Chronic myeloid leukemia (CML): association of treatment satisfaction, negative medication experience and treatment restrictions with health outcomes, from the patient's perspective

Abstract

Background: The availability of the tyrosine-kinase inhibitor (TKI), imatinib, and later introduction of second generation TKIs, dasatinib and nilotinib, have not only improved clinical outcomes of patients with chronic myeloid leukemia (CML), but also provide multiple therapeutic options for CML patients. Despite the widespread use of these oral therapies, little is known about the impact of different treatment regimens on patient-reported outcomes (PROs) among CML patients. The objective of this study was to assess the impact of patient-reported treatment restrictions and negative medication experiences (NMEs) on satisfaction and other health outcomes among patients with CML treated with oral TKIs.

Methods: Participants recruited from survey panels and patient networks in the United States (US) and Europe completed an online questionnaire. Respondents included adults (≥ 18 years) with chronic-phase CML currently on TKI treatment. Study variables included treatment difficulty (i.e., difficulty in following treatment regimens), CML dietary/dosing requirements, NMEs, and validated PROs assessing treatment satisfaction, health-related quality of life (HRQoL), activity impairment, and non-adherence. Structural equation models assessed associations among variables, controlling for covariates.

Results: 303 patients with CML (US n=152; Europe n=151; mean age 51.5 years; 46.2% male) completed the questionnaire. Approximately 30% of patients reported treatment difficulties; treatment difficulty was higher among nilotinib (63.3%) than among dasatinib (2.6%) or imatinib (19.2%) treated patients (p<0.0001). Non-adherence was generally low; however, patients on nilotinib vs. imatinib reported missing doses more often (p<0.05). Treatment satisfaction was associated with significantly increased HRQoL (p<0.05) and lower activity impairment (p<0.01). NMEs were associated with decreased treatment satisfaction (p<0.01) and HRQoL (p<0.05), and greater activity impairment (p<0.01). Higher overall treatment restrictions were associated with greater treatment difficulty (p<0.001), which correlated with non-adherence (p<0.01).

Conclusions: Treatment satisfaction and NMEs are important factors associated with HRQoL among patients with CML. Increased treatment restrictions and associated difficulty may affect adherence with TKIs. Choosing a CML treatment regimen that is simple and conveniently adaptable in patients' normal routine can be an important determinant of HRQoL and adherence.

Figure 1

Multivariate structural equation model predicting the associations of CML treatment restrictions, treatment doses, NME, CML treatment satisfaction, and patient-reported outcomes among CML patients. Note. The following covariates or non-significant predictors (of adherence, activity impairment, MCS, PCS, and health utilities) are not presented: age, gender, number of comorbidities, time since diagnosis, and number of non-CML medications taken per day. Straight lines indicate betas and curved lines indicate correlations. Residual error terms, estimated for all predicted variables and factors, are not presented; neither are correlation estimates. Non-parenthetical values are standardized estimates (ranging from −1 to +1, with 0 = no effect) indicating strength and direction of association; these values can be compared across predictors. P-values are based on the unstandardized path estimates. No p-values are available for the first indicators per factor, which set the scale. Fit statistics indicate a fair fit of the data to the model (χ² test of model fit=408.8; df=76; p-value<0.01. CFI=0.79; TLI=0.63; RMSEA=0.12). CML = chronic myeloid leukemia, NME = negative medication experience.

Figure 2

Multivariate structural equation model predicting the associations of CML treatment restrictions, patient reported difficulty following CML treatment, and non-adherence among CML patients. Note. Straight lines indicate betas and curved lines indicate correlations. Residual error terms, estimated for all predicted variables and factors, are not presented. Non-parenthetical values are standardized estimates (ranging from −1 to +1, with 0 = no effect) indicating strength and direction of association; these values can be compared across predictors. P-values are based on the unstandardized path estimates. No p-values are available for the first indicators per factor, which set the scale. Fit statistics indicate a good fit of the data to the model (χ² test of model fit=91.6; df=10; p-value<0.01. CFI=1.0; TLI=1.01; RMSEA<0.01). CML = chronic myeloid leukemia.