Risk factors associated with major HIV-1 subtypes in Bulgaria, results from multivariable logistic regression model.

1. Odds ratios (OR) are the estimated odds of a subtype occurring in the study population for a given risk factor relative to the referent group (Ref) as compared to occurrence of all other subtypes.2. CL, confidence limit.3. p, is the p-value for differences in subtype prevalence compared to the referent group.