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Objectives: The objective of this paper was to evaluate correlations between kidney biopsy indexes (activity and chronicity) and urinary sediment findings; the secondary objective was to find which components of urinary sediment can discriminate proliferative from other classes of lupus nephritis. Methods: Lupus nephritis patients scheduled for a kidney biopsy were included in our study. The morning before the kidney biopsy, we took urine samples from each patient. Receiver operating characteristic (ROC) curves were plotted to determine the area under the curve (AUC) of each test for detecting proliferative lupus nephritis; a classification tree was calculated to select a set of values that best-predicted lupus nephritis classes. Results: We included 51 patients, 36 of whom were women (70.6%). Correlations of lupus nephritis activity index with the counts in the urinary sediment of erythrocytes (isomorphic and dysmorphic), acanthocytes, and leukocytes were 0.65 (p<0.0001) 0.62 (p<0.0001) and 0.22 (p=0.1228), respectively. Correlations of lupus nephritis chronicity index with the counts of erythrocytes, acanthocytes, and leukocytes were 0.60 (p≤0.0001), 0.52 (p=0.0001) and 0.17 (p=0.2300), respectively. Our classification tree had an accuracy of 84.3%. Conclusions: Evaluation of urine sediment reflects lupus nephritis histology. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article on the use of rituximab fro treating systemic lupus erythematosus by M. Ramos-Casals and colleague in the 2009 issue.

Introduction: Systemic lupus erythematosus (SLE) is an autoimmune disease that often requires hospitalization. Most hospitalizations are due to infections and/or disease activity, for which several risk factors have been described in non-Mestizo patients., Objective: To identify risk factors for hospitalization in patients with systemic lupus erythematosus (SLE)., Methods: This was an observational case-control study of patients with SLE in San Luis Potosí, Mexico, evaluated from January 2019 to October 2020. We compared hospitalized lupus patients with non-hospitalized lupus patients. We used descriptive statistics and logistic regression to describe potential risk factors., Results: Of a total of 202 patients, 89 (45.1%) were hospitalized; these patients were younger, had shorter disease duration, higher disease activity scores (systemic lupus erythematosus disease activity index-SLEDAI), and more accumulated damage than non-hospitalized patients. The primary reasons for hospitalization were disease activity (60.7%), kidney disease, infection, and drug toxicity (5.6%). Multivariate analysis revealed several risk factors associated with hospitalization, including elevated creatinine, C-reactive protein, neutrophil levels, and constitutional symptoms, while prolonged international normalized ratio (INR), longer stay in the intensive care unit (ICU), and vasopressor use were associated with mortality. The use of antimalarials was a protective factor against hospitalization. Survival analysis revealed that patients with hospital-acquired infections had a lower probability of survival., Conclusions: Disease activity was the most common reason for hospitalization; kidney, constitutional, and hematological factors were associated with hospitalization; and the use of antimalarial was a protective factor for hospitalization., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: Hospitalizations due to systemic lupus erythematosus (SLE) incur substantial resource use. Hospitalization trends provide a key benchmark of the disease burden. However, there is little long-term data in Mexico. Therefore, we evaluated Mexican hospitalization trends for SLE during 2000-2019., Methods: Hospitalization trends of SLE were studied using data from 2000 to 2019 releases of the National Dynamic Cubes of the General Direction of Health Information, which provides data on hospitalization discharges in Mexico. Patients aged ≥15 years hospitalized during the study period with a principal discharge diagnosis of SLE (ICD-10 code M32) were included., Results: From 2000 to 2019, there were 17,081 hospitalizations for SLE, of which 87.6% were in females and 87% in subjects aged 15-44 years. From 2000 to 2019, the age-standardized hospitalization rate for patients with SLE increased from 0.38 per 100,000 persons to 0.65 per 100,000 persons with an average annual percentage change (APC) of 2.9% (95% CI 6.2-63.2). Although there was a significant uptrend from 2000 through 2011, there was a significant decline from 2011 to 2019 (APC: -4.8%, 95% CI -7.0% to -2.5%). Similar trends were identified in subjects aged 15-44 years and in both sexes. The length of stay and inpatient mortality decreased between 2000-2009 and 2010-2019., Conclusions: Although there was a substantial increase in SLE hospitalizations in 2000-2019, in 2011-2019, a decreased trend was reported in younger patients and in females and males. The length of stay was also reduced.

Introduction: Lupus nephritis requires antinuclear antibodies as classification criteria. There is a group of patients with nephrotic syndrome and conclusive histopathological findings for lupus nephritis, without classification criteria for systemic lupus erythematosus (SLE) or extrarenal manifestations. These groups of patients have been described as "lupus-like" nephritis or "renal-limited lupus nephritis"., Methods: Renal biopsy with histopathological evaluation with "full-house" immune-reactants in patients with negative antinuclear antibodies., Results: We report four cases with nephrotic syndrome and one with hematuria-proteinuria syndrome: two with impaired glomerular filtration rate and three with preserved renal function; urinary sediment with hematuria without dysmorphia and without extrarenal manifestations for autoimmune disease, negative antinuclear antibodies (ANA) and anti-double stranded DNA (anti-dsDNA); normal C3 and C4 complement levels. Renal biopsy in all cases was consistent for lupus nephritis class V. All patients received treatment as lupus nephritis protocol; only one case received induction with cyclophosphamide and methylprednisolone boluses, the rest received mycophenolic acid and prednisone as induction and maintenance. Two of the cases induced with mycophenolic acid relapsed, requiring cyclophosphamide for 6 months, achieving complete remission. All patients received renin-angiotensin-aldosterone system blockade and hydroxychloroquine. At follow-up, 4 cases still have negative antibodies and are without extrarenal manifestations for SLE classification criteria. The other case, during pregnancy several years after initial diagnosis, had preeclampsia with nephrotic proteinuria and a new determination of positive ANA and anti-dsDNA antibodies, complement levels below normal limits., Conclusion: The follow-up of patients with membranous glomerulopathy must be close; lupus like nephritis may be the first manifestation of the disease.

Introduction: After more than 20 years of sustained work, the Latin American Group for the Study of Lupus (GLADEL) has made a significant number of contributions to the field of lupus, not only in the differential role that race/ethnicity plays in its course and outcome but also in several other studies including the beneficial effects of using antimalarials in lupus patients and the development of consensus guidelines for the treatment of lupus in our region. Methods: A new generation of "Lupus Investigators" in more than 40 centers throughout Latin America has been constituted in order to continue the legacy of the investigators of the original cohort and to launch a novel study of serum and urinary biomarkers in patients with systemic lupus erythematosus. Results: So far, we have recruited 807 patients and 631 controls from 42 Latin-American centers including 339 patients with SLE without renal involvement, 202 patients with SLE with prevalent but inactive renal disease, 176 patients with prevalent and active renal disease and 90 patients with incident lupus nephritis. Conclusions: The different methodological aspects of the GLADEL 2.0 cohort are discussed in this manuscript, including the challenges and difficulties of conducting such an ambitious project.

Background: Mycophenolic acid (MPA) is an effective oral immunosuppressive drug used to treat lupus nephritis (LN), which exhibits large pharmacokinetic variability. This study aimed to characterize MPA pharmacokinetic behaviour in Mexican LN patients and to develop a population pharmacokinetic model which identified factors that influence MPA pharmacokinetic variability., Methods: Blood samples from LN patients treated with mycophenolate mofetil (MMF) were collected pre dose and up to six hours post dose. MPA concentrations were determined by a validated ultra-performance liquid chromatography tandem mass spectrometry technique. Patients were genotyped for polymorphisms in enzymes (UGT1A8, 1A9 and 2B7) and transporters (ABCC2 and SLCO1B3). The anthropometric, clinical, genetic and co-medication characteristics of each patient were considered as potential covariates to explain the variability., Results: A total of 294 MPA concentrations from 40 LN patients were included in the development of the model. The data were analysed using NONMEM software and were best described by a two-compartment linear model. MPA CL, Vc, Vp, Ka and Q were 15.4 L/h, 22.86 L, 768 L, 1.28 h -1 and 20.3 L/h, respectively. Creatinine clearance and prednisone co-administration proved to have influence on clearance, while body weight influenced Vc. The model was internally validated, proving to be stable. MMF dosing guidelines were obtained through stochastic simulations performed with the final model., Conclusions: This is the first MPA population pharmacokinetic model to have found that co-administration of prednisone results in a considerable increase on clearance. Therefore, this and the other covariates should be taken into account when prescribing MMF in order to optimize the immunosuppressant therapy in patients with LN.