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In this paper we propose a calculation of LDL-cholesterol (LDL-C) not affected by hypertriglyceridemia by using lipid quantities directly measured in total serum. We also propose an algorithm for the classification of nonchylomicronemic dyslipemias. Plasma apolipoproteins (apo) A-I, B, total cholesterol (TC), triglycerides (TG), and cholesterol of lipoproteins were measured in a group of 38 normolipemic and 120 dyslipemic patients (42 phenotype IIa, 38 IIb, and 40 IV) classified according to TG and LDL-C values. Discriminant analysis was applied to obtain the best classification with the lowest number of quantities directly measured from total serum (TC, TG, and apo B), and multiple regression analysis was performed to find an equation to calculate LDL-C from these quantities. Apo B seems to be a useful discriminator between normolipemic and phenotype IIa patients, by using a cutoff value of 1.35 g/L obtained by ROC curve analysis. The proposed algorithm, based on lipid quantities measured by easily automated methods, is shown to be a good alternative for the classification of nonhyperchylomicronemic dyslipemia. LDL-C calculated from TC, TG, and apo B proved a better estimate of true LDL-C than the estimate obtained with Friedewald’s formula.

Serum beta 2-microglobulin, neopterin, immunoglobulins A, G and M, adenosine deaminase and CD4+ lymphocyte count were evaluated as predictors of progression of HIV-1 infection to AIDS. A population of HIV-1 seropositive, initially asymptomatic men (n = 213) and women (n = 101) was followed up quarterly. We estimated the AIDS-free time using the actuarial method (median survival time 47.2 months). Cox proportional hazard analysis revealed that all markers studied were significant (p < 0.05) in relation to progression to AIDS. The best markers for predicting progression to AIDS were, in descending order, CD4+ lymphocyte count, beta 2-microglobulin, IgA, neopterin, IgG, IgM and adenosine deaminase. On stratifying population into four groups (divided at percentiles 25, 50 and 75--from group 1, with values nearest to reference ranges, to group 4, with most abnormal values) we observed statistically significant differences (p < 0.05) for all markers except for adenosine deaminase. The relative risk from the Cox proportional hazards model were used to quantify the effects of the best markers and compared to the risk obtained in group 1. CD4+ lymphocyte count was the best predictor of progression to AIDS. When considering beta 2-microglobulin and CD4+ together, the relative risk in the group with lowest CD4+ cell count (group 4) ranged from 25.6% (with lower beta 2-microglobulin values) to 41.1% (with higher beta 2-microglobulin values). Similar results were obtained when considering neopterin and CD4+ together. The addition of beta 2-microglobulin or neopterin values to CD4+ lymphocyte count improved the predictive value of CD4+ lymphocyte count.

Reference change values of six biochemical quantities (beta 2-microglobulin, neopterin, adenosine deaminase and immunoglobulins IgA, IgG and IgM) have been established in asymptomatic human immunodeficiency virus (HIV)-infected patients following the method described by Harris and Yasaka in 1983. Patients included in the evaluation were classified as A1, A2 or A3 according to the classification of the Centers for Disease Control (CDC) (January 1993). All patients were followed-up quarterly, with a minimum of four samples each available for statistical analysis. The main objective of this paper was to study whether differences found to be greater than calculated reference change values could predict clinical or immunological worsening in patients' status. Retrospective analysis was made in asymptomatic patients (n = 256) included in an HIV infection protocol carried out in our hospital. Of these patients, 179 showed clinical or immunological worsening during the study period and 77 maintained their clinical and immunological status. Changes in beta 2-microglobulin showed the greatest sensitivity to detect clinical or immunological worsening (43.0%), whereas changes in adenosine deaminase showed the lowest (21.8%). Clinical or immunological worsening in 169 of the 179 patients was detected by one of the six biochemical quantities evaluated. Ten patients showed clinical or immunological worsening, although differences between measurements were lower than the reference change values calculated. Of 77 patients whose clinical state did not deteriorate, there was a change in biochemical analytes greater than the reference value calculated in 29 patients (a period of 12 months had elapsed since detection). In 48 patients, no increases greater than calculated reference change values were detected. The sensitivity obtained using the six analytes was 94.4% and the specificity was 62.3%.

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