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Background Due to clinical and methodological diversity, clinical studies included in meta-analyses often differ in ways that lead to differences in treatment effects across studies. Meta-regression analysis is generally recommended to explore associations between study-level characteristics and treatment effect, however, three key pitfalls of meta-regression may lead to invalid conclusions. Our aims were to determine the frequency of these three pitfalls of meta-regression analyses, examine characteristics associated with the occurrence of these pitfalls, and explore changes between 2002 and 2012. Methods A meta-epidemiological study of studies including aggregate data meta-regression analysis in the years 2002 and 2012. We assessed the prevalence of meta-regression analyses with at least 1 of 3 pitfalls: ecological fallacy, overfitting, and inappropriate methods to regress treatment effects against the risk of the analysed outcome. We used logistic regression to investigate study characteristics associated with pitfalls and examined differences between 2002 and 2012. Results Our search yielded 580 studies with meta-analyses, of which 81 included meta-regression analyses with aggregated data. 57 meta-regression analyses were found to contain at least one pitfall (70%): 53 were susceptible to ecological fallacy (65%), 14 had a risk of overfitting (17%), and 5 inappropriately regressed treatment effects against the risk of the analysed outcome (6%). We found no difference in the prevalence of meta-regression analyses with methodological pitfalls between 2002 and 2012, nor any study-level characteristic that was clearly associated with the occurrence of any of the pitfalls. Conclusion The majority of meta-regression analyses based on aggregate data contain methodological pitfalls that may result in misleading findings.

A fashionable concept, resilience is now a must in both academic research and management. However, its polysemy nourishes many debates on its uses, heuristics and operational relevance. The purpose of this article is not to bring these debates to a close. Starting from a cross-disciplinary state of the art, we point out the incompatibilities between certain meanings and uses of the term. These inconsistencies raise theoretical issues, leading some researchers to reject the term for that matter, especially those outside the cindynics field. The analysis of the concept also brings out some methodological pitfalls. These are evident when attempting to translate theory into operational terms. Resilience is indeed seen as a promising response to recurrent difficulties in risk management. Nevertheless, it solves them only partially and produces new ones. Lastly, its implementation involves ethical and political risks. The injunction to resilience that seems to prevail internationally is in fact implying a number of moral and ideological assumptions which are not always clearly stated and remain serious issues. Concept à la mode, la résilience s’impose désormais tant dans les recherches académiques que dans les pratiques gestionnaires. La polysémie du terme nourrit de nombreux débats sur son utilisation et sa pertinence heuristique et opérationnelle. L’objet de cet article n’est pas de trancher dans ces débats mais de montrer, à partir d’un état de l’art pluridisciplinaire, qu’il y a incompatibilités entre certaines acceptions du terme. Ces incompatibilités soulèvent des questions théoriques, qui conduisent d’ailleurs certains chercheurs, en particulier en dehors de la cindynique, à rejeter l’utilisation du terme. L’analyse du concept fait également émerger des écueils méthodologiques. Ces derniers sont manifestes lorsque l’on cherche à traduire la théorie en termes opérationnels. La résilience apparaît en effet comme une réponse prometteuse aux difficultés récurrentes rencontrées dans la gestion du risque. Or, elle ne les résout que partiellement et en suscite de nouvelles. Enfin, sa mise en œuvre comporte des risques éthiques et politiques. L’injonction à la résilience qui semble s’imposer jusqu’à l’échelon international, implique en effet un certain nombre de présupposés moraux et idéologiques, qui ne sont pas toujours clairement énoncés mais qui posent problème.

To the Editor: In their recent paper, Hemkens et al. conclude that their ‘results based on observational data support safety concerns surrounding the mitogenic properties of glargine in diabetic patients’, because given ‘the overall relationship between insulin dose and cancer, and the lower dose with glargine, the cancer incidence with glargine was higher than expected compared with human insulin’ [1]. Indeed, if it is obvious that the mean daily insulin dose was lower in insulin glargine compared with human insulin users (25.9 ± 22.5 vs 43.8 ± 37.4 IU), and if, using models to adjust for a few potential confounders, a higher incidence of malignant neoplasms was found with insulin glargine at similar insulin dose, in our opinion, this does not support any safety concern surrounding the mitogenic properties of insulin glargine in diabetic patients. I will demonstrate this in two steps. First, over-adjustment for insulin doses should be considered. Unfortunately, Hemkens et al. did not report data concerning glycaemic control. If identical glycaemic control had been obtained in the treatment groups, using lower doses in insulin glargine users, adjustment for insulin dose would not have been appropriate. However, two randomised clinical trials in which insulin glargine and NPH insulin were up-titrated to reach identical glycaemic targets have shown no difference between insulin glargine and human insulin in terms of the dose needed: 68 ± 39 vs 70 ± 42 IU (NS) in the Lantus plus Metformin (LANMET) Study [2], and 32.1 ± 17.6 vs 32.8 ± 18.9 IU (NS) in the Lantus Evaluation in Asian Diabetics (LEAD) Study [3], respectively. Furthermore, the Treat-to-Target Trial reported that higher doses of insulin glargine were needed: 47.2 ± 24.9 vs 41.8 ± 25.6 IU (p