Psychosocial factors associated with use of multivitamins by women of childbearing age.

To determine the association between psychosocial factors and use of multivitamins among women (18-40 years; N=3438) who were enrolled in Kaiser Permanente Health Plan in southern California. A telephone survey elicited information about multivitamins and psychosocial and demographic characteristics. The outcome variables were any and regular use (> or =4 times per week) of multivitamins. Four psychosocial factors were: perceived need to take multivitamins and perceived benefits, barriers, and locus of control. Data were analyzed using exploratory factor analysis and multivariate analyses that adjusted for age, race or ethnicity, marital status, education, and discussion of multivitamin use with a health care provider. Fifty one percent of women reported using multivitamins; of this group, 79% were regular users. After adjusting for several covariates, factors positively associated with any use of multivitamins were perceived need (odds ratio [OR] = 1.22; 95% confidence interval [CI] = 1.15-1.29), perceived benefit (OR = 1.15; CI 1.08-1.22); and perceived barriers had a negative association with any use (OR = 0.64; CI 0.59-0.68). When regular users were compared to irregular users in a multivariate analysis, regular use was positively associated with perceived benefits (OR = 1.13; 95% CI: 1.02-1.25) and negatively associated with barriers (OR = 0.47; 95% CI: 0.41-0.53). Women who were not advised by their providers about multivitamins were less likely to use them (OR = 0.43; 95% CI: 0.36-0.52) or to be regular users (OR = 0.68; 95% CI: 0.50-0.91). Results suggest that certain psychosocial factors as well as advice from a health care provider help women to make decisions about multivitamin use.