Design, implementation, and preliminary in-vivo assessment of a high-CMRR low-NEF wireless EEG miniaturized platform.

This work presents the design, manufacture, test, and preliminary in-vivo assessment of the proof-of-concept of a miniaturized wireless platform for acquiring electroencephalography signals, where the input stage is a high-CMRR current-efficiency custom-made integrated neural preamplifier.Clinical relevance- Small, low-power consumption, wireless, wearable devices for chronically monitoring EEG recordings may contribute to the diagnosis of transient neurological events, the characterization and potential forecasting of epileptic seizures, and provide signals for controlling prosthetic and aid devices.

Vaccination trends in people with HIV infection participanting in the hospital-based survey of patients infected with HIV, 2006-2021.

OBJECTIVE: To assess the trend in hepatitis A, hepatitis B, pneumococcal, tetanus and seasonal influenza vaccination in people with HIV infection and to analyse associated factors. METHODS: The Hospital Survey of Patients with HIV, an annual cross-sectional study conducted on a fixed day (2006-2021), was used. Inpatients and outpatients were included. Trends in vaccination and associated factors were analysed using logistic regression. RESULTS: A total of 8643 participants were included. Vaccination rates increased to 65.3% for hepatitis A, 83.7% for hepatitis B, 49.3% for tetanus, 68.9% for pneumococcal and 74.5% for seasonal influenza in 2021. Factors positively associated with vaccination were older age for pneumococcal and influenza vaccination; higher educational level for hepatitis A and tetanus; living in a closed institutions or prison for tetanus, pneumococcal and influenza; and having acquired HIV through sex between men for hepatitis A, B and pneumococcal. In addition, being on antiretroviral treatment and having a high CD4 count were positively associated with vaccination for all these diseases. Factors inversely associated with vaccination were being older (hepatitis A, B and tetanus), being an immigrant (tetanus and seasonal influenza) and being an injection drug user/ex-user for hepatitis A and B. CONCLUSIONS: Vaccination in people with HIV has increased in the study period. The results are in line with the recommendations in this population, although there is still room to reach the established vaccination indicators.

Allogeneic Hematopoietic Stem Cell Transplantation in Transformed Follicular Lymphoma (tFL): Results of a Retrospective Multicenter Study from GELTAMO/GETH-TC Spanish Groups.

BACKGROUND: Transformation of follicular lymphoma into an aggressive lymphoma (tFL) worsens the prognosis and the standard treatment is not completely defined. Allogeneic hematopoietic stem cell transplantation (alloSCT) could be a potentially curative option for these patients, but it has not been widely explored. METHODS: We designed a retrospective multicenter study to analyze the efficacy and toxicity of alloSCT in tFL patients and potential prognostic factors of survival. RESULTS: A total of 43 patients diagnosed with tFL who underwent alloSCT in 14 Spanish centers between January 2000 and January 2019 were included. Median age was 44 (31-67) years. After a median follow-up of 58 months, estimated 5-year overall survival (OS) and progression-free survival (PFS) were both 35%. Estimated 100-day and 1-year non-relapse mortality (NRM) were 20% and 34%, respectively. The type of conditioning regimen (3-year OS of 52% vs. 20%, respectively, for reduced-intensity vs. myeloablative conditioning) and development of chronic graft versus host disease (cGVHD) (3-year OS of 75% vs. 40%) were the only factors significantly associated with OS. The only variable with an independent association with OS was cGVHD (HR, 3.4; 95% CI, 1.2-9.6). CONCLUSIONS: Our results indicate that alloSCT continues to be a potentially curative option for patients with tFL.

Allogeneic Stem Cell Transplantation in Mantle Cell Lymphoma; Insights into Its Potential Role in the Era of New Immunotherapeutic and Targeted Therapies: The GETH/GELTAMO Experience.

Allo-SCT is a curative option for selected patients with relapsed/refractory (R/R) MCL, but with significant NRM. We present the long-term results of patients receiving allo-SCT in Spain from March 1995 to February 2020. The primary endpoints were EFS, OS, and cumulative incidence (CI) of NRM, relapse, and GVHD. We included 135 patients, most (85%) receiving RIC. After a median follow-up of 68 months, 5-year EFS and OS were 47 and 50%, respectively. Overall and CR rates were 86 and 80%. The CI of relapse at 1 and 3 years were 7 and 12%. NRM at day 100 and 1 year were 17 and 32%. Previous ASCT and Grade 3-4 aGVHD were associated with a higher NRM. Grade 3-4 aGVHD, donor type (mismatch non-related), and the time-period 2006-2020 were independently related to worse EFS. Patients from 1995-2005 were younger, most from HLA-identical sibling donors, and were pretreated less. Our data confirmed that allo-SCT may be a curative option in R/R MCL with low a CI of relapse, although NRM is still high, being mainly secondary to aGVHD. The arrival of new, highly effective and low toxic immunotherapeutic or targeted therapies inevitably will relegate allo-SCT to those fit patients who fail these therapies, far away from the optimal timing of treatment.

Allogeneic Stem Cell Transplantation in Mature T Cell and Natural Killer/T Neoplasias: A Registry Study from Spanish GETH/GELTAMO Centers.

Despite advances in understanding the biology of mature T and natural killer (NK)/T cell neoplasia, current therapies, even the most innovative ones, are still far from ensuring its cure. The only treatment to date that has been shown to control aggressive T cell neoplasms in the long term is allogeneic stem cell transplantation (alloSCT). We aim to report the results of alloSCT for advanced mature T and NK/T neoplasias performed in centers from our national GELTAMO/GETH (Grupo Español de Linfoma y Trasplante de Médula Ósea/Grupo Español de Trasplante Hematopoyético y Terapia Celular) over the past 25 years. As a secondary objective, we analyzed the results of alloSCT from haploidentical donors. We performed a retrospective analysis of all patients who received an alloSCT in Spanish centers (n = 201) from September 1995 to August 2018. The 2-year overall survival (OS) and disease-free survival (DFS) were 65.5% and 58.2%, respectively. The univariate for OS and DFS showed statistically different hazard ratios for conditioning intensity, response pre-alloSCT, comorbidity index, donor/receptor cytomegalovirus status and Eastern Cooperative Oncology Group (ECOG) pre-alloSCT, but only a better ECOG pre-alloSCT remained significant in the multivariate analysis. There was an increased incidence of relapse in those patients who did not develop chronic graft-versus-host disease (GVHD) and an increased risk of death in those developing moderate to severe acute GVHD. The 1-year nonrelapse mortality was 21.9% and was mainly due to GVHD (30%) and bacterial infections (17%). When comparing unrelated donors with haploidentical donors, we found similar results in terms of OS and DFS. There was, however, a reduction of acute GVHD in the haploidentical group (P = .04) and trend to a reduction of chronic GVHD. In conclusion, alloSCT is the only curative option for most aggressive T cell neoplasias. Haploidentical donors offer similar results to related donors in terms of survival with a reduction of acute GVHD.

Self-rated health among people living with HIV in Spain in 2019: a cross-sectional study.

BACKGROUND: HIV infection has become a chronic disease and well-being of people living with HIV (PLHIV) is now of particular concern. The objectives of this paper were to describe self-rated health among PLHIV, on ART and on ART virally suppressed and to analyse its determinants. METHODS: Data were obtained from a second-generation surveillance system based on a cross-sectional one-day survey in public hospitals. Epidemiological and clinical data were collected among HIV-infected inpatients and outpatients receiving HIV-related care the day of the survey in 86 hospitals in 2019. Self-rated health was measured using a question included in the National Health Survey: "In the last 12 months, how would you rate your health status?" an ordinal variable with five categories (very good, good, moderate, bad and very bad). For the analysis, these responses were dichotomized into two categories: 1 = very good/good and 0 = moderate, bad or very bad health status. Factors associated with very good/good self-rated health were estimated using logistic regression. RESULTS: Of 800 PLHIV, 67.5% perceived their health as very good/good, 68.4% among PLHIV on ART and 71.7% of those virally suppressed. Having university education (adjusted odds ratio (aOR):2.1), being unemployed (aOR:0.3) or retired (aOR:0.2), ever being diagnosed of AIDS (aOR:0.6), comorbidities (aOR:0.3), less than 2 year since HIV diagnosis (aOR:0.3) and not receiving ART (aOR:0.3) were associated with good self-rated health. Moreover, among PLHIV on ART, viral load less than 200 copies (aOR:3.2) were related to better perceived health. Bad adherence was inversely associated with good self-rated health among PLHIV on ART (aOR:0.5) and of those virally suppressed (aOR:0.4). CONCLUSIONS: Nearly seven in 10 PLHIV in Spain considered their health status as very good/good, being higher among virally suppressed PLHIV. Both demographic and clinical determinants affect quality of life.

Assessment of Sclerodermoid Chronic Graft-versus-host Disease with Colour Doppler Ultrasound.

Sclerodermoid chronic graft-versus-host disease (scGVHD) is a severe complication of allogeneic haema-- topoietic stem cell transplantation. The aim of this study was to investigate the usefulness of high-frequency ultrasound of the skin in assessing the inflammatory patterns and prognosis of patients with scGVHD. A prospective study was carried out with patients who developed scGVHD in the period June 2016 to April 2018. Clinical and ultrasound examinations were performed on the first visit and at 6-month follow-up. A total of 24 patients were included in the study. A 6-month follow-up high-frequency ultrasound of the skin was performed on 20 of the 24 patients. Abnormal B-mode findings in high-frequency ultrasound of the skin consisted of hypoechogenic dermis, hypoechogenicity of septa and hyperechogenicity of lobules in hypodermis. No differences were observed in these basal parameters between treatment progressive/non-responding and inactive/responding scGVHD groups of patients. Basal Doppler showing increased vascular flow with a systolic peak ≥10 cm/s and a vascular resistance index ≥ 0.70 was observed only in those patients who developed progressive/non-responding scGVHD (62.5% vs 0% p = 0.006). In conclusion, Doppler ultrasound is a useful tool to assess the inflammatory activity and outcome of scGVHD. These findings could enhance patient management and help to guide treatment decisions.

Oral levetiracetam for prevention of busulfan-induced seizures in adult hematopoietic cell transplant.

Background Antiseizure prophylaxis is recommended when high-dose of busulfan is given as part of the conditioning regimens in the allogenic hematopoietic stem cell transplant. Phenytoin has been widely used but its pharmacokinetics and pharmacodynamics profile makes its use complicated. Levetiracetam is a safe, effective and well tolerated antiseizure drug with good results in epileptic patients. Objective To describe our experience using oral (p.o) levetiracetam 1000 mg every 12 h (q12h) as an antiseizure prophylaxis, evaluating its preventive effects and adverse event rates after a high-dose of intravenous (i.v.) busulfan, as part of the conditioning regimen Methods Retrospective study of patients who underwent an allogenic hematopoietic stem cell transplant with a conditioning regimen based on high-dose of busulfan between January and November 2017. Results The study population comprised 36 patients, of whom 18 (50%) had acute myeloid leukemia as diagnosis. No seizures occurred in any patient. Levetiracetam was well tolerated and no serious adverse events were reported. Conclusions Our results suggest that giving levetiracetam at 1000 mg q12h p.o starting 12 h before the administration of i.v. busulfan until 48 h after the last dose, can be used as an alternative in the prevention of busulfan-induced seizures in adults.

Precursors to plastic failure in a numerical simulation of CuZr metallic glass.

We deform, in pure shear, a thin sample of Cu50Zr50 metallic glass using a molecular dynamics simulation up to, and including, failure. The experiment is repeated ten times in order to have average values and standard deviations. Although failure occurs at the same value of the externally imposed strain for the ten samples, there is significant sample-to-sample variation in the specific microscopic material behavior. Failure can occur along one, two, or three planes, located at the boundaries of previously formed shear bands (SBs). These SBs form shortly before failure. However, well before their formation and at external strains where plastic deformation just begins to be significant, non-affine displacement organizes itself along localized bands. The SBs subsequently form at the edges of these non-affine-displacement-bands, and present an alternating rotation-quadrupole structure, as found previously by Sopu et al (2017 Phys. Rev. Lett. 119 195503) in the case of a notched sample loaded in tension. The thickness of SBs is roughly determined by the available plastic energy. The onset of shear banding is accompanied by a sharp increase in the rate of change of the rotation angle localization, the strain localization, and the non-affine square displacement.

Complications during multiorgan retrieval and pancreas preservation.

In pancreas transplantation, complications can arise at each step of the process, from the initial selection of donors and recipients through the surgical technique itself and the post-operative period, when lifelong immunosuppression is required. In the early steps, careful retrieval and preservation of the pancreas are crucial for the viability of the organ and ultimate success of the transplant. The pancreas is a low-flow gland, making it highly sensitive to transplantation conditions and presenting risk of pancreatitis due to periods of ischemia. The two groups of donors - after brain death (DBD) or after cardiac arrest (DCD) - require different strategies of retrieval and preservation to avoid or reduce the risk of complications developing during and after the transplantation. For DBD donor transplantation, multiorgan retrieval and cold preservation is the conventional technique. Asystole donor (DCD) transplantation, in contrast, can benefit from the newest technologies, such as hypothermic and especially normothermic preservation machines (referred to as NECMO), to optimize organ preservation. The latter has led to an increase in the pool of donors by facilitating recuperation of organs for transplantation that would have been discarded otherwise.

Response to Novel Drugs before and after Allogeneic Stem Cell Transplantation in Patients with Relapsed Multiple Myeloma.

Multiple myeloma (MM) remains as an incurable disease and, although allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative approach, most patients ultimately relapse, and their treatment remains challenging. Because allo-HSCT can modify not only the biology of the disease, but also the immune system and the microenvironment, it can potentially enhance the response to rescue therapies. Information on the efficacy and safety of novel drugs in patients relapsing after allo-HSCT is lacking, however. The objectives of this study were to evaluate the efficacy and toxicity of rescue therapies in patients with MM who relapsed after allo-HSCT, as well as to compare their efficacy before and after allo-HSCT. This retrospective multicenter study included 126 consecutive patients with MM who underwent allo-HSCT between 2000 and 2013 at 8 Spanish centers. All patients engrafted. The incidence of grade II-IV acute graft-versus-host disease (GVHD) was 47%, and nonrelapse mortality within the first 100 days post-transplantation was 13%. After a median follow-up of 92 months, overall survival (OS) was 51% at 2 years and 43% at 5 years. The median progression-free survival after allo-HSCT was 7 months, whereas the median OS after relapse was 33 months. Patients relapsing in the first 6 months after transplantation had a dismal prognosis compared with those who relapsed later (median OS, 11 months versus 120 months; P < .001). The absence of chronic GVHD was associated with reduced OS after relapse (hazard ratio, 3.44; P < .001). Most patients responded to rescue therapies, including proteasome inhibitors (PIs; 62%) and immunomodulatory drugs (IMiDs; 77%), with a good toxicity profile. An in-depth evaluation, including the type and intensity of PI- and IMiD-based combinations used before and after allo-HSCT, showed that the overall response rate and duration of response after allo-HSCT were similar to those seen in the pretransplantation period. Patients with MM who relapse after allo-HSCT should be considered candidates for therapy with new drugs, which can achieve similar response rates with similar durability as seen in the pretransplantation period. This pattern does not follow the usual course of the disease outside the transplantation setting, where response rates and time to progression decreases with each consecutive line of treatment.

Single Antigen-Mismatched Unrelated Hematopoietic Stem Cell Transplantation Using High-Dose Post-Transplantation Cyclophosphamide Is a Suitable Alternative for Patients Lacking HLA-Matched Donors.

The optimal prophylaxis regimen for graft-versus-host disease (GVHD) in the setting of mismatched unrelated donor (MMUD) allogeneic hematopoietic stem cell transplantation (alloHSCT) is not defined. The use of high-dose post-transplant cyclophosphamide (PTCy) in haploidentical transplantation has proven feasible and effective in overcoming the negative impact of HLA disparity on survival. We hypothesized that PTCy could also be effective in the setting of MMUD transplantation. We retrospectively analyzed 86 consecutive adult recipients of alloHSCT in our institution, comparing 2 contemporaneous groups: PTCy MMUD (n = 26) versus matched unrelated donor (MUD) (n = 60). Graft source was primarily peripheral blood (92%). All PTCy MMUD were HLA 7/8 (differences in HLA class I loci in 92% of patients) and received PTCy plus tacrolimus ± mofetil mycophenolate as GVHD prophylaxis. No differences were observed between PTCy MMUD and MUD in the 100-day cumulative incidence of acute GVHD grades II to IV (31% versus 22%, respectively; P = .59) and III to IV (8% versus 10%, P = .67). There was a trend for a lower incidence of moderate to severe chronic GVHD at 1 year after PTCy MMUD in comparison with MUD (22% versus 41%, P = .098). No differences between PTCy MMUD and MUD were found regarding nonrelapse mortality (25% versus 18%, P = .52) or relapse rate (11% versus 19%, P = .18). Progression-free survival and overall survival at 2 years were similar in both cohorts (67% versus 54% [HR, .84; 95% CI, .38 to 1.88; P = .68] and 72% versus 57% [HR, .71; 95% CI, .31 to 1.67; P = .44], respectively). The 2-year cumulative incidence of survival free of moderate to severe chronic GVHD and relapse tended to be higher in the PTCy MMUD group (47% versus 24%; HR, .60; 95% CI, .31 to 1.14; P = .12). We conclude that HLA 7/8 MMUD transplantation using PTCy plus tacrolimus is a suitable alternative for those patients who lack a MUD.

Probabilistic Inference for Dynamical Systems.

A general framework for inference in dynamical systems is described, based on the language of Bayesian probability theory and making use of the maximum entropy principle. Taking the concept of a path as fundamental, the continuity equation and Cauchy's equation for fluid dynamics arise naturally, while the specific information about the system can be included using the maximum caliber (or maximum path entropy) principle.

Vigilancia en salud pública: una necesidad inaplazable / Public health surveillance: a pressing need

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Autologous Haematopoietic Stem Cell Transplantation for Refractory Crohn's Disease: Efficacy in a Single-Centre Cohort.

BACKGROUND: Haematopoietic stem cell transplantation [HSCT] is considered a therapeutic option for patients with severe Crohn's disease [CD] unresponsive to currently available therapies. METHODS: Autologous HSCT was considered for CD patients with active disease, unresponsive or intolerant to approved medications and unsuitable for surgery. After HSCT, patients were closely followed up every 6 weeks during the first 2 years and every 6 months thereafter up to 5 years. Colonoscopy and/or magnetic resonance imaging were performed at Months 6, 12, 24, and 48 after HSCT. RESULTS: From December 1, 2007 to December 31, 2015, 37 CD patients were assessed for HSCT. Of these, 35 patients [13 within the ASTIC trial] underwent mobilisation. Six patients did not complete the transplant for various reasons and 29 patients were finally transplanted. Patients were followed up during a median of 12 months [6-60]. At 6 months, 70% of patients achieved drug-free clinical remission (Crohn's Disease Index of Severity [CDAI] < 150). The proportion of patients in drug-free remission (CDAI < 150, Simple Endoscopic activity Score [SES]-CD < 7] was 61% at 1 year, 52% at 2 years, 47% at 3 years, 39% at 4 years, and 15% at 5 years. Patients who relapsed were re-treated and 80% regained clinical remission. Six out of the 29 [21%] required surgery. One patient died due to systemic cytomegalovirus infection 2 months after transplant. CONCLUSIONS: HSCT is a salvage therapy for patients with extensive and refractory CD. Although relapse occurs in a majority of patients within 5 years after transplant, drug responsiveness is regained and clinical remission achieved in 80% of cases.

Melting curve of SiO2 at multimegabar pressures: implications for gas giants and super-Earths.

Ultrahigh-pressure phase boundary between solid and liquid SiO2 is still quite unclear. Here we present predictions of silica melting curve for the multimegabar pressure regime, as obtained from first principles molecular dynamics simulations. We calculate the melting temperatures from three high pressure phases of silica (pyrite-, cotunnite-, and Fe2P-type SiO2) at different pressures using the Z method. The computed melting curve is found to rise abruptly around 330 GPa, an increase not previously reported by any melting simulations. This is in close agreement with recent experiments reporting the α-PbO2-pyrite transition around this pressure. The predicted phase diagram indicates that silica could be one of the dominant components of the rocky cores of gas giants, as it remains solid at the core of our Solar System's gas giants. These results are also relevant to model the interior structure and evolution of massive super-Earths.

Improving safety of autologous haematopoietic stem cell transplantation in patients with Crohn's disease.

OBJECTIVE: To evaluate the feasibility and toxicity of autologous haematopoietic stem cell transplantation (HSCT) for the treatment of refractory Crohn's disease (CD). DESIGN: In this prospective study, patients with refractory CD suffering an aggressive disease course despite medical treatment, impaired quality of life and in whom surgery was not an acceptable option underwent HSCT. Toxicity and complications during the procedure and within the first year following transplantation were evaluated, along with the impact of the introduction of supportive measures on safety outcomes. RESULTS: 26 patients were enrolled. During mobilisation, 16 patients (62%) presented febrile neutropaenia, including one bacteraemia and two septic shocks. Neutropaenia median time after mobilisation was 5 days. 5 patients withdrew from the study after mobilisation and 21 patients entered the conditioning phase. Haematopoietic recovery median time for neutrophils (>0.5×10(9)/L) was 11 days and for platelets (>20×10(9)/L) 4 days. Twenty patients (95%) suffered febrile neutropaenia and three patients (27%) presented worsening of the perianal CD activity during conditioning. Among non-infectious complications, 6 patients (28.5%) presented antithymocyte globulin reaction, 12 patients (57%) developed mucositis and 2 patients (9.5%) had haemorrhagic complications. Changes in supportive measures over the study, particularly antibiotic prophylaxis regimes during mobilisation and conditioning, markedly diminished the incidence of severe complications. During the first 12-month follow-up, viral infections were the most commonly observed complications, and one patient died due to systemic cytomegalovirus infection. CONCLUSIONS: Autologous HSCT for patients with refractory CD is feasible, but extraordinary supportive measures need to be implemented. We suggest that this procedure should only be performed in highly experienced centres.

Determinantes de la asistencia irregular a consulta médica en pacientes con infección por el virus de la inmunodeficiencia humana: resultados de la Encuesta Hospitalaria de pacientes con el virus de la inmunodeficiencia humana, 2002-2012 / Factors determining irregular attendance to follow-up visits among human immunodeficiency virus patients: Results of the hospital survey of patients infected with human immunodeficiency virus

INTRODUCCIÓN: Describir la frecuencia de la asistencia irregular a consulta médica de pacientes con VIH y analizar sus determinantes. MÉTODOS: Estudio transversal realizado anualmente (2002-2012) en un día prefijado. Se recogen datos epidemiológicos, clínicos y conductuales de los pacientes con VIH (hospitalizados y ambulatorios) atendidos ese día en los hospitales públicos participantes. Se definió «asistencia irregular a consulta» como asistencia a consulta de forma esporádica, según la valoración del médico. Se realizó un análisis descriptivo, bivariante y multivariante de regresión logística para estimar los factores asociados a asistencia irregular a la consulta. RESULTADOS: En total se incluyeron 7.304 pacientes de los que el 13,7% acudían irregularmente a la consulta. La probabilidad de asistencia irregular aumentó en pacientes entre 25 y 49 años, subsaharianos o latinoamericanos, con menor nivel de estudios, aquellos sin domicilio fijo o que estaban en prisión, los que vivían solos o en establecimientos colectivos, los desempleados o jubilados, los que se infectaron por compartir material de inyección, los que no usaron condón en su última relación sexual y los inyectores activos. Por el contrario, los pacientes diagnosticados hacía menos de un año y los hombres homo/bisexuales tenían menor probabilidad de acudir irregularmente. CONCLUSIÓN: A pesar de la universalidad de nuestro sistema de salud existen variables sociales y demográficas que actúan como barreras para la asistencia a consulta, lo que puede comprometer la efectividad del tratamiento en determinados grupos de población. Estos determinantes deberían tenerse en cuenta a la hora de planificar políticas de control de la infección por el VIH

INTRODUCTION: To describe the occurrence of non-regular attendance to follow-up visits among HIV patients and to analyze the determining factors. METHODS: One-day survey carried out annually (2002-2012) in public hospitals. Epidemiological, clinical and behavioral data are collected in all HIV-infected inpatients and outpatients receiving HIV-related care on the day of the survey. «Non-regular attendance to a follow-up visit» was defined as sporadic attendance to the medical appointments, according to the judgment of the attending physician. Descriptive and bivariate analyses were performed, and factors associated to non-regular attendance to follow-up visits were estimated using logistic regression. RESULTS: A total of 7,304 subjects were included, of whom 13.7% did not attend medical appointments regularly. Factors directly associated with non-regular attendance were: age between 25-49 years; birth in Sub-Saharan Africa or Latin-America; low educational level; being homeless or in prison; living alone or in closed institutions; being unemployed or retired; being an intravenous drug user; not using a condom at last sexual encounter, and injecting drugs in the last 30 days. Conversely, HIV diagnosis within the last year and being men who have sex with men were factors inversely associated with non-regular attendance to follow-up visits. CONCLUSION: In spite of health care beings free of charge for everyone in Spain, social factors can act as barriers to regular attendance to medical appointments, which, in turn, can endanger treatment effectiveness in some population groups. This should be taken into account when planning HIV policies in Spain