Factors associated with adherence to disease modifying therapy in multiple sclerosis: An observational survey from a referral center in Lithuania ☆

Abstract Aim of the study To investigate adherence to disease modifying therapy (DMT) in Lithuanian population of multiple sclerosis patients and factors associated to it. Methods Patients receiving one of the following DMT's: Interferon β 1a (Rebif) 44 micrograms three times a week subdermally (s/c) or Interferon β 1a (Avonex) 30 micrograms weekly intramuscularly (i/m), or Interferon β 1b (Betaferon, Extavia) 250 micrograms once in two days s/c, or Glatiramer acetate (Copaxone) 20 mg daily s/c, were presented with a questionnaire inquiring their demographic and clinical characteristics and adherence to treatment profile, as well as HAD scale and SF-36 questionnaire. Those who missed at least one dose of DMT during last three months were considered non-adherent. Results In total, 207 patients were enrolled, 73 (35.3%) of them were non adherent during last three months. More patients with university education (p=0.004, χ 2 =8.466 high school/vocational vs. university) as well as consuming >4 units/year of alcohol were non-adherent during last three months (p=0.005). Average score for anxiety (6.69±4.03 vs. 6.92±4.24) and depression (4.74±3.9 vs. 4.7±3.83) in HAD scale did not differ significantly between adherent and non-adherent groups. We did not find any significant difference in quality of life scores (SF-36 v.2) between the groups. No significant difference of adherence was found then comparing patients often suffering from drug side effects with those who experience rare or no side effects. In logistic regression model, patients consuming more than 4 alcohol units per year and patients with university education were more likely to miss at least one dose during last three months: 2.121 (95% CI: 1.143–3.937, p=0.017) and 2.409 (95% CI: 1.260–4.642, p=0.008) times accordingly. Patients with better quality of life scores were slightly less likely to be non adherent (OR 0.997 (95% CI: 0.994–0.999), p=0.0017). Conclusions One third of patients were non-adherent during last three months. Worse adherence rates were associated with higher education and higher alcohol consumption. Education, alcohol consumption and quality of life scores were found to be significant factors for predicting non-adherence. We found no associations between adherence and anxiety, depression, or drugs side effects.