ABSRISK.EXE: A Program for Estimating Absolute Risks from Relative Risks Version 1.0, August 1995 INTRODUCTION: This MS-DOS program uses age-specific mortality and morbidity data to convert relative risk estimates into absolute risk estimates. That is, it estimates the probability that a patient will suffer a specific morbid or mortal outcome in a given time interval. The user first specifies a data file that contains the needed mortality and morbidity data for the disease of interest. She then gives her patient's age and relative risk, and the time interval over which the risk estimate is to be derived. The program derives this risk, which is given both interactively and in a log file. The use of this program is discussed in Dupont and Plummer (1996). Users should read this paper before running this program. Technical details are given in Dupont (1989). OBTAINING A COPY OF THE ABSRISK PROGRAM: This program, its FORTRAN source code, program documentation, and sample input data sets are available via the Internet. You may copy the material to your computer using any widely available Web browser (e.g. Netscape). Alternately, you may use a file transfer protocol (FTP) program to get the files. Both methods are discussed below. Using a Web browser Go to http://biostat.mc.vanderbilt.edu/wiki/Main/RelativeToAbsoluteRisks. This will take you to the Absolute Risk web page. Click on ABSRISK.ZIP to copy the software to your computer. You may also obtain a copy of this documentation by clicking on ABSRISK.TXT and then printing the displayed page. After getting the files The file ABSRISK.ZIP should be saved in an empty subdirectory on your computer and unzipped. If you are using a web browser you may obtain an unzipping program by clicking on UNZIP.EXE on the Absolute Risk web page mentioned above. Copy UNZIP.EXE to you computer and use it to unzip the ABSRISK.ZIP file. See the appendix below if you need further details on using the unzip program. After unzipping absrisk.zip you should have the following files on your personal computer: File Name Function ------------------------------------------------------------- ABSRISK.EXE Executable image of the ABSRISK program ABSRISK.TXT Program documentation BREAST.DAT Input data for breast cancer morbidity COLRECM.DAT Input data for colorectal cancer morbidity in men COLRECW.DAT Input data for colorectal cancer morbidity in women CVMEN.DAT Input data for cardiovascular mortality in men CVWOMEN.DAT Input data for cardiovascular mortality in women LUNGM.DAT Input data for lung cancer morbidity in men LUNGW.DAT Input data for lung cancer morbidity in women OVARY.DAT Input data for ovarian cancer morbidity PROSTATE.DAT Input data for prostate cancer morbidity STOMACHM.DAT Input data for stomach cancer morbidity in men URINARYM.DAT Input data for urinary cancer morbidity in men UTERUS.DAT Input data for uterine cancer morbidity In addition, the FORTRAN source code is given as 12 files in a subdirectory named SOURCE. ABSRISK INPUT DATA FILES: The ABSRISK program requires an input data file that specifies the age-specific morbidity and mortality rates that are needed for the disease of interest. We have provided such files for common cancers in American men and women. For example, the breast cancer file BREAST.DAT is listed below: ! BREAST.DAT ! ! OUTCOME: Invasive Breast Cancer. ! ! POPULATION: U. S. Women 1987-91. ! ! SOURCE: SEER data: NIH Pub # 94-2789, pages 117-118, ! breast cancer mortality and morbidity rates. ! ! NCHS data: DHHS Pub. # (PHS)93-1101, Table ! 291, total mortality data in 1989. ! ! See ABSRISK.TXT for complete citations. ! ! NOTES: 1. Age-specific rates are per 100,000 ! population. ! ! 2. This file is formatted as a data input ! file for the ABSRISK.EXE program. Instructions ! for writing and using these files are given in ! ABSRISK.TXT. ! !------------------------------------------------------------ ! Age Interval Total Breast Breast ! Start End Mortality Cancer Mortality Cancer ! Incidence !------------------------------------------------------------- ! 15 19 48.7 0.0 0.0 20 24 53.0 0.1 1.0 25 29 65.2 1.2 7.8 30 34 86.1 4.8 25.6 35 39 113.2 12.4 63.6 40 44 168.2 23.3 126.9 45 49 265.1 37.5 198.3 50 54 438.6 54.5 228.9 55 59 699.5 71.6 274.8 60 64 1080.3 88.8 348.3 65 69 1623.9 102.9 412.1 70 74 2499.3 118.8 450.3 75 79 3925.2 134.4 483.9 80 84 6498.6 154.9 477.1 For other diseases or patient groups you must write your own input data file using an editor or word processor that can create text files. An arbitrary number of comment lines can be included in these files by typing an exclamation point (!) in column 1. These lines will be written to the program's log file and are useful to document the source of your age-specific data. The comment lines are followed by 5 columns separated by blanks that give the following: 1. The start of an age interval. 2. The end of and age interval. 3. The total age-specific mortality rate for the population of interest in the age group specified in columns 1 and 2. 4. The corresponding age-specific mortality rate due to the cause of interest. 5. The corresponding age-specific morbidity rate due to the cause of interest. The age intervals must be consecutive and of equal length. If necessary, the program will use linear extrapolation from the rates of the last two age intervals to estimate rates for older ages. The start of the first age interval must be younger than the youngest patient for whom you wish to make absolute risk estimates. This program can also be used to estimate the absolute risk of a mortal event. In this case the input data file is created in the same way as before, only now, columns 4 and 5 give identical age- specific mortality rates. See, for example, CVWOMEN.DAT. RUNNING THE ABSRISK PROGRAM: First, open an MS-DOS window and set the default directory to where you have located the ABSRISK files. To execute the program, type ABSRISK and then enter the name of your input data set. The program lists the contents of the input data set and then asks you for your patient's age, relative risk, and the number of years over which the absolute risk estimate is to be calculated. After receiving this data, the program responds with the absolute risk estimate and prompts you for additional data. The absolute risk estimates are also written to a log file with the same name as the input data file and the extension .LOG. After completing your absolute risk estimates, type EXIT. An example of a the use of this program is given below. Upper case text in this example is entered by the user; other text is the response of the program. c:\>ABSRISK this program estimates absolute risks from relative risks and age-specific morbidity and mortality data. See pub/biostat/absrisk.txt on the ftp.vanderbilt.edu server for documentation on using this program. enter the name of the input data file: CVWOMEN.DAT do you want to correct absolute risks for the prevalence of risk factor in the general population? (y=yes, n=no, h=help): NO ! cvwomen.dat ! ! outcome: major cardiovascular mortality (idc-9 codes 390-448) ! ! population: u.s. women, 1989 ! ! source: nchs data: dhhs pub. # (phs)93-1101, table 291 ! ! see absrisk.txt for complete citation. ! ! notes: 1. age-specific rates are per 100,000 population. ! ! 2. this file is formatted as a data input file ! for the absrisk.exe program. instructions for ! writing and using these files are given in ! absrisk.txt. ! !------------------------------------------------------------- ! age interval total cardiovascular cardiovascular ! start end mortality mortality mortality !------------------------------------------------------------- ! 15 19 48.7 2.0 2.0 20 24 53.0 3.4 3.4 25 29 65.2 5.6 5.6 30 34 86.1 9.7 9.7 35 39 113.2 16.2 16.2 40 44 168.2 30.9 30.9 45 49 265.1 58.2 58.2 50 54 438.6 112.8 112.8 55 59 699.5 201.8 201.8 60 64 1080.3 353.6 353.6 65 69 1623.9 602.4 602.4 70 74 2499.3 1063.9 1063.9 75 79 3925.2 1923.5 1923.5 80 84 6498.6 3583.4 3583.4 ------extrapolated values follow-------------------- 85 90 9072.0 5243.3 5243.3 90 95 11645.4 6903.2 6903.2 95 100 14218.8 8563.1 8563.1 enter patient's age: 50 enter patient's relative risk: 10 enter number of years over which absolute risk is to be estimated: 15 probability that patient will suffer outcome by age 65 = 0.294 enter patient's age: 60 enter patient's relative risk: 5 enter number of years over which absolute risk is to be estimated: 20 probability that patient will suffer outcome by age 80 = 0.585 enter patient's age: EXIT see cvwomen.log for a record of the preceding calculations. finished. c:\> APPENDIX Using UNZIP.EXE to unzip the files Open an MS-DOS window and set your default directory to be where you copied ABSRISK.ZIP and UNZIP.EXE. Type the command "UNZIP ABSRISK". Unzip will create the desire files, giving the following information as it runs. inflating: absrisk.exe inflating: absrisk.txt inflating: breast.dat inflating: colrecm.dat inflating: colrecw.dat inflating: cvmen.dat inflating: cvwomen.dat inflating: lungm.dat inflating: lungw.dat inflating: ovary.dat inflating: prostate.dat creating: source/ inflating: stomachm.dat inflating: urinarym.dat inflating: uterus.dat inflating: source/absrisk.for inflating: source/absrisk.inc inflating: source/calpas.for inflating: source/getent.for inflating: source/igrand.for inflating: source/integ.for inflating: source/interp.for inflating: source/interpre.for inflating: source/intrp2.for inflating: source/rrisk.for inflating: source/simint.for inflating: source/strlen.for inflating: source/upcase.for You are now ready to run the ABSRISK program. REFERENCES: 1. Dupont WD, Plummer WD Jr. Understanding the relationship between relative and absolute risk. Cancer 1996; 77:2193-9. 2. Dupont WD. Converting relative risks to absolute risks: a graphical approach. Statistics in Medicine 1989; 8:641-651. 3. Ries LAG, Miller BA, Hankey BF, Kosary CL, Harras A, Edwards BK (eds). SEER Cancer Statistics Review, 1973-1991; Tables and Graphs, National Cancer Institute, NIH Pub. No. 94- 2789. Bethesda,MD, 1994. 4. National Center for Health Statistics. Vital Statistics of the United States, 1989, Vol. II, Mortality, Part A. Washington: Public Health Service, 1993. DHHS Pub. No. (PHS) 93-1101, U.S. Government Printing Office.