Interpretación de las pruebas de laboratorio habituales en las enfermedades reumatológicas inflamatorias

EMC - Tratado de Medicina 01/2006; 10(1):1–9. DOI: 10.1016/S1636-5410(06)70375-0

ABSTRACT Resulta difícil identificar la causa de las poliartritis en fase inicial, y no existe un acuerdo sobre las pruebas de laboratorio o radiológicas que se deben realizar en estos casos. Al revisar la literatura reciente, se ha podido comprobar que los artículos relativos a este tema, con cohortes de reumatismos en fase inicial, son menos de 30, y tratan sobre todo los factores reumatoideos, los anticuerpos anticitrulina y la tipificación del antígeno HLA. Una encuesta de opinión demuestra que, aunque existen grandes variaciones, las pruebas de laboratorio que se prescriben en las fases iniciales de los reumatismos inflamatorios son limitadas (NFS, VSG, CRP, fibrina, creatinina, ASAT, ALAT, proteinuria, hierro, CPK, serología de hepatitis B, de hepatitis C y de Lyme, TCA, anticuerpos antinucleares, factores reumatoideos, anticuerpos antiqueratina o anti-CCP y HLA B27). Una vez establecido el diagnóstico, el laboratorio sigue siendo esencial para la detección de afecciones viscerales y para el seguimiento de la inflamación.

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    ABSTRACT: To investigate whether the determination of serum procalcitonin (PCT) in systemic autoimmune disease will help to discriminate invasive infection from highly active underlying disease. Three hundred ninety-seven serum samples, from 18 patients with systemic lupus erythematosus (SLE) and 35 patients with systemic antineutrophil cytoplasmic antibody-associated vasculitis (AAV), were analyzed. Clinical disease activity was assessed by the Systemic Lupus Activity Measure in SLE patients and by the Birmingham Vasculitis Activity Score in AAV patients. Procalcitonin concentrations were determined in parallel with concentrations of neopterin, interleukin-6 (IL-6), and C-reactive protein (CRP). Additionally, serum creatinine values were obtained. In 321 of the 324 samples from the 42 patients with autoimmune disease but without systemic infection, serum PCT levels were within the normal range (i.e., <0.5 ng/ml), whereas the values for neopterin, IL-6, and CRP were elevated in patients with active underlying disease. All 16 systemic infections occurred in 11 patients with AAV, and were associated with PCT levels that were markedly elevated, to a mean +/- SD of 1.93 +/- 1.19 ng/ml. No correlation between the degree of renal impairment and PCT concentrations was seen. PCT may serve as a useful marker for the detection of systemic bacterial infection in patients with systemic autoimmune disease.
    Arthritis & Rheumatology 07/1997; 40(7):1250-6. DOI:10.1002/1529-0131(199707)40:7<1250::AID-ART9>3.0.CO;2-A · 7.87 Impact Factor
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    ABSTRACT: Trials of rheumatoid arthritis (RA) treatments report the average response in multiple outcome measures for treated patients. It is more clinically relevant to test whether individual patients improve with treatment, and this identifies a single primary efficacy measure. Multiple definitions of improvement are currently in use in different trials. The goal of this study was to promulgate a single definition for use in RA trials. Using the American College of Rheumatology (ACR) core set of outcome measures for RA trials, we tested 40 different definitions of improvement, using a 3-step process. First, we performed a survey of rheumatologists, using actual patient cases from trials, to evaluate which definitions corresponded best to rheumatologists' impressions of improvement, eliminating most candidate definitions of improvement. Second, we tested 20 remaining definitions to determine which maximally discriminated effective treatment from placebo treatment and also minimized placebo response rates. With 8 candidate definitions of improvement remaining, we tested to see which were easiest to use and were best in accord with rheumatologists' impressions of improvement. The following definition of improvement was selected: 20% improvement in tender and swollen joint counts and 20% improvement in 3 of the 5 remaining ACR core set measures: patient and physician global assessments, pain, disability, and an acute-phase reactant. Additional validation of this definition was carried out in a comparative trial, and the results suggest that the definition is statistically powerful and does not identify a large percentage of placebo-treated patients as being improved. We present a definition of improvement which we hope will be used widely in RA trials.
    Arthritis & Rheumatology 07/1995; 38(6):727-35. · 7.87 Impact Factor
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    ABSTRACT: Six systems for defining and evaluating disease activity in patients with systemic lupus erythematosus (SLE) (the Ropes system, the National Institutes of Health [NIH] system, the New York Hospital for Special Surgery system, the British Isles Lupus Assessment Group [BILAG] scale, the University of Toronto SLE Disease Activity Index [SLE-DAI], and the Systemic Lupus Activity Measure [SLAM]) were tested on 25 SLE patients who were selected to represent a range of disease activity. The patients were evaluated independently by 2 physicians on 2 occasions approximately 1 month apart. Differences between patients demonstrated the largest source of variation in scores, accounting for 56–84% of the total variance, depending on the instrument. Differences between physicians (i.e., error) showed the next largest variation, 11–28% of the total variance, and differences between visits made up 5–16% of the total. The BILAG, SLE-DAI, and SLAM had the best inter-visit and inter-rater reliability. Convergent validity was shown by the strong correlations of scores among the different instruments (r = 0.81–0.97). All instruments correlated highly with the physicians' clinical impression of disease but less well with their evaluation of disease severity. The number of American Rheumatism Association criteria for SLE that were met by the patients correlated poorly with the physicians' global evaluation and with the scores of the instruments. The patients' self-reported disease activity scores correlated highly with the physicians' assessments of disease activity (r = 0.85–0.91), and the mean values from self-reports and from physicians' assessments were nearly equal. In contrast, severity scores correlated less well between self-reports and physician assessments (r = 0.49–0.69), and mean self-reported severity values were lower than the means from physicians. The BILAG, SLE-DAI, and SLAM systems appear to have better psychometric properties than the others for clinical research.
    Arthritis & Rheumatology 09/1989; 32(9):1107 - 1118. DOI:10.1002/anr.1780320909 · 7.87 Impact Factor