Observational Studies in Neurosurgery: Structure, Functioning, and Uses.

INTRODUCTION: Although randomized interventional studies are the gold standard of clinical study designs, they are not always feasible or necessary. In such cases, observational studies can bring insights into critical questions while minimizing harm and cost. There are numerous observational study designs, each with strengths and demerits. Unfortunately, it is not uncommon for observational study designs to be poorly designed or reported. In this article, the authors discuss similarities and differences between observational study designs, their application, and tenets of good use and proper reporting focusing on neurosurgery. METHODS: The authors illustrated neurosurgical case scenarios to describe case reports, case series, and cohort, cross-sectional, and case-control studies. The study design definitions and applications are taken from seminal research methodology readings and updated observational study reporting guidelines. RESULTS: The authors have given a succinct account of the structure, functioning, and uses of common observational study designs in Neurosurgery. Specifically, they discussed the concepts of study direction, temporal sequence, advantages, and disadvantages. Also, they highlighted the differences between case reports and case series; case series and descriptive cohort studies; and cohort and case-control studies. Also, they discussed their impacts on internal validity, external validity, and relevance. CONCLUSION: This paper disambiguates widely held misconceptions on the different observational study designs. In addition, it uses case-based scenarios to facilitate comprehension and relevance to the academic neurosurgery audience.

Misclassification of Case-Control Studies in Neurosurgery and Proposed Solutions.

OBJECTIVE: Case-control studies (CCS) and cohort studies (CS) are common research designs in neurosurgery. But the term case-control study is frequently misused in the neurosurgical literature, with many articles reported as CCS, even although their methodology does not respect the basic components of a CCS. We sought to estimate the extent of these discrepancies in neurosurgical literature, explore factors contributing to mislabeling, and shed some light on study design reporting. METHODS: We identified 31 top-ranking pure neurosurgical journals and searched them for articles reported as CCS, either in the title or in the abstract. The articles were read to determine if they really were CCS according to STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) guidelines. Article assessment was conducted in duplicate (agreement [κ statistics] = 99.82%). RESULTS: Two hundred and twenty-four articles met our inclusion criteria, 133 of which (59.38%) correctly labeled the case-control design, whereas 91 (40.62%) misclassified this study design. Cohort studies (CS) were the most common design mislabeled as case-control studies in 76 articles (33.93%), 57 of which (25.45%) were retrospective CS. The mislabeling of CCS impairs the appropriate indexing, classification, and sorting of evidence. Mislabeling CS for CCS leads to a downgrading of evidence as CS represent the highest level of evidence for observational studies. Odds ratios instead of relative risk are reported for these studies, resulting in a distortion of the measurement of the effect size, compounded when these are summarized in systematic reviews and pooled in meta-analyses. CONCLUSIONS: Many studies reported as CCS are not true CCS. Reporting guidelines should include items that ensure that studies are labeled correctly. STROBE guidelines should be implemented in assessment of observational studies. Researchers in neurosurgery need better training in research methods and terminology. We also recommend accrued vigilance from reviewers and editors.

Case series and descriptive cohort studies in neurosurgery: the confusion and solution.

BACKGROUND: Case series (CS) are well-known designs in contemporary use in neurosurgery but are sometimes used in contexts that are incompatible with their true meaning as defined by epidemiologists. This inconsistent, inappropriate and incorrect use, and mislabeling impairs the appropriate indexing and sorting of evidence. METHOD: Using PubMed, we systematically identified published articles that had "case series" in the "title" in 15 top-ranked neurosurgical journals from January 2008 to December 2012. The abstracts and/or full articles were scanned to identify those with descriptions of the principal method as being "case series" and then classified as "true case series" or "non-case series" by two independent investigators with 100 % inter-rater agreement. RESULTS: Sixty-four articles had the label "case series" in their "titles." Based on the definition of "case series" and our appraisal of the articles using Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines, 18 articles (28.13 %) were true case series, while 46 (71.87 %) were mislabeled. Thirty-five articles (54.69 %) mistook retrospective (descriptive) cohorts for CS. CS are descriptive with an outcome-based sampling, while "descriptive cohorts" have an exposure-based sampling of patients, followed over time to assess outcome(s). A comparison group is not a defining feature of a cohort study and distinguishes descriptive from analytic cohorts. CONCLUSION: A distinction between a case report, case series, and descriptive cohorts is absolutely necessary to enable the appropriate indexing, sorting, and application of evidence. Researchers need better training in methods and terminology, and editors and reviewers should scrutinize more carefully manuscripts claiming to be "case series" studies.

Action Africa!

In Sub-Saharan Africa because of the prevailing economy, the equipping of neurological and neurosurgical services, as well the training of younger colleagues remains a recurrent problem. Therefore, all currently available resources ought to be mobilized and put together to obtain very rapid, short-term results. This is not a dream. The forces of the improvement of development lie in our hands.

Les méningiomes intrâcraniens en milieu ivoirien. Étude d/'une serie chirurgicale

Objectif. Presenter les particularites epidemiologiques; cliniques et therapeutiques des meningiomes intracraniens en milieu sous medicalise; a travers l'experience ivoirienne. Materiel et Methode. Il s'agit d'une etude retrospective d'une serie de 96 cas de meningiomes intracraniens traites au service de neurochirurgie d'Abidjan de 1991 a 200 . Le diagnostic pre chirurgical ou avant la biopsie fait par le scanner etait confirme par l'examen neuro-pathologique. Le suivi postoperatoire a ete clinique et quelquefois un examen tomodensitometrique a ete realise.Resultats. Les meningiomes ont represente 33;43des tumeurs intracraniennes. La moyenne d'age au moment du diagnostic etait de 43 ans avec des extremes de 07 a 72 ans. Le sexe feminin a predomine avec un sex-ratio de 3/2. Le tableau clinique etait domine par les cephalees. Le delai precedant le diagnostic etait d'environ 22 mois. Les meningiomes de la convexite etaient les plus frequents (47;36). Dans la majorite des cas le diametre tumoral se situait entre 3 cm et 6 cm. L'exerese chirurgicale a constitue l'essentiel du traitement avec une mortalite operatoire de 12;63. Les meningiomes usuels de type meningothelial ont predomine (55;78). Conclusion .Les meningiomes ont represente les plus frequents des tumeurs intracraniennes en milieu ivoirien. Des etudes ulterieures africaines epidemiologiques permettront de le verifier. Les meningiomes ont ete diagnostiques chez des patients relativement plus jeunes (43 ans) que ceux des pays occidentaux (58 ans). Depuis l'avenement du scanner des services de neurochirurgie et de neuropathologie; les meningiomes ne posent moins de probleme de diagnostic. Les unites de recherche sur l'oncogenese et sur les therapeutiques complementaires a la chirurgie sont encore inexistantes