Statistical elements in clinical research

¶ … population?

The study in question was a multinational PROBE classification trial (i.e., Prospective Randomized Open Blinded End-point) that covered multiple private specialist and ambulatory cardiology centers (190, to be precise). It represented a comprehensive report centered on baseline elements of those patients potentially requiring screening. The study population constituted males and females aged below 80 years with confirmed heart attack (myocardial infarction; MI) history, and eligible for statin medication (Pedersen et al., 2005).

What is the study sample?

Sample comprised patients who have suffered one or more heart attacks, and for whom intensive reduction in LDL-C (low-density lipoprotein cholesterol) levels did not appreciably decrease primary outcome of serious coronary incidents, but decreased risks of non-fatal acute myocardial infarction and other combined secondary end points. No difference was found in all-cause or cardiovascular mortality cases. MI patients might gain from intensive LDL-C lowering without a rise in risk of non-cardiovascular mortality, and other acute adverse results. In such cases, comparison of low and high atorvastatin dosages in non-acute stable coronary heart disease demonstrated a considerable improvement in cardiovascular disease prognosis. Also, in such cases, higher mortality from non-cardiovascular causes seemed to offset benefits of decreased cardiovascular mortality (Pedersen et al., 2005; Perk, 2007).

3. Identify the categorical variables that were measured. Which are ordinal and which are nominal? Which are independent and which are dependent?

Identified statin contraindications, history of statin intolerance (in high as well as low quantities), levels of liver enzyme more than double the normal upper limit, breastfeeding or pregnancy, uncontrolled diabetes, nephrotic syndrome, uncontrolled hypothyroidism, heart failure (classification IIIB/IV of New York Heart Association), levels of plasma triglyceride >6.8 millimoles/liter (or 600 milligrams/deciliter), hemo-dynamically significant valvular heart issues, medications that severely impact statin's pharmacokinetics, therapy using lipid-reducing medication, and gastrointestinal conditions impacting drug absorption are key exclusion criteria. Ordinal patients were those prescribed 20 milligrams/day of simvastatin, or any other statin of equivalent amounts during randomization by which lipoprotein and lipid level changes for the overall group were small. Categorical or nominal patients belonged to the group prescribed 80 milligrams/day of atorvastatin. Mean LDL-C decrease in statin-naive study participants was 49%. Simvastatin therapy was estimated to bring about a meanLDL-C reduction of 35% from untreated LDL-C levels -- these are dependent. On the other hand, independent variable was atorvastatin-induced reduction (per day consumption=80 mg) would be a minimum of 55%, generating around 1 millimole/liter (40 milligram/deciliter) plasma level difference (Pedersen et al., 2005).

4. Identify the numerical variables that were measured. Which are discrete and which are continuous? Which are independent and which are dependent?

Patients aged below 80 years with acute heart attack history constituted the measured numerical variables. Discrete variables occurred among 8.4% (or 374) belonging to the simvastatin cluster and 8.2% (or 366) belonging to the atorvastatin cluster (HR, 0.98; 95% CI, 0.85-1.13; P = .81). Continuous variables in the latter cluster showed higher medication discontinuation rates because of non-serious adverse effects; 1.0% (43) showed transaminase elevation while withdrawals constituted 0.1% (5) (P

5. What is the efficacy measurement?

This marked primary endpoint of cardiac arrest, coronary death, or acute MI.10.4% (i.e. 463 patients belonging to the simvastatin cluster, and 9.3% (i.e. 411 patients) belonging to the atorvastatin cluster, revived; this indicates 11% relative risk decrease with 80 mg a day of atorvastatin (HR, 0.89; 95% CI, 0.78-1.01; P = .07) (Pedersen et al., 2005).