Objectives To evaluate the effects of different testing environments and repeat testing using a computerised, automatically scored, self-administered MS cognitive battery: MSreactor (www.msreactor.com).

Methods MSreactor monitors processing speed, attention and working memory. Participants confirm a ball’s appearance (Simple Reaction Test, (SRT)), react to the ball’s colour (Choice Reaction Test (CRT)) and detect if consecutive cards are identical (One Back Test (OBT)). Participants were offered 6 months clinic, or home-based testing every 1 to 3 months. Linear mixed models were constructed where the dependent variable was reaction time outcomes (SRT, CHRT, OBK), and independent variables were location or the home test number/order. Fixed effects included: EDSS, time of day and sex.

Results Three-hundred and seventy four MS patients completed baseline clinic testing; 166 had repeated clinic testing at the time of extraction. 84.5% of the cohort agreed to home and clinic testing with repeat testing compliance of 80%. Reaction times for all tests were 3% faster (p<0.001) at first home compared with the first clinic test, with no difference detected between second clinic/home test. Reaction times for SRT, CRT and OBK was 5.7% to 6.8% slower in the morning (p<0.001) regardless of location. EDSS was associated with slower reaction times in the first clinic/home comparison only. Reaction times during repeat home testing increased by 1.5%–2% with each unit increase in EDSS. Analysis of repeat home testing (first 5 home tests) showed no practice effect on SRT and CHRT scores but OBK reaction times decreased slightly by 0.8% (p<0.001) for each additional home test.

Conclusions Our results demonstrate the reliability of MSreactor scores with minimal testing environment or practice related effects observed on SRT and CHRT reaction times. MSreactor provides a feasible testing platform for cognitive monitoring in MS and our results will assist in defining clinically relevant changes in cognitive monitoring scores over time.