Stratum. Include the patient in the Initial Patient Population for the appropriate measures. Return to Transmission Data Processing Flow: Clinical in the Data Transmission section.
      

Sampling / Sample Size Requirements

Abstract a minimum of 10 inpatient hip cases and 10 inpatient knee cases per month (e.g. 20 cases for July, 20 cases for August, etc.).

• If a site has a monthly population of 10 or less inpatient hip cases, abstract all inpatient hip cases. Similarly, if 10 or less inpatient knee cases per month were performed, abstract all inpatient knee cases.
• If a site has a monthly population of greater than 10 inpatient hip cases, it is acceptable to abstract a sample of 10 hip cases. Similarly, if more than 10 inpatient knee cases per month were performed, it is acceptable to abstract a sample of 10 knee cases.

Sampling is a process of selecting a representative part of a population in order to estimate the organization’s performance, without collecting data for its entire population. Using a statistically valid sample, an organization can measure its performance in an effective and efficient manner. Sampling is a particularly useful technique for performance measures that require primary data collection from a source such as the medical record. Sampling should not be used unless the organization has a large number of cases in the Initial Patient Population because a fairly large number of sample cases are needed to achieve a representative sample of the population. For the purpose of sampling the project measures, the terms “sample” and “case” are defined as: “sample” is the fraction of the population that is selected for further study; “case” refers to a single record (or an episode of care [EOC]) within the population. Organizations are NOT required to sample their data. If sampling offers minimal benefit (i.e., a hospital has 13 cases for the month and must select a sample of 10 cases), the organization may choose to use all cases.

Sampling Approaches Simple random sampling - selecting a sample size (n) from a population of size (N) in such a way that every case has the same chance of being selected. Systematic random sampling - selecting every kth record from a population of size N in such a way that a sample size of n is obtained, where k ≤ N/n. The first sample record (i.e., the starting point) must be randomly selected before taking every kth record. This is a two-step process: a) randomly select the starting point by choosing a number between one and k using a table of random numbers or a computer-generated random number; and b) then select every kth record thereafter until the selection of the sample size is completed.

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