Background: Successive European guideline updates have modified the estimation and categorisation of cardiovascular risk. The transition from the Belgian SCORE calibration to SCORE2 in 2021, followed by revision of SCORE2 thresholds in 2025, may substantially alter clinical interpretation without changes in individual patient characteristics.Methods: Adults aged 40-69 years in primary prevention were retrospectively included from two Belgian centres. Both cohorts were pooled into a single analytical population. Cardiovascular risk was assessed using the HDL-corrected SCORE-Belgium model (2019), SCORE2 (2021), and the updated SCORE2 thresholds (2025), applied to identical baseline data. Low and moderate categories were harmonised. Reclassification was analysed descriptively.Results: Among 413 individuals, 84.3% were classified as low-moderate risk with SCORE-Belgium, 11.6% as high risk, and 4.1% as very high risk. With SCORE2 (2021), 58.8% were categorised as high risk and 7.3% as very high risk. Application of the 2025 thresholds reversed this distribution: 93.5% were classified as low-moderate risk, 6.5% as high risk, and none as very high risk. These variations affected largely the same individuals and occurred despite identical underlying risk estimates.Conclusion: Guideline updates markedly influence cardiovascular risk categorisation in primary prevention. The changes observed are predominantly attributable to the definitions of thresholds, rather than to differences in the underlying risk estimates. Risk categories should, therefore, be interpreted in the context of the specific assessment framework employed. In addition, supplementary methods for refining individual risk remain necessary.