We identified over 70 personal, socioeconomic, treatment-related and disease-related characteristics within the HIV Futures 6 data set that were likely to be associated with treatment adherence and/or difficulty taking ART. A full list of the potential explanatory variables included in this analysis is provided in Figure 1. Most continuous exposure variables were categorized for inclusion in our analysis. Categorization

was based on the distribution of the specific variable and/or logical categories for the variable. The respondent’s most recent CD4 cell count was categorized based on whether the respondent had moderate to severe immune system damage (CD4 count <500 cells/μL) or little immune system damage (CD4 count ≥500 cells/μL). The ‘timing of HIV diagnosis’ variable was categorized according to the ART period at the time at which the respondent this website was diagnosed (1983–1988, pre-ART period; 1989–1995, early ART/monotherapy APO866 clinical trial period, and 1996 onwards, post-cART period), as previously defined by Rawstorne

et al. [31]. The ‘period of commencing ART’ variable was categorized in a similar manner (prior to 1996, pre-cART era; 1996–2003, early cART era; 2004–2009, late cART era). Our data set contained a number of attitude variables which captured respondents’ views about ART/cART and the impact HIV infection had on respondents’ health, physical appearance, health management strategies, relationships and sex life. These variables were scored on Likert scales (1=strongly disagree, 2=disagree, 3=agree, and 4=strongly agree). To reduce the total number of attitude variables included in our analysis, we conducted principal components analysis with oblique rotation to identify appropriate attitude scales that could be included RVX-208 in our analysis. Mean scores were computed

for each scale when responses had been given for at least two-thirds of the variables in the scale. Where a suitable scale could not be identified, attitude variables were analysed as separate variables. Bivariate associations between the potential explanatory variables and our dichotomous outcome variable were assessed using the χ2-test or Fisher’s exact test for categorical exposure variables and the t test for continuous exposure variables (mean scale scores for attitude scales). Variables that showed a significant association at the level of α=0.2 in bivariate analyses were included in multivariable analyses. The multivariable analysis consisted of a two-step logistic regression modelling procedure based on backwards stepwise logistic regression using the likelihood ratio statistic. At step 1, we computed four separate logistic regression models including factors that were expected to exhibit a high degree of collinearity, using α=0.1 as the exit criterion. Variables that remained significant at α=0.1 during step 1 modelling were entered into a single step 2 model where α=0.05 was set as the exit criterion.