'It might happen or it might not': how patients with multiple sclerosis explain their perception of prognostic risk.

This qualitative study aimed to examine risk perception and seriousness of wheelchair dependence in patients with multiple sclerosis. Perceived absolute risk and perceived seriousness were assessed for 2-year, 10-year and lifetime prognosis of wheelchair dependence using visual analogue scales (VAS). In semi-structured interviews, patients (n = 85) were asked to elucidate these VAS scores. Explaining perceived absolute risk, patients mentioned disease-related factors as well as psychological factors. Uncertainty about future disease progression was a predominant factor for all patients, even those with low and high perceptions of risk. Wheelchair dependence was perceived as a serious outcome primarily because of its possible implications, such as loss of independence. When perceptions of 2-year, 10-year and the lifetime prospect of wheelchair dependence were compared, it was found that patients discriminated in their perception of absolute risk, but less in that of seriousness. Comparison of quantitative and qualitative assessments indicated good construct validity for perception of the absolute risk and seriousness of wheelchair dependence.