Comprehensive Stroke (CSTK)

Comprehensive Stroke (CSTK) Initial Patient Population

The CSTK Initial Patient Population is unique in that it is comprised of three distinct subpopulations: ischemic stroke patients who do not undergo a reperfusion therapy (i.e., procedure), ischemic stroke patients who undergo a reperfusion therapy (IV t-PA, IA t-PA, or mechanical endovascular reperfusion (MER) therapy), and hemorrhagic stroke patients.

Ischemic Stroke
The population of the CSTK 1-Ischemic Stroke measures (CSTK-01) are identified using 4 data elements:

• Admission Date
• Birthdate
• Discharge Date
• ICD-10-CM-Principal Diagnosis Code

Patients admitted to the hospital for inpatient acute care are included in the CSTK 1-Ischemic Stroke Without Procedure subpopulation sampling group if they have: ICD-10-CM Principal Diagnosis Code as defined in Appendix A, Table 8.1, a Patient Age (Admission Date – Birthdate) ≥ 18 years and a Length of Stay (Discharge Date - Admission Date) ≤ 120 days.

Note: Hospitals are NOT required to sample their data. If sampling offers minimal benefit (i.e., a hospital has 45 cases for the quarter and must select a sample of 42 cases), the hospital may choose to use all cases.

Ischemic Stroke With IV t-PA, IA t-PA, or MER
The population of the CSTK 2-Ischemic Stroke With IV t-PA, IA t-PA, or MER measures (CSTK-01, CSTK-02, CSTK-05, CSTK-07, CSTK-08, CSTK-09) are identified using 5 data elements:

• Admission Date
• Birthdate
• Discharge Date
• ICD-10-CM Principal Diagnosis Code
• ICD-10-PCS Principal or Other Procedure Codes

Patients admitted to the hospital for inpatient acute care are included in the CSTK-2 Ischemic Stroke With IV t-PA, IA t-PA, or MER subpopulation sampling group if they have: ICD-10-CM Principal Diagnosis Code as defined in Appendix A, Table 8.1 AND ICD-10-PCS Principal or Other Procedure Codes as defined in Appendix A, Table 8.1a OR Table 8.1b, a Patient Age (Admission Date – Birthdate) ≥ 18 years and a Length of Stay (Discharge Date - Admission Date) ≤ 120 days.

Note: Hospitals are NOT required to sample their data. If sampling offers minimal benefit (i.e., a hospital has 45 cases for the quarter and must select a sample of 42 cases), the hospital may choose to use all cases.

Hemorrhagic Stroke
The population of the CSTK 3-Hemorrhagic Stroke measures (CSTK-03, CSTK-04, CSTK-06) are identified using 4 data elements:

• Admission Date
• Birthdate
• Discharge Date
• ICD-10-CM-Principal Diagnosis Code

Patients admitted to the hospital for inpatient acute care are included in the CSTK 3-Hemorrhagic Stroke subpopulation sampling group if they have: ICD-10-CM Principal Diagnosis Code as defined in Appendix A, Table 8.2, a Patient Age (Admission Date – Birthdate) ≥ 18 years and a Length of Stay (Discharge Date - Admission Date) ≤ 120 days.

Note: Hospitals are NOT required to sample their data. If sampling offers minimal benefit (i.e., a hospital has 80 cases for the quarter and must select a sample of 75 cases), the hospital may choose to use all cases.

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CSTK Sample Size Requirements

Hospitals that choose to sample have the option of sampling quarterly or sampling monthly. A hospital may choose to use a larger sample size than is required. Hospitals whose Initial Patient Population size is less than the minimum number of cases per quarter for the measure set cannot sample. Hospitals that have five or fewer CSTK discharges (both Medicare and non-Medicare combined) in a quarter are not required to submit CSTK patient level data to the QIO Clinical Warehouse or the Joint Commission’s Data Warehouse.

Regardless of the option used, hospital samples must be monitored to ensure that sampling procedures consistently produce statistically valid and useful data. Due to exclusions, hospitals selecting sample cases MUST submit AT LEAST the minimum required sample size.

The following sample size tables for each option automatically build in the number of cases needed to obtain the required sample sizes. For information concerning how to perform sampling, refer to the Population and Sampling Specifications section in this manual.

Quarterly Sampling

Hospitals performing quarterly sampling for CSTK must ensure that its Initial Patient Population and sample size meet the following conditions for each sampling group:

Quarterly Sample Size
Based on CSTK Subpopulation 1 for Ischemic Stroke Without Procedure
(CSTK-01 Measure)

Hospital’s Measure (Table 1)

Average Quarterly Initial Patient Population Size "“N”"	Minimum Required Sample Size "“n"”
> 420	84
211-419	20% of Patient Population size
43-210	42
≤ 42	No sampling; 100% Patient Population required

Quarterly Sample Size
Based on CSTK Subpopulation 2 for Ischemic Stroke With IV t-PA, IA t-PA,or MER
(CSTK-01, CSTK-02, CSTK-05, CSTK-07, CSTK-08, CSTK-09)

Hospital’s Measure (Table 2)

Average Quarterly Initial Patient Population Size "“N”"	Minimum Required Sample Size "“n"”
> 420	84
211-419	20% of Patient Population size
43-210	42
≤ 42	No sampling; 100% Patient Population required

Quarterly Sample Size
Based on CSTK Subpopulation 3 for Hemorrhagic Stroke
(CSTK-03, CSTK-04, CSTK-06)

Hospital’s Measure (Table 3)

Average Quarterly Initial Patient Population Size "“N”"	Minimum Required Sample Size "“n”"
> 750	150
376-750	20% of Patient Population size
76-375	75
≤ 75	No sampling; 100% Patient Population required

Monthly Sampling

Hospitals performing monthly sampling for CSTK must ensure that its Initial Patient Population and sample size meet the following conditions for each sampling group:

Monthly Sample Size
Based on CSTK Subpopulation 1 for Ischemic Stroke Without Procedure
(CSTK-01 Measure)
Hospital’s Measure (Table 4)

Average Monthly Initial Patient Population Size "“N”"	Minimum Required Sample Size "“n"”
> 140	28
71-140	20% of Patient Population size
15-70	14
≤ 14	No sampling; 100% Patient Population required

Monthly Sample Size
Based on CSTK Subpopulation 2 for Ischemic Stroke With IV t-PA, IA t-PA, or MER
(CSTK-01, CSTK-02, CSTK-05, CSTK-07, CSTK-08, CSTK-09)
Hospital’s Measure (Table 5)

Average Monthly Initial Patient Population Size "“N"”	Minimum Required Sample Size "“n"”
> 140	28
71-140	20% of Patient Population size
15-70	14
≤ 14	No sampling; 100% Patient Population required

Monthly Sample Size
Based on CSTK Subpopulation 3 for Hemorrhagic Stroke
(CSTK-03, CSTK-04, CSTK-06)
Hospital’s Measure (Table 6)

Average Monthly Initial Patient Population Size "“N"”	Minimum Required Sample Size "“n"”
> 250	50
126-250	20% of Patient Population size
26-125	25
≤ 25	No sampling; 100% Patient Population required

Sample Size Examples

NOTE: Two subpopulations make-up the population for the CSTK-01 measure; CSTK Subpopulation 1 for Ischemic Stroke Without Procedure and CSTK Subpopulation 2 for Ischemic Stroke With IV t-PA, IA t-PA, or MER. Both sampling groups must be sampled to meet the minimum sampling requirement for CSTK-01.
Examples:

• A hospital’s ischemic stroke patient population size is 200 patients during the second quarter. Fifty (50) ischemic stroke patients had a procedure for thrombolysis or mechanical clot removal. The required quarterly sample size for the CSTK-01 measure is a minimum of 84 cases (42 cases from Table 1 plus 42 cases from Table 2 equals 84).
• A hospital’s ischemic stroke patient population size is 200 patients during March. Twenty (20) ischemic stroke patients had a procedure for thrombolysis or mechanical clot removal. The required sample size for the CSTK-01 measure is a minimum of 42 cases for the month (28 cases from Table 4 plus 14 cases from Table 5 equals 42).

Quarterly sampling
CSTK Subpopulation 1 for Ischemic Stroke Without Procedure

• A hospital’s ischemic stroke patient population size is 495 cases during the second quarter. Using the quarterly sampling table for the ischemic stroke subpopulation, the sample size required is 84 cases for the quarter.
• A hospital’s ischemic stroke patient population size is 392 cases during the second quarter. Using the quarterly sampling table for the ischemic stroke subpopulation, the sample size required is 20% of this subpopulation or 78 cases for the quarter (20% of 392 equals 78.4 rounded to the next highest whole number equals 78).
• A hospital’s ischemic stroke patient population size is 200 cases during the second quarter. Using the quarterly sampling table for the ischemic stroke subpopulation, the sample size required is 42 cases for the quarter.
• A hospital’s ischemic stroke patient population size is 37 cases during the second quarter. Using the quarterly sampling table for the ischemic stroke subpopulation, the sample size is less than the minimum required quarterly sample size, so 100% of the subpopulation or all 37 cases are sampled.

CSTK Subpopulation 2 for Ischemic Stroke With IV t-PA, IA t-PA, or MER

• Four-hundred and twenty-eight (428) ischemic stroke cases had IV or IA thrombolysis or a mechanical clot removal procedure during the second quarter. Using the quarterly sampling table for the ischemic stroke with IV t-PA, IA t-PA or MER subpopulation, the sample size required is 84 cases for the quarter.
• Two-hundred and twenty-three (223) ischemic stroke cases had IV or IA thrombolysis or a mechanical clot removal procedure during the second quarter. Using the quarterly sampling table for the ischemic stroke with IV t-PA, IA t-PA or MER subpopulation, the sample size required is 20% of this subpopulation or 45 cases for the quarter (20% of 223 equals 44.6 rounded to the next highest whole number equals 45).
• Fifty (50) ischemic stroke cases had IV or IA thrombolysis or a mechanical clot removal procedure during the second quarter. Using the quarterly sampling table for the ischemic stroke with IV t-PA, IA t-PA or MER subpopulation, the sample size required is 42 cases for the quarter.
• Nineteen (19) ischemic stroke cases had IV or IA thrombolysis or a mechanical clot removal procedure during the second quarter. Using the quarterly sampling table for the ischemic stroke with IV t-PA, IA t-PA or MER subpopulation, the sample size is less than the minimum required quarterly sample size, so 100% of the subpopulation or all 19 cases are sampled.

CSTK Subpopulation 3 for Hemorrhagic Stroke

• A hospital’s hemorrhagic stroke patient population size is 795 cases during the second quarter. Using the quarterly sampling table for the hemorrhagic stroke subpopulation, the sample size required is 150 cases for the quarter.
• A hospital’s hemorrhagic stroke patient population size is 392 cases during the second quarter. Using the quarterly sampling table for the hemorrhagic stroke subpopulation, the sample size required is 20% of this subpopulation or 78 cases for the quarter (20% of 392 equals 78.4 rounded to the next highest whole number equals 78).
• A hospital’s hemorrhagic stroke patient population size is 200 cases during the second quarter. Using the quarterly sampling table for the hemorrhagic stroke subpopulation, the sample size required is 75 cases for the quarter.
• A hospital’s hemorrhagic stroke patient population size is 67 cases during the second quarter. Using the quarterly sampling table for the hemorrhagic stroke subpopulation, the sample size is less than the minimum required quarterly sample size, so 100% of the subpopulation or all 67 cases are sampled.

Monthly sampling
CSTK Subpopulation 1 for Ischemic Stroke Without Procedure

• A hospital’s ischemic stroke patient population size is 295 cases during March. Using the monthly sampling table for the ischemic stroke subpopulation, the sample size required is 28 cases for the month.
• A hospital’s ischemic stroke patient population size is 129 cases during March. Using the monthly sampling table for the ischemic stroke subpopulation, the sample size required is 20% of this subpopulation or 26 cases for the month (20% of 129 equals 25.8 rounded to the next highest whole number equals 26).
• A hospital’s ischemic stroke patient population size is 70 cases during March. Using the monthly sampling table for the ischemic stroke subpopulation, the sample size required is 14 cases for the month.
• A hospital’s ischemic stroke patient population size is 7 cases during March. Using the monthly sampling table for the ischemic stroke subpopulation, the sample size is less than the minimum required monthly sample size, so 100% of the subpopulation or all 7 cases are sampled.

CSTK Subpopulation 2 for Ischemic Stroke With IV t-PA, IA t-PA, or MER

• One-hundred and forty-eight (148) ischemic stroke cases had IV or IA thrombolysis or a mechanical clot removal procedure during March. Using the monthly sampling table for the ischemic stroke with IV t-PA, IA t-PA or MER subpopulation, the sample size required is 28 cases for the month.
• One-hundred and twenty-three (123) ischemic stroke cases had IV or IA thrombolysis or a mechanical clot removal procedure during March. Using the monthly sampling table for the ischemic stroke with IV t-PA, IA t-PA or MER subpopulation, the sample size required is 20% of this subpopulation or 25 cases for the month (20% of 123 equals 24.6 rounded to the next highest whole number equals 25).
• Sixty (60) ischemic stroke cases had IV or IA thrombolysis or a mechanical clot removal procedure during March. Using the monthy sampling table for the ischemic stroke with IV t-PA, IA t-PA or MER subpopulation, the sample size required is 14 cases for the month.
• Eleven (11) ischemic stroke cases had IV or IA thrombolysis or a mechanical clot removal procedure during March. Using the monthly sampling table for the ischemic stroke with IV t-PA, IA t-PA or MER subpopulation, the sample size is less than the minimum required monthly sample size, so 100% of the subpopulation or all 11 cases are sampled.

CSTK Subpopulation 3 for Hemorrhagic Stroke

• A hospital’s hemorrhagic stroke patient population size is 295 cases during March. Using the monthly sampling table for the hemorrhagic stroke subpopulation, the sample size required is 50 cases for the month.
• A hospital’s hemorrhagic stroke patient population size is 129 cases during March. Using the monthly sampling table for the hemorrhagic stroke subpopulation, the sample size required is 20% of this subpopulation or 26 cases for the month (20% of 129 equals 25.8 rounded to the next highest whole number equals 26).
• A hospital’s hemorrhagic stroke patient population size is 60 cases during March. Using the monthly sampling table for the hemorrhagic stroke subpopulation, the sample size required is 25 cases for the month.
• A hospital’s hemorrhagic stroke patient population size is 17 cases during March. Using the monthly sampling table for the hemorrhagic stroke subpopulation, the sample size is less than the minimum required monthly sample size, so 100% of the subpopulation or all 17 cases are sampled.