Publication Bias in Psychology: A Diagnosis Based on the Correlation between Effect Size and Sample Size

Background

The p value obtained from a significance test provides no information about the magnitude or importance of the underlying phenomenon. Therefore, additional reporting of effect size is often recommended. Effect sizes are theoretically independent from sample size. Yet this may not hold true empirically: non-independence could indicate publication bias.

Methods

We investigate whether effect size is independent from sample size in psychological research. We randomly sampled 1,000 psychological articles from all areas of psychological research. We extracted p values, effect sizes, and sample sizes of all empirical papers, and calculated the correlation between effect size and sample size, and investigated the distribution of p values.

Results

We found a negative correlation of r = −.45 [95% CI: −.53; −.35] between effect size and sample size. In addition, we found an inordinately high number of p values just passing the boundary of significance. Additional data showed that neither implicit nor explicit power analysis could account for this pattern of findings.

Conclusion

The negative correlation between effect size and samples size, and the biased distribution of p values indicate pervasive publication bias in the entire field of psychology.     

Willingness to share research data is related to the strength of the evidence and the quality of reporting of statistical results

Background

The widespread reluctance to share published research data is often hypothesized to be due to the authors'' fear that reanalysis may expose errors in their work or may produce conclusions that contradict their own. However, these hypotheses have not previously been studied systematically.

Methods and Findings

We related the reluctance to share research data for reanalysis to 1148 statistically significant results reported in 49 papers published in two major psychology journals. We found the reluctance to share data to be associated with weaker evidence (against the null hypothesis of no effect) and a higher prevalence of apparent errors in the reporting of statistical results. The unwillingness to share data was particularly clear when reporting errors had a bearing on statistical significance.

Conclusions

Our findings on the basis of psychological papers suggest that statistical results are particularly hard to verify when reanalysis is more likely to lead to contrasting conclusions. This highlights the importance of establishing mandatory data archiving policies.     

Vaccination Management and Vaccination Errors: A Representative Online-Survey among Primary Care Physicians

Background

Effective immunizations require a thorough, multi-step process, yet few studies comprehensively addressed issues around vaccination management.

Objectives

To assess variations in vaccination management and vaccination errors in primary care.

Methods

A cross sectional, web-based questionnaire survey was performed among 1157 primary physicians from North Rhine-Westphalia, Germany: a representative 10% random sample of general practitioners (n = 946) and all teaching physicians from the University Duisburg-Essen (n = 211). Four quality aspects with three items each were included: patient-related quality (patient information, patient consent, strategies to increase immunization rates), vaccine-related quality (practice vaccine spectrum, vaccine pre-selection, vaccination documentation), personnel-related quality (recommendation of vaccinations, vaccine application, personnel qualification) and storage-related quality (storage device, temperature log, vaccine storage control). For each of the four quality aspects, “good quality” was reached if all three criteria per quality aspect were fulfilled. Good vaccination management was defined as fulfilling all twelve items. Additionally, physicians’ experiences with errors and nearby-errors in vaccination management were obtained.

Results

More than 20% of the physicians participated in the survey. Good vaccination management was reached by 19% of the practices. Patient-related quality was good in 69% of the practices, vaccine-related quality in 73%, personnel-related quality in 59% and storage-related quality in 41% of the practices. No predictors for error reporting and good vaccination management were identified.

Conclusions

We identified good results for vaccine- and patient-related quality but need to improve issues that revolve around vaccine storage.     

Predictors of Seizure Outcomes in Children with Tuberous Sclerosis Complex and Intractable Epilepsy Undergoing Resective Epilepsy Surgery: An Individual Participant Data Meta-Analysis

Objective

To perform a systematic review and individual participant data meta-analysis to identify preoperative factors associated with a good seizure outcome in children with Tuberous Sclerosis Complex undergoing resective epilepsy surgery.

Data Sources

Electronic databases (MEDLINE, EMBASE, CINAHL and Web of Science), archives of major epilepsy and neurosurgery meetings, and bibliographies of relevant articles, with no language or date restrictions.

Study Selection

We included case-control or cohort studies of consecutive participants undergoing resective epilepsy surgery that reported seizure outcomes. We performed title and abstract and full text screening independently and in duplicate. We resolved disagreements through discussion.

Data Extraction

One author performed data extraction which was verified by a second author using predefined data fields including study quality assessment using a risk of bias instrument we developed. We recorded all preoperative factors that may plausibly predict seizure outcomes.

Data Synthesis

To identify predictors of a good seizure outcome (i.e. Engel Class I or II) we used logistic regression adjusting for length of follow-up for each preoperative variable.

Results

Of 9863 citations, 20 articles reporting on 181 participants were eligible. Good seizure outcomes were observed in 126 (69%) participants (Engel Class I: 102(56%); Engel class II: 24(13%)). In univariable analyses, absence of generalized seizure semiology (OR = 3.1, 95%CI = 1.2–8.2, p = 0.022), no or mild developmental delay (OR = 7.3, 95%CI = 2.1–24.7, p = 0.001), unifocal ictal scalp electroencephalographic (EEG) abnormality (OR = 3.2, 95%CI = 1.4–7.6, p = 0.008) and EEG/Magnetic resonance imaging concordance (OR = 4.9, 95%CI = 1.8–13.5, p = 0.002) were associated with a good postoperative seizure outcome.

Conclusions

Small retrospective cohort studies are inherently prone to bias, some of which are overcome using individual participant data. The best available evidence suggests four preoperative factors predictive of good seizure outcomes following resective epilepsy surgery. Large long-term prospective multicenter observational studies are required to further evaluate the risk factors identified in this review.     

Blinded by PRISMA: Are Systematic Reviewers Focusing on PRISMA and Ignoring Other Guidelines?

Background

PRISMA guidelines have been developed to improve the reporting of systematic reviews (SRs). Other reporting guidelines and techniques to assess methodological quality of SRs have been developed. We aimed to assess the frequency of the use of reporting and other guidelines in SRs to assess whether PRISMA is being used inappropriately as a substitute for other relevant guidelines.

Methods

Web of Knowledge was searched to identify articles citing the PRISMA guidelines over a 12-month period. The use of reporting guidelines (including PRISMA and MOOSE) and tools for assessing methodological quality (including QUADAS) was assessed. Factors associated with appropriate use of guidelines including review type, field of publication and involvement of a methodologist were investigated.

Results

Over the 12-month period, 701 SRs were identified. MOOSE guidelines were cited in just 17% of epidemiologic reviews; QUADAS or QUADAS-2 was referred to in just 40% of diagnostic SRs. In the multivariable analysis, medical field of publication and methodologist involvement (OR = 1.97, 95% CI: 1.37, 2.83) were significant predictors of appropriate use of guidelines. Inclusion of a meta-analysis resulted in 73% higher odds of appropriate usage of systematic review guidelines (OR = 1.73, 95% CI: 1.22, 2.35).

Conclusions

Usage of SR reporting guidelines and tools for assessment of methodological quality other than PRISMA may be under-utilized with negative implications both for the reporting and methodological quality of systematic reviews.     

A Scoping Review of Strategies for the Prevention of Hip Fracture in Elderly Nursing Home Residents

Background

Elderly nursing home residents are at increased risk of hip fracture; however, the efficacy of fracture prevention strategies in this population is unclear.

Objective

We performed a scoping review of randomized controlled trials of interventions tested in the long-term care (LTC) setting, examining hip fracture outcomes.

Methods

We searched for citations in 6 respective electronic searches, supplemented by hand searches. Two reviewers independently reviewed all citations and full-text papers; consensus was achieved on final inclusion. Data was abstracted in duplicate.

Findings

We reviewed 22,349 abstracts or citations and 949 full-text papers. Data from 20 trials were included: 7 - vitamin D (n = 12,875 participants), 2 - sunlight exposure (n = 522), 1 - alendronate (n = 327), 1 - fluoride (n = 460), 4 – exercise or multimodal interventions (n = 8,165), and 5 - hip protectors (n = 2,594). Vitamin D, particularly vitamin D₃ ≥800 IU orally daily, reduced hip fracture risk. Hip protectors reduced hip fractures in included studies, although a recent large study not meeting inclusion criteria was negative. Fluoride and sunlight exposure did not significantly reduce hip fractures. Falls were reduced in three studies of exercise or multimodal interventions, with one study suggesting reduced hip fractures in a secondary analysis. A staff education and risk assessment strategy did not significantly reduce falls or hip fractures. In a study underpowered for fracture outcomes, alendronate did not significantly reduce hip fractures in LTC.

Conclusions

The intervention with the strongest evidence for reduction of hip fractures in LTC is Vitamin D supplementation; more research on other interventions is needed.     

Suicidality,Bullying and Other Conduct and Mental Health Correlates of Traumatic Brain Injury in Adolescents

Objective

Our knowledge on the adverse correlates of traumatic brain injuries (TBI), including non-hospitalized cases, among adolescents is limited to case studies. We report lifetime TBI and adverse mental health and conduct behaviours associated with TBI among adolescents from a population-based sample in Ontario.

Method and Findings

Data were derived from 4,685 surveys administered to adolescents in grades 7 through 12 as part of the 2011 population-based cross-sectional Ontario Student Drug Use and Health Survey (OSDUHS). Lifetime TBI was defined as head injury that resulted in being unconscious for at least 5 minutes or being retained in the hospital for at least one night, and was reported by 19.5% (95%CI:17.3,21.9) of students. When holding constant sex, grade, and complex sample design, students with TBI had significantly greater odds of reporting elevated psychological distress (AOR = 1.52), attempting suicide (AOR = 3.39), seeking counselling through a crisis help-line (AOR = 2.10), and being prescribed medication for anxiety, depression, or both (AOR = 2.45). Moreover, students with TBI had higher odds of being victimized through bullying at school (AOR = 1.70), being cyber-bullied (AOR = 2.05), and being threatened with a weapon at school (AOR = 2.90), compared with students who did not report TBI. Students with TBI also had higher odds of victimizing others and engaging in numerous violent as well as nonviolent conduct behaviours.

Conclusions

Significant associations between TBI and adverse internalizing and externalizing behaviours were found in this large population-based study of adolescents. Those who reported lifetime TBI were at a high risk for experiencing mental and physical health harms in the past year than peers who never had a head injury. Primary physicians should be vigilant and screen for potential mental heath and behavioural harms in adolescent patients with TBI. Efforts to prevent TBI during adolescence and intervene at an early stage may reduce injuries and comorbid problems in this age group.     

Potential Reporting Bias in fMRI Studies of the Brain

Background

Functional magnetic resonance imaging (fMRI) studies have reported multiple activation foci associated with a variety of conditions, stimuli or tasks. However, most of these studies used fewer than 40 participants.

Methodology

After extracting data (number of subjects, condition studied, number of foci identified and threshold) from 94 brain fMRI meta-analyses (k = 1,788 unique datasets) published through December of 2011, we analyzed the correlation between individual study sample sizes and number of significant foci reported. We also performed an analysis where we evaluated each meta-analysis to test whether there was a correlation between the sample size of the meta-analysis and the number of foci that it had identified. Correlation coefficients were then combined across all meta-analyses to obtain a summary correlation coefficient with a fixed effects model and we combine correlation coefficients, using a Fisher’s z transformation.

Principal Findings

There was no correlation between sample size and the number of foci reported in single studies (r = 0.0050) but there was a strong correlation between sample size and number of foci in meta-analyses (r = 0.62, p<0.001). Only studies with sample sizes <45 identified larger (>40) numbers of foci and claimed as many discovered foci as studies with sample sizes ≥45, whereas meta-analyses yielded a limited number of foci relative to the yield that would be anticipated from smaller single studies.

Conclusions

These results are consistent with possible reporting biases affecting small fMRI studies and suggest the need to promote standardized large-scale evidence in this field. It may also be that small studies may be analyzed and reported in ways that may generate a larger number of claimed foci or that small fMRI studies with inconclusive, null, or not very promising results may not be published at all.     

Association of GSTM1 Null Allele with Prostate Cancer Risk: Evidence from 36 Case-Control Studies

Background

Glutathione S-transferase M1 (GSTM1) is thought to be involved in detoxifying several carcinogens and may play a vital role in tumorigenesis. Numerous studies have evaluated the association between GSTM1 null/present polymorphism and risk of prostate cancer (PCa). However, the results remain inconsistent. To derive a more precise estimation, we performed a meta-analysis.

Methodology/Principal Findings

A comprehensive search was conducted to identify all eligible case-control studies. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association. The overall association was significant (OR = 1.28, 95% CI: 1.11–1.48, P = 0.001). Moreover, subgroup analyses showed GSTM1 null genotype significantly associated with PCa risk among Asians (OR = 1.35, 95% CI: 1.03–1.78, P = 0.03) but not among Caucasians (OR = 1.12, 95% CI: 0.96–1.31, P = 0.16). In addition, we did not find that smoking modified the genotype effect on the risk of PCa.

Conclusions/Significance

The present meta-analysis suggested that GSTM1 null allele was a low-penetrant risk factor for PCa among Asians.     

GSTT1 Null Genotype Contributes to Lung Cancer Risk in Asian Populations: A Meta-Analysis of 23 Studies

Background

Genetic variation in glutathione S-transferases (GSTs) may contribute to lung cancer risk. Many studies have investigated the correlation between the Glutathione S-transferase T1 (GSTT1) null genotype and lung cancer risk in Asian population but yielded inconclusive results.

Methodology/Principal Findings

We performed a meta-analysis of 23 studies including 4065 cases and 5390 controls. We assessed the strength of the association of GSTT1 with lung cancer risk and performed sub-group analyses by source of controls, smoking status, histological types, and sample size. A statistically significant correlation between GSTT1 null genotype and lung cancer in Asian population was observed (OR = 1.28, 95% CI = 1.10, 1.49; P_{heterogeneity}<0.001 and I² = 62.0%). Sub-group analysis revealed there was a statistically increased lung cancer risk in ever-smokers who carried the GSTT1 null genotype (OR = 1.94, 95% CI = 1.27, 2.96; P heterogeneity = 0.02 and I² = 58.1%). It was also indicated that GSTT1 null genotype could increase lung cancer risk among population-based studies (OR = 1.25, 95% CI = 1.04, 1.50; P_{heterogeneity} = 0.003 and I² = 56.8%). The positive association was also found in studies of sample size (≤500 participants) (OR = 1.34, 95% CI = 1.10, 1.62; P_{heterogeneity}<0.001 and I² = 65.4%).

Conclusions

These meta-analysis results suggest that GSTT1 null genotype is associated with a significantly increased risk of lung cancer in Asian population.     

Effects of Pre-Experience of Social Exclusion on Hypothalamus-Pituitary-Adrenal Axis and Catecholaminergic Responsiveness to Public Speaking Stress

Backround

Being socially excluded is associated with a variety of psychological changes and with an increased risk of disease. Today, the immediate physiological consequences of being socially excluded are not well understood. In two recent studies employing a standardized exclusion paradigm (Cyberball) we found social exclusion in this virtual game did not alter cortisol secretion directly. However, exclusion pre-experience suppresses the normal cortisol response to public speaking stress in women. The present study aims to replicate our previous finding and further elucidate it by analyzing for the first time whether this alteration of cortisol-responsiveness is associated to ACTH and whether the catecholaminergic system is affected as well.

Methods

Women were randomly assigned to Cyberball-induced exclusion (SE, n = 22) or inclusion (SI, n = 21), respectively. Immediately afterwards they were subjected to public speaking stress. Salivary cortisol, plasma ACTH, catecholamines and estradiol were assessed as were psychological distress and mood.

Results

Cyberball exclusion led to a highly significant immediate increase in negative affect in excluded women. After public speaking negative affect in included women increased as well and groups no longer differed. We replicate our previous finding of cortisol non-responsiveness to public speaking stress after exclusion pre-experience and find this effect to be significantly correlated with ACTH alterations. No such effects are observed for catecholamines.

Conclusions

We replicated our previous study result of a supressed cortisol stress response after a short exclusion experience via Cyberball, thereby underlining the profound effects of social exclusion on a subsequent cortisol stress response. This further demonstrates that these alterations are associated with ACTH. Lack of effects on catecholamines is discussed in view of the tend-and-befriend hypothesis but also from a methodological perspective.     

Accuracy of the Interpretation of Chest Radiographs for the Diagnosis of Paediatric Pneumonia

Introduction

World Health Organization (WHO) radiological classification remains an important entry criterion in epidemiological studies of pneumonia in children. We report inter-observer variability in the interpretation of 169 chest radiographs in children suspected of having pneumonia.

Methods

An 18-month prospective aetiological study of pneumonia was undertaken in Northern England. Chest radiographs were performed on eligible children aged ≤16 years with clinical features of pneumonia. The initial radiology report was compared with a subsequent assessment by a consultant cardiothoracic radiologist. Chest radiographic changes were categorised according to the WHO classification.

Results

There was significant disagreement (22%) between the first and second reports (kappa = 0.70, P<0.001), notably in those aged <5 years (26%, kappa = 0.66, P<0.001). The most frequent sources of disagreement were the reporting of patchy and perihilar changes.

Conclusion

This substantial inter-observer variability highlights the need for experts from different countries to create a consensus to review the radiological definition of pneumonia in children.     

Overestimation of Vitamin A Supplementation Coverage from District Tally Sheets Demonstrates Importance of Population-Based Surveys for Program Improvement: Lessons from Tanzania

Background

Tanzania has conducted a national twice-yearly Vitamin A supplementation (VAS) campaign since 2001. Administrative coverage rates based on tally sheets consistently report >90% coverage; however the accuracy of these rates are uncertain due to potential errors in tally sheets and their aggregation, incomplete or inaccurate reporting from distribution sites, and underestimating the target population.

Objectives

The post event coverage survey in Mainland Tanzania sought to validate tally-sheet based national coverage estimates of VAS and deworming for the June 2010 mass distribution round, and to characterize children missed by the national campaign.

Methods

WHO/EPI randomized cross-sectional cluster sampling methodology was adapted for this study, using 30 clusters by 40 individuals (n = 1200), in addition to key informant interviews. Households with children 6–59 months of age were included in the study (12–59 months for deworming analysis). Chi-squared tests and logistic regression analysis were used to test differences between children reached and not reached by VAS. Data was collected within six weeks of the June 2010 round.

Results

A total of 1203 children, 58 health workers, 30 village leaders and 45 community health workers were sampled. Preschool VAS coverage was 65% (95% CI: 62.7–68.1), approximately 30% lower than tally-sheet coverage estimates. Factors associated with not receiving VAS were urban residence [OR = 3.31; p = 0.01], caretakers who did not hear about the campaign [OR = 48.7; p<0.001], and Muslim households [OR<3.25; p<0.01]. There were no significant differences in VAS coverage by child sex or age, or maternal age or education.

Conclusion

Coverage estimation for vitamin A supplementation programs is one of most powerful indicators of program success. National VAS coverage based on a tally-sheet system overestimated VAS coverage by ∼30%. There is a need for representative population-based coverage surveys to complement and validate tally-sheet estimates.     

A systematic evaluation of the impact of STRICTA and CONSORT recommendations on quality of reporting for acupuncture trials

Background

We investigated whether there had been an improvement in quality of reporting for randomised controlled trials of acupuncture since the publication of the STRICTA and CONSORT statements. We conducted a before-and-after study, comparing ratings for quality of reporting following the publication of both STRICTA and CONSORT recommendations.

Methodology and Principal Findings

Ninety peer reviewed journal articles reporting the results of acupuncture trials were selected at random from a wider sample frame of 266 papers. Papers published in three distinct time periods (1994–1995, 1999–2000 and 2004–2005) were compared. Assessment criteria were developed directly from CONSORT and STRICTA checklists. Papers were independently assessed for quality of reporting by two assessors, one of whom was blind to information which could have introduced systematic bias (e.g. date of publication). We detected a statistically significant increase in the reporting of CONSORT items for papers published in each time period measured. We did not, however, find a difference between the number of STRICTA items reported in journal articles published before and 3 to 4 years following the introduction of STRICTA recommendations.

Conclusions and Significance

The results of this study suggest that general standards of reporting for acupuncture trials have significantly improved since the introduction of the CONSORT statement in 1996, but that quality in reporting details specific to acupuncture interventions has yet to change following the more recent introduction of STRICTA recommendations. Wider targeting and revision of the guidelines is recommended.     

Tooth Erosion and Eating Disorders: A Systematic Review and Meta-Analysis

Background

Eating disorders are associated with the highest rates of morbidity and mortality of any mental disorders among adolescents. The failure to recognize their early signs can compromise a patient''s recovery and long-term prognosis. Tooth erosion has been reported as an oral manifestation that might help in the early detection of eating disorders.

Objectives

The aim of this systematic review and meta-analysis was to search for scientific evidence regarding the following clinical question: Do eating disorders increase the risk of tooth erosion?

Methods

An electronic search addressing eating disorders and tooth erosion was conducted in eight databases. Two independent reviewers selected studies, abstracted information and assessed its quality. Data were abstracted for meta-analysis comparing tooth erosion in control patients (without eating disorders) vs. patients with eating disorders; and patients with eating disorder risk behavior vs. patients without such risk behavior. Combined odds ratios (ORs) and a 95% confidence interval (CI) were obtained.

Results

Twenty-three papers were included in the qualitative synthesis and assessed by a modified version of the Newcastle-Ottawa Scale. Fourteen papers were included in the meta-analysis. Patients with eating disorders had more risk of tooth erosion (OR = 12.4, 95%CI = 4.1–37.5). Patients with eating disorders who self-induced vomiting had more risk of tooth erosion than those patients who did not self-induce vomiting (OR = 19.6, 95%CI = 5.6–68.8). Patients with risk behavior of eating disorder had more risk of tooth erosion than patients without such risk behavior (Summary OR = 11.6, 95%CI = 3.2–41.7).

Conclusion

The scientific evidence suggests a causal relationship between tooth erosion and eating disorders and purging practices. Nevertheless, there is a lack of scientific evidence to fulfill the basic criteria of causation between the risk behavior for eating disorders and tooth erosion.     

The Associations between Two Vital GSTs Genetic Polymorphisms and Lung Cancer Risk in the Chinese Population: Evidence from 71 Studies

Background

The genetic polymorphisms of glutathione S-transferase (GSTs) have been suspected to be related to the development of lung cancer while the current results are conflicting, especially in the Chinese population.

Methods

Data on genetic polymorphisms of glutathione S-transferase Mu 1 (GSTM1) from 68 studies, glutathione S-transferase theta 1 (GSTT1) from 17 studies and GSTM1-GSTT1 from 8 studies in the Chinese population were reanalyzed on their association with lung cancer risk. Odds ratios (OR) were pooled using forest plots. 9 subgroups were all or partly performed in the subgroup analyses. The Galbraith plot was used to identify the heterogeneous records. Potential publication biases were detected by Begg''s and Egger''s tests.

Results

71 eligible studies were identified after screening of 1608 articles. The increased association between two vital GSTs genetic polymorphisms and lung cancer risk was detected by random-effects model based on a comparable heterogeneity. Subgroup analysis showed a significant relationship between squamous carcinoma (SC), adenocarcinoma (AC) or small cell lung carcinoma (SCLC) and GSTM1 null genotype, as well as SC or AC and GSTT1 null genotype. Additionally, smokers with GSTM1 null genotype had a higher lung cancer risk than non-smokers. Our cumulative meta-analysis demonstrated a stable and reliable result of the relationship between GSTM1 null genotype and lung cancer risk. After the possible heterogeneous articles were omitted, the adjusted risk of GSTs and lung cancer susceptibility increased (fixed-effects model: OR_GSTM1 = 1.23, 95% CI: 1.19 to 1.27, P<0.001; OR_GSTT1 = 1.18, 95% CI: 1.10 to 1.26, P<0.001; OR_GSTM1-GSTT1 = 1.33, 95% CI: 1.10 to 1.61, P = 0.004).

Conclusions

An increased risk of lung cancer with GSTM1 and GSTT1 null genotype, especially with dual null genotype, was found in the Chinese population. In addition, special histopathological classification of lung cancers and a wide range of gene-environment and gene-gene interaction analysis should be taken into consideration in future studies.     

Gram Negative Wound Infection in Hospitalised Adult Burn Patients-Systematic Review and Metanalysis-

Background

Gram negative infection is a major determinant of morbidity and survival. Traditional teaching suggests that burn wound infections in different centres are caused by differing sets of causative organisms. This study established whether Gram-negative burn wound isolates associated to clinical wound infection differ between burn centres.

Methods

Studies investigating adult hospitalised patients (2000–2010) were critically appraised and qualified to a levels of evidence hierarchy. The contribution of bacterial pathogen type, and burn centre to the variance in standardised incidence of Gram-negative burn wound infection was analysed using two-way analysis of variance.

Primary Findings

Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumanni, Enterobacter spp., Proteus spp. and Escherichia coli emerged as the commonest Gram-negative burn wound pathogens. Individual pathogens’ incidence did not differ significantly between burn centres (F (4, 20) = 1.1, p = 0.3797; r2 = 9.84).

Interpretation

Gram-negative infections predominate in burn surgery. This study is the first to establish that burn wound infections do not differ significantly between burn centres. It is the first study to report the pathogens responsible for the majority of Gram-negative infections in these patients. Whilst burn wound infection is not exclusive to these bacteria, it is hoped that reporting the presence of this group of common Gram-negative “target organisms” facilitate clinical practice and target research towards a defined clinical demand.