Comparability of contraceptive prevalence etimates for women from the 2002 Behavioral Risk Factor Surveillance System

OBJECTIVE: This article assesses the comparability of contraceptive use estimates for adult women obtained from the 2002 Behavioral Risk Factor Surveillance System (BRFSS), using the 2002 National Survey of Family Growth (NSFG) as a benchmark. The 2002 BRFSS uses data collection methods that are considerably different from the NSFG. METHOD: We compared demographic differences and national estimates of current contraceptive methods being used and reasons for nonuse. Variables were recoded in the BRFSS and NSFG systems to make the two samples comparable. RESULTS: Women in the NSFG and BRFSS were similar in age and race/ethnicity. Compared with the NSFG, the BRFSS sample was more educated and of higher income, less likely to be cohabiting, and more likely to be married. After adjusting for differences in the coding of hysterectomy, many BRFSS estimates for current contraceptive use were statistically similar to those from the NSFG. Small but statistically significant differences were found for vasectomy (7.7% and 6.3%), the pill (21.9% and 19.6%), rhythm (1.5% and 1.0%), the diaphragm (0.5% and 0.2%), and withdrawal (0.3% and 2.7%) for the BRFSS and NSFG, respectively. Major reasons for nonuse were similar: seeking pregnancy and currently pregnant. The percentage of women who were not currently sexually active was higher in the BRFSS (16.0%) compared with the NSFG (12.5%). CONCLUSIONS: The BRFSS is a useful source of population-based data on contraceptive use for reproductive health program planning; however, planners should be cognizant that lower-income women are not fully represented in telephone surveys.