title: Predicting adherence to combination antiretroviral therapy for HIV in Tanzania: A test of an extended theory of planned behaviour model.
abstract: OBJECTIVE
  Combination antiretroviral therapy (cART) for HIV is widely available in sub-Saharan Africa. Adherence is crucial to successful treatment. This study aimed to apply an extended theory of planned behaviour (TPB) model to predict objectively measured adherence to cART in Tanzania.
  
  
  METHODS
  Prospective observational study (n = 158) where patients completed questionnaires on demographics (Month 0), socio-cognitive variables including intentions (Month 1), and action planning and self-regulatory processes hypothesised to mediate the intention-behaviour relationship (Month 3), to predict adherence (Month 5).
  
  
  METHODS
  Taking adherence was measured objectively using the Medication Events Monitoring System (MEMS) caps. Model tests were conducted using regression and bootstrap mediation analyses.
  
  
  RESULTS
  Perceived behavioural control (PBC) was positively (β = .767, p < .001, R2= 57.5%) associated with adherence intentions. Intentions only exercised an indirect effect on adherence (B = 1.29 [0.297-3.15]) through self-regulatory processes (B = 1.10 [0.131-2.87]). Self-regulatory processes (β = .234, p = .010, R2= 14.7%) predicted better adherence.
  
  
  CONCLUSIONS
  This observational study using an objective behavioural measure, identified PBC as the main driver of adherence intentions. The effect of intentions on adherence was only indirect through self-regulatory processes, which were the main predictor of objectively assessed adherence.
authors.affiliation: a Health Psychology, Institute of Applied Health Sciences , University of Aberdeen , Aberdeen , UK.|b Department of Psychology , University of Edinburgh , Edinburgh , UK.
authors.forename: Kasia
authors.initials: K
authors.lastname: Banas
authors.affiliation: c Kilimanjaro Clinical Research Institute/Kilimanjaro Christian Medical Center , Moshi , Tanzania.
authors.forename: Ramsey A
authors.initials: RA
authors.lastname: Lyimo
authors.affiliation: d University College Maastricht, Maastricht University , Maastricht , The Netherlands.
authors.forename: Harm J
authors.initials: HJ
authors.lastname: Hospers
authors.affiliation: e Department of Internal Medicine , Radboud University Nijmegen Medical Center , Nijmegen , The Netherlands.
authors.forename: Andre
authors.initials: A
authors.lastname: van der Ven
authors.affiliation: a Health Psychology, Institute of Applied Health Sciences , University of Aberdeen , Aberdeen , UK.
authors.forename: Marijn
authors.initials: M
authors.lastname: de Bruin
mesh_terms: D000328:Adult; D019380:Anti-HIV Agents / Q000627:therapeutic use*; D004359:Drug Therapy, Combination; D005260:Female; D015658:HIV Infections / Q000188:drug therapy*; D006801:Humans; D033182:Intention; D008297:Male; D055118:Medication Adherence / Q000523:psychology*; D008875:Middle Aged; D008960:Models, Psychological; D011446:Prospective Studies; D011582:Psychological Theory; D011795:Surveys and Questionnaires; D013636:Tanzania; D016903:Drug Monitoring
chemical_list: D019380:Anti-HIV Agents
keywords: HIV/AIDS; Tanzania; adherence; antiretroviral therapy; theory of planned behaviour