Benefits and harms of direct oral anticoagulation and low molecular weight heparin for thromboprophylaxis in patients undergoing non-cardiac surgery: systematic review and network meta-analysis of randomised trials.

OBJECTIVE: To systematically compare the effect of direct oral anticoagulants and low molecular weight heparin for thromboprophylaxis on the benefits and harms to patients undergoing non-cardiac surgery. DESIGN: Systematic review and network meta-analysis of randomised controlled trials. DATA SOURCES: Medline, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL), up to August 2021. REVIEW METHODS: Randomised controlled trials in adults undergoing non-cardiac surgery were selected, comparing low molecular weight heparin (prophylactic (low) or higher dose) with direct oral anticoagulants or with no active treatment. Main outcomes were symptomatic venous thromboembolism, symptomatic pulmonary embolism, and major bleeding. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used for network meta-analyses. Abstracts and full texts were screened independently in duplicate. Data were abstracted on study participants, interventions, and outcomes, and risk of bias was assessed independently in duplicate. Frequentist network meta-analysis with multivariate random effects models provided odds ratios with 95% confidence intervals, and GRADE (grading of recommendations, assessment, development, and evaluation) assessments indicated the certainty of the evidence. RESULTS: 68 randomised controlled trials were included (51 orthopaedic, 10 general, four gynaecological, two thoracic, and one urological surgery), involving 45 445 patients. Low dose (odds ratio 0.33, 95% confidence interval 0.16 to 0.67) and high dose (0.19, 0.07 to 0.54) low molecular weight heparin, and direct oral anticoagulants (0.17, 0.07 to 0.41) reduced symptomatic venous thromboembolism compared with no active treatment, with absolute risk differences of 1-100 per 1000 patients, depending on baseline risks (certainty of evidence, moderate to high). None of the active agents reduced symptomatic pulmonary embolism (certainty of evidence, low to moderate). Direct oral anticoagulants and low molecular weight heparin were associated with a 2-3-fold increase in the odds of major bleeding compared with no active treatment (certainty of evidence, moderate to high), with absolute risk differences as high as 50 per 1000 in patients at high risk. Compared with low dose low molecular weight heparin, high dose low molecular weight heparin did not reduce symptomatic venous thromboembolism (0.57, 0.26 to 1.27) but increased major bleeding (1.87, 1.06 to 3.31); direct oral anticoagulants reduced symptomatic venous thromboembolism (0.53, 0.32 to 0.89) and did not increase major bleeding (1.23, 0.89 to 1.69). CONCLUSIONS: Direct oral anticoagulants and low molecular weight heparin reduced venous thromboembolism compared with no active treatment but probably increased major bleeding to a similar extent. Direct oral anticoagulants probably prevent symptomatic venous thromboembolism to a greater extent than prophylactic low molecular weight heparin. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42018106181.

Pharmacologic thromboprophylaxis in adult patients undergoing neurosurgical interventions for preventing venous thromboembolism.

The impact of pharmacologic prophylaxis for venous thromboembolism in patients undergoing neurosurgical intervention remains uncertain. We reviewed the efficacy and safety of pharmacologic compared with nonpharmacologic thromboprophylaxis in neurosurgical patients. Three databases were searched through April 2018, including those for randomized controlled trials (RCTs) and for nonrandomized controlled studies (NRSs). Independent reviewers assessed the certainty of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. Seven RCTs and 3 NRSs proved eligible. No studies reported on symptomatic proximal and distal deep vein thrombosis (DVT). Two RCTs reported on screening-detected proximal and distal DVTs. We used the findings of these 2 RCTs as the closest surrogate outcomes to inform the proximal and distal DVT outcomes. These 2 RCTs suggest that pharmacologic thromboprophylaxis may decrease the risk of developing asymptomatic proximal DVT (relative risk [RR], 0.50; 95% confidence interval [CI], 0.30-0.84; low certainty). Findings were uncertain for mortality (RR, 1.27; 95% CI, 0.57-2.86; low certainty), symptomatic pulmonary embolism (PE) (RR, 0.84; 95% CI, 0.03-27.42; very low certainty), asymptomatic distal DVT (RR, 0.54; 95% CI, 0.27-1.08; very low certainty), and reoperation (RR, 0.43; 95% CI, 0.06-2.84; very low certainty) outcomes. NRSs also reported uncertain findings for whether pharmacologic prophylaxis affects mortality (RR, 0.72; 95% CI, 0.46-1.13; low certainty) and PE (RR, 0.18; 95% CI, 0.01-3.76). For risk of bleeding, findings were uncertain in both RCTs (RR, 1.57; 95% CI, 0.70-3.50; low certainty) and NRSs (RR, 1.45; 95% CI, 0.30-7.12; very low certainty). In patients undergoing neurosurgical procedures, low certainty of evidence suggests that pharmacologic thromboprophylaxis confers benefit for preventing asymptomatic (screening-detected) proximal DVT with very low certainty regarding its impact on patient-important outcomes.

Thrombolytics for venous thromboembolic events: a systematic review with meta-analysis.

Thrombolytic therapy might reduce venous thromboembolism-related mortality and morbidity, but it could also increase the risk of major bleeding. We systematically reviewed the literature to evaluate the effectiveness and safety of thrombolytics in patients with pulmonary embolism (PE) and/or deep venous thrombosis (DVT). We searched Medline, Embase, and Cochrane databases for relevant randomized controlled trials up to February 2019. Multiple investigators independently screened and collected data. We included 45 studies (4740 participants). Pooled estimates of PE studies indicate probable reduction in mortality with thrombolysis (risk ratio [RR], 0.61; 95% confidence interval [CI], 0.40-0.94) (moderate certainty) and possible reduction in nonfatal PE recurrence (RR, 0.56; 95% CI, 0.35-0.89) (low certainty). Pooled estimates of DVT studies indicate the possible absence of effects on mortality (RR, 0.77; 95% CI, 0.26-2.28) (low certainty) and recurrent DVT (RR, 0.99; 95% CI, 0.56-1.76) (low certainty), but possible reduction in postthrombotic syndrome (PTS) with thrombolytics (RR, 0.70; 95% CI, 0.59-0.83) (low certainty). Pooled estimates of the complete body of evidence indicate increases in major bleeding (RR, 1.89; 95% CI, 1.46-2.46) (high certainty) and a probable increase in intracranial bleeding (RR, 3.17; 95% CI 1.19-8.41) (moderate certainty) with thrombolytics. Our findings indicate that thrombolytics probably reduce mortality in patients with submassive- or intermediate-risk PE and may reduce PTS in patients with proximal DVT at the expense of a significant increase in major bleeding. Because the balance between benefits and harms is profoundly influenced by the baseline risks of critical outcomes, stakeholders involved in decision making would need to weigh these effects to define which clinical scenarios merit the use of thrombolytics.

Omega 3 fatty acid supplementation after myocardial infarction: a systematic review and meta-analysis.

BACKGROUND: The purpose of this review is to examine the effect of Omega-3 Fatty acids on mortality, morbidity, and adverse events in patients with acute myocardial infarction (AMI). METHODS: Data Sources: MEDLINE, EMBASE, and the Cochrane Library through May 2018. STUDY SELECTION: Randomized Controlled trials (RCT). Certainty of evidence was assessed with the GRADE system. INTERVENTIONS: omega 3 fatty acids against placebo or no treatment. Primary and secondary outcomes: All-cause death, cardiovascular death, new AMI, stroke, need for therapeutic angioplasty or By-pass, new diagnosis of cancer and incidence of adverse events. RESULTS: For the efficacy endpoints we included 10 RCT (24,414 patients). Omega 3 fatty acids probably make little or no difference to all-cause mortality (4 studies 9141 patients RR 1.06 - CI95% 0.90 to 1.27, moderate certainty), cardiovascular mortality (3 studies 4304 patients RR 0.93 - CI95% 0.63 to 1.37, moderate certainty), new AMI (RR 1.24 CI95% 0.71 to 2.14 - moderate certainty), any cardiovascular event (RR 0.95 95%CI 0.86 to 1.05; low certainty due to risk of bias and imprecision), and stroke (RR 1.2 95%CCI 0,66-2,19 - moderate certainty). Regarding adverse events, we are uncertain if Omega 3 fatty acids improve/reduce non severe adverse events (RR 1.39 95% CI 0.36 to 5.34; very low certainty). There is probably little or no difference in the outcome suspension due to adverse events (RR 1.19 CI 95% 0.97 to 1.47; moderate certainty). CONCLUSIONS: For adult patients with AMI, omega 3 fatty-acids probably yield no benefit to patient important outcomes.

First Latin American clinical practice guidelines for the treatment of systemic lupus erythematosus: Latin American Group for the Study of Lupus (GLADEL, Grupo Latino Americano de Estudio del Lupus)-Pan-American League of Associations of Rheumatology (PANLAR).

Systemic lupus erythematosus (SLE), a complex and heterogeneous autoimmune disease, represents a significant challenge for both diagnosis and treatment. Patients with SLE in Latin America face special problems that should be considered when therapeutic guidelines are developed. The objective of the study is to develop clinical practice guidelines for Latin American patients with lupus. Two independent teams (rheumatologists with experience in lupus management and methodologists) had an initial meeting in Panama City, Panama, in April 2016. They selected a list of questions for the clinical problems most commonly seen in Latin American patients with SLE. These were addressed with the best available evidence and summarised in a standardised format following the Grading of Recommendations Assessment, Development and Evaluation approach. All preliminary findings were discussed in a second face-to-face meeting in Washington, DC, in November 2016. As a result, nine organ/system sections are presented with the main findings; an 'overarching' treatment approach was added. Special emphasis was made on regional implementation issues. Best pharmacologic options were examined for musculoskeletal, mucocutaneous, kidney, cardiac, pulmonary, neuropsychiatric, haematological manifestations and the antiphospholipid syndrome. The roles of main therapeutic options (ie, glucocorticoids, antimalarials, immunosuppressant agents, therapeutic plasma exchange, belimumab, rituximab, abatacept, low-dose aspirin and anticoagulants) were summarised in each section. In all cases, benefits and harms, certainty of the evidence, values and preferences, feasibility, acceptability and equity issues were considered to produce a recommendation with special focus on ethnic and socioeconomic aspects. Guidelines for Latin American patients with lupus have been developed and could be used in similar settings.

Answering medical questions at the point of care: a cross-sectional study comparing rapid decisions based on PubMed and Epistemonikos searches with evidence-based recommendations developed with the GRADE approach.

INTRODUCTION: Using the best current evidence to inform clinical decisions remains a challenge for clinicians. Given the scarcity of trustworthy clinical practice guidelines providing recommendations to answer clinicians' daily questions, clinical decision support systems (ie, assistance in question identification and answering) emerge as an attractive alternative. The trustworthiness of the recommendations achieved by such systems is unknown. OBJECTIVE: To evaluate the trustworthiness of a question identification and answering system that delivers timely recommendations. DESIGN: Cross-sectional study. METHODS: We compared the responses to 100 clinical questions related to inpatient management provided by two rapid response methods with 'Gold Standard' recommendations. One of the rapid methods was based on PubMed and the other on Epistemonikos database. We defined our 'Gold Standard' as trustworthy published evidence-based recommendations or, when unavailable, recommendations developed locally by a panel of six clinicians following the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. Recommendations provided by the rapid strategies were classified as potentially misleading or reasonable. We also determined if the potentially misleading recommendations could have been avoided with the appropriate implementation of searching and evidence summary tools. RESULTS: We were able to answer all of the 100 questions with both rapid methods. Of the 200 recommendations obtained, 6.5% (95% CI 3% to 9.9%) were classified as potentially misleading and 93.5% (95% CI 90% to 96.9%) as reasonable. 6 of the 13 potentially misleading recommendations could have been avoided by the appropriate usage of the Epistemonikos matrix tool or by constructing summary of findings tables. No significant differences were observed between the evaluated rapid response methods. CONCLUSION: A question answering service based on the GRADE approach proved feasible to implement and provided appropriate guidance for most identified questions. Our approach could help stakeholders in charge of managing resources and defining policies for patient care to improve evidence-based decision-making in an efficient and feasible manner.

Early mobilization versus bed rest for deep vein thrombosis. / Deambulación precoz versus reposo para pacientes con trombosis venosa profunda.

Aiming to prevent thromboembolic events, bed rest was historically considered in the management of patient with deep vein thrombosis. Nevertheless early ambulation could have beneficial effects. Searching in Epistemonikos database, which is maintained by screening 30 databases, we identified seven systematic reviews including 10 randomized trials answering this question. We combined the evidence using meta-analysis and generated a summary of findings table following the GRADE approach. We concluded early ambulation is probably effective in reducing deep vein thrombosis progression and improving limb pain, and might not increase the risk of thromboembolism.

Históricamente el reposo en cama fue incluido como parte del esquema de manejo de pacientes con trombosis venosa profunda con el objetivo de evitar eventos tromboembólicos. Sin embargo, la deambulación precoz podría asociarse a beneficios importantes. Utilizando la base de datos Epistemonikos, la cual es mantenida mediante búsquedas en 30 bases de datos, identificamos siete revisiones sistemáticas que en conjunto incluyen 10 estudios controlados aleatorizados pertinentes. Realizamos un metanálisis y tablas de resumen de los resultados utilizando el método GRADE. Concluimos que la deambulación temprana probablemente disminuye el dolor y el riesgo de progresión de la trombosis, y podría no aumentar el riesgo de tromboembolismo pulmonar.

[How much can we trust health related information provided by mass media in Argentina?]. / ¿Cuán confiable es la información médica proporcionada por los medios de comunicación en Argentina?

To evaluate the certainty and accuracy of the healthcare information provided by the mass media in Argentina, a group of senior medical students, blind to the study objectives, identified healthcare related statements transmitted through mass media. These findings were challenged against the recommendations of a group of physicians trained in evidence-based decision making (EBDM). We compared the strength and direction of the mass media recommendations with those of experts on EBDM. Eighty one recommendations/questions were identified and answered by the experts on EBDM, 15 with high, 18 with moderate, 30 with low and 18 with very low quality of evidence. Only 53% (CI95% 42-64%) of the mass media recommendations agreed with the expert recommendation in direction (for or against) and 28% (CI95% 18-39%) were classified as inappropriate (significant discrepancies both in direction and strength). Subgroup analysis revealed that 71% (CI95% 56-86%) of there commendations made by professionals in mass media agreed with experts in direction and 17% (IC95% 6-33%) were classified as inappropriate, OR = 0.35 (CI95% 0.1-1.1) compared to recommendations in mass media by non-professionals. We conclude that the healthcare information provided by mass media in Argentina is unreliable; this fact can probably have a negative impact in the health system performance and physician-patient relationship.

¿Cuán confiable es la información médica proporcionada por los medios de comunicación en Argentina? / How much can we trust health related information provided by mass media in Argentina?

Para evaluar la confiabilidad y precisión de la información médica proporcionada por los medios de comunicación en Argentina, alumnos avanzados de medicina, que desconocían los objetivos del estudio, identificaron aseveraciones relacionadas a temas médicos transmitidas por medios de comunicación. Los hallazgos fueron contrastados con recomendaciones realizadas por médicos expertos en la toma de decisiones basada en evidencias. Las recomendaciones de los medios y las confeccionadas por los expertos fueron comparadas en relación a su fuerza y dirección. Se identificaron 81 recomendaciones/preguntas las que fueron contestadas por los expertos, 15 con alta, 18 con moderada, 30 con baja y 18 con muy baja calidad de evidencia. Solamente el 53% (IC95% 42-64%) de las recomendaciones hechas por los medios de comunicación coincidieron en la dirección (a favor o en contra de la intervención) con las realizadas por los expertos y el 28% (IC95% 18-39%) fueron calificadas como inadecuadas (diferencias significativas tanto en dirección como en fuerza). El análisis del subgrupo de recomendaciones realizadas en los medios por profesionales de la salud mostró una coincidencia en la dirección del 71% (IC95% 56-86%) con 17% (IC95% 6-33%) de recomendaciones inadecuadas, OR = 0.35 (IC95% 0.1-1.1) en relación a las no realizadas por profesionales de la salud. Se concluye que la información médica que proveen los medios de comunicación en Argentina es poco confiable, lo que posiblemente tenga un impacto negativo sobre el funcionamiento del sistema de salud y la relación de los médicos con sus pacientes.

To evaluate the certainty and accuracy of the healthcare information provided by the mass media in Argentina, a group of senior medical students, blind to the study objectives, identified healthcare related statements transmitted through mass media. These findings were challenged against the recommendations of a group of physicians trained in evidence-based decision making (EBDM). We compared the strength and direction of the mass media recommendations with those of experts on EBDM. Eighty one recommendations/questions were identified and answered by the experts on EBDM, 15 with high, 18 with moderate, 30 with low and 18 with very low quality of evidence. Only 53% (CI95% 42-64%) of the mass media recommendations agreed with the expert recommendation in direction (for or against) and 28% (CI95% 18-39%) were classified as inappropriate (significant discrepancies both in direction and strength). Subgroup analysis revealed that 71% (CI95% 56-86%) of there commendations made by professionals in mass media agreed with experts in direction and 17% (IC95% 6-33%) were classified as inappropriate, OR = 0.35 (CI95% 0.1-1.1) compared to recommendations in mass media by non-professionals. We conclude that the healthcare information provided by mass media in Argentina is unreliable; this fact can probably have a negative impact in the health system performance and physician-patient relationship.

Should trypanocidal therapy be used to treat patients in the chronic phase of Chagas disease?

Antiparasitic treatment of patients with Chagas’ disease in chronic stage could prevent the complications related to the disease. Searching in Epistemonikos database, which is maintained by screening 30 databases, we identified five systematic reviews including eight randomized trials and 11 observational studies. We combined the evidence using meta-analysis and generated a summary of findings table following the GRADE approach. We concluded it is not clear whether antiparasitic treatment improves survival or reduces complications related to chronic Chagas’ disease because the certainty of the evidence is very low.

El tratamiento con antiparasitarios de pacientes con enfermedad de Chagas en fase crónica podría evitar las complicaciones asociadas a esta enfermedad. Utilizando la base de datos Epistemonikos, la cual es mantenida mediante búsquedas en 30 bases de datos, identificamos cinco revisiones sistemáticas que en conjunto incluyen ocho estudios aleatorizados. Realizamos un metanálisis y tablas de resumen de los resultados utilizando el método GRADE. Concluimos que no está clara la efectividad del tratamiento antiparasitario para prolongar la sobrevida y evitar las complicaciones asociadas a la enfermedad de Chagas en el periodo crónico porque la certeza de la evidencia es muy baja.

Inequality as a Powerful Predictor of Infant and Maternal Mortality around the World.

BACKGROUND: Maternal and infant mortality are highly devastating, yet, in many cases, preventable events for a community. The human development of a country is a strong predictor of maternal and infant mortality, reflecting the importance of socioeconomic factors in determinants of health. Previous research has shown that the Human Development Index (HDI) predicts infant mortality rate (IMR) and the maternal mortality ratio (MMR). Inequality has also been shown to be associated with worse health in certain populations. The main purpose of the present study was to determine the correlation and predictive power of the Inequality Adjusted Human Development Index (IHDI) as a measure of inequality with the Infant Mortality Rate (IMR), Maternal Mortality Rate (MMR), Early Neonatal Mortality Rate (ENMR), Late Neonatal Mortality Rate (LNMR), and the Post Neonatal Mortality Rate (PNMR). METHODS AND FINDINGS: Data for the present study were downloaded from two sources: infant and maternal mortality data were downloaded from the Global Burden of Disease 2013 Cause of Death Database and the Human Development Index (HDI) and Inequality-Adjusted Human Development Index (IHDI) data were downloaded from the United Nations Development Program (UNDP). Pearson correlation coefficients were estimated, following logarithmic transformations to the data, to examine the relationship between HDI and IHDI with MMR, IMR, ENMR, LNMR, and PNMR. Steiger's Z test for the equality of two dependent correlations was utilized in order to determine whether the HDI or IHDI was more strongly associated with the outcome variables. Lastly, we constructed OLS regression models in order to determine the predictive power of the HDI and IHDI in terms of the MMR, IMR, ENMR, LNMR, and PNMR. Maternal and infant mortality were both strongly and negatively correlated with both HDI and IHDI; however, Steiger's Z test for the equality of two dependent correlations revealed that IHDI was more strongly correlated than HDI with MMR (Z = 4.897, p < 0.001), IMR (Z = 2.524, p = 0.012), ENMR (Z = 2.936, p = 0.003), LNMR (Z = 2.272, p = 0.023), and PNMR (Z = 2.277, p = 0.023). Furthermore, side-by-side OLS regression models revealed that, when IHDI was used as the predictor variable instead of HDI, the R2 value was 0.053 higher for MMR, 0.025 higher for IMR, 0.038 higher for ENMR, 0.029 higher for LNMR, and 0.026 higher for PNMR. CONCLUSIONS: Even when both the HDI and the IHDI correlate with the infant and maternal mortality rates, the IHDI is a better predictor for these two health indicators. Therefore, these results add more evidence that inequality is playing an important role in determining the health status of various populations in the world and more efforts should be put into programs to fight inequality.

[Ticagrelor in acute coronary syndrome. Explaining the inexplicable]. / Ticagrelor en el síndrome coronario agudo. Explicando lo inexplicable.

The PLATO study evaluated the efficacy of adding ticagrelor, instead of clopidogrel, to aspirin in patients with acute coronary syndrome, which showed surprisingly positive results making the drug acceptable to regulatory agencies and specialty societies worldwide. Notwithstanding the aforementioned success, contradictory information supplied by critical analysis was submitted by the sponsor. The controversial findings revealed several aspects that are difficult to explain, threatening the veracity of the study's conclusions. Mortality rate pattern, excessive benefit not comparable to prior studies, unexplained loss of follow-up development and inconsistency in findings in accordance with the country, the type of events arbitrator and monitoring committee are some of the most questionable issues. Dubious reaction to this trial is based on the fact that the information could not be found in published articles. This complex situation poses a challenge to the critical analysis of the text and raises questions as to how far the conflicts of financial interest influenced the development of the study, the communication of its results and probably, acceptance of the drug for commercial use.

Ticagrelor en el síndrome coronario agudo. Explicando lo inexplicable / [Ticagrelor in acute coronary syndrome. Explaining the inexplicable]

The PLATO study evaluated the efficacy of adding ticagrelor, instead of clopidogrel, to aspirin in patients with acute coronary syndrome, which showed surprisingly positive results making the drug acceptable to regulatory agencies and specialty societies worldwide. Notwithstanding the aforementioned success, contradictory information supplied by critical analysis was submitted by the sponsor. The controversial findings revealed several aspects that are difficult to explain, threatening the veracity of the study’s conclusions. Mortality rate pattern, excessive benefit not comparable to prior studies, unexplained loss of follow-up development and inconsistency in findings in accordance with the country, the type of events arbitrator and monitoring committee are some of the most questionable issues. Dubious reaction to this trial is based on the fact that the information could not be found in published articles. This complex situation poses a challenge to the critical analysis of the text and raises questions as to how far the conflicts of financial interest influenced the development of the study, the communication of its results and probably, acceptance of the drug for commercial use.

Ticagrelor en el síndrome coronario agudo. Explicando lo inexplicable. / [Ticagrelor in acute coronary syndrome. Explaining the inexplicable].

The PLATO study evaluated the efficacy of adding ticagrelor, instead of clopidogrel, to aspirin in patients with acute coronary syndrome, which showed surprisingly positive results making the drug acceptable to regulatory agencies and specialty societies worldwide. Notwithstanding the aforementioned success, contradictory information supplied by critical analysis was submitted by the sponsor. The controversial findings revealed several aspects that are difficult to explain, threatening the veracity of the studys conclusions. Mortality rate pattern, excessive benefit not comparable to prior studies, unexplained loss of follow-up development and inconsistency in findings in accordance with the country, the type of events arbitrator and monitoring committee are some of the most questionable issues. Dubious reaction to this trial is based on the fact that the information could not be found in published articles. This complex situation poses a challenge to the critical analysis of the text and raises questions as to how far the conflicts of financial interest influenced the development of the study, the communication of its results and probably, acceptance of the drug for commercial use.

A colorectal mosaic pattern might be an endoscopic feature of collagenous colitis.

BACKGROUND AND AIMS: The endoscopic aspect of the colorectal mucosa in those patients with collagenous colitis is usually normal, or with non-specific changes. Until now it had never been related to a mucosal pattern of mosaic type. Our aim was to determine the diagnostic accuracy of the presence of mosaic pattern in the colorectal mucosa for collagenous colitis. METHODS: Patients who had undergone a colonoscopy with random biopsies performed in the diagnostic evaluation of chronic diarrhea between 2004 and 2008 were studied. We defined patients with chronic diarrhea and mosaic mucosal pattern as "cases", and patients with chronic diarrhea without mosaic pattern as "controls". The odds ratio (OR) of finding a collagenous colitis in view of a mosaic pattern in colon was determined; as well as sensitivity and specificity; positive and negative likelihood ratios (LR+, LR-), considering this finding as a diagnostic instrument for collagenous colitis. RESULTS: 252 patients who had undergone colonoscopy with biopsy due to chronic diarrhea were analyzed. In 6 patients, a mosaic pattern was identified in the colorectal mucosa. The histological diagnose of 36 of the 252 patients (14%) was microscopic colitis, 27 of which (11%) had collagenous colitis. The colonoscopy was found normal in 21 of these 27 patients; in 2 patients, congestion or petechiae was found in the rectum; and in 4 patients (15%), all women, a mosaic pattern was found in the rectosigmoid mucosa. The OR of this finding was 19.4 (CI 95% 3.9-95.4) for collagenous colitis. It had a sensitivity of 14.8% (CI 95% 6.8-20), a specificity of 99.1% (CI 95% 98.2-99.7), LR+ of 16.6 (CI 95% 3.7-76.4), and LR- of 0.86 (CI 95% 0.80-0.95) for a collagenous colitis. CONCLUSION: The mosaic pattern in the colorectal mucosa of patients studied due to chronic diarrhea could be a distinguishing feature of collagenous colitis.