In multivariate analysis , the Bloemfontein site -LSB- odds ratio ( OR ) : @ ; @ % confidence interval ( CI ) : @ to @ -RSB- and liking the pill color ( OR : @ ; @ % CI : @ to @ ) were positively associated with good adherence , whereas using oral contraceptive pills at enrollment was negatively associated with good adherence ( OR : @ ; @ % CI : @ to @ ) .