Objective: To estimate numbers affected by a recent change in UK guidelines for statin use in primary prevention of cardiovascular disease. Method: We modelled cholesterol ratio over time using a sample of 45,151 men (≥ 40 years) and 36,168 women (≥ 55 years) in 2006, without statin treatment or previous cardiovascular disease, from the Clinical Practice Research Datalink. Using simulation methods, we estimated numbers indicated for new statin treatment, if cholesterol was measured annually and used in the QRISK2 CVD risk calculator, using the previous 20% and newly recommended 10% thresholds. Results: We estimate that 58% of men and 55% of women would be indicated for treatment by five years and 71% of men and 73% of women by ten years using the 20% threshold. Using the proposed threshold of 10%, 84% of men and 90% of women would be indicated for treatment by 5. years and 92% of men and 98% of women by ten years. Conclusion: The proposed change of risk threshold from 20% to 10% would result in the substantial majority of those recommended for cholesterol testing being indicated for statin treatment. Implications depend on the value of statins in those at low to medium risk, and whether there are harms.