Investigating Personal and Treatment Related Factors Associated with Adherence Behavior in Patients with Chronic Myeloid Leukemia Receiving Long Term Imatinib Therapy

Previous experiences documented that strict adherence to the prescribed Imatinib dose is of paramount importance to maximize treatment effectiveness in patients with chronic myeloid leukemia (CML). There might be several reasons of non-adherence to therapy and these include treatment factors and personal factors. However, scarce evidence exists on reasons why patients might be non-adherent to Imatinib therapy.

The main objective of this study was to investigate the association of factors with a relevant impact on sub-optimal adherence behavior in a population of CML patient receiving long term therapy with Imatinib. Personal, sociodemographic and treatment related factors were analyzed.

Analysis was conducted on 413 CML patients undergoing long term therapy with IM who already achieved a stable complete cytogenetic response (CCyR). Adherence was measured with the previously validated self-reported Morisky scale. Patients were classified in two categories based on their reported level of adherence to therapy (“suboptimal” versus “optimal adherence”). Concurrent validity of self-reported adherence was also investigated. Personal factors investigated included: quality of life, social support, fatigue, symptom burden, psychological wellbeing and desire for additional information. Previously validated standardized scales were used to evaluate personal factors including the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36), the Multidimensional Scale of Perceived Social Support (MSPSS) scale, the Psychological General Well-Being Index short-form (PGWB-S) and the FACIT-Fatigue scale. Socio-demographic and treatment related factors analyzed included: age, gender, marital status, education, performance status, comorbidity, risk classification, dose and time in treatment with Imatinib, toxicity, assumption of concomitant drugs and time to response to treatment. Univariate and multivariate logistic regression analyses were fitted to investigate the association with a sub-optimal adherence behavior. Possible multicollinearity among selected potential predictors (p<.2 in univariate analysis) was also investigated by Variance Inflation Factor (VIF). Significance level in multivariate models was α=.05.

The sample consisted of CML patients whose median age was 57 years (40% female and 60% male). Median duration of Imatinib treatment was 5 years (range 3 to 9 years). Out of the overall sample, there was 47% patients reporting a “suboptimal adherence” to treatment. Patients reporting a full adherence behavior showed shorter median time to reach the first complete molecular response (CMR) than those reporting a sub-optimal adherence, being respectively 4.2 years (95% CI, 3.8 to 4.7) and 4.9 years (95% CI, 4.4 to 5.8). The final multivariate model retained the following variables as independent predictors of suboptimal adherence: desire for more information (ref. No), OR= 2.30 (95% CI, 1.51–3.5; P<.001), social support (higher score representing greater support), OR= 0.77 (95% CI, 0.67 –0.90; P<.001) and assuming concomitant drugs (ref. No), OR=0.55 (95% CI, 0.36–0.84; P<.01).

This is the first evidence based data suggesting that a low social support and the desire for additional information are associated with a suboptimal adherence behavior in CML patients receiving long term Imatinib therapy. These data could help identify patients who might benefit most from targeted interventions aimed at improving adherence to therapy.

Efficace:Bristol Myers Squibb: Consultancy; Novartis: Research Funding. Baccarani:Pfizer: Honoraria; Bristol Myers Squibb: Honoraria; Novartis: Honoraria; Bristol Myers Squibb: Consultancy; Novartis: Consultancy; Ariad: Honoraria. Breccia:Novartis: Consultancy; Bristol Myers Squibb: Consultancy. Alimena:Novartis: Honoraria; Bristol Myers Squibb: Honoraria. Rosti:Novartis: Consultancy; Bristol Myers Squibb: Consultancy; Novartis: Research Funding; Novartis: Honoraria; Bristol Myers Squibb: Honoraria. Castagnetti:Bristol Myers Squibb: Honoraria; Novartis: Honoraria. Russo Rossi:Novartis: Honoraria; Bristol Myers Squibb: Honoraria.