Data Resource Center
Code library

Behavioral Risk Factor Surveillance System (BRFSS)

SAS/SAS-callable SUDAAN programs

Programs to create estimates published in NOHSS and CDI
Programs to convert data files provided on BRFSS Web site to SAS data files
Example code for SAS and SUDAAN

The code library currently contains programs for use with BRFSS surveys for the years 1999, 2002, and 2004.

The programs:
produce estimates published in the National Oral Health Surveillance System (NOHSS)
produce age-adjusted estimates published in the Chronic Disease Indicators project (CDI)
are written for SAS and SAS-callable SUDAAN
were tested using SAS v8.2 with SAS-callable SUDAAN 9.0.1

Considerations: 
These programs are written for novice SAS and SUDAAN users and do not use macros, thus they are not optimized to conserve computing resources.  The SAS-callable SUDAAN code blocks (beginning "proc crosstab" and "proc descript") ran very slowly in testing (15+ minutes each).  For examples of programs that use macros, consult a SAS user's manual or text book, or see the example program "SAS_SUD99.sas" on the BRFSS Web site under Data and Technical Info, 1999, SAS Resources.  Macros will reduce the running time considerably.  Running the programs a block at a time will help in identifying issues with different software versions or individual user set-ups.

Each program:
Creates variables for oral health indicators, demographic categories, and age adjustment
Generates estimates – both age-adjusted and unadjusted – for indicators:
  past year dental visit (yes, no)
  past year dental cleaning (yes, no)
  complete tooth loss among adults aged 65+ (yes, no)
  lost 6 or more teeth among adults aged 65+ (yes, no)
Includes calculation of 95% confidence intervals, cell sizes, denominators, and flags for unstable estimates based on BRFSS criteria of denominator <50 or confidence interval halfwidth <10.

Example code to convert a SAS transport data file (file extension ".xpt") to a SAS data file (file extension .sas7bdat or .sd7)

/*Program Name: BRFSS2004_xpt.sas*/
/*create SAS v8 file from SAS xport file*/
/*for BRFSS 2004*/
/*07/15/2005*/
LIBNAME BRF04IN XPORT "C:/BRFSS/BRFSS2004/SASXPORT/cdbrfs04.xpt";
libname  BRF04OUT v8 "C:/BRFSS/BRFSS2004/SASV8";
  PROC COPY IN=BRF04IN OUT=BRF04OUT;
  RUN;
/*end BRFSS2004_xpt.sas*/

In the SAS enhanced editor, it will look like this:
(Comments written to document the program appear in green between special symbols "/*" and "*/", or between "*" and ";".):

/*Program Name: BRFSS2004_xpt.sas*/
/*create SAS v8 file from SAS xport file*/
/*for BRFSS 2004*/
/*07/15/2005*/
LIBNAME BRF04IN XPORT "C:/BRFSS/BRFSS2004/SASXPORT/cdbrfs04.xpt";
libname BRF04OUT v8 "C:/BRFSS/BRFSS2004/SASV8";
PROC COPY IN=BRF04IN OUT=BRF04OUT;
RUN;
/*end BRFSS2004_xpt.sas*/

Example SAS Data step to recode a variable

Data Brf04ss.BRFDOH04; *write out data set;
set Brf04ss.cdbrfs04;  *read in data set;

*Age groups - 18 and older in 6 groups;
if age in (7,9) then agegrp = . ; *refused, did not respond, missing omitted;
else if 18 <= age <= 24 then agegrp = 1 ; *18 to 24 years;
else if 25 <= age <= 34 then agegrp = 2 ; *25 to 34 years;
else if 35 <= age <= 44 then agegrp = 3 ; *35 to 44 years;
else if 45 <= age <= 54 then agegrp = 4 ; *45 to 54 years;
else if 55 <= age <= 64 then agegrp = 5 ; *55 to 64 years;
else if age ge 65 then agegrp = 6 ; *65 years and older;

RUN;

Example SUDAAN Code block to produce estimates for Past year dental visits for all states, by several demographic groupings

*Table for 2004 Dental visits: 18 and older - Not age adjusted;

Proc crosstab Data = Brf04ss.BRFDOH04 design=wr filetype=sas CONF_LIM=95;
 Nest _ststr _psu/missunit;
 Weight _finalwt;

 Subpopn agegrp >= 1 and _finalwt>0;
 Class _state;
 Subgroup visit sex agegrp racegrp income educat ;
 Levels     2    2    6       5       5     4    ;

 Tables _state*visit
       (sex income educat racegrp agegrp)*_state*visit;

 Print nsum rowper lowrow uprow/ rowperfmt=f5.1 lowrowfmt=f5.1 uprowfmt=f5.1 style=nchs;
 output nsum rowper lowrow uprow/ filename=brf04ss.vis04 REPLACE filetype=SAS;

 rtitle "NOHSS 2005 release - BRFSS 2004 Estimates for Dental Visits - not age adjusted";

Run;
 

Need to have SAS and SAS-callable SUDAAN installed either on local machine or have access to these programs through a network (See About SAS and SAS-callable SUDAAN).  The SAS-callable SUDAAN code in these programs can be copied into a separate file and edited to run in SUDAAN.

• Change file path in "libname" statements to the locations where you have saved the BRFSS data files or want to output new data files you create: 

Libname BRF99SS 'C:\BRFSS\BRFSS1999\SASV8'; /*Location of SAS version of data set*/
Libname OUT 'C:\BRFSS\BRFSS1999\OUT'; /*Location to save output data sets*/
 

• Change file path in "libname" statements to the locations where you want to save the formats (if you want to use permanent formats): 

Libname LIBRARY 'C:\BRFSS\BRFSS1999\SASV8'; /*Formats library*/

If you don't want to save permanent formats: 

delete this statement
Libname LIBRARY 'C:\BRFSS\BRFSS1999\SASV8'; /*Formats library*/

and change this statement
*Formats;
Proc Format library=LIBRARY; *creates permanent format library;

to this statement
*Formats;
Proc Format ; *creates temporary format library;
 

• Change file path in "outfile" statements to the locations where you want to write the output Excel files:

*Exporting file to Excel;
Proc Export Data = Brf97ss.CDIInd92_1997
Outfile = "Q:\BRFSS\Brfss1997\ExcelTables\CDIInd92_1997.xls"
DBMS = Excel2000 Replace;
Run;
 

• Converted the data file provided on the BRFSS Web site to a SAS data file using the programs provided above
   
• Programs direct the results tables output from SUDAAN code to a file instead of to the SAS output window, because there is lots of output.  It also saves the contents of the tables as SAS files, and prints a more concise listing of the output at the end of the program using the SAS procedure "proc print".  The programs also create Excel files containing the estimates published in the NOHSS and CDI Web sites.