Original Article
Screening for gestational diabetes: variation in guidelines

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Abstract

Objective: To compare published guidelines concerning screening for gestational diabetes. Study design: Systematic search and comparative analysis of published guidelines. Appraisal of guidelines quality. Simulation analysis. Results: Ten published guidelines proposed either universal screening (5), selective screening (3) or screening when clinically indicated (2). Variations of testing schedules and blood glucose thresholds were observed. The quality of the published guidelines was low, on average 22 (8–51) percentage points on the assessment scale. These differences would have led to large variations in the number of patients to be screened. Conclusions: Large variations between guidelines have been observed which would translate in large practice variations, if the guidelines were systematically applied. These variations are partially explained by the absence of definite evidence that universal or selective screening for gestational diabetes do more good than harm on infant and maternal health. The methodology of developing guidelines should be more evidence based, systematic and explicit.

Introduction

Practice guidelines have been defined as ‘systematically developed statements to assist physicians and patients about appropriate health care for specific clinical circumstances’ [1]. Numerous guidelines have been developed and published, but much less are regularly used, and the effectiveness of only a small number has been examined [2]. The common wisdom is that there is little evidence about the efficacy of guidelines to improve quality of care [3], [4]. However, a few studies indicate that clinical guideline programmes may improve appropriateness of care, for instance screening for breast and colon cancer [5]. A systematic review by Grimshaw and Russell has indicated that guidelines may favourably influence clinical practice [2], [6]. Variations among guidelines have been acknowledged [7] that may result in various practices of care [8], [9]. These variations in care delivery are however largely undetermined, but unless guidelines are produced using appropriate methods they may replace normal in-between clinician variation with consistently inappropriate practice.

Gestational diabetes mellitus is usually defined as any degree of glucose intolerance, with onset or first recognition during pregnancy [10]. It is the principal metabolic disorder of pregnancy associated with an increased incidence of hypertension, preeclampsia, urinary infections, higher Caesarean section rates and an elevated risk of future development of diabetes mellitus in the mother. The risk of developing adverse events such as macrosomia, neonatal hypoglycaemia, hypocalcaemia, hypomagnesiaemia or hyperbilirubinaemia is also higher for the newborn, and the incidence of obstetrical traumas and neonatal respiratory distress syndrome is increased [11], [12]. However, the effectiveness of systematic screening for gestational diabetes during pregnancy has not been demonstrated in appropriate studies. In the absence of evidence based on the results of clinical trials, or observational studies, guidelines based on consensus and expert opinion may be used as hierarchically inferior evidence.

Variation between these guidelines may exist and contribute to the variation of care delivered. The aim of the study was to collect published guidelines concerning screening for gestational diabetes in order to compare these recommendations and to examine the potential impact of variations of care when applying those guidelines to a population of pregnant women.

Section snippets

Sources of information

The Medline and Embase databases, as well as the Cochrane Library, were searched for published guidelines for gestational diabetes screening. We used a general extensive and sensitive search strategy designed to find published guidelines (including for instance the words guideline/s – as textword or publication type – recommendations, position statement, consensus conference, practice standards or parameters) combined with a search strategy for articles related with screening for gestational

Results

The electronic search resulted in 33 references for articles possibly containing a published guideline, to which 8 articles obtained by hand searching were added. Among these 41 articles, 10 were considered as published guidelines; 7 were produced by organisations or task forces and 3 by independent authors (Table 1). The documents (articles, book chapters) examined were between 2 and 111 pages of length; screening for gestational diabetes made only a part of the text for most of the reviewed

Discussion

Ten guidelines about screening for gestational diabetes, published after 1990 were considered, most often supported by national or international speciality societies or organisations. It is obvious that many more guidelines do exist at the national, regional or local level, published in non-indexed journals, in the grey literature, or unpublished. In a pragmatic approach, our goal was not to conduct an exhaustive search, but to retrieve and compare published guidelines easily available to an

Conclusion

A comparison of guidelines concerning screening for gestational diabetes has shown large differences between the recommendations made, mainly by international or national bodies, from ‘screening when clinically indicated’ to ‘universal screening’. These differences would translate into a large variation in the number of screening tests to order, and related cost, when applying these guidelines in practice.

These variations are explained, at least partly, by the absence of definite evidence that

Acknowledgments

We thank Willy Kamm, MD, and the collaborators of the Documentation Service of the Swiss Academy of Medical Sciences (DOKDI) for their contribution to the search of published guidelines.

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