Why have meta-analyses of randomized controlled trials of the association between non-white-blood-cell-reduced allogeneic blood transfusion and postoperative infection produced discordant results?

Transfusion of stored autologous blood in patients with low-grade pseudomyxoma peritonei: A retrospective analysis of its safety and outcome

BACKGROUND

Pseudomyxoma peritonei is a rare disease that presents as a malignant tumor on the peritoneal surface. Cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy is the standard treatment for this disease and frequently requires a red blood cell transfusion. However, due to the limited collection and supply of allogeneic blood, surgical treatment may be delayed due to inadequate preparation of allogeneic blood in the course of clinical treatment. This study aimed to evaluate the safety and efficacy of transfusion of stored autologous blood in patients with low-grade pseudomyxoma peritonei.

METHODS

Pseudomyxoma peritonei patients who received cytoreductive surgery combined with heat-infused peritoneal chemotherapy were divided into two groups: transfusion of allogeneic blood and transfusion of stored autologous blood. A comparison of the differences in multiple factors between the two groups was performed, including tumor recurrence, survival time, hemoglobin and hematocrit levels, coagulation function (prothrombin time, activated partial thromboplastin time, and fibrinogen), total hospital stay duration, and incidence of serious adverse events after surgery.

RESULTS

Propensity scores matching analysis yielded 34 patients with allogeneic blood transfusion and 34 patients with stored autologous blood transfusion. Comparison analysis did not show statistical differences in several factors, including age, tumor grade, tumor recurrence rate after surgery, etc., between the two groups. The cytoreductive degree was considered an independent risk factor for tumor recurrence. The pseudomyxoma peritonei patients in the autologous transfusion group had a higher 5-year survival rate and a longer survival time. Moreover, transfusion of stored autologous blood did not increase the rate of tumor recurrence, or the total hospital stay duration after surgery, the hemoglobin level and coagulation function were well stabilized within 24 h after surgery, and there was a low incidence of serious adverse events.

CONCLUSION

The clinical application of transfusion of stored autologous blood in pseudomyxoma peritonei patients is safe and effective.

Association between perioperative allogeneic red blood cell transfusion and infection after clean-contaminated surgery: a retrospective cohort study

BACKGROUND

Allogeneic red blood cell (RBC) transfusion can induce immunosuppression, which can then increase the susceptibility to postoperative infection. However, studies in different types of surgery show conflicting results regarding this effect.

METHODS

In this retrospective cohort study conducted in a tertiary referral centre, we included adult patients undergoing clean-contaminated surgery from 2014 to 2018. Patients who received allogeneic RBC transfusion from preoperative Day 30 to postoperative Day 30 were included into the transfusion group. The control group was matched for the type of surgery in a 1:1 ratio. The primary outcome was infection within 30 days after surgery, which was defined by healthcare-associated infection, and identified mainly based on antibiotic regimens, microbiology tests, and medical notes.

RESULTS

Among the 8098 included patients, 1525 (18.8%) developed 1904 episodes of postoperative infection. Perioperative RBC transfusion was associated with an increased risk of postoperative infection after controlling for 27 confounders by multivariable regression analysis (odds ratio [OR]: 1.60; 95% confidence interval [CI]: 1.39-1.84; P<0.001) and propensity score weighing (OR: 1.64; 95% CI: 1.45-1.85; P<0.001) and matching (OR: 1.70; 95% CI: 1.43-2.01; P<0.001), and a dose-response relationship was observed. The transfusion group also showed higher risks of surgical site infection, pneumonia, bloodstream infection, multiple infections, intensive care admission, unplanned reoperation, prolonged postoperative length of hospital stay, and all-cause death.

CONCLUSIONS

Perioperative allogeneic RBC transfusion is associated with an increased risk of infection after clean-contaminated surgery in a dose-response manner. Close monitoring of infections and enhanced prophylactic strategies should be considered after transfusion.

Vibration of effects from diverse inclusion/exclusion criteria and analytical choices: 9216 different ways to perform an indirect comparison meta-analysis

BACKGROUND

Different methodological choices such as inclusion/exclusion criteria and analytical models can yield different results and inferences when meta-analyses are performed. We explored the range of such differences, using several methodological choices for indirect comparison meta-analyses to compare nalmefene and naltrexone in the reduction of alcohol consumption as a case study.

METHODS

All double-blind randomized controlled trials (RCTs) comparing nalmefene to naltrexone or one of these compounds to a placebo in the treatment of alcohol dependence or alcohol use disorders were considered. Two reviewers searched for published and unpublished studies in MEDLINE (August 2017), the Cochrane Library, Embase, and ClinicalTrials.gov and contacted pharmaceutical companies, the European Medicines Agency, and the Food and Drug Administration. The indirect comparison meta-analyses were performed according to different inclusion/exclusion criteria (based on medical condition, abstinence of patients before inclusion, gender, somatic and psychiatric comorbidity, psychological support, treatment administered and dose, treatment duration, outcome reported, publication status, and risk of bias) and different analytical models (fixed and random effects). The primary outcome was the vibration of effects (VoE), i.e. the range of different results of the indirect comparison between nalmefene and naltrexone. The presence of a "Janus effect" was investigated, i.e. whether the 1st and 99th percentiles in the distribution of effect sizes were in opposite directions.

RESULTS

Nine nalmefene and 51 naltrexone RCTs were included. No study provided a direct comparison between the drugs. We performed 9216 meta-analyses for the indirect comparison with a median of 16 RCTs (interquartile range = 12-21) included in each meta-analysis. The standardized effect size was negative at the 1st percentile (- 0.29, favouring nalmefene) and positive at the 99th percentile (0.29, favouring naltrexone). A total of 7.1% (425/5961) of the meta-analyses with a negative effect size and 18.9% (616/3255) of those with a positive effect size were statistically significant (p < 0.05).

CONCLUSIONS

The choice of inclusion/exclusion criteria and analytical models for meta-analysis can result in entirely opposite results. VoE evaluations could be performed when overlapping meta-analyses on the same topic yield contradictory result.

TRIAL REGISTRATION

This study was registered on October 19, 2016, in the Open Science Framework (OSF, protocol available at https://osf.io/7bq4y/ ).

Perioperative Allogeneic Red Blood-Cell Transfusion Associated with Surgical Site Infection After Total Hip and Knee Arthroplasty

BACKGROUND

Perioperative allogeneic red blood-cell transfusion is a suspected risk factor for surgical site infection (SSI) after total joint arthroplasty (TJA), but the interrelationships among SSI risk, transfusion dose, preoperative anemia, and the presence of coagulopathies have not been well described.

METHODS

Data on SSI within 1 year after surgery as well as on transfusion with blood products within 30 days after surgery were obtained for 6,788 patients who had undergone primary or revision total hip or knee arthroplasty from 2000 to 2011 in a single hospital system. Multivariate logistic regression modeling was used to determine the independent association between allogeneic red blood-cell transfusion and SSI.

RESULTS

There was a dose-dependent association between allogeneic red blood-cell transfusion and SSI, with the infection rate increasing as the transfusion dose increased from 1 unit (odds ratio [OR] = 1.97; 95% confidence interval [CI] = 1.38, 2.79; p < 0.001), to 2 units (OR = 2.20; CI = 1.37, 3.44; p = 0.002), to 3 units (OR = 3.66; CI = 1.72, 7.16; p = 0.001), and to >3 units (OR = 7.40; CI = 4.91, 11.03; p < 0.001) after controlling for medical comorbidities, planned procedure, preoperative anemia, and preexisting coagulopathies. A preexisting bleeding disorder (OR = 2.09; CI = 1.57, 2.80; p < 0.001) and clotting disorder (OR = 1.37; CI = 1.14, 1.64; p = 0.001) and preoperative anemia (OR = 3.90; CI = 3.31, 4.61; p < 0.001) were all independent risk factors for transfusion after adjusting for the planned procedure.

CONCLUSIONS

We found a dose-dependent relationship between allogeneic red blood-cell transfusion and SSI risk after total hip or knee arthroplasty. Additionally, preoperative anemia or a known bleeding or clotting disorder were risk factors for the need for allogeneic red blood-cell transfusion. Our findings underscore the need for preoperative risk assessment, methods to limit surgical tissue injury, and optimized blood conservation strategies.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

The Mass Production of Redundant, Misleading, and Conflicted Systematic Reviews and Meta-analyses

POLICY POINTS

Currently, there is massive production of unnecessary, misleading, and conflicted systematic reviews and meta-analyses. Instead of promoting evidence-based medicine and health care, these instruments often serve mostly as easily produced publishable units or marketing tools. Suboptimal systematic reviews and meta-analyses can be harmful given the major prestige and influence these types of studies have acquired. The publication of systematic reviews and meta-analyses should be realigned to remove biases and vested interests and to integrate them better with the primary production of evidence.

CONTEXT

Currently, most systematic reviews and meta-analyses are done retrospectively with fragmented published information. This article aims to explore the growth of published systematic reviews and meta-analyses and to estimate how often they are redundant, misleading, or serving conflicted interests.

METHODS

Data included information from PubMed surveys and from empirical evaluations of meta-analyses.

FINDINGS

Publication of systematic reviews and meta-analyses has increased rapidly. In the period January 1, 1986, to December 4, 2015, PubMed tags 266,782 items as "systematic reviews" and 58,611 as "meta-analyses." Annual publications between 1991 and 2014 increased 2,728% for systematic reviews and 2,635% for meta-analyses versus only 153% for all PubMed-indexed items. Currently, probably more systematic reviews of trials than new randomized trials are published annually. Most topics addressed by meta-analyses of randomized trials have overlapping, redundant meta-analyses; same-topic meta-analyses may exceed 20 sometimes. Some fields produce massive numbers of meta-analyses; for example, 185 meta-analyses of antidepressants for depression were published between 2007 and 2014. These meta-analyses are often produced either by industry employees or by authors with industry ties and results are aligned with sponsor interests. China has rapidly become the most prolific producer of English-language, PubMed-indexed meta-analyses. The most massive presence of Chinese meta-analyses is on genetic associations (63% of global production in 2014), where almost all results are misleading since they combine fragmented information from mostly abandoned era of candidate genes. Furthermore, many contracting companies working on evidence synthesis receive industry contracts to produce meta-analyses, many of which probably remain unpublished. Many other meta-analyses have serious flaws. Of the remaining, most have weak or insufficient evidence to inform decision making. Few systematic reviews and meta-analyses are both non-misleading and useful.

CONCLUSIONS

The production of systematic reviews and meta-analyses has reached epidemic proportions. Possibly, the large majority of produced systematic reviews and meta-analyses are unnecessary, misleading, and/or conflicted.

Leucoreduction of blood components: an effective way to increase blood safety?

Over the past 30 years, it has been demonstrated that removal of white blood cells from blood components is effective in preventing some adverse reactions such as febrile non-haemolytic transfusion reactions, immunisation against human leucocyte antigens and human platelet antigens, and transmission of cytomegalovirus. In this review we discuss indications for leucoreduction and classify them into three categories: evidence-based indications for which the clinical efficacy is proven, indications based on the analysis of observational clinical studies with very consistent results and indications for which the clinical efficacy is partial or unproven.

Effects of the Sangvia blood collection system on patients undergoing elective hip surgery

We have conducted a randomized controlled study where 164 patients were randomized to receive autologous salvaged blood collected by Sangvia™ Blood Salvage System or allogeneic red cell concentrates if transfusion was indicated by clinical judgement. The study was powered to detect if transfusion of autologous blood reduced the occurrence of postoperative infections. We found no statistical significant difference in postoperative infection rate between the groups, but this may be due to the fact that postoperative infections were diagnosed in only five patients. Increased C-reactive protein concentrations slightly above level of significance indicate that autologous blood transfusions stimulate the patient's immune system. However, there was no indication of increased transfusion reaction rate, including febrile reactions, in the autologous group. Transfusion of autologous blood did not reduce the use of allogeneic red cell concentrates. The mean use of allogeneic red cell concentrates was 0.93 units (both groups combined), indicating that the transfusion policy may have been too liberal. There was a highly significant inverse correlation between pre-operative haemoglobin concentration and transfusion of allogeneic blood. In a patient population with a low frequency of postoperative infection, a larger study is needed to clarify if autologous salvaged blood protects against postoperative infections.

Prevention and control of neglected tropical diseases: overview of randomized trials, systematic reviews and meta-analyses

OBJECTIVE

To analyse evidence from randomized controlled trials (RCTs) on the prevention and control of neglected tropical diseases (NTDs) and to identify areas where evidence is lacking.

METHODS

The Cochrane Central Register of Controlled Trials and PubMed were searched for RCTs and the Cochrane Database of Systematic Reviews and PubMed were searched for meta-analyses and systematic reviews, both from inception to 31 December 2012.

FINDINGS

Overall, 258 RCTs were found on American trypanosomiasis, Buruli ulcer, dengue, geohelminth infection, leishmaniasis, leprosy, lymphatic filariasis, onchocerciasis, rabies, schistosomiasis or trachoma. No RCTs were found on cysticercosis, dracunculiasis, echinococcosis, foodborne trematodes, or human African trypanosomiasis. The most studied diseases were geohelminth infection (51 RCTs) and leishmaniasis (46 RCTs). Vaccines, chemoprophylaxis and interventions targeting insect vectors were evaluated in 113, 99 and 39 RCTs, respectively. Few addressed how best to deliver preventive chemotherapy, such as the choice of dosing interval (10) or target population (4), the population coverage needed to reduce transmission (2) or the method of drug distribution (1). Thirty-one publications containing 32 systematic reviews (16 with and 16 without meta-analyses) were found on American trypanosomiasis, dengue, geohelminths, leishmaniasis, leprosy, lymphatic filariasis, onchocerciasis, schistosomiasis or trachoma. Together, they included only 79 of the 258 published RCTs (30.6%). Of 36 interventions assessed, 8 were judged effective in more than one review.

CONCLUSION

Few RCTs on the prevention or control of the principal NTDs were found. Trials on how best to deliver preventive chemotherapy were particularly rare.

Does prolonged storage of red blood cells cause harm?

Red blood cells (RBCs) degrade progressively during the weeks of refrigerated storage. No universally accepted definition of 'fresh' or 'old' RBCs exists. While practices vary from country to country, preservative solutions permitting shelf life as long as 7 weeks have been licenced. Transfusion of stored RBCs, particularly those at the end of the approved shelf life, has been implicated in adverse clinical outcomes. The results of observational analyses, animal models and studies in volunteers have proved provocative, controversial and contradictory. A recently completed randomized controlled trial (RCT) in premature infants exemplifies the difficulties with moderately sized clinical studies. Several other RCTs are in progress. The effect of RBC storage may well vary according to the clinical setting. Resolution of the importance of the storage lesion may require large pragmatic clinical trials. In the meantime, institutions involved in blood collection and transfusion should explore strategies that assure blood availability, while limiting the use of the oldest RBCs currently approved by regulation.

Transfusion immunomodulation--the case for leukoreduced and (perhaps) washed transfusions

During the last three decades, a growing body of clinical, basic science and animal model data has demonstrated that blood transfusions have important effects on the immune system. These effects include: dysregulation of inflammation and innate immunity leading to susceptibility to microbial infection, down-regulation of cellular (T and NK cell) host defenses against tumors, and enhanced B cell function that leads to alloimmunization to blood group, histocompatibility and other transfused antigens. Furthermore, transfusions alter the balance between hemostasis and thrombosis through inflammation, nitric oxide scavenging, altered rheologic properties of the blood, immune complex formation and, no doubt, several mechanisms not yet elucidated. The net effects are rarely beneficial to patients, unless they are in imminent danger of death due to exsanguination or life threatening anemia. These findings have led to appeals for more conservative transfusion practice, buttressed by randomized trials showing that patients do not benefit from aggressive transfusion practices. At the risk of hyperbole, one might suggest that if the 18th and 19th centuries were characterized by physicians unwittingly harming patients through venesection and bleeding, the 20th century was characterized by physicians unwittingly harming patients through current transfusion practices. In addition to the movement to more parsimonious use of blood transfusions, an effort has been made to reduce the toxic effects of blood transfusions through modifications such as leukoreduction and saline washing. More recently, there is early evidence that reducing the storage period of red cells transfused might be a strategy for minimizing adverse outcomes such as infection, thrombosis, organ failure and mortality in critically ill patients particularly at risk for these hypothesized effects. The present review will focus on two approaches, leukoreduction and saline washing, as means to reduce adverse transfusion outcomes.

Reducing noninfectious risks of blood transfusion

As screening for transfusion-associated infections has improved, noninfectious complications of transfusion now cause the majority of morbidity and mortality associated with transfusion in the United States. For example, transfusion-related acute lung injury, transfusion-associated circulatory overload, and hemolytic transfusion-reactions are the first, second, and third leading causes of death from transfusion, respectively. These complications and others are reviewed, and several controversial methods for prevention of noninfectious complications of transfusion are discussed, including universal leukoreduction of erythrocyte units, use of male-only plasma, and restriction of erythrocyte storage age.

Blood storage duration and biochemical recurrence of cancer after radical prostatectomy

OBJECTIVE

To test the hypothesis that perioperative transfusion of allogeneic and autologous red blood cells (RBCs) stored for a prolonged period speeds biochemical recurrence of prostate cancer after prostatectomy.

PATIENTS AND METHODS

We evaluated biochemical prostate cancer recurrence in men who had undergone radical prostatectomy and perioperative blood transfusions from July 6, 1998, through December 27, 2007. Those who received allogeneic blood transfusions were assigned to nonoverlapping "younger," "middle," and "older" RBC storage duration groups. Those who received autologous RBC transfusions were analyzed using the maximum storage duration as the primary exposure. We evaluated the association between RBC storage duration and biochemical recurrence using multivariable Cox proportional hazards regression.

RESULTS

A total of 405 patients received allogeneic transfusions. At 5 years, the biochemical recurrence-free survival rate was 74%, 71%, and 76% for patients who received younger, middle, and older RBCs, respectively; our Cox model indicated no significant differences in biochemical recurrence rates between the groups (P=.82; Wald test). Among patients who received autologous transfusions (n=350), maximum RBC age was not significantly associated with biochemical cancer recurrence (P=.95). At 5 years, the biochemical recurrence-free survival rate was 85% and 81% for patients who received younger and older than 21-day-old RBCs, respectively.

CONCLUSION

In patients undergoing radical prostatectomy who require RBC transfusion, recurrence risk does not appear to be independently associated with blood storage duration.

Meta-analysis of clinical studies of the purported deleterious effects of "old" (versus "fresh") red blood cells: are we at equipoise?

BACKGROUND

A meta-analysis examined whether the available data support an adequate suspicion that transfusion of old red blood cells (RBCs) is associated with increased mortality, organ failure, infection, prolonged mechanical ventilation, and prolonged stay in the hospital or the intensive care unit. Such suspicion is required for intentionally exposing patients enrolled in randomized controlled trials (RCTs) to the known or probable--but rare--risks of old RBCs, to document (and prevent) purported common adverse effects of old RBCs.

STUDY DESIGN AND METHODS

Observational studies presenting adjusted results were eligible for analysis if the adequacy of the adjustment for confounding factors could be assessed. Three RCTs and 24 observational studies were retrieved. Medically and statistically homogeneous studies were integrated by fixed-effects methods. Otherwise homogeneous studies conducted in different clinical settings were integrated by random-effects methods.

RESULTS

Based on "as-treated" analysis, transfusion of old RBCs was associated with a significant reduction in mortality (summary odds ratio, 0.38; 95% confidence interval, 0.14-0.99; p < 0.05) across two small RCTs. Integration of adjusted findings on the same outcome, from observational studies conducted in the same setting, produced summary results that were either negative (in six analyses) or impossible to evaluate owing to uncontrolled confounding by the number of transfused RBCs (in two analyses).

CONCLUSION

The available data do not support an adequate suspicion that old RBCs may be associated with common adverse morbidity and/or mortality outcomes, so as to justify exposing experimental subjects to the other known or probable--but rare--risks of old RBCs.

Blood transfusion promotes cancer progression: a critical role for aged erythrocytes

BACKGROUND

In cancer patients, allogeneic blood transfusion is associated with poorer prognosis, but the independent effect of the transfusion is controversial. Moreover, mediating mechanisms underlying the alleged cancer-promoting effects of blood transfusion are unknown, including the involvement of donors' leukocytes, erythrocytes, and soluble factors.

METHOD

Two syngeneic tumor models were used in Fischer 344 rats, the MADB106 mammary adenocarcinoma and the CRNK-16 leukemia. Outcomes included host ability to clear circulating cancer cells, and host survival rates. The independent impact of blood transfusion was assessed, and potential deleterious characteristics of the transfusion were studied, including blood storage duration; the role of erythrocytes, leukocyte, and soluble factors; and the kinetics of the effects.

RESULTS

Blood transfusion was found to be an independent and significant risk factor for cancer progression in both models, causing up to a fourfold increase in lung tumor retention and doubling mortality rates. Blood storage time was the critical determinant of these deleterious effects, regardless of whether the transfused blood was allogeneic or autogenic. Surprisingly, aged erythrocytes (9 days and older), rather than leukocytes or soluble factors, mediated the effects, which occurred in both operated and nonoperated animals. The effects of erythrocytes transfusion in the MADB106 model emerged immediately and dissipated within 24 h.

CONCLUSIONS

In rats, transfusion of fresh blood is less harmful than transfusion of stored blood in the context of progressing malignancies. Further studies should address mediating mechanisms through which erythrocytes' storage duration can impact the rate of complications while treating malignant diseases and potentially other pathologies.

Strategies for blood management in orthopaedic and trauma surgery

Several aspects of the management of an orthopaedic surgical patient are not directly related to the surgical technique but are nevertheless essential for a successful outcome. Blood management is one of these. This paper considers the various strategies available for the management of blood loss in patients undergoing orthopaedic and trauma surgery.

Transfusion-related immunomodulation by platelets is dependent on their expression of MHC Class I molecules and is independent of white cells

BACKGROUND

Transfusion-related immunomodulation (TRIM) has been correlated with the presence of white cells (WBCs) in blood transfusions, but the role of components such as platelets (PLTs) in mediating TRIM has not been extensively examined. We designed a murine PLT transfusion model to study whether leukoreduced PLTs mediate TRIM effects.

STUDY DESIGN AND METHODS

CBA recipient mice were administered four weekly transfusions of either fresh (4 hr) or aged (24 and 72 hr) donor leukoreduced PLTs from allogeneic BALB/c mice and then transplanted with skin grafts from donor-matched mice. TRIM was measured by comparing the times to graft rejection and these were correlated with immunoglobulin G (IgG) antibody development measured by flow cytometry.

RESULTS

Compared with nontransfused control recipients, four transfusions of fresh, extremely leukoreduced (<0.05 WBCs/mL), allogeneic PLTs significantly (p < 0.002) reduced the recipient's ability to reject donor-matched skin grafts (survival >49 days compared with <14 days in nontransfused controls) despite the presence of high-titered serum IgG donor antibodies. In contrast, however, aged PLTs or fresh PLTs devoid of MHC Class I molecules were unable to affect skin graft survival nor stimulate antibody production. The PLT age-related inability to induce TRIM was shown to be due to loss of PLT-associated MHC Class I molecules; soluble supernatant MHC molecules that were transfused were unable to induce TRIM.

CONCLUSION

These results suggest that fresh PLTs can induce TRIM independently of WBCs due to their MHC antigen expression whereas aging results in loss of MHC and ability to mediate TRIM. The findings support the concept that either active MHC removal from fresh PLTs or passive removal by, for example, storage, may reduce any deleterious effects of TRIM in transfusion recipients.