George Mason University

 

Statistics for Health Services Management

Matched Case Controls 

Lecture

Assignment

  1. These data show a list of 9 patients.  Two of the patients have received an experimental treatment.  Identify which of the patients in the following table could serve as controls for the two cases.  Select the possible controls randomly using the lowest random number.  Match on age. 

  2. Patient ID

    Received Intervention

    Age

    Months to Fall

    Random Number

    Observation Period

    Follow-up Period

    1

    Yes

    65

     

    3

    0.24

    2

    No

    60

     

    2

    0.85

    3

    Yes

    84

    2

     

    0.64

    4

    No

    82

    4

     

    0.7

    5

    No

    78

     

    0.87

    6

    No

    80

    3

     

    0.72

    7

    No

    79

     

     

    0.86

    8

    No

    64

     

     

    0.16

    9

    No

    70

     

    2

    0.17

  3. For the follow-up period in problem 1, show a Kaplan Meier survival curve.  For each month, show the percent of cases or controls that have not fallen since the start of the study.  Solution►
  4. Establish the percent of days the following patient is in therapeutic range.  On days when blood pressure was not measured, assume that blood pressure is the same as the nearest data point less than 7 days away.  For all other days assume that the blood pressure is unknown.  Solution►   

Days Since Enrollment

BP

Therapeutic Range

In
range

Lower

Upper

0

125

120

140

Yes

20

150

120

140

No

60

130

120

140

Yes

70

110

120

140

No

90

130

120

140

Yes

120

135

120

140

Yes


For additional optional problem complete the following:

  1. Repeat the matching but this time use as the criterion for matching the number of months of no falls during the observation period.  Does your answer differ from your answer to question 1, if so which is the better criterion to match, age or history of falls during the observation period?
  2. For the cases and controls selected in problem 5, show a survival curve for data in the observation period.  Are these survival curves similar?  Should they be similar, why?

For assistance with these problems please contact Nate Stocks, Jenny Li,  or Juan Hernandez .

Submit an Excel file. Each assignment must be a separate sheet appropriately labeled within one file.  Do not send multiple files.  All cells except the data cells must be computed cells.  Send assignment to Blackboard and early preparation to instructor's email.  Email► Blackboard►

More

  • Kaplan Meier survival analysis using Excel Video►