Stroke (STK)

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Initial Patient Population Algorithm

Stroke (STK) Initial Patient Population Algorithm Narrative

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

1. Start STK Initial Patient Population logic sub-routine. Process all cases that have successfully reached the point in the Clinical Data Processing Flow which calls this Initial Patient Population Algorithm. Do not process cases that have been rejected before this point in the Clinical Data Processing Flow.
2. 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.
   
3. Check Patient Age:
   1. If the Patient Age is less than 18 years, the patient is not in the STK Initial Patient Population and is not eligible to be sampled for the STK measure set. Set the Initial Patient Population Reject Case Flag to equal Yes. Return to Clinical Data Processing Flow in the Data Processing section.
   2. If the Patient Age is greater than or equal to 18 years, continue processing and proceed to Length of Stay Calculation.
4. Calculate the Length of Stay. Length of Stay, in days, is equal to the Discharge Date minus the Admission Date.
5. Check Length of Stay:
   1. If the Length of Stay is greater than 120 days, the patient is not in the STK Initial Patient Population and is not eligible to be sampled for the STK measure set. Set the Initial Patient Population Reject Case Flag to equal Yes. Return to Clinical Data Processing Flow in the Data Processing section.
   2. If the Length of Stay is less than or equal to 120 days, continue processing and proceed to ICD-10-CM Principal Diagnosis Code Check.
6. Check ICD-10-CM Principal Diagnosis Code
   1. If the ICD-10-CM Principal Diagnosis Code is on Table 8.1, the patient is in the first Ischemic Stroke sub-population and is eligible to be sampled for the first STK sub-population. Set the Initial Patient Population Reject Case Flag to equal No. Include the patient in the Initial Patient Population for the appropriate measures. Return to Clinical Data Processing Flow in the Data Processing section.
   2. For Joint Commission Only, if submitting data for STK Certification Program: If the ICD-10-CM Principal Diagnosis Code is on Table 8.2, the patient is in the second Hemorrhagic Stroke sub-population and is eligible to be sampled for the second STK sub-population. Set the Initial Patient Population Reject Case Flag to equal No. Include the patient in the Initial Patient Population for the appropriate measures. Return to Clinical Data Processing Flow in the Data Processing section.

STK 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/month for the sub-population cannot sample that sub-population. 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

A modified sampling procedure is required for hospitals performing quarterly sampling for STK. The measure set contains two independent sub-populations: Ischemic STK patients and Hemorrhagic STK patients. The two sub-populations must be sampled independently from each other.

1.Hospitals selecting sample cases for the Ischemic sub-population must ensure that its Initial Patient Population and sample size for the Ischemic sub-population meets the following conditions:

Quarterly Sample Size
Based on Initial Patient Population Size
for Ischemic Patient Sub-Population
Hospital’s Measure

Average Quarterly Initial Patient Population “N”	Minimum Required Sample Size “n”
≥ 900	180
226-899	20% of the Initial Patient Population
45-225	45
6 - 44	No sampling; 100% of the Initial Patient Population is required
0 - 5	Patient level data must be processed in order to submit your aggregate data. Submission of aggregate data is still required. The required quarterly sample size would be 100% of the patient population or 5 cases for the quarter

2.Hospitals submitting STK data for Joint Commission certification purposes will select sample cases for the Hemorrhagic sub-population, ensuring that its Initial Patient Population and sample size for the Hemorrhagic sub-population meets the following conditions:

Quarterly Sample Size
Based on Initial Patient Population Size
for Hemorrhagic Patient Sub-Population
Hospital’s Measure

Average Quarterly Initial Patient Population “N”	Minimum Required Sample Size “n”
≥ 900	180
226-899	20% of the Initial Patient Population
45-225	45
6 - 44	No sampling; 100% of the Initial Patient Population is required
0 - 5	Patient level data must be processed in order to submit your aggregate data. Submission of aggregate data is still required. The required quarterly sample size would be 100% of the patient population or 5 cases for the quarter

Monthly Sampling A modified sampling procedure is required for hospitals performing monthly sampling for STK. The measure set contains two independent sub-populations: Ischemic STK patients and Hemorrhagic STK patients. The two sub-populations must be sampled independently from each other.

1. Hospitals selecting sample cases for the Ischemic sub-population must ensure that its Initial Patient Population and sample size for the Ischemic sub-population meets the following conditions:

Monthly Sample Size
Based on Initial Patient Population Size
for Ischemic Patient Sub-Population
Hospital’s Measure

Average Monthly Initial Patient Population “N”	Minimum Required Sample Size “n”
≥ 300	60
76-299	20% of the Initial Patient Population
15-75	15
< 15	No sampling; 100% Initial Patient Population required

2. Hospitals submitting STK data for Joint Commission certification purposes will select sample cases for the Hemorrhagic sub-population, ensuring that its Initial Patient Population and sample size for the Hemorrhagic sub-population meets the following conditions:

Monthly Sample Size
Based on Initial Patient Population Size
for Hemorrhagic Patient Sub-Population
Hospital’s Measure

Average Monthly Initial Patient Population “N”	Minimum Required Sample Size “n”
≥ 300	60
76-299	20% of the Initial Patient Population
15-75	15
< 15	No sampling; 100% Initial Patient Population required

Sample Size Examples
Note: Hospitals utilizing STK for Joint Commission certification purposes must include all sampled STK sub-populations in the calculation of all STK measures. All of the STK measures’ specific exclusion criteria are used to filter out cases that do not belong in the measure denominator.

Quarterly sampling

• Quarterly sampling for the Ischemic sub-population:
  
  • A hospital’s Ischemic sub-population is 392 during the first quarter. Using the quarterly sampling table for the Ischemic sub-population, the sample size required is 20% of this sub-population, or 79 cases for the quarter (twenty percent of 392 equals 78.4 rounded up to the next whole number equals 79)
  • A hospital’s Ischemic sub-population is 100 during the first quarter. The required quarterly sample is 45 cases.
  • A hospital’s Ischemic sub-population is 5 patients during the first quarter. Using the quarterly sampling table for the Ischemic sub-population, the sample size is less than the minimum required quarterly sample size, so 100% of this sub-population is sampled.
• Quarterly sampling for the Hemorrhagic sub-population for Joint Commission certification purposes:
  • A hospital’s Hemorrhagic sub-population is 392 during the first quarter. Using the quarterly sampling table for the Hemorrhagic sub-population, the sample size required is 20% of this sub-population, or 79 cases for the quarter (twenty percent of 392 equals 78.4 rounded up to the next whole number equals 79).
  • A hospital’s Hemorrhagic sub-population is 3 patients during the first quarter. Using the quarterly sampling table for the Hemorrhagic sub-population, the sample size is less than the minimum required quarterly sample size, so 100% of this sub-population is sampled.
  • A hospital’s Hemorrhagic sub-population is 100 during the first quarter. The required quarterly sample is 45 cases.
• Quarterly sampling for the two combined populations for Joint Commission certification purposes.
  • The STK Initial Patient Population sizes for a hospital are 392 and 5 patients respectively per the sub-populations for the quarter. The required quarterly sample sizes for each sub-population would be 79 and 5.
    • The Ischemic sub-population has 392 patients per quarter, which requires a 20% sample size, or 79 cases (twenty percent of 392 equals 78.4 rounded to the next highest whole number equals 79).
    • The Hemorrhagic sub-population is less than the minimum required quarterly sample size, so 100% of this sub-population is sampled.
  • The STK Initial Patient Population sizes for a hospital are 1 and 3 patients respectively per the sub-populations for the quarter.

Monthly Sampling

• Monthly sampling for the Ischemic sub-population:
  
  • A hospital’s Ischemic sub-population is 228 during March. Using the monthly sampling table for the Ischemic sub-population, the sample size required is 20% of this sub-population, or 46 cases for the quarter (twenty percent of 228 equals 45.6 rounded up to the next whole number equals 46).
    
  • A hospital’s Ischemic sub-population is 316 during January. The required quarterly sample is 60 cases.
    
  • A hospital’s Ischemic sub-population is 5 patients during February. Using the monthly sampling table for the Ischemic sub-population, the sample size is less than the minimum required monthly sample size, so 100% of this sub-population is sampled.
    
• Monthly sampling for the Hemorrhagic sub-population for Joint Commission certification purposes:
  
  • A hospital’s Hemorrhagic sub-population is 228 during March. Using the monthly sampling table for the Hemorrhagic sub-population, the sample size required is 20% of this sub-population, or 46 cases for the quarter (twenty percent of 228 equals 45.6 rounded up to the next whole number equals 46).
    
  • A hospital’s Hemorrhagic sub-population is 3 patients during January. Using the monthly sampling table for the Hemorrhagic sub-population, the sample size is less than the minimum required quarterly sample size, so 100% of this sub-population is sampled.
    
  • A hospital’s Hemorrhagic sub-population is 316 during February. The required monthly sample is 60 cases.