Background Multiple sclerosis (MS) is a disabling disease that affects the central nervous system.

Switching of first-line drugs (interferon β, glatiramer acetate) or initiation of a second-line treatment (natalizumab, mitoxantrone, cyclophosphamide, rituximab) should be considered if suboptimal response is observed with first-line drugs.

Purpose To analyse the treatment pattern and the main reasons for changing MS treatment.

Materials and methods Cross-sectional, retrospective descriptive study in MS patients, in a reference unit, in a tertiary hospital. A sample of 100 patients was analysed (10% of complete MS population) who picked up medicines from the outpatient pharmacy unit, following a database that included demographic and clinical information.

Results 30% of patients had switched treatment once and 7% at least twice (23.3% of the MS population that had changed previously). The main reasons for changing treatment, from initial to second and second to third treatment were: lack of efficacy: 65.4% and 20% respectively; drug withdrawal: 15.4% and 20%; pregnancy: 15.4% and 0%; drug intolerance: 3.8% and 0%; adverse reaction: 0% and 20%; maximum tolerated dose: 0% and 10%. By drugs, main reasons for changing MS treatment, from the initial to second treatment were: Avonex: lack of efficacy (75%) and pregnancy (25%); Betaferon: lack of efficacy (20%) and drug withdrawal (80%); Rebif 22 mcg lack of efficacy (75%) and pregnancy (25%); Rebif 44 mcg: lack of efficacy (100%); Copaxone: lack of efficacy (50%), intolerance (25%) and pregnancy (25%). The treatment mean time was 51±43 months prior to the first change, which decreased to 23.5±21.9 months for the second change of treatment. The mean Expanded Disability Status Scale (EDSS) score increased from 2.5±1.4 at the beginning to 3.9±1.9 in second-line treatment and 5.7±1.8 in third-line treatment.

Conclusions 30% of patients with MS had changed treatment. The main reason was progression of the disease.