Psychological Factors Associated with Episodic Chelation Adherence in Thalassemia.

β-Thalassemia major (β-TM) is a life-long genetic hemoglobin (Hb) disorder requiring intensive treatment regimens, including frequent blood transfusions and daily chelation therapy. Understanding psychosocial correlates of chelation adherence is important for developing interventions to improve adherence. This study investigated within-participant correlates of oral chelation adherence on a daily (episodic) basis. Thirty-seven adult participants with β-TM were recruited from clinics at two hospitals (22 males, 9 females, mean age 34.5 years, range 19-54 years). A structured interview was used to assess behavioral and psychological situational variables related to an adherent and a nonadherent episode for each participant. Positive outcome expectancies and higher self-efficacy were both significantly associated with adherent episodes. Behavioral variables, including difficulty in accessing medication, location, and whether alone or with others, were also associated with nonadherent episodes. Findings suggested that situational psychological factors are important for chelation adherence. Adherence interventions should consider focusing on potentially modifiable situational variables (psychological and behavioral).