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Effectiveness of antiepileptic prophylaxis used with supratentorial craniotomies: a meta-analysis |
Kuijlen J M, Teernstra O P, Kessels A G, Herpers M J, Beuls E A |
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Authors' objectives To examine the effectiveness of antiepileptic prophylaxis with supratentorial craniotomies.
Searching MEDLINE (Jan 1980-Nov 1995) and Excerpta Medica (1984-1995) were searched using the following search terms: preoperative, anti-convulsants, prophylactic, phenytoin, phenobarbital, carbamazepine, postoperative, epilepsy, and craniotomy. The bibliographies of retrieved articles were searched for additional references. Only English, German, French and Dutch articles were included in the review.
Study selection Study designs of evaluations included in the reviewControlled studies (randomised and non-randomised) were included if they used an index group. Reviews and editorials were excluded.
Specific interventions included in the reviewAntiepileptic drugs (AED) alone or in combination with other AEDs. Drugs reported in the review included phenytoin, carbamazepine and barbiturates (e.g. phenobarbitol), administered within 1 week prior to surgery until one day after surgery.
Participants included in the reviewIndividuals undergoing a supratentorial craniotomy for either therapeutic or diagnostic reasons. Patients with head trauma and preoperative epileptic seizures were excluded. Where populations contained these patient groups they were still included if the excluded patient data could easily be removed.
Outcomes assessed in the reviewOccurrence of post operative seizures. Adverse events were also recorded.
How were decisions on the relevance of primary studies made?The authors do not state how the papers were selected for the review, or how many of the reviewer performed the selection.
Assessment of study quality Study validity was judged on 22 criteria in the following categories: comparability of prognosis, intervention and external variables, effect measurement, proper and relevant outcome measures, and analysis (further details provided). Each of the 22 validity criteria were assigned a score ranging from 2 to 10, giving a maximum possible total of 145 points. The total score for each study was expressed as a percentage of the maximum possible score (145). The number and way in which points were assigned to the criteria was decided by the authors. An arbitrary score of 55% (80 out of 145 points) was selected as a cutoff point for good methodological quality and only studies meeting this cutoff were included in the meta-analysis.
Data extraction The authors do not state how the data were extracted for the review, or how many of the reviewers performed the data extraction. However, tables included in the review reported details about study design, population, quality, intervention and results.
Methods of synthesis How were the studies combined?Odds ratios (ORs) were calculated and pooled using the Mantel-Haenszel fixed-effect model. 95% confidence intervals (95% CI) and p values were calculated.
How were differences between studies investigated?The authors do not state how differences between the studies were investigated, although they did comment that two of the studies were more comparable.
Results of the review Four randomised controlled studies (RCTs) and two retrospective controlled studies were included (839 participants in total). Three of the studies (621 participants) all RCTs with quality scores greater than 55% were included in the meta-analysis.
Details of six of the studies were presented. Only one of the RCTs showed a statistically significant difference (data not reported) between the AED and control group, however this difference disappeared when trauma patients (excluded from the review) were removed from the analysis. Three of the six studies (all RCTs) were combined in a meta-analysis which showed that prophylactically used AEDs showed a tendency to prevent postoperative seizures, however the effect was not statistically significant (OR=0.74, 95% CI: 0.46, 1.19; P=0.1). The two most comparable of the three studies (one study only reported 3 day follow-up data) were also combined but again the overall effect failed to reach significance (OR=0.78, 95% CI: 0.48, 1.19; P=0.16).
Quality of studies:
The quality scores for the six studies varied from 15.9% to 87%. The three studies included in the meta-analysis had quality scores above 55% (range 72.4 -87%).
Authors' conclusions In conclusion, no empirical data supporting the attitude of using AEDs prophylactically with supratentorial intracranial surgery have been presented on a scientific basis.
CRD commentary This review was based on clearly defined inclusion criteria and used a reasonable search of the literature, although there were restrictions on the date and language of publication. No specific attempts were made to locate unpublished articles and so the possibility of publication bias exists. The authors fail to describe how studies were selected for inclusion and how data were extracted and their quality assessed. The number of individuals involved in these processes was also unclear.
The validity of the studies was assessed using an extensive range of criteria and details were presented for each of the six studies included in the review. However, the review focuses on a meta-analysis including only three of the six studies, all of which had a quality score of above 55%. The authors do not discuss the homogeneity of these studies in detail, however they do carry out a further meta-analysis including only two of the three studies which they report as been more comparable. In view of the data presented the authors conclusions would appear to be valid, however the possibility of publication bias and the exclusion of relevant data through language and date restrictions must be borne in mind.
Implications of the review for practice and research Practice: The authors stated that there was no empirical data to support the use of antiepileptic prophylaxis in supratentorial intracranial surgery.
Research: The authors stated that in the publications studied only sparse attention was given to adverse side-effects, discomfort to the patient and costs of the medication. In addition 'in future trials it might be useful to start AEDs seven days before elective neurosurgery in order to achieve adequate plasma-levels at the time of operation'. The authors also suggest that the size of study populations should be increased and the use of modern AEDs, which possibly have fewer side effects and shorter loading up periods, should be investigated.
Bibliographic details Kuijlen J M, Teernstra O P, Kessels A G, Herpers M J, Beuls E A. Effectiveness of antiepileptic prophylaxis used with supratentorial craniotomies: a meta-analysis. Seizure 1996; 5(4): 291-298 Indexing Status Subject indexing assigned by NLM MeSH Brain Diseases /surgery; Craniotomy; Epilepsy /prevention & Humans; Postoperative Complications /prevention & Premedication; Supratentorial Neoplasms /surgery; Treatment Outcome; control; control AccessionNumber 11997003316 Date bibliographic record published 30/11/2000 Date abstract record published 30/11/2000 Record Status This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn. |
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