Prevention of hyperemesis gravidarum is better than treatment. To the Editors: 1 read with interest the article of van Stu- ijvenberg et al. (van Stuijvenberg ME ...
LETTERS TO THE EDITORS Prevention of hyperemesis gravidarum is better than treatment To the Editors: 1 read with interest the article of van Stuijvenberg et al. (van Stuijvenberg ME, Schabort I, Labadarios D, NelJT. The nutritional status and treatment of patients with hyperemesis gravidarum. AM J OBSTET GYN~COL1995;172:1585-91) about the effective treatment of hyperemesis gravidarum with an intravenous saline solution containing a multivitamin preparationl Our intervention study indicated that periconceptional supplementation with a multivitamin (Elevit prenatal) can reduce the first occurrence of neural tube defects? This primary preventive method has a great medical and ethical significance as a better alternative than prenatal diagnosis (maternal serum (x-fetoprotein or ultrasonographic scanning) and selective abortion of fetuses affected with neural tube defects. An unexpected finding of the Hungarian randomized double blind controlled trial of periconceptional multivitamin supplementation was a significant reduction in the occurrence of hyperemesis gravidarum (i.e., severe nausea and vomiting that resulted in dehydration and weight loss of >5% of body weight usually requiring hospitalization but at least medical treatment~). This figure was 3.0% in the supplemented and 6.6% in unsupplemented groups. In addition, there was a significant decrease in the rate of moderate nausea and vomiting. Thus the expected extensive use ofpericonceptional folic-containing multivitamin supplementation will contribute the reduction of these pregnancy complic a t i o n s - a n d prevention is better than cure. Andrew E. Czeizel Department of Human Genetics and Teratology, National Institute of Ityg~ene-WHO Collaborating Centre for the Community Control of Hev'editary Diseases, 1966 OK[ Gydli ut 2-6, Budapest, Hungary
REFERENCES 1. Czeizel AE, Dud~ I. Prevention of the first occurrence of neural tube defects by periconceptional vitamin supplementation. N EnglJ Med 1992;21:1832-5. 2. Czeizel AE, Dudfis I, Fritz G, T6cs6i A, Hanck A, Kunovits G. The effect of periconceptional multivitamin-mineral supplementation on vertigo, nausea and vomiting in the first trimester of pregnancy. Arch Gyuecol Obstet 1992;251:181-5. 6/8/72221
Reply To the Editors: We thank Czeizel for his comment on our study. We are aware of the findings of their excellent study, namely, the reduction in the occurrence of hyperemesis gravidarum and a reduction in moderate nausea and vomiting with periconceptional multivitamin supplementation. Their findings strengthen our speculation that the improvement in the vitamin status of our patients may have contributed to the disappearance of their symptoms. We do agree with Czeizel that prevention is always better than cure. However, if prevention has not been
American Journal of Obstetrics and Gynecology
possible, the only other option is p r o m p t and appropriate treatment. Martha E. van Stuijvenberg, MSc, and Demetre Labadarios, MB, ChB, PhD Department of Human Nutrition, University of Stellenbosch and TygerbergHospital and the Medical Research Council, P.OI Box 19063, Tygerberg, South Africa 6/8/72222
Office-based blood glucose meters in screening for gestational diabetes To the Editors: Carr et al. (Carr SR, Slocum J, Tefft L, Haydon B, Carpenter M. Precision of office-based blood glucose meters in screening for gestational diabetes. AMJ OBSTET G'~ECOL 1995;173:1267-72) studied the precision of three models of blood glucose meters to determine whether they would be adequate for screening for gestational diabetes. Some aspects of the design of the study and the interpretation of the results are questionable. To evaluate precision, the authors collected paired venous and capillary blood samples. Each specimen was then analyzed 10 times by a single operator. This protocol is inadequate for the evaluation of total imprecision. Any analytic instrument repeats itself better in the short term (few minutes as in the authors' study) than in the long term (days or months). The estimate of imprecision obtained by the authors must thus be increased by an amount corresponding to the contribution of interassay imprecision/ Furthermore, the study protocol cannot take into account the variability induced by the blood sampling itself. An adequate sampling technique is critical to obtain a representative capillary sample that is not contaminated by extracellular fluid. Adequate training is required, and acceptable results by one operator does not guarantee a similar performance by others. A more informative way to analyze the results is to examine the concordance of the results between the paired specimens (capillary whole blood by glucose meter vs venous plasma by laboratory instrument). A high dispersion of the results around the regression line can reflect problems with blood glucose meter precision, blood sampling, or interindividual variability in capillary-venous difference of blood glucose levels. In fact, the blood glucose meter the authors considered as best performing showed the least concordance with the laboratory (relatively low correlation coefficient of 0.86). Several results exceed the 95% confidence intervals shown in the authors' Fig. 1 (estimated as +2 SDs of the repeated measurements), showing clearly the inadequacy of the estimates. As a further proof of the superiority of the more "precise" instrument, Carr et al. evaluated the proportion of tested individuals that would require confirmatory testing. The authors calculated a cutoff value for each meter that would theoretically have a 95% probability of maintaining the sensitivity as high as with laboratory mea-
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