Cholesterol level monitoring is a common clinical activity, but the optimal monitoring interval is unknown and practice varies.
To estimate, in patients receiving cholesterol-lowering medication, the variation in initial response to treatment, the long-term drift from initial response, and the detectability of long-term changes in on-treatment cholesterol level ("signal") given short-term, within-person variation ("noise").
Analysis of cholesterol measurement data in the LIPID (Long-Term Intervention with Pravastatin in Ischaemic Disease) study.
Randomized, placebo-controlled trial in Australia and New Zealand (June 1990 to May 1997).
9014 patients with past coronary heart disease who were randomly assigned to receive pravastatin or placebo.
Serial cholesterol concentrations at randomization, 6 months, and 12 months, and then annually to 5 years.
Both the placebo and pravastatin groups showed small increases in within-person variability over time. The estimated within-person SD increased from 0.40 mmol/L (15 mg/dL) (coefficient of variation, 7%) to 0.60 mmol/L (23 mg/dL) (coefficient of variation, 11%), but it took almost 4 years for the long-term variation to exceed the short-term variation. This slow increase in variation and the modest increase in mean cholesterol level, about 2% per year, suggest that most of the variation in the study is due to short-term biological and analytic variability. Our calculations suggest that, for patients with levels that are 0.5 mmol/L or more (> or =19 mg/dL) under target, monitoring is likely to detect many more false-positive results than true-positive results for at least the first 3 years after treatment has commenced.
Patients may respond differently to agents other than pravastatin. Future values for nonadherent patients were imputed.
The signal-noise ratio in cholesterol level monitoring is weak. The signal of a small increase in cholesterol level is difficult to detect against the background of a short-term variability of 7%. In annual rechecks in adherent patients, many apparent increases in cholesterol level may be false positive. Independent of the office visit schedule, the interval for monitoring patients who are receiving stable cholesterol-lowering treatment could be lengthened.
"As we reviewed the claims data, new claims involved not only early detection of CVD-related health conditions but also early interventions to deal with the CVD-related health conditions. These associations were not evident in our secondary analysis , however, possibly because a two-year screening interval might be too short to detect additional new cases of CVD-related health conditions (Glasziou et al., 2008; Mancia et al., 2007; Takahashi et al., 2012; Williams et al., 2004). We also found that screening participation was associated with lower inpatient use and cost and with lower outpatient cost. "
"Preventive maintenance is routine for any complex mechanical device and is increasingly acceptable to healthy people. In most European countries, general medical checkups are encouraged to ensure blood pressure control, and blood tests are used to guide the use of lipid-lowering drugs . Highly successful screening methods are used for specific cancers, as discussed above. "
[Show abstract][Hide abstract] ABSTRACT: Diagnosis of cancer at an early stage leads to improved survival. However, most current blood tests detect single biomarkers that are of limited suitability for screening, and existing screening programmes look only for cancers of one particular type. A new approach is needed. Recent developments suggest the possibility of blood-based screening for multiple tumour types. It may be feasible to develop a high-sensitivity general screen for cancer using multiple proteins and nucleic acids present in the blood of cancer patients, based on the biological characteristics of cancer. Positive samples in the general screen would be submitted automatically for secondary screening using tests to help define the likelihood of cancer and provide some indication of its type. Only those at high risk would be referred for further clinical assessment to permit early treatment and mitigate potential overdiagnosis. While the assays required for each step exist, they have not been used in this way. Recent experience of screening for breast, cervical and ovarian cancers suggest that there is likely to be widespread acceptance of such a strategy.
BMC Cancer 11/2011; 11(1):499. DOI:10.1186/1471-2407-11-499 · 3.36 Impact Factor
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