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Chapter 3 60 mental quality of life at baseline ( 0.46, 95% CI 0.15; 0.77, P =0.004), but not baseline depression or anxiety scores, predicted higher mental quality of life at follow-up. When looking for characteristics at follow-up that were associated with quality of life at follow-up, general anxiety ( -1.49, 95% CI -1.90; -1.07, P <0.001), and depression levels ( -1.00, 95% CI -1.48; -0.53, P <0.001) at follow-up were the only two parameters independently associated with mental quality of life at follow-up after correcting the model for age, gender, IBS-subtype, GI symptom severity, GI-specific anxiety, and general anxiety and depression. No characteristics at follow-up were found to independently associate with physical quality of life at follow-up. Baseline IBS-subtypes were not included in the models that looked for baseline predictors, as univariate analyses showed no significant differences in subtypes between groups, that is , the distribution in baseline subtypes did not differ significantly between Rome III-negative and -positive patients. Inclusion of these variables into the model would have decreased statistical validity and increased the probability of type I errors. Discussion In the current prospective study, we evaluated the natural symptom evolution of patients with IBS in the Maastricht IBS cohort over time. 33 We demonstrated that 30.4% of patients did no longer fulfill the Rome III criteria after a five-year follow-up period. The most salient finding is that quality of life did not improve significantly in patients who showed a decrease in gastrointestinal symptom severity ( i.e. being Rome III-negative at follow-up), compared to patients who had unaltered symptom severity over time (Rome III-positive). In addition, general wellbeing in terms of comorbid general anxiety and depression, work absenteeism and productivity, and life satisfaction were also comparable in those who still fulfilled the Rome III criteria at follow-up, when compared to those who did not. Several studies have investigated IBS symptom evolution in relation to diagnostic criteria in patient cohorts, with varying results. A study by Williams et al. using the Rome II criteria reported that 52% had no IBS two years after web-based diagnosis 12 , Ford et al . found that 28% did not meet the Manning criteria after 10 years 34 , Mearin et al . reported that abdominal pain frequency decreased in 26% after one year 35 , and more recently, Card et al . reported that 27% of their large study population did not fulfill the Rome III criteria after one year. 36 Except for the study by Williams et al ., the proportion of