Conditional Covariance-Based Subtest Selection for Polytomous DIMTEST.

Dimensionality assessment is an important component of test validation. While the vast majority of statewide standardized tests contain both dichotomous and polytomous items, much of the work in dimensionality assessment has focused on the case of dichotomous item exams. Poly-NEWDIM is a polytomous version of DIMTEST that is a nonparametric hypothesis testing procedure for dimensionality assessments based on comparison of an assessment subtest (AT) with a partitioning subtest (PT). A good AT and PT selection is vital to the performance of Poly-NEWDIM. The proposed two new AT-selection procedures, HCA/CCPROX-PolyDIMTEST (HCP) and HCA/CCPROX-PolyNEWDIM (HCN), perform better than the previous AT-selection method (HCD) in terms of power. Moreover, HCN shows less sensitivity than HCP to sample size, correlation, and structural complexity. The results also indicate that 70% of data for AT selection is appropriate for all three kinds of tests (dichotomous only, polytomous only, and mixed) with large sample sizes and dichotomous tests with small sample sizes, while 50% is good for polytomous tests and mixed tests with small sample sizes.

A study on the outcome of percutaneous transluminal renal angioplasty in patients with renal failure.

BACKGROUND: The indications for percutaneous transluminal renal angioplasty (PTRA) in renovascular disease, as well as its benefits, remain a matter of debate. The aim of this study was to evaluate the outcome of angioplasty and to identify risk factors associated with less successful outcomes in patients with atheromatous renal artery stenosis and renal failure of varying degrees. METHODS: The results of PTRA were analyzed retrospectively in 144 patients with serum creatinine levels of >130 micromol/l. Patients were divided into 5 groups according to their indication for angioplasty: (1) deteriorating renal function; (2) accelerating hypertension; (3) a combination of 1 and 2; (4) peripheral vascular disease, and (5) miscellaneous conditions. RESULTS: The baseline mean (+/- SD) systolic and diastolic blood pressures of the entire group were lowered from 180 +/- 32 and 95 +/- 16 mm Hg to 162 +/- 23 and 86 +/- 12 mm Hg, respectively (p < 0.0005), 12 months after angioplasty. The blood pressure level was unaffected by angioplasty in patients with claudication. The mean number of antihypertensive drugs was reduced in the group with accelerating hypertension from 2.9 +/- 0.8 to 2.4 +/- 1.2 (p = 0.019), and in the group with unilateral renal artery stenosis and two kidneys from 2.4 +/- 1.0 to 1.8 +/- 1.1 (p = 0.002), 12 months after PTRA. Glomerular filtration rate at 3-month follow-up had increased from 23 +/- 11 to 27 +/- 14 ml/min/1.73 m(2) (p = 0.021) in group 1, from 25 +/- 11 to 28 +/- 14 ml/min/1.73 m(2) (p = 0.031) in the combined group of patients consisting of groups 1 and 3, and from 32 +/- 13 to 35 +/- 14 ml/min/1.73 m(2) (p = 0.019) in the group with unilateral renal artery stenosis. No statistically significant difference was found in any of these 3 groups 1 year after angioplasty. The first patient group had an increased prevalence of cardiovascular disease, aortic aneurysm, carotid occlusive disease, and peripheral vascular disease compared to the other patient groups (p < 0.05). Patients with baseline creatinine levels of >300 micromol/l had a lower survival rate at 12, 60, and 120 months after PTRA than patients with serum creatinine levels of <300 micromol/l (p < 0.005). Survival was also lower in patients with bilateral renal artery stenosis and those with a single kidney, compared to patients with a unilateral stenosis at both 5 and 10 years after PTRA (p < 0.05). Regression analysis of predictor variables of mortality rate showed that the relative risk (RR) associated with increased serum creatinine was 4.7 (CI 2.0-11.0; p < 0.0005). The RR for older patients was 1.1 (CI 1.0-1.2; p = 0.008), and the RR for former smokers was 6.0 (CI 1.6-24.0; p = 0.009). CONCLUSION: The results of the present study indicate that glomerular filtration can be improved in patients who primarily undergo angioplasty to rescue renal function. Renal function with creatinine levels of >300 micromol/l was associated with a lower survival rate. It is, therefore, possible that patients selected after a thorough evaluation of their renal function and comorbid disease factors may benefit from PTRA, even when the indication for angioplasty is to salvage renal function.

Apolipoprotein E polymorphism in 385 patients on renal replacement therapy in Sweden.

OBJECTIVE: To examine apolipoprotein (apo) E polymorphism and its possible link to kidney disease in all patients receiving renal replacement therapy in our region. MATERIAL AND METHODS: The apo E genotype, plasma (P) lipids, blood pressure and albumin excretion rate were determined retrospectively in 385 patients. RESULTS: No differences in apo E genotype or the allelic frequencies of epsilon2, epsilon3 or epsilon4 were found between the patient group and a control group of 343 healthy individuals. The apo E3/E4 genotype, however, was found in only 1/24 patients with non-insulin-dependent diabetes mellitus (NIDDM), a significantly lower frequency than that seen in the rest of the patient group (p = 0.041). Similarly, the apo E4/E4 genotype was absent in patients with glomerulonephritis (GN) (p = 0.027). The relative frequency of the epsilon4 allele in patients with GN (0.116) was significantly lower than that in the rest of the patients (0.193; p < 0.05) and that in the control group (0.186; p = 0.027). Furthermore, 19/47 patients (40.4%) with autosomal dominant polycystic kidney disease (ADPKD) had the E3/E4 genotype, as compared to 77/338 (22.8%) in the rest of the patient group (p = 0.035; odds ratio 2.07; CI 1.09-3.92). An increase in the relative frequency of the epsilon4 allele was seen in the same diagnostic group: 0.29 vs 0.16 in the rest of the patient group (p = 0.0023). The mean P-cholesterol level in patients with the epsilon4 allele was 5.9 +/- 1.0 mmol/l, compared to 5.0 +/- 1.1 mmol/l in patients without the epsilon4 allele (p = 0.026). CONCLUSIONS: In this study, variations in the frequencies of the apo epsilon4 allele and the apo E3/E4 and E4/E4 genotypes were found in patients with NIDDM, GN and ADPKD. This result may be a consequence of the effects of the apo epsilon4 and epsilon2 alleles on P-cholesterol and remnant lipoprotein levels. The decreased frequency of apo E3/E4 found in patients with NIDDM may be explained by the fact that the epsilon4 allele gives renoprotection against diabetic nephropathy by lowering plasma remnant lipoprotein levels. Conversely, there may be an association between the apo E3/E4 genotype and the epsilon4 allele in patients with ADPKD, due to the effect of the epsilon4 allele in elevating P-cholesterol levels. The most plausible explanation for the absence of the apo E4/E4 genotype and the lower prevalence of the epsilon4 allele in patients with GN, which is known to result in a higher P-cholesterol compared to the epsilon2 and epsilon3 alleles, ought to be an increase in cardiovascular morbidity, which is known to be associated with a higher P-cholesterol level.