SEER-Medicare: Using SEER*Stat to Analyze SEER-Medicare Data
SEER*Stat is statistical
software for the analysis of SEER and other cancer-related databases which can
be used to view individual cancer records and to produce incidence, mortality,
and survival statistics. A reason to use SEER*Stat rather than other statistical
packages for the analysis of SEER-Medicare linked data is that SEER*Stat
performs some statistical calculations which are either not available in other
statistical packages (e.g. relative survival) or are cumbersome to perform (e.g.
age-adjustment, linking the correct population denominators with incidence
files). In addition, there are now various "back-end" statistical programs
developed especially for the analysis of population-based cancer statistics
which have been made to work easily with SEER*Stat output. For a summary of
new methods and software for the analysis of population-based cancer statistics
The SEER*Prep software
converts ASCII text data files to the SEER*Stat database format, allowing you to
analyze your cancer data using SEER*Stat. If you are a new SEER*Prep user, see
How to use SEER*Prep to
Create a Database. Follow the steps below to create a database using
SEER-Medicare data for use in SEER*Stat.
I. Install SEER*Stat and SEER*Prep
To use SEER*Stat to analyze your data, you must use SEER*Prep
Version 1.9 or later and a compatible version of SEER*Stat. Current versions of
the SEER*Prep and SEER*Stat software are available on
the SEER Web site.
II. Download Files
- Download the appropriate SAS program from the table below. The number after 'infile' refers to the length of the PEDSF record. For example, if the PEDSF which you received has a record length 1234, you would need to download the "Create.SEERPrep.infile1234.sas" program.
- Next, download the Database Description file compatible with the SAS program that you selected. This file provides SEER*Prep with a description of the SAS program's output file.
III. Preparing SEER-Medicare data for use with SEER*Stat
- Make the necessary modifications to the "Create.SEERPrep.infile*.sas"
program. There are instructions at the top of the program in the comment block.
Search for 'USER' and make changes as described in the following steps.
- You will need to change the input and output filenames. These include the
PEDSF sent to you by IMS, any analysis file(s) from which you wish to use
variables, and the filename where you wish to save the output data from this
program. Your analysis file (your selected cohort with your constructed
variables) must contain the SEER Registry/Case number as a length 10 character
string and the SEER Sequence number for the tumor as a length 2 character
string. You may use multiple analysis files, but you will have to make more
extensive changes within the program to handle this. If you do choose to use an
analysis file, verify that the filename or libname statement has been
- You will need to select an end date (month and year) for your study. These
should be preset to the last year of Medicare claims files available, but you
can select other values more appropriate to your analysis.
- If you have chosen to merge with an analysis file, you must now modify the
'ANALYSIS MERGE SECTION'. This section of code assumes that the incoming file
is a SAS data library. If you have a text file, you will need to add an input
statement. You must select the variables you wish to add to the output file for
analysis in SEER*Stat. PLEASE NOTE: the variables you select for use in
SEER*Stat must be numeric. If you wish to use variables from multiple files,
you must add additional code to input and merge more data sets. Be sure to
un-comment this section (delete the 2 lines '/* USER comment out begins' and
'USER comment out ends */').
- Again, if you have chosen to merge with an analysis file, you must modify
the output statement where the lenX_n variables are shown. 'lenX' shows the
length of the variables which may be placed in the given location. You MUST put
your variables in fields of the same length. SEER*Stat will not correctly
handle data if you use this space in a manner not intended. Places have been
provided for 10 variables of length 1 and 10 of length 2. There is also space
for 5 variables each of length 3, length 4 and length 5. '_n' shows the count
of the given length (len3_2 is the 2nd variable of length 3). This is just a
convenience to make keeping track of your variables easier.
- Run the customized "Create.SEERPrep.infile*.sas" program.
- Use SEER*Prep to convert the data file you just created into a SEER*Stat database as described below.
- Open the database description file. Use the file menu to open the Database
Description file that you donwloaded in Step II.
- Edit the Database Name and provide a meaningful name for
your new database.
- Select the Input Case File(s) by using the Add... button
to select the file you created with the SAS program.
- Set the study cutoff
date. The date should match the end date of your study (see step 1b).
- You may edit the 'User-specified nth length x' variables starting in column
300 to have a name and format consistent with your analysis variables. Remove
the 'User-specified nth length x' variables that you are not using.
- Save the
modifications you have made to the "*.dd" file. Use Save
As... to save the dd file with a meaningful name.
- Use SEER*Prep's verify feature to check your data. Review the verify report.
If any problems require changes to the data, you will need to make these changes
outside of SEER*Prep.
- Create a database using the Create file command in
SEER*Prep. Be aware, if you select 'Exclude for all invalid values' on the
Record Exclusion screen, any record not found in your analysis file will be
excluded from the SEER*Stat database.
- Start the SEER*Stat application. Your new database will be listed on the
data tab in all appropriate session types. If it is not listed, check the
Secondary Data Location specified in SEER*Stat's Preferences. It should match
SEER*Prep's User-Defined Data location.