Objectives To estimate the long-term true change variation (‘signal’) and short-term within-person variation (‘noise’) of the different lipid measures and evaluate the best measure and the optimal interval for lipid re-screening.
Design Retrospective cohort study from 2005 to 2008.
Setting A medical health check-up programme at a centre for preventive medicine in a teaching hospital in Tokyo, Japan.
Participants 15 810 apparently healthy Japanese adults not taking cholesterol-lowering drugs at baseline, with a mean body mass index of 22.5 kg/m2 (SD 3.2).
Main outcome measures Annual measurement of the serum total cholesterol (TC), low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and calculation of the ratio of TC/HDL and LDL/HDL. Measurement of the ratio of long-term true change variation (‘signal’) to the short-term within-person variation (‘noise’) for each measure.
Results At baseline, participants (53% male) with a mean age of 49 years (range 21–92) and a mean TC level of 5.3 mmol/l (SD 0.9 mmol/l) had annual check-ups over 4 years. Short-term within-person variations of TC, LDL, HDL, TC/HDL, and LDL/HDL were 0.12 (coefficient of variation (CV) 6.4%), 0.08 (CV 9.4%), 0.02 (CV 8.0%) mmol2/l2, 0.08 (CV 7.9%) and 0.05 (CV 10.6%), respectively. The ratio of signal-to-noise at 3 years was largest for TC/HDL (1.6), followed by LDL/HDL (1.5), LDL (0.99), TC (0.8) and HDL (0.7), suggesting that cholesterol ratios are more sensitive re-screening measures.
Conclusion The signal-to-noise ratios of standard single lipid measures (TC, LDL and HDL) are weak over 3 years and decisions based on these measures are potentially misleading. The ratios, TC/HDL and LDL/HDL, seem to be better measures for monitoring assessments. The lipid re-screening interval should be >3 years for those not taking cholesterol-lowering drugs.
- mass screening
- primary prevention
- cardiovascular diseases
- diagnostic tests
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Linked article 177394.
Competing interests None.
Ethics approval This study was conducted with the approval of the St Luke's International Hospital ethical committee Institutional Review Board.
Provenance and peer review Not commissioned; not externally peer reviewed.