Use of an interrupted time-series design to evaluate a cancer screening program

An alternative approach to intervention-control designs to evaluate communi ty health education studies is to use a quasi-experimental design in which the outcomes of interest are examined over time in the intervention unit. T he Forsyth County Cancer Screening Project (FoCaS) was a comprehensive clin ic- and community-based education program to increase screening for cervica l cancer and breast cancer among low-income women. This paper reports the u se of piecewise regression accounting for potential effects of auto-correla tion in the data to evaluate the effectiveness of the project in increasing mammography screening. Data for the evaluation of trends in screening cons isted of all mammograms performed during the period of May 1992 through Jun e 1995 at the Reynolds Health Center in Forsyth County, North Carolina. The results suggested that the FoCaS project was effective in increasing mammo graphy screening among women age 40 or older in the study population. Analy sis of the trends by age indicated that the program had differential effect s on women age 40-49 and 50 or older. The results demonstrate that analyses of the type presented here can either complement or serve as an alternativ e to more traditional intervention-control analyses.